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Veterinary neurology—Past, present and future
Veterinary
NeurologyR. Fankhauser Inslitute
of Veterinary
Past, and Neurology.
Present
and
Future
M. Vandevelde Unisersity of Bernr.
The Journal of Comparative Pathology has always dealt with Pathology in the broad sense of the word, as the science of pathological processes in their clinical, aetiological and anatomo-pathological aspects. Therefore, it seems legitimate to give an account not only of the development of comparative neuropathology, but of neurology in veterinary medicine as such. Depending on ones viewpoint, it may be said that neurology is as old as veterinary medicine itself, or that it is a relatively new field that has-at least in many countries-still to fight for its recognition. In fact, if one peruses the veterinary literature from the foundation of the first schools in the second half of the 18th century, one realises that many diseases involving the nervous system were known, e.g. rabies, nervous distemper in dogs, epilepsy, meningitis and coenurosis. In fact, the last one was studied as early as 168 1 by J. J. Wepfer (1620 to 1695), the founder of a “medical school” in SchaIIhausen, Switzerland. A great number of neurological signs was known at that time such as convulsions, paralysis, ataxia, disturbances of behaviour and others, but their associa.tion with disturbed brain function was vague, because understanding of brain function itself was speculative and ill-founded. It was during the 19th century, especially its second half, that knowledge of pathological anatomy, histopathology and microbiology advanced to the point of understanding the nature of disease and, in this respect, there was no difIerence between the nervous and other organ systems. However, in veterinary medicine, progress on the clinical side was slow and this was especially so for nervous diseases with their generally poor prognosis. In that respect. human neurology (and psychiatry) differed fundamentally and an everincreasing amount of research work was done, wherein veterinary medicine and pathology hardly participated. In fact, many discoveries, particularly of an anatomical nature, were made by physicians on the animal nervous system. but used more for a better understanding of the human brain and cord than Ibr the benefit of the veterinary art. The same is true of the rapid development of technical methods during the last century; alcohol fixation of tissues (Rcil. 1809), demonstration of neurons and their processes (Purkinje, 1837), serial sections (Stilling, 1842), carmine staining of neurons (Gerlach, 1858), paraffin 1va.y embedding (E. Klebs, 1869), celloidin (Schiefferdecker, 1882), osmir acid stain of degenerating myelin (h/larchi, 1885), aniline stains for neurons f Nissl, 188.j). formaldehyde fixation (Blum, 1893) and many, many more. Such rnethods were widely used for recognizing the internal structure of the brain and cord and, in fact, to a large extent were developed in animals by.
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experimental methods, but veterinar). medicine only rarely took ad\,antagt. OI this rapidly growing body of knowledge. It must bc said. however. that 1i11. obvious reasons farm animals were less used than dogs and cats and laborator! species. It is not surprising that we still do not know, to give ,just one exampIt*. the exact extent of cortico-spinal fibres in horses or cattlc. After about 1850, in most of the European veterinary schools (and thcrc. were only European ones at that time!), pathological anatomy was introduced as a discipline and a teaching subject, but progress was very slow. l’he CNS especially, already of difficult access at necropsy, was f:dr from having priorit) for the veterinary pathologist. This was partly due to the fact that most of them were also responsible for bacteriology and both the attractiveness and the success of this new science detracted from the study of pathological morphology. This was perhaps less so in Germany and some other countries where the influence of Rudolf Virchow was dominant. Today, it seems rather invidious to stress the tensions between the two disciplines, because both stand in their own right and both are only facets of the same coin; pathology in its broad sense. Histology, indispensable for solving most of the morphological problems, came only slowly into USC in veterinary medicine. So, as late as 1881, Prof. Friedberger of Munich could state that, in canine distemper, brain oedcma was the only lesion responsible for the disturbed cerebral functions and that “a (macroscopically. of coursc:i. It real encephalitis has never been evidenced” was, therefore, a pioneer act when Gowers (the later famous British neurologist Sir William Gowers) and Sankey published their study of the histological examination of two cases of distemper myelitis under the title The Pathological Anatomy or Canine C’horea, in the year 1877 (Saunders, 1973). The rediscoverer of Crower’s and Sankey’s paper, Dr Leon Z. Saunders, rightly stresses the importance of this fact, when saying: “How typical of him then, to have examined histologically the CNS of dogs with distemper in 1877, at a time when neuropathology was still in its infancy, scientific polemics were popular and others were still debating the cause of the symptoms rather than doing something to seek them out.” As far as neuropathology is concerned, a factor of the utmost importance in human medicine was almost absent in the veterinary field, namely the stimulus coming from the clinical side. In fact, most of the progress made in the neurosciences until well into the present century was due to clinicians, dealing with internal medicine, surgery, neurology, psychiatry, or all together. This is admirably shown in the volume edited by Haymaker ( 1953) The Founder., I?/ .Neurolo~. The almost total lack of interest on the part of the vcterinar) clinicians was the main obstacle to an adequate development of neurology in animal medicine. It is only due to a handful of individuals (too fewj that the discipline survived here and there. It began to flourish only during the last 30 years and especially in the U.S.A., where clinical neurology, predominantly of small animals, rapidly evolved. One of those individuals, and probably the most outstanding one, was Hermann Dexler. He was born in Teesdorf near Vienna in 1866, studied veterinary medicine in the capital and graduated in 1888. After a few years as
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a district veterinarian which he spent in Leoben, he returned to the Vienrla veterinary college as an assistant of Prof. Schindelka. At the same time. motivated by his interest in neurology (interest which could not be satisfied at the veterinary school), he worked at the Hirnforschungs-institut (Institute for Brain Research) of Prof. Obersteiner, where he was competently trained in the neurosciences of that time. When trying to apply his knowledge to clinical cases in animals, mainly horses, he soon realized that most of the basic, even anatomical work had still to be done, and he invested part of his efforts into such investigations. His anatomical and physiological publications, approximately 15 out of a total of over 100 papers, reflect the additional training which he acquired in photography and drawing at the Vienna School of Graphics. After a series of original observations which he published on nervous diseases in dogs (he was the first to recognize disc protrusion and compression myelitis), he published a book on the nervous diseases of the horse which were essentially based on his personal observations (Dexler, 1899). It is still, in many respects, superior to a number of “modern” treatises. In 1898, Dexler became chairman of the Department of Veterinary Science of the German University of Prague (at that time in the AustroHungarian Empirej and starting from literally nothing, he created a laboratory for comparative neurology. From there, he published, most often alone, a great number of papers on neurology and ethological problems (at that time and not inaccurately, called Tierpsychologie: animal psychology). The reviews of books and papers which he wrote for the Jahresberichte uber die Leistungen auf dem Gebiete der VeterinarMedicin, and for the Ergebnisse der allgemeinen Pathologie are also countless. For decades, he was the leading, and only, authority for these matters in the veterinary field. Moreover, his contributions to Handbooks of human neurology (he had command of German, French and English) were probably the first important examples of the participation, on an equal footing, of a veterinary neurologist in human medicine. Dexler had a thorough knowledge of the pertinent literature, including Russian and never hesitated to acknowledge priority to others nor to refuse it when it was erroneously ascribed to him. His approach to animal neurology was critical, scientific and unbiased and he was fighting against ill-founded homologies which were a la mode at the turn of the century. Examples are his controversies with E. Joest on “canine chorea” (an erroneous term still used in the English language) or with Marchand (a French neurologist) on “progressive paralysis”. But it was at least a dispute on a higher plane, because both Joest and Marchand, too, examined their material histologically. In 193 1, Dexler was Dean of the Medical Faculty of the German University of Prague. He died that same year of heart failure. His eulogy was written by E. Frauchiger ( 195 1). Its inclusion in Haymakers’ Founders of .veurologv would have been well deserved (Innes and Saunders, 1962). Professor of’ so-called Eugenio Aruch (1853 to 1937j, up to his retirement, General Pathology and Head of the veterinary medical clinic of the Univrersity of Perugia (Italy), has to he considered as a forerunner of our discipline, although he contrasts sharply, and not to his advantage, with Dexler. In the obituaries, it is said that he was strongly interested in neurology throughout his
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life, as a clinician, but it seems that his efforts at verifying his clinical diagnoses, anatomo-pathologically and histologically, were modest. In 1900 and, as a second enlarged edition in 1914, he published his Malattie de1 Sistema flerooso (Aruch, 1914). His intention, to be applauded, was probably to stimulate the interest of his fellow veterinarians in neurological problems. In this sense, ht was in complete accordance with Dexler, who wrote in 1899 contesting the belief that neurology was of little importance for veterinary medicine; “intentional avoidance or neglect will not improve our knowledge about such diseases. Properly, with regard to the practical side of the problem, it is important-as it is for any group of diseases--to study and to uncover the causes and alterations, in order to make an eventual treatment meaningful”. But Aruch’s approach was totally different. The book is a mixture of’ personal, mainly clinical observations, reports from veterinary periodicals (of‘ very differing quality) and data taken from textbooks of human neurology, without making any distinctions. If Aruch shared Dexler’s interest in psychopathological problems in animals, he unfortunately did not share his critical attitude and offered even a chapter “La delinquenza negli animali”! It is probably not surprising that Aruch’s (1914) book, although its second edition is mentioned in the Jahresberichte (Ellenberger and Schlitz, 19 16), was never reviewed by Dexler. We suppose that he just didn’t deign to look at it. At the turn of the century, the then modern methods of histology had made their entrance in veterinary pathology and an increasing number of nervous conditions in animals was studied and described. It would be impossible to trace tbis development here. Canine distemper encephalitis, as a model of a demyelinating lesion, is one of the prominent examples. Its history has been described first by Saunders (1973) and later on by Fankhauser (1982). It must be stressed that diseases like distemper were studied more frequently and often more competently than others for their comparative interest. Quite often, human neurologists were engaged in such studies. The interest in the pathology of inflammatory lesions of the CNS was growing, together with virology and with the interest in some degenerative conditions, concomitantly with the development of the understanding of nutritional and toxicological problems. Exponents of the study of nervous diseases from the comparative standpoint were El. Weston Hurst (1900 to 1980) and 0. Seifried ( 1886 to 1947). ;\ particularly prolific tiesearcher in comparative neuropathology was J. R. M. Innrs (1903 to 1974) co-author of the leading and encyclopaedic volume I 1962) together with L. Z. Saunders. A Scotsman (born 1903) and a graduate of the Royal (Dick) Veterinar) College in Edinburgh, Innes got his training in pathology in several British institutions, but especially (for 3 years) as a Rockefeller fellow in Munich under Max Borst and in Freiburg under Ludwig Aschoff. Throughout his lifetime, he remained deeply impressed by his German teachers. His criticism of‘ the situation of British veterinary pathology in the 1930s and 1940s and the directness of his comments probably prevented an academic career in the United Kingdom. In 1948 he left for the United States where he found the discipline flourishing. His contributions to many fields of animal pathology ( nutritional pathology, laboratory animal pathology, comparative oncolog), 1
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were as numerous as outstanding, but his particular interests were in comparative neuropathology, where his name is linked with the authoritative descriptions of many diseases, for example, swayback, cerebellar hypoplasias, setariasis of the CNS. After having worked in a number of positions, Innes died in ( 1962), a standard 1974 in Bethesda, Maryland. His Comparative Neuropathology work of reference, unfortunately not followed by later editions, will be his lasting monument. Leon Z. Saunders, co-editor and co-author of the Comparative Neuropathology. born 1919, is still fully active. After completing the volume with Innrs. he stopped working in neuropathology and shifted to ophthalmic pathology and later to history, to which his Atlas of Ophthalmic Pathology of Animals ( 19751 with L. F. Rubin and his Veterinary Pathology in Russia 11980) testify. In the mid-1930s, E. Frauchiger in Berne (Switzerland), a human clinical neurologist, began working with people at the Ambulatory Clinic (a clinic for farm animals) of the Veterinary School. In 1941, he published the book “‘l‘hc Nervous Diseasesof Cattle”, which was an attempt at collecting and cataloguing the then knowledge about diseases of the nervous system in this species, oriented on the system used in human neurology as a guideline, but without undue homologies. The greater part of the clinical, anatomo-pathological and
Fig. ‘2.
Ernst Frauchiger,
1903 ttr 1975.
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histological data was furnished by his co-author W. Hofmann and staff. This marked the beginning of a slow, but steady growth of a laboratory, today called the Institute of Animal Neurology of the University of Berne, where a close connection between the clinical and pathological aspects of nervous diseases has always been considered essential. E. Frauchiger, born 1903 in Langenthal (Berne), studied medicine in Geneva, Paris, Rome and Vienna and graduated in Zurich. After working out his doctoral thesis on a surgical problem (under De Quervain, Berne), he was an assistant of 0. Veraguth in Zurich, his teacher in neurology. He was also deeply influenced by C. von Monakow (neurologist and neuropathologist) and E. Bleuler (psychiatrist). In Zurich, he met his college-friend W. Hofmann, at that time a young professor of buiatrics (diseases of cattle) who stimulated him to engage in scientific work. With a study on “Dummkoller” (idiopathic brain swelling) in horses, he obtained his veterinary Ph.D. in Zurich and, after having started a private practice in the Berne area (after Hofmann had moved back to Berne as head of the Ambulatory Clinic), he went on working parttime at the Veterinary Faculty of the University. Over the years, a small institute was built up. It must be said that Frauchiger, although in high esteem in the Swiss Neurological Society and internationally (in 1968 he was elected President of the Research Committee of the World Federation of Neurology) never held a position at the medical Faculty of Berne. He died on 15 April 1975 of intestinal cancer, in a regional hospital where he had been transferred, at his request, during his vacations in Ragaz (Fankhauser, 1975). ‘l’owards the end of World War II a book appeared which is another milestone in the development of comparative neurology, namely H. J. Scherer’s Vergleichende Neuropathologie ( 1944), based largely on materials collected by Dr Ludo van Bogaert at the Bunge Institute in Antwerp, Belgium. Although mainly devoted to the neuropathology of apes and monkeys, there is an important part on other zoo and domestic animals. Written by an expert neuropathologist, the morphological side is excellent, whereas clinical data art sometimes missing and sometimes misleading. So the author, lacking broad experience with everyday material, came to the conclusion that distemper plays a minor role in the canine “encephalitis complex” and that “acute multiple sclerosis” is its more important entity. clearly an untenable assumptiotl. The details of this story are discussed by Fankhauser (1982). Scherer’s book, which has excellent qualities, especially by the standards of‘ pre-existing veterinary literature, appeared at the wrong moment at a had place ( 1944 in Leipzig). Today, it is nearly forgotten by most people. It seems that the author died in an air raid on one of the cities of Saxony. In the Berne Institute, work slowly progressed. In 194.5, one of us 1R.I’. i ,joined Frauchiger and for many years commuted between periods at home I to keep the laboratory going) and periods of training in a considerable number of Swiss and foreign laboratories and clinics. In 1957, a volume on comparativt neuropathology (which included many clinical considerations) was published, the younger brother of Innes’ and Saunders’ book and, in 1968, the chapter on the “Nervous System” in E. Joest’s Handbook oj‘Animai Pathotogv came out as a monograph by Fankhauser and Luginbuhl. In the course of time, a large
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collection of neuro-histopathological material had been accumulated, partly by international cooperation, and serves as a basis for the 2 books. In 1957, on the occasion of the International Congress of Neurological Sciences held in Brussels, the World Federation of Neurology (WFN) was founded and during the following years, several so-called Problem Commissions including one on Comparative Neuropathology were created. The latter held its first meeting in November 1959 in our Institute in Berne. Later, on the occasions of International congresses of Neuropathology or Veterinary Congresses, special sessions on comparative neuropathology were organized ( 1962 Munich, 1967 Paris, 1974 Budapest and Brno). But, in contrast to the conditions in human neurology, where most working groups were merely outgrowths of pre-existing, large, well-organized (and wealthy) subspecialities (neuropathology, neurosurgery, epilepsy, EEG, to name just a few), it soon became obvious that there was no economic basis to hold such a group together. It was also clear that some of the founding members were themselves involved only part time, or temporarily, or not at all, in neurological work. As long as our Institute was officially recognized as a Collaborating Centre of WHO, it was possible, in order to satisfy the Statutes of the WFN, to pay a global annual fee for the group. We must confess that it was rather a shift of money from one organization to another and that all we could see (if we saw anything at all) was that it disappeared for bureaucratic activities. A few years ago, it was therefore decided, at our suggestion, to dissolve the group. In the meantime, however, veterinary neurology and neuropathology have gained ground and information is accumulating rapidly. In a leading journal of veterinary pathology, approximately 200 papers of predominantly neurological content appeared in the first 20 volumes (American College of Veterinary Pathologists, 1979, 1985). It is more and more common not to neglect the nervous system in anatomo-pathological descriptions and, slowly but steadily, clinical neurology expands. Organized or not organized, the activities of our Institute were always oriented towards international contacts, a concept as self-evident today as air and water. During the last 25 years, a great number of veterinary pathologists have visited the laboratory for short or long periods, the members of our group have lectured in many places in Europe and abroad and contacts, depending on the actual working problems, are maintained or established with many colleagues at home and in other countries. It has also been our preoccupation to maintain contacts with colleagues in states under socalled socialist rule, because we feel that they need it above all others. In a modest way, dictated by the modest size of our Institute, we still hope to function as a Collaborating Centre, collaborating not so much with a large international organization (which from time to time changes its policy) but with all those who share with us the belief that veterinary neurology has a future. Although earlier attempts were made to evaluate neurologically sick animals on a clinical basis, veterinary neurology as a recognized clinical speciality emerged during the past 3 decades mainly, but not only, through efforts in the U.S.A. As we have seen, during the 1950s and 1960s a large body of neuropathological knowledge had accumulated, enabling the classification of
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neurological diseases in animals according to pathological criteria and providing an important reference frame for the clinician. Not surprisingly, some of the first modern efforts to create a clinical diagnostic system came from the neuropathological side (McGrath, 1956) and were based on clinico-pathological observations and correlations, applying basic functional neuro-anatomical principles, which were of course much earlier available than pathological information, since much of the neurophysiological data were derived from animal experimentation including work done with dogs and cats. Methods for systematic neurological examination of the dog and cat were established and the techniques of collection and examination of the cerebrospinal fluid in animals were described by Hoerlein (1978) and by Innes and Saunders (1962). The differential diagnosis, as indicated, was predominantly based on neuropathological knowledge. Early on, spinal problems were recognized as an important and clinically separable group of diseases and the further development of clinical veterinary neurology was strongly associated with surgery and radiology. It was especially the work of Dr B. F. Hoerlein (1922 to 1987) who not only developed radiological methods to accurately diagnose spinal diseases in the dog, especially intervertebral disc problems, but also showed that these problems could be successfully treated by surgical techniques. He continued and expanded the work which has been initiated by the Swedish School after World War II. Before the era of Hoerlein, the prognosis of neurological diseases in animals was generally considered to be poor and therefore veterinary neurology was often regarded as unpractical and basically redundant. Hoerlein’s work, which was dedicated not only to the diagnosis, but also to the treatment of neurological diseases in animals, contributed significantly to a
Fig. 3.
Btmjamin
Franklin
Hoerlrin.
1922 to 1987
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change in mentality and facilitated thy rapid spread vf’\ c.tcrirtar\, ncurolog! itt many vctcrinary schools in thr U.S.A. Symptomatic ol‘this rapid cf~~vclop~tt~~t~~ was the appearance of‘ several tcxthooks on anirnal ncurol0g:)’ Jkom cfil~i~rc~ttl veterinary institutions during Iht 1970s and 1980s 1Ik 1,altttnta. IWi: Hoerlein, 1978). More and more’ emphasis was king placed ott ncurof’ll~sic,lc,gical aspects, localizing the lesion and application of‘ sophisticated ancillary aids such as ncuroradiology and clcctrodiagnostic tcchrtiqucs. :Uthough, tilt practical reasons, small animals wcrc of’ primary intt.rc.st fi)r the ~ctc*riri;tr~ neurologist, considcrablc progrcass has also been madr in largr animal rtcurology, especially fbr the horse. Clinical neurology has hccotnc a rccogttizcd subspeciality of the American Colle,~e of’\‘eterinar), Internal Mcdicinr with it> own training prc>,qrammes and board certification. Man> \,‘rterinary Ch~llc~rs in North America have now such trained and certified specialists on thrir c.littic. staff and many other schools are in thtb process of building such programmcs. In Europe, specialization in clinical medicine has been rather slow IO come (Palmer, 1976). However, clinical neurology is practkd in several \rctc‘rittar\ schools and an European Society fi)r Vctcrinary Neurology has IXTI~ fi~utdcd recently. Thr rvc’r increasing interest and rxprrtisc in clinic,al tteurology has ot‘c,oursc a strong impact on the f‘urther development of animal rteuropatholog-) ; a lat-gee number of new and interesting diseases has been discovered in recent years as can be sceti fi-om the impressive tiurnhers of literature rcfkrencrs compiled in the recent clinical neurology textbooks. ‘I‘hcse publications have appeared itt the veterinary literature but also to a large cxtettl in other hiomedical~juurttals, illustrating the t.act that the cornparativr mcdicinc idea is nlorr alive than ~~~cr in vctcrinary nc~urology. Many cx)nditions have ~XTI~ prol)osed and tfc\~c~lo~~~i as animal models fi)r human discascbs of‘thc ncr\.oLts system. Prime cxatnpl~~s of thr positive interaction hetweeri clinical work and ncuropatholog) art’ t ht. diseases of the peripheral nervous system and muscles. ‘l’hc* discovery of t hcsc. diseases and the study of‘ their patholog), became onI.> epossit,lc throqlt th(. application of‘ clcctrodiagnostic techniques enabling cl~ntc-al dctrction of’strc~lt lesions. Such techniques are now widely used in veterinar) ncurolo~)~ ’ IIurtcatt and Grifli t hs, 1984). As already indicated, comparative neuropathology is bring practiscd in several clinics and laboratories throughout the world and the concept of’ using animal tnodcls for thr study of human disease is still rcccnt. Of course, b). comparison with the huge amount of’ work going on in srnall laborator!, animals (also veterinary pathologists arc involved in such work). in which many different types of interesting neurological diseases have been identified and which are for practical and genetic reasons often much easier 10 work with, neuropathological research in domestic animals is rather modest. However, high quality research is going on with many diflcrent neurological diseases in domestic animals. Whereas earlier work was focusscd on the descriptive evaluation of spontaneously occurring lesions and comparing these morphological features with those seen in similar human conditions, recent and current neuropathological work is also concerned with dissecting disease mechanisms. We can distinguish two types of veterinary neuropathology currently being
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practised; one type is clinically oriented and is important for the clinicalpathological correlations and further development and refinement of clinical neurology. Clinical neuropathology is also still instrumental in describing and classifying new disease entities and the associated discovery of potential useful animal models; this will remain so for many years to come and it is to be hoped that it will reach comparable standards to human medicine. All too often, one can see that in veterinary pathological situations, the examination of the CNS (and PNS) is still practised on a rather primitive basis. International cooperation would be of great benefit in this respect. The second type of neuropathology is concerned with pathogenesis research starting from a certain type of lesion and by applying various techniques, to explain why and how it develops. Sequential morphological studies including light microscopy and electron microscopy are often the bases of such projects and provide useful information. The advent of easy and reproducible immuno-cytochemical methods which can often be successfully applied to fixed and embedded tissues and allow specific demonstration of a wide varirt! of molecules, has extended the scope of morphological techniques considerably. Naturally, these methods also have their limits and neurologists often extend their work beyond morphology, by applying techniques derived from other disciplines such as biochemistry and immunology. In addition to the work in vivo, cell biological methods such as brain cell culture systems are used to study certain problems. Molecular techniques such as gene-cloning will also become important in the near future. It can be expected that the application 01‘ new technologies will steadily increase in the study of the pathogenrsis of neurological diseases in animals and that molecular biological techniques will eventually dominate the field.
References
American College of Veterinary Pathologists (1979). C umulative Index to LPterinarr Pathology, Vols 1-15 (1964-1978). American College of Veterinary Pathology i 1985). <:umulative Index to lbterinarl Pathology, Vols 16-20 ( 1978- 1983). Aruch, E. (1914). Malattie de1 Sistema Nervosa, 2nd Edit. Vallardi, Milano. De I,ahunta, A. (1983). Veterinary Neuroanatory and Clinical ,?l’euroioLv, 2nd Edit. 12:. B. Saunders Co., Philadelphia. Dexler, H. ( 1899). Die Nervenkrankheiten des Pferde.c. Deuticke, Witm and Leipzig. Duncan, I. D. and Griffiths, I. R. (1984). Peripheral neuropathies ofdomestic animals. In Peripheral Neuropathy, Dyck, Thomas, Lambert and Burge, Eds., Vol. I. Saunders Co., Philadelphia. Ellellberger, W. and Schlitz, W. (1916). 3 ah res b erichte iiber die Leistungen auj‘dem Cvbirtr der Ileteriniir-Medicin 34, 85. Fankhauser, R. (1975). Nachruf Prof. Dr med. Ernst Frauchiger, Bern. Acta .hPuropathologica Berlin, 32, 87-89. Fankhauser, R. (1982). Hundestaupe-Geschichte einer Krankheit. Schweiser Archirl,flir ‘Tierheilkunde, 124, 245-256. Fankhauser, R. and Luginbiihl, H. (1968). Pathologische Anatomie des zentralen und Peripheren .~~rvensystems der Haustiere. P. Parey, Berlin and Hamburg. Frauchiger, E. (1951). Den AManen eines Grossen unserer Wissenschaft. Prof. Hrrmann Dexler ( 1866-l 93 1) . Schweizer Archizl ftir ‘Tierheilkunde, 93, 359-364. Frau<-higer, E. and Hofmann, W. f 1941). Die .!~ervenkrankheitrn des Rindes. Huber, Bern.
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Frauchiger, E. and Fankhauser, R. ( 1957). l’ergleichende Neuropathologie des .2lenschen u71d der 7%~. Springer, Berlin, Gottingen, Heidelberg. Haymaker, W. (Ed. J ( 1953). The Founder.c ~f‘.,Veurolo~~v. Ch. C. Thomas Pub1ishtr.s. Springfield, Illinois. Hoerlein, B. E’. (1978). Canine .‘Veurology, Diagnosis and ‘Treatment, 3rd Edit. \\;. B. Saunders Co., Philadelphia, London, Toronto. Innes, J. R. M. and Saunders, L. Z. j 1962). c’ om/Jaratioe .,Veuropathologv. Academic Press, New York, London. McGrath, J. T. [ 1956). .hurologic Examination of the Dog. H.ith C’linico-pathologic, Obseruations. Lea and Febiger, Philadelphia. Palmer, ;I. C. (1976). Introduction to .4nimal ..Veurology. 2nd Edit. Blackwells, Oxford, London, Edinburgh, .Melbourne. Saunders, L. Z. ( 1973). Some historical aspects of the neuropathology of canine 112, 34 1~ distemper. &hale&r Archiz!. .ftir .Veurologie , ,Veurorhirurgie und Pychiatrie, 351. Saunders, L. Z. ! 1980). Veterinary Pathologv in Russia 1860-1930. Cornell Universit) ,Press, Ithaca and London. Saunders, L. Z. and Rubin, L. F. (1975). Ophth a 1mic- Pathologl! oJ‘dnimals. An Atlas and Reference Book. S. Karger, Basel. Scherer, H. J. i 1944). 6.ergleichende Pathologir des ,Verz~ensvstems der Sauge-tiete. G. Thieme, Leipzig.
NeurologyR. Fankhauser Inslitute
of Veterinary
Past, and Neurology.
Present
and
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M. Vandevelde Unisersity of Bernr.
The Journal of Comparative Pathology has always dealt with Pathology in the broad sense of the word, as the science of pathological processes in their clinical, aetiological and anatomo-pathological aspects. Therefore, it seems legitimate to give an account not only of the development of comparative neuropathology, but of neurology in veterinary medicine as such. Depending on ones viewpoint, it may be said that neurology is as old as veterinary medicine itself, or that it is a relatively new field that has-at least in many countries-still to fight for its recognition. In fact, if one peruses the veterinary literature from the foundation of the first schools in the second half of the 18th century, one realises that many diseases involving the nervous system were known, e.g. rabies, nervous distemper in dogs, epilepsy, meningitis and coenurosis. In fact, the last one was studied as early as 168 1 by J. J. Wepfer (1620 to 1695), the founder of a “medical school” in SchaIIhausen, Switzerland. A great number of neurological signs was known at that time such as convulsions, paralysis, ataxia, disturbances of behaviour and others, but their associa.tion with disturbed brain function was vague, because understanding of brain function itself was speculative and ill-founded. It was during the 19th century, especially its second half, that knowledge of pathological anatomy, histopathology and microbiology advanced to the point of understanding the nature of disease and, in this respect, there was no difIerence between the nervous and other organ systems. However, in veterinary medicine, progress on the clinical side was slow and this was especially so for nervous diseases with their generally poor prognosis. In that respect. human neurology (and psychiatry) differed fundamentally and an everincreasing amount of research work was done, wherein veterinary medicine and pathology hardly participated. In fact, many discoveries, particularly of an anatomical nature, were made by physicians on the animal nervous system. but used more for a better understanding of the human brain and cord than Ibr the benefit of the veterinary art. The same is true of the rapid development of technical methods during the last century; alcohol fixation of tissues (Rcil. 1809), demonstration of neurons and their processes (Purkinje, 1837), serial sections (Stilling, 1842), carmine staining of neurons (Gerlach, 1858), paraffin 1va.y embedding (E. Klebs, 1869), celloidin (Schiefferdecker, 1882), osmir acid stain of degenerating myelin (h/larchi, 1885), aniline stains for neurons f Nissl, 188.j). formaldehyde fixation (Blum, 1893) and many, many more. Such rnethods were widely used for recognizing the internal structure of the brain and cord and, in fact, to a large extent were developed in animals by.
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experimental methods, but veterinar). medicine only rarely took ad\,antagt. OI this rapidly growing body of knowledge. It must bc said. however. that 1i11. obvious reasons farm animals were less used than dogs and cats and laborator! species. It is not surprising that we still do not know, to give ,just one exampIt*. the exact extent of cortico-spinal fibres in horses or cattlc. After about 1850, in most of the European veterinary schools (and thcrc. were only European ones at that time!), pathological anatomy was introduced as a discipline and a teaching subject, but progress was very slow. l’he CNS especially, already of difficult access at necropsy, was f:dr from having priorit) for the veterinary pathologist. This was partly due to the fact that most of them were also responsible for bacteriology and both the attractiveness and the success of this new science detracted from the study of pathological morphology. This was perhaps less so in Germany and some other countries where the influence of Rudolf Virchow was dominant. Today, it seems rather invidious to stress the tensions between the two disciplines, because both stand in their own right and both are only facets of the same coin; pathology in its broad sense. Histology, indispensable for solving most of the morphological problems, came only slowly into USC in veterinary medicine. So, as late as 1881, Prof. Friedberger of Munich could state that, in canine distemper, brain oedcma was the only lesion responsible for the disturbed cerebral functions and that “a (macroscopically. of coursc:i. It real encephalitis has never been evidenced” was, therefore, a pioneer act when Gowers (the later famous British neurologist Sir William Gowers) and Sankey published their study of the histological examination of two cases of distemper myelitis under the title The Pathological Anatomy or Canine C’horea, in the year 1877 (Saunders, 1973). The rediscoverer of Crower’s and Sankey’s paper, Dr Leon Z. Saunders, rightly stresses the importance of this fact, when saying: “How typical of him then, to have examined histologically the CNS of dogs with distemper in 1877, at a time when neuropathology was still in its infancy, scientific polemics were popular and others were still debating the cause of the symptoms rather than doing something to seek them out.” As far as neuropathology is concerned, a factor of the utmost importance in human medicine was almost absent in the veterinary field, namely the stimulus coming from the clinical side. In fact, most of the progress made in the neurosciences until well into the present century was due to clinicians, dealing with internal medicine, surgery, neurology, psychiatry, or all together. This is admirably shown in the volume edited by Haymaker ( 1953) The Founder., I?/ .Neurolo~. The almost total lack of interest on the part of the vcterinar) clinicians was the main obstacle to an adequate development of neurology in animal medicine. It is only due to a handful of individuals (too fewj that the discipline survived here and there. It began to flourish only during the last 30 years and especially in the U.S.A., where clinical neurology, predominantly of small animals, rapidly evolved. One of those individuals, and probably the most outstanding one, was Hermann Dexler. He was born in Teesdorf near Vienna in 1866, studied veterinary medicine in the capital and graduated in 1888. After a few years as
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a district veterinarian which he spent in Leoben, he returned to the Vienrla veterinary college as an assistant of Prof. Schindelka. At the same time. motivated by his interest in neurology (interest which could not be satisfied at the veterinary school), he worked at the Hirnforschungs-institut (Institute for Brain Research) of Prof. Obersteiner, where he was competently trained in the neurosciences of that time. When trying to apply his knowledge to clinical cases in animals, mainly horses, he soon realized that most of the basic, even anatomical work had still to be done, and he invested part of his efforts into such investigations. His anatomical and physiological publications, approximately 15 out of a total of over 100 papers, reflect the additional training which he acquired in photography and drawing at the Vienna School of Graphics. After a series of original observations which he published on nervous diseases in dogs (he was the first to recognize disc protrusion and compression myelitis), he published a book on the nervous diseases of the horse which were essentially based on his personal observations (Dexler, 1899). It is still, in many respects, superior to a number of “modern” treatises. In 1898, Dexler became chairman of the Department of Veterinary Science of the German University of Prague (at that time in the AustroHungarian Empirej and starting from literally nothing, he created a laboratory for comparative neurology. From there, he published, most often alone, a great number of papers on neurology and ethological problems (at that time and not inaccurately, called Tierpsychologie: animal psychology). The reviews of books and papers which he wrote for the Jahresberichte uber die Leistungen auf dem Gebiete der VeterinarMedicin, and for the Ergebnisse der allgemeinen Pathologie are also countless. For decades, he was the leading, and only, authority for these matters in the veterinary field. Moreover, his contributions to Handbooks of human neurology (he had command of German, French and English) were probably the first important examples of the participation, on an equal footing, of a veterinary neurologist in human medicine. Dexler had a thorough knowledge of the pertinent literature, including Russian and never hesitated to acknowledge priority to others nor to refuse it when it was erroneously ascribed to him. His approach to animal neurology was critical, scientific and unbiased and he was fighting against ill-founded homologies which were a la mode at the turn of the century. Examples are his controversies with E. Joest on “canine chorea” (an erroneous term still used in the English language) or with Marchand (a French neurologist) on “progressive paralysis”. But it was at least a dispute on a higher plane, because both Joest and Marchand, too, examined their material histologically. In 193 1, Dexler was Dean of the Medical Faculty of the German University of Prague. He died that same year of heart failure. His eulogy was written by E. Frauchiger ( 195 1). Its inclusion in Haymakers’ Founders of .veurologv would have been well deserved (Innes and Saunders, 1962). Professor of’ so-called Eugenio Aruch (1853 to 1937j, up to his retirement, General Pathology and Head of the veterinary medical clinic of the Univrersity of Perugia (Italy), has to he considered as a forerunner of our discipline, although he contrasts sharply, and not to his advantage, with Dexler. In the obituaries, it is said that he was strongly interested in neurology throughout his
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life, as a clinician, but it seems that his efforts at verifying his clinical diagnoses, anatomo-pathologically and histologically, were modest. In 1900 and, as a second enlarged edition in 1914, he published his Malattie de1 Sistema flerooso (Aruch, 1914). His intention, to be applauded, was probably to stimulate the interest of his fellow veterinarians in neurological problems. In this sense, ht was in complete accordance with Dexler, who wrote in 1899 contesting the belief that neurology was of little importance for veterinary medicine; “intentional avoidance or neglect will not improve our knowledge about such diseases. Properly, with regard to the practical side of the problem, it is important-as it is for any group of diseases--to study and to uncover the causes and alterations, in order to make an eventual treatment meaningful”. But Aruch’s approach was totally different. The book is a mixture of’ personal, mainly clinical observations, reports from veterinary periodicals (of‘ very differing quality) and data taken from textbooks of human neurology, without making any distinctions. If Aruch shared Dexler’s interest in psychopathological problems in animals, he unfortunately did not share his critical attitude and offered even a chapter “La delinquenza negli animali”! It is probably not surprising that Aruch’s (1914) book, although its second edition is mentioned in the Jahresberichte (Ellenberger and Schlitz, 19 16), was never reviewed by Dexler. We suppose that he just didn’t deign to look at it. At the turn of the century, the then modern methods of histology had made their entrance in veterinary pathology and an increasing number of nervous conditions in animals was studied and described. It would be impossible to trace tbis development here. Canine distemper encephalitis, as a model of a demyelinating lesion, is one of the prominent examples. Its history has been described first by Saunders (1973) and later on by Fankhauser (1982). It must be stressed that diseases like distemper were studied more frequently and often more competently than others for their comparative interest. Quite often, human neurologists were engaged in such studies. The interest in the pathology of inflammatory lesions of the CNS was growing, together with virology and with the interest in some degenerative conditions, concomitantly with the development of the understanding of nutritional and toxicological problems. Exponents of the study of nervous diseases from the comparative standpoint were El. Weston Hurst (1900 to 1980) and 0. Seifried ( 1886 to 1947). ;\ particularly prolific tiesearcher in comparative neuropathology was J. R. M. Innrs (1903 to 1974) co-author of the leading and encyclopaedic volume I 1962) together with L. Z. Saunders. A Scotsman (born 1903) and a graduate of the Royal (Dick) Veterinar) College in Edinburgh, Innes got his training in pathology in several British institutions, but especially (for 3 years) as a Rockefeller fellow in Munich under Max Borst and in Freiburg under Ludwig Aschoff. Throughout his lifetime, he remained deeply impressed by his German teachers. His criticism of‘ the situation of British veterinary pathology in the 1930s and 1940s and the directness of his comments probably prevented an academic career in the United Kingdom. In 1948 he left for the United States where he found the discipline flourishing. His contributions to many fields of animal pathology ( nutritional pathology, laboratory animal pathology, comparative oncolog), 1
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were as numerous as outstanding, but his particular interests were in comparative neuropathology, where his name is linked with the authoritative descriptions of many diseases, for example, swayback, cerebellar hypoplasias, setariasis of the CNS. After having worked in a number of positions, Innes died in ( 1962), a standard 1974 in Bethesda, Maryland. His Comparative Neuropathology work of reference, unfortunately not followed by later editions, will be his lasting monument. Leon Z. Saunders, co-editor and co-author of the Comparative Neuropathology. born 1919, is still fully active. After completing the volume with Innrs. he stopped working in neuropathology and shifted to ophthalmic pathology and later to history, to which his Atlas of Ophthalmic Pathology of Animals ( 19751 with L. F. Rubin and his Veterinary Pathology in Russia 11980) testify. In the mid-1930s, E. Frauchiger in Berne (Switzerland), a human clinical neurologist, began working with people at the Ambulatory Clinic (a clinic for farm animals) of the Veterinary School. In 1941, he published the book “‘l‘hc Nervous Diseasesof Cattle”, which was an attempt at collecting and cataloguing the then knowledge about diseases of the nervous system in this species, oriented on the system used in human neurology as a guideline, but without undue homologies. The greater part of the clinical, anatomo-pathological and
Fig. ‘2.
Ernst Frauchiger,
1903 ttr 1975.
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histological data was furnished by his co-author W. Hofmann and staff. This marked the beginning of a slow, but steady growth of a laboratory, today called the Institute of Animal Neurology of the University of Berne, where a close connection between the clinical and pathological aspects of nervous diseases has always been considered essential. E. Frauchiger, born 1903 in Langenthal (Berne), studied medicine in Geneva, Paris, Rome and Vienna and graduated in Zurich. After working out his doctoral thesis on a surgical problem (under De Quervain, Berne), he was an assistant of 0. Veraguth in Zurich, his teacher in neurology. He was also deeply influenced by C. von Monakow (neurologist and neuropathologist) and E. Bleuler (psychiatrist). In Zurich, he met his college-friend W. Hofmann, at that time a young professor of buiatrics (diseases of cattle) who stimulated him to engage in scientific work. With a study on “Dummkoller” (idiopathic brain swelling) in horses, he obtained his veterinary Ph.D. in Zurich and, after having started a private practice in the Berne area (after Hofmann had moved back to Berne as head of the Ambulatory Clinic), he went on working parttime at the Veterinary Faculty of the University. Over the years, a small institute was built up. It must be said that Frauchiger, although in high esteem in the Swiss Neurological Society and internationally (in 1968 he was elected President of the Research Committee of the World Federation of Neurology) never held a position at the medical Faculty of Berne. He died on 15 April 1975 of intestinal cancer, in a regional hospital where he had been transferred, at his request, during his vacations in Ragaz (Fankhauser, 1975). ‘l’owards the end of World War II a book appeared which is another milestone in the development of comparative neurology, namely H. J. Scherer’s Vergleichende Neuropathologie ( 1944), based largely on materials collected by Dr Ludo van Bogaert at the Bunge Institute in Antwerp, Belgium. Although mainly devoted to the neuropathology of apes and monkeys, there is an important part on other zoo and domestic animals. Written by an expert neuropathologist, the morphological side is excellent, whereas clinical data art sometimes missing and sometimes misleading. So the author, lacking broad experience with everyday material, came to the conclusion that distemper plays a minor role in the canine “encephalitis complex” and that “acute multiple sclerosis” is its more important entity. clearly an untenable assumptiotl. The details of this story are discussed by Fankhauser (1982). Scherer’s book, which has excellent qualities, especially by the standards of‘ pre-existing veterinary literature, appeared at the wrong moment at a had place ( 1944 in Leipzig). Today, it is nearly forgotten by most people. It seems that the author died in an air raid on one of the cities of Saxony. In the Berne Institute, work slowly progressed. In 194.5, one of us 1R.I’. i ,joined Frauchiger and for many years commuted between periods at home I to keep the laboratory going) and periods of training in a considerable number of Swiss and foreign laboratories and clinics. In 1957, a volume on comparativt neuropathology (which included many clinical considerations) was published, the younger brother of Innes’ and Saunders’ book and, in 1968, the chapter on the “Nervous System” in E. Joest’s Handbook oj‘Animai Pathotogv came out as a monograph by Fankhauser and Luginbuhl. In the course of time, a large
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collection of neuro-histopathological material had been accumulated, partly by international cooperation, and serves as a basis for the 2 books. In 1957, on the occasion of the International Congress of Neurological Sciences held in Brussels, the World Federation of Neurology (WFN) was founded and during the following years, several so-called Problem Commissions including one on Comparative Neuropathology were created. The latter held its first meeting in November 1959 in our Institute in Berne. Later, on the occasions of International congresses of Neuropathology or Veterinary Congresses, special sessions on comparative neuropathology were organized ( 1962 Munich, 1967 Paris, 1974 Budapest and Brno). But, in contrast to the conditions in human neurology, where most working groups were merely outgrowths of pre-existing, large, well-organized (and wealthy) subspecialities (neuropathology, neurosurgery, epilepsy, EEG, to name just a few), it soon became obvious that there was no economic basis to hold such a group together. It was also clear that some of the founding members were themselves involved only part time, or temporarily, or not at all, in neurological work. As long as our Institute was officially recognized as a Collaborating Centre of WHO, it was possible, in order to satisfy the Statutes of the WFN, to pay a global annual fee for the group. We must confess that it was rather a shift of money from one organization to another and that all we could see (if we saw anything at all) was that it disappeared for bureaucratic activities. A few years ago, it was therefore decided, at our suggestion, to dissolve the group. In the meantime, however, veterinary neurology and neuropathology have gained ground and information is accumulating rapidly. In a leading journal of veterinary pathology, approximately 200 papers of predominantly neurological content appeared in the first 20 volumes (American College of Veterinary Pathologists, 1979, 1985). It is more and more common not to neglect the nervous system in anatomo-pathological descriptions and, slowly but steadily, clinical neurology expands. Organized or not organized, the activities of our Institute were always oriented towards international contacts, a concept as self-evident today as air and water. During the last 25 years, a great number of veterinary pathologists have visited the laboratory for short or long periods, the members of our group have lectured in many places in Europe and abroad and contacts, depending on the actual working problems, are maintained or established with many colleagues at home and in other countries. It has also been our preoccupation to maintain contacts with colleagues in states under socalled socialist rule, because we feel that they need it above all others. In a modest way, dictated by the modest size of our Institute, we still hope to function as a Collaborating Centre, collaborating not so much with a large international organization (which from time to time changes its policy) but with all those who share with us the belief that veterinary neurology has a future. Although earlier attempts were made to evaluate neurologically sick animals on a clinical basis, veterinary neurology as a recognized clinical speciality emerged during the past 3 decades mainly, but not only, through efforts in the U.S.A. As we have seen, during the 1950s and 1960s a large body of neuropathological knowledge had accumulated, enabling the classification of
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neurological diseases in animals according to pathological criteria and providing an important reference frame for the clinician. Not surprisingly, some of the first modern efforts to create a clinical diagnostic system came from the neuropathological side (McGrath, 1956) and were based on clinico-pathological observations and correlations, applying basic functional neuro-anatomical principles, which were of course much earlier available than pathological information, since much of the neurophysiological data were derived from animal experimentation including work done with dogs and cats. Methods for systematic neurological examination of the dog and cat were established and the techniques of collection and examination of the cerebrospinal fluid in animals were described by Hoerlein (1978) and by Innes and Saunders (1962). The differential diagnosis, as indicated, was predominantly based on neuropathological knowledge. Early on, spinal problems were recognized as an important and clinically separable group of diseases and the further development of clinical veterinary neurology was strongly associated with surgery and radiology. It was especially the work of Dr B. F. Hoerlein (1922 to 1987) who not only developed radiological methods to accurately diagnose spinal diseases in the dog, especially intervertebral disc problems, but also showed that these problems could be successfully treated by surgical techniques. He continued and expanded the work which has been initiated by the Swedish School after World War II. Before the era of Hoerlein, the prognosis of neurological diseases in animals was generally considered to be poor and therefore veterinary neurology was often regarded as unpractical and basically redundant. Hoerlein’s work, which was dedicated not only to the diagnosis, but also to the treatment of neurological diseases in animals, contributed significantly to a
Fig. 3.
Btmjamin
Franklin
Hoerlrin.
1922 to 1987
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change in mentality and facilitated thy rapid spread vf’\ c.tcrirtar\, ncurolog! itt many vctcrinary schools in thr U.S.A. Symptomatic ol‘this rapid cf~~vclop~tt~~t~~ was the appearance of‘ several tcxthooks on anirnal ncurol0g:)’ Jkom cfil~i~rc~ttl veterinary institutions during Iht 1970s and 1980s 1Ik 1,altttnta. IWi: Hoerlein, 1978). More and more’ emphasis was king placed ott ncurof’ll~sic,lc,gical aspects, localizing the lesion and application of‘ sophisticated ancillary aids such as ncuroradiology and clcctrodiagnostic tcchrtiqucs. :Uthough, tilt practical reasons, small animals wcrc of’ primary intt.rc.st fi)r the ~ctc*riri;tr~ neurologist, considcrablc progrcass has also been madr in largr animal rtcurology, especially fbr the horse. Clinical neurology has hccotnc a rccogttizcd subspeciality of the American Colle,~e of’\‘eterinar), Internal Mcdicinr with it> own training prc>,qrammes and board certification. Man> \,‘rterinary Ch~llc~rs in North America have now such trained and certified specialists on thrir c.littic. staff and many other schools are in thtb process of building such programmcs. In Europe, specialization in clinical medicine has been rather slow IO come (Palmer, 1976). However, clinical neurology is practkd in several \rctc‘rittar\ schools and an European Society fi)r Vctcrinary Neurology has IXTI~ fi~utdcd recently. Thr rvc’r increasing interest and rxprrtisc in clinic,al tteurology has ot‘c,oursc a strong impact on the f‘urther development of animal rteuropatholog-) ; a lat-gee number of new and interesting diseases has been discovered in recent years as can be sceti fi-om the impressive tiurnhers of literature rcfkrencrs compiled in the recent clinical neurology textbooks. ‘I‘hcse publications have appeared itt the veterinary literature but also to a large cxtettl in other hiomedical~juurttals, illustrating the t.act that the cornparativr mcdicinc idea is nlorr alive than ~~~cr in vctcrinary nc~urology. Many cx)nditions have ~XTI~ prol)osed and tfc\~c~lo~~~i as animal models fi)r human discascbs of‘thc ncr\.oLts system. Prime cxatnpl~~s of thr positive interaction hetweeri clinical work and ncuropatholog) art’ t ht. diseases of the peripheral nervous system and muscles. ‘l’hc* discovery of t hcsc. diseases and the study of‘ their patholog), became onI.> epossit,lc throqlt th(. application of‘ clcctrodiagnostic techniques enabling cl~ntc-al dctrction of’strc~lt lesions. Such techniques are now widely used in veterinar) ncurolo~)~ ’ IIurtcatt and Grifli t hs, 1984). As already indicated, comparative neuropathology is bring practiscd in several clinics and laboratories throughout the world and the concept of’ using animal tnodcls for thr study of human disease is still rcccnt. Of course, b). comparison with the huge amount of’ work going on in srnall laborator!, animals (also veterinary pathologists arc involved in such work). in which many different types of interesting neurological diseases have been identified and which are for practical and genetic reasons often much easier 10 work with, neuropathological research in domestic animals is rather modest. However, high quality research is going on with many diflcrent neurological diseases in domestic animals. Whereas earlier work was focusscd on the descriptive evaluation of spontaneously occurring lesions and comparing these morphological features with those seen in similar human conditions, recent and current neuropathological work is also concerned with dissecting disease mechanisms. We can distinguish two types of veterinary neuropathology currently being
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practised; one type is clinically oriented and is important for the clinicalpathological correlations and further development and refinement of clinical neurology. Clinical neuropathology is also still instrumental in describing and classifying new disease entities and the associated discovery of potential useful animal models; this will remain so for many years to come and it is to be hoped that it will reach comparable standards to human medicine. All too often, one can see that in veterinary pathological situations, the examination of the CNS (and PNS) is still practised on a rather primitive basis. International cooperation would be of great benefit in this respect. The second type of neuropathology is concerned with pathogenesis research starting from a certain type of lesion and by applying various techniques, to explain why and how it develops. Sequential morphological studies including light microscopy and electron microscopy are often the bases of such projects and provide useful information. The advent of easy and reproducible immuno-cytochemical methods which can often be successfully applied to fixed and embedded tissues and allow specific demonstration of a wide varirt! of molecules, has extended the scope of morphological techniques considerably. Naturally, these methods also have their limits and neurologists often extend their work beyond morphology, by applying techniques derived from other disciplines such as biochemistry and immunology. In addition to the work in vivo, cell biological methods such as brain cell culture systems are used to study certain problems. Molecular techniques such as gene-cloning will also become important in the near future. It can be expected that the application 01‘ new technologies will steadily increase in the study of the pathogenrsis of neurological diseases in animals and that molecular biological techniques will eventually dominate the field.
References
American College of Veterinary Pathologists (1979). C umulative Index to LPterinarr Pathology, Vols 1-15 (1964-1978). American College of Veterinary Pathology i 1985). <:umulative Index to lbterinarl Pathology, Vols 16-20 ( 1978- 1983). Aruch, E. (1914). Malattie de1 Sistema Nervosa, 2nd Edit. Vallardi, Milano. De I,ahunta, A. (1983). Veterinary Neuroanatory and Clinical ,?l’euroioLv, 2nd Edit. 12:. B. Saunders Co., Philadelphia. Dexler, H. ( 1899). Die Nervenkrankheiten des Pferde.c. Deuticke, Witm and Leipzig. Duncan, I. D. and Griffiths, I. R. (1984). Peripheral neuropathies ofdomestic animals. In Peripheral Neuropathy, Dyck, Thomas, Lambert and Burge, Eds., Vol. I. Saunders Co., Philadelphia. Ellellberger, W. and Schlitz, W. (1916). 3 ah res b erichte iiber die Leistungen auj‘dem Cvbirtr der Ileteriniir-Medicin 34, 85. Fankhauser, R. (1975). Nachruf Prof. Dr med. Ernst Frauchiger, Bern. Acta .hPuropathologica Berlin, 32, 87-89. Fankhauser, R. (1982). Hundestaupe-Geschichte einer Krankheit. Schweiser Archirl,flir ‘Tierheilkunde, 124, 245-256. Fankhauser, R. and Luginbiihl, H. (1968). Pathologische Anatomie des zentralen und Peripheren .~~rvensystems der Haustiere. P. Parey, Berlin and Hamburg. Frauchiger, E. (1951). Den AManen eines Grossen unserer Wissenschaft. Prof. Hrrmann Dexler ( 1866-l 93 1) . Schweizer Archizl ftir ‘Tierheilkunde, 93, 359-364. Frau<-higer, E. and Hofmann, W. f 1941). Die .!~ervenkrankheitrn des Rindes. Huber, Bern.
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Frauchiger, E. and Fankhauser, R. ( 1957). l’ergleichende Neuropathologie des .2lenschen u71d der 7%~. Springer, Berlin, Gottingen, Heidelberg. Haymaker, W. (Ed. J ( 1953). The Founder.c ~f‘.,Veurolo~~v. Ch. C. Thomas Pub1ishtr.s. Springfield, Illinois. Hoerlein, B. E’. (1978). Canine .‘Veurology, Diagnosis and ‘Treatment, 3rd Edit. \\;. B. Saunders Co., Philadelphia, London, Toronto. Innes, J. R. M. and Saunders, L. Z. j 1962). c’ om/Jaratioe .,Veuropathologv. Academic Press, New York, London. McGrath, J. T. [ 1956). .hurologic Examination of the Dog. H.ith C’linico-pathologic, Obseruations. Lea and Febiger, Philadelphia. Palmer, ;I. C. (1976). Introduction to .4nimal ..Veurology. 2nd Edit. Blackwells, Oxford, London, Edinburgh, .Melbourne. Saunders, L. Z. ( 1973). Some historical aspects of the neuropathology of canine 112, 34 1~ distemper. &hale&r Archiz!. .ftir .Veurologie , ,Veurorhirurgie und Pychiatrie, 351. Saunders, L. Z. ! 1980). Veterinary Pathologv in Russia 1860-1930. Cornell Universit) ,Press, Ithaca and London. Saunders, L. Z. and Rubin, L. F. (1975). Ophth a 1mic- Pathologl! oJ‘dnimals. An Atlas and Reference Book. S. Karger, Basel. Scherer, H. J. i 1944). 6.ergleichende Pathologir des ,Verz~ensvstems der Sauge-tiete. G. Thieme, Leipzig.