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Tuberculosis in Camels
80
GENERAL ARTICLES.
The scrapings which were forwarded to us by Mr Williams when treated by Sheather's method, as described in this Journal, Vol. XXVII I., p. 64, showed an extraordinary number of sarcoptic acari and their eggs in all stages of development. I t has not been considered necessary to reproduce any photographs of the parasites beyond the one shown, which is quite conclusive as to the genus of the acari present in the cases.]
TUBERCULOSIS IN CAMELS.
By Major F. E. MASON, A.V.c., Sub-Director and Veterinary Pathologist, Veterinary Service, Minister of Agriculture, Cairo. TUBERCULOSIS appears to be very rare in camels living under normal or natural conditions in all countries except Egypt. With the exception of cases occurring in camels living in Zoological Gardens, where the conditions are unnatural, only very few have been recorded, and evidently the observers who signalled these cases considered the condition sufficiently rare to merit publication. Thus, we find one case recorded in India by Lingard 1 in 1905, and one case recorded by Leese 2 in 1908, also in an Indian camel. One case was recorded by Archibald 3 in 1910 in the Sudan. One case was signalled from Algeria,4 in which the tubercle bacilli found were described as belonging to avian type. In the Annual Report of the Camel Specialist, Indian Civil Veterinary Department, 1915-16,5 we note two deaths in camels ascribed to tuberculosis in the summary of mortality compiled from the returns sent in by the Silladar Camel Corps. However, these two cases cannot be accepted as authentic, as the writer himself states that too much reliance cannot be placed on these mortality returns, which are compiled from the statements of the camelmen. 6 In Egypt tuberculosis has long been known to be common in camels. It was first reported by Littlewood 7 in 1888, when he observed the gross lesions macroscopically during investigations into camel mortality. For several years after this no records appear to have been kept. In the Annual Report for 1900 of the Veterinary Service, Egypt, it is recorded that 3 per cent. of the camels slaughtered at Cairo Abattoir had tuberculosis. In 1910, 1786 camels were slaughtered at Cairo Abattoir, of which fifty (2'8 per cent.) were found to be tuberculous. Four of these had generalised tuberculosis, twelve had lesions 1 Lingard: "Annual Report of Imperial Bacteriologist," India, 1905·06. 2 Leese: "Annual Report of Officer investigating Camel Diseases," 1908; quoted in "Journal of Comparative Pathology and Therapeutics," 1910. 3 Archibald: "Journal of Comparative Pathology and Therapeutics," 1910, p. 56. 4 I remember reading the account, but cannot trace the literature. 5 Page 2, para. 14. 6 Page 4. para. 24. 7 " Journal Officiel Egyptien," 1888.
GENERAL ARTICLES.
necessitating the condemnation of half the carcase, twenty-eight were affected in the lungs only, and six in the lungs and liver. In 191 I, out of 2695 camels slaughtered, thirty-four were found tuberculous (1'63 per cent.); of these there were condemned for generalised tuberculosis two whole carcases, five half carcases, and three quarter carcases, while nineteen had lung lesions only and six had lung and liver lesions. During 1912, fourteen cases of tuberculosis in Egyptian camels were diagnosed by bacteriological examination in the veterinary laboratory. In 1915,1351 camels, which were almost exclusively of Egyptian origin, were slaughtered, Syrian and Arabian export having ceased; of these, seventy-.three (5'4 per cent.) were tuberculous, and, in addition, .fifteen cases were recorded in Egyptian camels in various parts of the country. The records for 1916 show that fifty-one cases of tuberculosis were detected in 1579 camels (3'2 per cent.) slaughtered at Cairo Abattoir during the year, and nineteen other cases were diagnosed by examination of lesions in the laboratory. As far as it has been possible to ascertain, all the above-mentioned cases were found in Egyptian camels; the figures, however, do not show the actual percentage of tuberculous camels in Egypt, which is certainly much lower than that calculated from abattoir returns. Previous to the war thirty to forty thousand camels were annually imported into Egypt from Syria and Arabia. A considerable number of these were slaughtered in Cairo Abattoir, and were shown in the general returns of camels slaughtered without distinction as to the country of origin. We have paid particular attention to such importations, and have never found tuberculosis in Syrian or Arabian camels of recent arrival. Of Egyptian camels, only the old and the useless for work are slaughtered. Investigations into the true nature of the "tuberculous" lesions so frequently encountered were first made by the writer early in 191 I, and the results of the first year's investigations, which were published in 1912,1 showed that the disease was indeed tuberculosis. Acid-fast bacilli having all the characteristics of tubercle bacilli were found in varying numbers in suspected lesions or their discharges from twenty different camels. The histology of the lesions conformed to that accepted of tuberculous lesions, with the exception that giant cells were rare. Guinea-pigs inoculated subcutaneously with emulsions of tuberculous material from camels succumbed to generalised tuberculosis in about two months, and rabbits in about two and a half months. Tubercle bacilli were recovered in very large numbers from the lesions in the experimental animals. Pure cultures of tubercle bacilli were obtained on solid camel-blood serum from portions of tuberculous glands of the inoculated rabbits. They grew very slowly, with all the appearances of cultures of tubercle bacilli of the bovine type. The experiments conducted thus tended to show that the variety 1 Mason: "Journal of Comparative Pathology and Therapeutics," 1912, and" Annual Report, Department of Public Health," Paper No.5, 1912.
F
82
GENERAL ARTICLES.
of bacilli responsible for tuberculosis in camels conformed to the bovine type. At this stage of the investigations, which included a systematic survey of all tuberculous camels met with to determine the distribution of the lesions, the writer considered that, although Koch's postulates had not been rigidly adhered to, matter of sufficient interest had been collected, and, as before mentioned, the facts were then published. During the subsequent investigations pure cultures of tubercle bacilli of the bovine type were obtained on solid camel-blood serum from tuberculous gland material from ten camels. Sub-cultures on glycerine bouillon showed all the characteristics of bovine tubercle bacilli. Subcutaneous inoculation of minute doses of pure cultures invariably produced generalised tuberculosis in both guinea-pigs and rabbits. Cultures of the tubercle bacilli grown from material obtained from the experimental animals were thus proved to be of the bovine type. These experiments, beyond proving the nature of the disease, appear to shed some light on the origin of tuberculosis in camels in Egypt. Source of Tuberculosis in Camels.- The custom amongst the fellaheen of keeping camels in close association with cattle, both in houses and even at work, seems to provide susceptible camels with excellent opportunities of contracting the disease from infected cattle. The constancy with which tubercle bacilli of the bovine type have been found in tuberculous lesions in camels supports the theory of infection from cattle. There is no doubt that an infected camel introduced into a herd of healthy camels becomes a source of danger to his fellows and may spread the disease. All the evidence collected during the last six years tends to show that tuberculosis is not par excellence a disease of camels, but that infection takes place primarily from cattle. \Ve have paid particular attention to autopsies on many camels from the Sinai Peninsula, and to those of the Coast Guard Administration, which are not bred in the country and never come into contact with cattle; in no case have we found them tuberculous. The same applies to Sudanese camels in general; we have never found them tuberculous. Even should they come into contact with cattle in the Sudan, the danger is infinitesimal, as tuberculosis is extremely rare in Sudanese cattle. Metltod of lnfection.- There seems to be little doubt that the usual method is by inhalation. Apparently the lungs never escape infection; in a notable proportion of cases the lesions are limited to the lungs and their lymph glands, and even in advanced cases it is usually evident that the oldest lesions are in the lungs. Course of tlte Disease.-Under the conditions in which camels are kept by the fellaheen, which include a generous and bulky diet, daily watering, intermittent slow work, and plenty of rest, the disease as a rule runs a very chronic but progressive course. The camel shows considerable resistance to the disease. Under adverse conditions, such as continuous transport work in the desert, wasting occurs rapidly, until in a very few months the animal is reduced to a mere skeleton, with all the symptoms seen in bovines.
GENERAL ARTICLES.
Almost continuous elevation of temperature, cough, profuse glairy discharge from the nostrils, pleurisy or peritonitis or both, cold hard swelling of the principal accessible lymph glands. Distribution 0./ Tuberculous Lesions in the Camel.- The lungs and the bronchial and mediastinal glands are most frequently affected; in no case that has come to our notice have the two first-named of these organs escaped infection. About 60 per cent. of cases are affected in these organs only. This, taken into consideration with the age and development of the lesions, has led us to conclude that tuberculosis in camels is primarily a lung disease. The pleura is frequently affected, showing masses of grape- or pearl-like nodules on the surface of the pleura, and particularly on the free fringe of it attached to the lower borders of the posterior lobes. A peculiarity we have observed is that, with an advanced tuber<:ulosis of the lungs, bronchial glands, and visceral pleura, the parietal pleura and lymph glands of the chest wall not infrequently escape infection. The lung lesions found may take the form of discrete miliary tubercles on the surface and in the substance of the organ, varying greatly in number; or, in addition to discrete tubercles, masses of confluent tubercles may be present. Frequently large masses of lung tissue, up to a considerable part of a lobe, may be completely solid and filled with caseous matter and fibrous tissue. There is marked tendency towards formation of fibrous tissue in <:onnection with the lesions of chronic tuberculous broncho-pneumonia in camels. Tuberculous pericarditis has been observed, and tuberculous peritonitis is not uncommon, with lesions similar to those of the pleura. The liver is fairly commonly affected, the lesions having no special characters to distinguish them from liver lesions in cattle. The spleen is not uncommonly affected in advanced cases, with the formation of prominent spheroidal caseous masses varying in size from that of a hazel nut to a large walnut. Tuberculous disease of the kidneys has also been observed on several occasions. Sometimes lesions are seen in the trachea, in the form of oval, prominent yellow patches, or ulcerations on the mucous membrane, in which cases the tracheal glands are tuberculous also. Generalised tuberculosis, with very numerous lesions in the principal organs and the near and remote lymph glands of the body, has been observed in about 7 per cent. of cases. Histology 0./ Tuberculous Lesions in the Camel.-Microscopic examination of sections shows the lesions to consist of the accepted constituents of tuberculous lesions in general, with the difference that giant cells are rare. Usually there is very little difficulty in finding the bacilli in young tubercles stained by the Ziehl-Neelsen method. Calcification in a fine granular form appears to set in very early, even in quite small tubercles, as evidenced by the use of hcematoxylin. In connection with older lesions much fibrous tissue is frequently formed, evidently for purposes of repair. The Tuberculin Test applied to Camels.- The subcutaneous test
ABSTRACTS.
with ordinary tuberculin may be successfully employed on suspected camels. We have tried no other form of test. For the benefit of those unfamiliar with the variations in the normal temperature of camels, I give the following table compiled from observations of a large number of healthy camels at rest.! Extreme variation between early morning and late afternoon, from 35° C. (95° F.) to 38.6° C. (101·6° F.). At 6 A.M., 35° C. (95° F.) to 37·5° C. (99.6° F.); usual temperature. 36.2° C. (97° F.). At 6 P.M., 37·4° C. (99.2° F.) to 38.6° C. (101·6° F.). A temperature over 37"5° C. (99.6° F.) at 9 A.M. is abnormal. A temperature over 38"70 C. (102° F.) at 6 P.M. is abnormal.
OTACARIASIS AND THE PROPHYLAXIS OF PSOROPTIC MANGE. PSOROPTIC otacariasis is a common infection in the rabbit and in the goat, and it has also been demonstrated in the gazelle and in the argali (wild sheep) of America. In this article Henry brings forward evidence to show that the disease is far from being rare in the horse, ass, mule, and sheep. Otacariasis of the Horse.-Hitherto psoroptic mange of the horse has been considered to attack in the first place the regions covered with long hairs. (forelock, mane, and tail), and then under bad hygienic conditions to extend along the trunk. The most commonly occurring clinical form, which, however, appears to have completely escaped the notice of observers, is. otacariasis. The condition in the first place was observed by the author (eighteen months before the publication of this article) in 7 I per cent. of the carcases of horses that had died from different affections at a veterinary hospital. This frequency was then attributed to the fact that nearly all the horses were affected with mange, although the most notable form was sarcoptic mange, and psoropts could only be held accountable for from 7 to 8 percent. of the cases. Later, when the symptoms of otacariasis in living animals were recognised, the condition was found affecting 42 per cent. of the sick horses at another veterinary hospital where mange was rare and of the sarcoptic form only. It is thought that this percentage would undoubtedly be too high to be considered as the general state of affairs among all the cavalry horses, but,. nevertheless, it is held that otacariasis is of great frequency in comparison. with psoroptic mange of the mane and body, and that the first-named affection must be considered as the fundamental form of the disease. Macroscopic Lesions.-The lesions are rarely unilateral, and nearly always the two ears are affected. The mange remains localised in the deepest part of the external auditory meatus, and in order to demonstrate its presence in a carcase it is necessary to sever the ear at its base on a level with the skull; 1 These observations agree with those made by Leese. and Therapeutics," 1909.
.. Journal of Comparative Pathology'
GENERAL ARTICLES.
The scrapings which were forwarded to us by Mr Williams when treated by Sheather's method, as described in this Journal, Vol. XXVII I., p. 64, showed an extraordinary number of sarcoptic acari and their eggs in all stages of development. I t has not been considered necessary to reproduce any photographs of the parasites beyond the one shown, which is quite conclusive as to the genus of the acari present in the cases.]
TUBERCULOSIS IN CAMELS.
By Major F. E. MASON, A.V.c., Sub-Director and Veterinary Pathologist, Veterinary Service, Minister of Agriculture, Cairo. TUBERCULOSIS appears to be very rare in camels living under normal or natural conditions in all countries except Egypt. With the exception of cases occurring in camels living in Zoological Gardens, where the conditions are unnatural, only very few have been recorded, and evidently the observers who signalled these cases considered the condition sufficiently rare to merit publication. Thus, we find one case recorded in India by Lingard 1 in 1905, and one case recorded by Leese 2 in 1908, also in an Indian camel. One case was recorded by Archibald 3 in 1910 in the Sudan. One case was signalled from Algeria,4 in which the tubercle bacilli found were described as belonging to avian type. In the Annual Report of the Camel Specialist, Indian Civil Veterinary Department, 1915-16,5 we note two deaths in camels ascribed to tuberculosis in the summary of mortality compiled from the returns sent in by the Silladar Camel Corps. However, these two cases cannot be accepted as authentic, as the writer himself states that too much reliance cannot be placed on these mortality returns, which are compiled from the statements of the camelmen. 6 In Egypt tuberculosis has long been known to be common in camels. It was first reported by Littlewood 7 in 1888, when he observed the gross lesions macroscopically during investigations into camel mortality. For several years after this no records appear to have been kept. In the Annual Report for 1900 of the Veterinary Service, Egypt, it is recorded that 3 per cent. of the camels slaughtered at Cairo Abattoir had tuberculosis. In 1910, 1786 camels were slaughtered at Cairo Abattoir, of which fifty (2'8 per cent.) were found to be tuberculous. Four of these had generalised tuberculosis, twelve had lesions 1 Lingard: "Annual Report of Imperial Bacteriologist," India, 1905·06. 2 Leese: "Annual Report of Officer investigating Camel Diseases," 1908; quoted in "Journal of Comparative Pathology and Therapeutics," 1910. 3 Archibald: "Journal of Comparative Pathology and Therapeutics," 1910, p. 56. 4 I remember reading the account, but cannot trace the literature. 5 Page 2, para. 14. 6 Page 4. para. 24. 7 " Journal Officiel Egyptien," 1888.
GENERAL ARTICLES.
necessitating the condemnation of half the carcase, twenty-eight were affected in the lungs only, and six in the lungs and liver. In 191 I, out of 2695 camels slaughtered, thirty-four were found tuberculous (1'63 per cent.); of these there were condemned for generalised tuberculosis two whole carcases, five half carcases, and three quarter carcases, while nineteen had lung lesions only and six had lung and liver lesions. During 1912, fourteen cases of tuberculosis in Egyptian camels were diagnosed by bacteriological examination in the veterinary laboratory. In 1915,1351 camels, which were almost exclusively of Egyptian origin, were slaughtered, Syrian and Arabian export having ceased; of these, seventy-.three (5'4 per cent.) were tuberculous, and, in addition, .fifteen cases were recorded in Egyptian camels in various parts of the country. The records for 1916 show that fifty-one cases of tuberculosis were detected in 1579 camels (3'2 per cent.) slaughtered at Cairo Abattoir during the year, and nineteen other cases were diagnosed by examination of lesions in the laboratory. As far as it has been possible to ascertain, all the above-mentioned cases were found in Egyptian camels; the figures, however, do not show the actual percentage of tuberculous camels in Egypt, which is certainly much lower than that calculated from abattoir returns. Previous to the war thirty to forty thousand camels were annually imported into Egypt from Syria and Arabia. A considerable number of these were slaughtered in Cairo Abattoir, and were shown in the general returns of camels slaughtered without distinction as to the country of origin. We have paid particular attention to such importations, and have never found tuberculosis in Syrian or Arabian camels of recent arrival. Of Egyptian camels, only the old and the useless for work are slaughtered. Investigations into the true nature of the "tuberculous" lesions so frequently encountered were first made by the writer early in 191 I, and the results of the first year's investigations, which were published in 1912,1 showed that the disease was indeed tuberculosis. Acid-fast bacilli having all the characteristics of tubercle bacilli were found in varying numbers in suspected lesions or their discharges from twenty different camels. The histology of the lesions conformed to that accepted of tuberculous lesions, with the exception that giant cells were rare. Guinea-pigs inoculated subcutaneously with emulsions of tuberculous material from camels succumbed to generalised tuberculosis in about two months, and rabbits in about two and a half months. Tubercle bacilli were recovered in very large numbers from the lesions in the experimental animals. Pure cultures of tubercle bacilli were obtained on solid camel-blood serum from portions of tuberculous glands of the inoculated rabbits. They grew very slowly, with all the appearances of cultures of tubercle bacilli of the bovine type. The experiments conducted thus tended to show that the variety 1 Mason: "Journal of Comparative Pathology and Therapeutics," 1912, and" Annual Report, Department of Public Health," Paper No.5, 1912.
F
82
GENERAL ARTICLES.
of bacilli responsible for tuberculosis in camels conformed to the bovine type. At this stage of the investigations, which included a systematic survey of all tuberculous camels met with to determine the distribution of the lesions, the writer considered that, although Koch's postulates had not been rigidly adhered to, matter of sufficient interest had been collected, and, as before mentioned, the facts were then published. During the subsequent investigations pure cultures of tubercle bacilli of the bovine type were obtained on solid camel-blood serum from tuberculous gland material from ten camels. Sub-cultures on glycerine bouillon showed all the characteristics of bovine tubercle bacilli. Subcutaneous inoculation of minute doses of pure cultures invariably produced generalised tuberculosis in both guinea-pigs and rabbits. Cultures of the tubercle bacilli grown from material obtained from the experimental animals were thus proved to be of the bovine type. These experiments, beyond proving the nature of the disease, appear to shed some light on the origin of tuberculosis in camels in Egypt. Source of Tuberculosis in Camels.- The custom amongst the fellaheen of keeping camels in close association with cattle, both in houses and even at work, seems to provide susceptible camels with excellent opportunities of contracting the disease from infected cattle. The constancy with which tubercle bacilli of the bovine type have been found in tuberculous lesions in camels supports the theory of infection from cattle. There is no doubt that an infected camel introduced into a herd of healthy camels becomes a source of danger to his fellows and may spread the disease. All the evidence collected during the last six years tends to show that tuberculosis is not par excellence a disease of camels, but that infection takes place primarily from cattle. \Ve have paid particular attention to autopsies on many camels from the Sinai Peninsula, and to those of the Coast Guard Administration, which are not bred in the country and never come into contact with cattle; in no case have we found them tuberculous. The same applies to Sudanese camels in general; we have never found them tuberculous. Even should they come into contact with cattle in the Sudan, the danger is infinitesimal, as tuberculosis is extremely rare in Sudanese cattle. Metltod of lnfection.- There seems to be little doubt that the usual method is by inhalation. Apparently the lungs never escape infection; in a notable proportion of cases the lesions are limited to the lungs and their lymph glands, and even in advanced cases it is usually evident that the oldest lesions are in the lungs. Course of tlte Disease.-Under the conditions in which camels are kept by the fellaheen, which include a generous and bulky diet, daily watering, intermittent slow work, and plenty of rest, the disease as a rule runs a very chronic but progressive course. The camel shows considerable resistance to the disease. Under adverse conditions, such as continuous transport work in the desert, wasting occurs rapidly, until in a very few months the animal is reduced to a mere skeleton, with all the symptoms seen in bovines.
GENERAL ARTICLES.
Almost continuous elevation of temperature, cough, profuse glairy discharge from the nostrils, pleurisy or peritonitis or both, cold hard swelling of the principal accessible lymph glands. Distribution 0./ Tuberculous Lesions in the Camel.- The lungs and the bronchial and mediastinal glands are most frequently affected; in no case that has come to our notice have the two first-named of these organs escaped infection. About 60 per cent. of cases are affected in these organs only. This, taken into consideration with the age and development of the lesions, has led us to conclude that tuberculosis in camels is primarily a lung disease. The pleura is frequently affected, showing masses of grape- or pearl-like nodules on the surface of the pleura, and particularly on the free fringe of it attached to the lower borders of the posterior lobes. A peculiarity we have observed is that, with an advanced tuber<:ulosis of the lungs, bronchial glands, and visceral pleura, the parietal pleura and lymph glands of the chest wall not infrequently escape infection. The lung lesions found may take the form of discrete miliary tubercles on the surface and in the substance of the organ, varying greatly in number; or, in addition to discrete tubercles, masses of confluent tubercles may be present. Frequently large masses of lung tissue, up to a considerable part of a lobe, may be completely solid and filled with caseous matter and fibrous tissue. There is marked tendency towards formation of fibrous tissue in <:onnection with the lesions of chronic tuberculous broncho-pneumonia in camels. Tuberculous pericarditis has been observed, and tuberculous peritonitis is not uncommon, with lesions similar to those of the pleura. The liver is fairly commonly affected, the lesions having no special characters to distinguish them from liver lesions in cattle. The spleen is not uncommonly affected in advanced cases, with the formation of prominent spheroidal caseous masses varying in size from that of a hazel nut to a large walnut. Tuberculous disease of the kidneys has also been observed on several occasions. Sometimes lesions are seen in the trachea, in the form of oval, prominent yellow patches, or ulcerations on the mucous membrane, in which cases the tracheal glands are tuberculous also. Generalised tuberculosis, with very numerous lesions in the principal organs and the near and remote lymph glands of the body, has been observed in about 7 per cent. of cases. Histology 0./ Tuberculous Lesions in the Camel.-Microscopic examination of sections shows the lesions to consist of the accepted constituents of tuberculous lesions in general, with the difference that giant cells are rare. Usually there is very little difficulty in finding the bacilli in young tubercles stained by the Ziehl-Neelsen method. Calcification in a fine granular form appears to set in very early, even in quite small tubercles, as evidenced by the use of hcematoxylin. In connection with older lesions much fibrous tissue is frequently formed, evidently for purposes of repair. The Tuberculin Test applied to Camels.- The subcutaneous test
ABSTRACTS.
with ordinary tuberculin may be successfully employed on suspected camels. We have tried no other form of test. For the benefit of those unfamiliar with the variations in the normal temperature of camels, I give the following table compiled from observations of a large number of healthy camels at rest.! Extreme variation between early morning and late afternoon, from 35° C. (95° F.) to 38.6° C. (101·6° F.). At 6 A.M., 35° C. (95° F.) to 37·5° C. (99.6° F.); usual temperature. 36.2° C. (97° F.). At 6 P.M., 37·4° C. (99.2° F.) to 38.6° C. (101·6° F.). A temperature over 37"5° C. (99.6° F.) at 9 A.M. is abnormal. A temperature over 38"70 C. (102° F.) at 6 P.M. is abnormal.
OTACARIASIS AND THE PROPHYLAXIS OF PSOROPTIC MANGE. PSOROPTIC otacariasis is a common infection in the rabbit and in the goat, and it has also been demonstrated in the gazelle and in the argali (wild sheep) of America. In this article Henry brings forward evidence to show that the disease is far from being rare in the horse, ass, mule, and sheep. Otacariasis of the Horse.-Hitherto psoroptic mange of the horse has been considered to attack in the first place the regions covered with long hairs. (forelock, mane, and tail), and then under bad hygienic conditions to extend along the trunk. The most commonly occurring clinical form, which, however, appears to have completely escaped the notice of observers, is. otacariasis. The condition in the first place was observed by the author (eighteen months before the publication of this article) in 7 I per cent. of the carcases of horses that had died from different affections at a veterinary hospital. This frequency was then attributed to the fact that nearly all the horses were affected with mange, although the most notable form was sarcoptic mange, and psoropts could only be held accountable for from 7 to 8 percent. of the cases. Later, when the symptoms of otacariasis in living animals were recognised, the condition was found affecting 42 per cent. of the sick horses at another veterinary hospital where mange was rare and of the sarcoptic form only. It is thought that this percentage would undoubtedly be too high to be considered as the general state of affairs among all the cavalry horses, but,. nevertheless, it is held that otacariasis is of great frequency in comparison. with psoroptic mange of the mane and body, and that the first-named affection must be considered as the fundamental form of the disease. Macroscopic Lesions.-The lesions are rarely unilateral, and nearly always the two ears are affected. The mange remains localised in the deepest part of the external auditory meatus, and in order to demonstrate its presence in a carcase it is necessary to sever the ear at its base on a level with the skull; 1 These observations agree with those made by Leese. and Therapeutics," 1909.
.. Journal of Comparative Pathology'