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Laminitis – What’s in a name?
The Veterinary Journal 183 (2010) 245–246
Contents lists available at ScienceDirect
The Veterinary Journal journal homepage: www.elsevier.com/locate/tvjl
Guest Editorial
Laminitis – What’s in a name?
It seems that for the word laminitis, a very great deal is ‘in the name’. At present, the nomenclature surrounding this condition mirrors the confusion of its aetiopathology (Parks and Mair, 2009). As scientists, we should be able to describe a clinical condition so that others may be able to recognise it without confusion. With this in mind, I offer here a simple system of terminology that needs only the use of hands and eyes, has proven prognostic significance (Eustace and Cripps, 1999) and can be used by both researchers and clinicians (Fig. 1). There are five key definitions. Developmental laminitis – the period between the administration of a known laminitis-inducing diet/toxin and lameness becoming evident. Laminitis – lameness characteristic of the condition, namely, strong digital pulses, toe relieving stance, and weight shifting from one affected foot to another. Acute founder – the clinical signs of laminitis plus palpable supra-coronary depressions extending part way around the coronary contour. The deeper and longer the depressions, the worse the distal displacement will be. Sinker – no characteristic laminitis lameness seen but the animal is reluctant to move, has strong digital pulses and supra-coronary depressions which extend completely around the coronary contour. Chronic founder – any horse with a hoof displaying the following clinical changes: concave dorsal hoof walls, abnormally wide dorsal white lines from quarter to quarter, and divergent growth rings on the hoof walls. The growth rings are more widely spaced at the heels than the toes leading to relative over-growth of the hoof wall at the heels. On palpation the coronary bands often seem soft or indistinct and the skin seems to merge directly with the horn with no recognisable perioplic ring. The term acute laminitis is omitted as all laminitis cases are acutely painful and of relatively sudden onset. Laminitis cases never die or are euthanased because of hoof pathology (there is no displacement – they only die due to medical complications or uncontrollable pain. When a horse has laminitis it will either recover fully, suffer acute founder or sink; there are no other alternatives. The development of supra-coronary depressions indicates that there has been recent displacement of the distal phalanx in relation to the hoof capsule. This means a minimum reduction in prognosis of 20% from a laminitis case, and unless effective treatments can be applied quickly (Eustace and Emery, 2009), the development of a distorted hoof characteristic of the chronic 1090-0233/$ - see front matter Ó 2009 Elsevier Ltd. All rights reserved. doi:10.1016/j.tvjl.2009.05.027
founder case is inevitable. Abnormalities of radiological measurements are significant in these first-time founder cases. The term acute founder also covers those cases that develop unilateral distal (medio-lateral) displacement as there is always a degree of proximo-distal displacement in these cases. Neither plain radiographs nor venograms will indicate the duration of an acute founder case, and the clinician needs to know whether supra-coronary depressions were present when the exposures were made. The palpable depth of supra-coronary depressions is significantly correlated with the radiological measurement of founder distance, which is of prognostic significance in acute founder cases (Eustace and Cripps, 1999). The characteristic signs on the hooves of chronic founder cases confirm that the horse has suffered displacement in the past; in such cases, radiological measurements will be abnormal and have little prognostic significance. The treatments used for acute founder cases are not appropriate. The foot is scarred and treatments may optimise the animal’s athletic function by the regular use of appropriate trimming and shoeing treatments. Sometimes division of the deep flexor tendon can improve lameness. To call these cases chronic laminitis is confusing as the majority do not have laminitis, although they do have the distorted hooves resulting from having had acute founder in the past. Chronic laminitis means a horse displaying the signs of laminitis for an unexpectedly long time. Acquired deep digital flexure contracture is the only condition which causes the same changes on the hoof as chronic founder but these can usually be differentiated by clinical history and accurate measurement of founder distance. If a chronic founder case should suffer laminitis again, it is termed a chronic founder case with laminitis. If it should develop supra-coronary depressions as well, it is termed a chronic founder case having recently foundered again. ‘Laminitis’ defines the painful lameness, ‘founder’ identifies that displacement has occurred. The 20% of sinkers which survive do not develop hooves with the characteristic chronic founder distortions. Founder distance is the vertical distance between the proximal limit of the extensor process of the distal phalanx and the rim of mature horn palpable distal to the perioplic ring (coronary band). It is not the distance from the coronary band to the extensor process. There are two reasons why the latter distance is not used: firstly, the distance between the coronary band and the palpable rim of hard horn can measure 10 mm in large horses, and, secondly, when the distal phalanx displaces distally in relation to the hoof capsule, the perioplic ring and soft horn under it is
246
Guest Editorial / The Veterinary Journal 183 (2010) 245–246
Fig. 1. Flow chart of ‘laminitis’ terminology.
dragged down palmar or plantar to the rim so the coronary band is no longer available for comparative measurements of distal displacement. Having described how the results of laminitis on the horse might be described, it is refreshing to read in this issue of The Veterinary Journal that Dr. Ali Reza Nourian and his colleagues at the University of Queensland School of Veterinary Science have developed a technique which should soon shed some light on the nature of the ‘laminitis trigger factors’ which recent research has incriminated as causing the detachment of the dermal and epidermal lamellae (Nourian et al., 2010). This protocol has the great benefit of use in the standing conscious horse so that any effects of analgesics, anaesthesia, variation in normal vascularity or recumbency cannot compromise the validity of the results. It is admirable that such work is being conducted into the investigation of laminitis. The authors are to be commended and we must hope that as much logic can now be applied to nomenclature as is being employed on clarifying aetiopathology.
Robert A. Eustace The Laminitis Clinic, Mead House, Dauntsey, Chippenham, Wiltshire SN15 4JA, UK E-mail address: [email protected]
References Eustace, R.A., Cripps, P.J., 1999. Factors involved in the prognosis of equine laminitis in the UK. Equine Veterinary Journal 31, 433–442. Eustace, R.A., Emery, S.L., 2009. Partial coronary epidermectomy (coronary peel), dorso-distal wall fenestration and deep digital flexor tenotomy to treat severe acute founder in a Connemara pony. Equine Veterinary Education 21, 91–99. Nourian, A.R., Mills, P.C., Pollitt, C.C., 2010. Development of intraosseous infusion of the distal phalanx to access the hoof lamellar circulation in the standing, conscious horse. The Veterinary Journal 183, 273–277. Parks, A.H., Mair, T.S., 2009. Laminitis: a call for a unified terminology. Equine Veterinary Education 21, 102–106.
Contents lists available at ScienceDirect
The Veterinary Journal journal homepage: www.elsevier.com/locate/tvjl
Guest Editorial
Laminitis – What’s in a name?
It seems that for the word laminitis, a very great deal is ‘in the name’. At present, the nomenclature surrounding this condition mirrors the confusion of its aetiopathology (Parks and Mair, 2009). As scientists, we should be able to describe a clinical condition so that others may be able to recognise it without confusion. With this in mind, I offer here a simple system of terminology that needs only the use of hands and eyes, has proven prognostic significance (Eustace and Cripps, 1999) and can be used by both researchers and clinicians (Fig. 1). There are five key definitions. Developmental laminitis – the period between the administration of a known laminitis-inducing diet/toxin and lameness becoming evident. Laminitis – lameness characteristic of the condition, namely, strong digital pulses, toe relieving stance, and weight shifting from one affected foot to another. Acute founder – the clinical signs of laminitis plus palpable supra-coronary depressions extending part way around the coronary contour. The deeper and longer the depressions, the worse the distal displacement will be. Sinker – no characteristic laminitis lameness seen but the animal is reluctant to move, has strong digital pulses and supra-coronary depressions which extend completely around the coronary contour. Chronic founder – any horse with a hoof displaying the following clinical changes: concave dorsal hoof walls, abnormally wide dorsal white lines from quarter to quarter, and divergent growth rings on the hoof walls. The growth rings are more widely spaced at the heels than the toes leading to relative over-growth of the hoof wall at the heels. On palpation the coronary bands often seem soft or indistinct and the skin seems to merge directly with the horn with no recognisable perioplic ring. The term acute laminitis is omitted as all laminitis cases are acutely painful and of relatively sudden onset. Laminitis cases never die or are euthanased because of hoof pathology (there is no displacement – they only die due to medical complications or uncontrollable pain. When a horse has laminitis it will either recover fully, suffer acute founder or sink; there are no other alternatives. The development of supra-coronary depressions indicates that there has been recent displacement of the distal phalanx in relation to the hoof capsule. This means a minimum reduction in prognosis of 20% from a laminitis case, and unless effective treatments can be applied quickly (Eustace and Emery, 2009), the development of a distorted hoof characteristic of the chronic 1090-0233/$ - see front matter Ó 2009 Elsevier Ltd. All rights reserved. doi:10.1016/j.tvjl.2009.05.027
founder case is inevitable. Abnormalities of radiological measurements are significant in these first-time founder cases. The term acute founder also covers those cases that develop unilateral distal (medio-lateral) displacement as there is always a degree of proximo-distal displacement in these cases. Neither plain radiographs nor venograms will indicate the duration of an acute founder case, and the clinician needs to know whether supra-coronary depressions were present when the exposures were made. The palpable depth of supra-coronary depressions is significantly correlated with the radiological measurement of founder distance, which is of prognostic significance in acute founder cases (Eustace and Cripps, 1999). The characteristic signs on the hooves of chronic founder cases confirm that the horse has suffered displacement in the past; in such cases, radiological measurements will be abnormal and have little prognostic significance. The treatments used for acute founder cases are not appropriate. The foot is scarred and treatments may optimise the animal’s athletic function by the regular use of appropriate trimming and shoeing treatments. Sometimes division of the deep flexor tendon can improve lameness. To call these cases chronic laminitis is confusing as the majority do not have laminitis, although they do have the distorted hooves resulting from having had acute founder in the past. Chronic laminitis means a horse displaying the signs of laminitis for an unexpectedly long time. Acquired deep digital flexure contracture is the only condition which causes the same changes on the hoof as chronic founder but these can usually be differentiated by clinical history and accurate measurement of founder distance. If a chronic founder case should suffer laminitis again, it is termed a chronic founder case with laminitis. If it should develop supra-coronary depressions as well, it is termed a chronic founder case having recently foundered again. ‘Laminitis’ defines the painful lameness, ‘founder’ identifies that displacement has occurred. The 20% of sinkers which survive do not develop hooves with the characteristic chronic founder distortions. Founder distance is the vertical distance between the proximal limit of the extensor process of the distal phalanx and the rim of mature horn palpable distal to the perioplic ring (coronary band). It is not the distance from the coronary band to the extensor process. There are two reasons why the latter distance is not used: firstly, the distance between the coronary band and the palpable rim of hard horn can measure 10 mm in large horses, and, secondly, when the distal phalanx displaces distally in relation to the hoof capsule, the perioplic ring and soft horn under it is
246
Guest Editorial / The Veterinary Journal 183 (2010) 245–246
Fig. 1. Flow chart of ‘laminitis’ terminology.
dragged down palmar or plantar to the rim so the coronary band is no longer available for comparative measurements of distal displacement. Having described how the results of laminitis on the horse might be described, it is refreshing to read in this issue of The Veterinary Journal that Dr. Ali Reza Nourian and his colleagues at the University of Queensland School of Veterinary Science have developed a technique which should soon shed some light on the nature of the ‘laminitis trigger factors’ which recent research has incriminated as causing the detachment of the dermal and epidermal lamellae (Nourian et al., 2010). This protocol has the great benefit of use in the standing conscious horse so that any effects of analgesics, anaesthesia, variation in normal vascularity or recumbency cannot compromise the validity of the results. It is admirable that such work is being conducted into the investigation of laminitis. The authors are to be commended and we must hope that as much logic can now be applied to nomenclature as is being employed on clarifying aetiopathology.
Robert A. Eustace The Laminitis Clinic, Mead House, Dauntsey, Chippenham, Wiltshire SN15 4JA, UK E-mail address: [email protected]
References Eustace, R.A., Cripps, P.J., 1999. Factors involved in the prognosis of equine laminitis in the UK. Equine Veterinary Journal 31, 433–442. Eustace, R.A., Emery, S.L., 2009. Partial coronary epidermectomy (coronary peel), dorso-distal wall fenestration and deep digital flexor tenotomy to treat severe acute founder in a Connemara pony. Equine Veterinary Education 21, 91–99. Nourian, A.R., Mills, P.C., Pollitt, C.C., 2010. Development of intraosseous infusion of the distal phalanx to access the hoof lamellar circulation in the standing, conscious horse. The Veterinary Journal 183, 273–277. Parks, A.H., Mair, T.S., 2009. Laminitis: a call for a unified terminology. Equine Veterinary Education 21, 102–106.