Skin Disorders of the Donkey and Mule.

Skin disease in donkeys is less common than in horses, but is easily overlooked. Little published material exists on this important area of equine medicine. Skin tumors continue to challenge veterinarians working with donkeys. This article outlines the main disease entities that the author has encountered, although there are many other diseases and disorders that occur in different parts of the world that are not yet appreciated. When investigating a skin disease, a logical and comprehensive clinical approach should always be made; many conditions are similar in clinical presentation or are complicated by comorbidity or secondary infection, infestation, or self-trauma.

The Equine Sarcoid: Why Are There so Many Treatment Options?

This article discusses the main treatments for sarcoid and the specific difficulties of these. It explains to some extent why the frustrations of a condition for which there is no single treatment option have led to the burgeoning of an industry of irrational treatments. The factors that need to be considered before selecting an option for treatment are wider than is the case in most other disease entities as a result of the complexity of the condition, its variable phenotypes, and the individual perceptions and experiences of both veterinarians and owners.

Integumentary Disorders Including Cutaneous Neoplasia in Older Horses.

Few skin diseases specifically or exclusively affect older horses and donkeys. Hypertrichosis (hirsutism) associated with pituitary pars intermedia dysfunction is probably the most recognized and best understood exception and is the most common age-related skin condition in equids. Many other conditions are known to be more serious in older horses. Horses affected with immune-compromising conditions can be more severely affected by infectious diseases of the skin or heavy and pathologically significant parasitism. Neoplasia of the skin is probably more prevalent and worse in older horses, although many of the more serious skin tumors develop initially at a younger age.

Equine sarcoid: In situ demonstration of matrix metalloproteinase expression.

Sarcoids are the most prevalent equine skin tumours and remain a therapeutic challenge due to their differing clinical morphology, local aggressive behaviour, and high recurrence following surgical treatment. In vitro, sarcoid derived fibroblasts are invasive and express matrix metalloproteinase (MMP) -1, -2 and -9. It was hypothesised that the MMPs produced by neoplastic cells play a role in both their local invasiveness and interaction with the overlying epidermis (picket fence formation). The objective of this morphological study was to investigate the local behaviour and in situ MMP expression pattern in sarcoids of different clinical types. A total of 43 surgically excised sarcoids were examined by histology, immunohistology for the expression of MMP-1, -2 and -9, and transmission electron microscopy. Regardless of the clinical type, sarcoids showed local invasion of the dermis and damage to the basement membrane in areas of interaction with the epidermis. This was associated with MMP-1 expression in both neoplastic cells and epidermis. The results suggest a link between MMP-1 expression and the local aggressiveness of sarcoids regardless of the clinical type.

The approach to the equine dermatology case in practice.

A logical and thorough clinical investigation should provide the best basis for the diagnosis of skin diseases. Where no diagnosis can be reached despite a full range of investigations, the clinician can justifiably attempt symptomatic treatment, but it is always better to focus treatment on a specific condition based on properly accumulated and tested clinical evidence. Unfortunately, in equine dermatology there are few text descriptions of the majority of the conditions encountered in practice. While a few diseases are well recognized, there is still little consensus on the best treatments for many of them. Individual veterinarians will have treatments that they rely on, but frequently the same treatment applied by another person inexplicably fails to work in the same way. In dermatology cases, there is no substitute for experience. Referencing to quality textbooks and to colleagues who might have encountered the condition before is often advisable. Unusual presentations are frequently encountered in horses. For example, there are many manifestations of the pemphigus group of diseases, and not all will have a clear diagnostic pathway. It is important to remember that the skin is one of the biggest organs in the body and yet little is known of its function and pathology! While there are many significant primary dermatologic conditions, there are also important systemic diseases that have more or less pathognomonic secondary dermatologic signs; this makes the proper clinical examination even more imperative. One of the biggest problems with equine dermatology is the dearth of scientific reports. Many experienced clinicians have much useful information, but this may never reach the rest of the profession. Also there are few useful reference textbooks dedicated to the equine species. Equine dermatology most likely suffers the most of all disciplines in this respect. As a result, every clinician is expected to reinvent the wheel! There is a need for publications and discussions about the problem cases; even the commonest skin diseases are poorly understood. To make the most use of the supporting specialties of microbiology and pathology, it is important to involve the relevant specialists in the diagnostic process. This means that these specialists must have as much information as they can get; it helps enormously if a photograph can be taken of the disease. Without such information, pathologists and microbiologists may make gratuitous statements about treatment options. For example, a biopsy from an upper eyelid lesion might be easily diagnosed as a sarcoid, and any statement concerning wide surgical excision might be both misleading and nonsensical but would be totally avoidable had the specialist been provided more information. The approach to the dermatologic case requires a logical and exhaustive clinical investigation involving a thorough history and a detailed clinical examination. Diagnostic tests should be carefully selected to rule-out or confirm a suspected diagnosis. Frequent reexaminations are often required because it is sometimes difficult to establish the primary condition: this is often due to extensive self-inflicted trauma or iatrogenic interference by the owner. By proceeding in a systematic and stepwise manner, equine ambulatory clinicians can frequently bring dermatologic problems to a successful resolution.

Identification of a mutation associated with fatal Foal Immunodeficiency Syndrome in the Fell and Dales pony.

The Fell and Dales are rare native UK pony breeds at risk due to falling numbers, in-breeding, and inherited disease. Specifically, the lethal Mendelian recessive disease Foal Immunodeficiency Syndrome (FIS), which manifests as B-lymphocyte immunodeficiency and progressive anemia, is a substantial threat. A significant percentage (∼10%) of the Fell ponies born each year dies from FIS, compromising the long-term survival of this breed. Moreover, the likely spread of FIS into other breeds is of major concern. Indeed, FIS was identified in the Dales pony, a related breed, during the course of this work. Using a stepwise approach comprising linkage and homozygosity mapping followed by haplotype analysis, we mapped the mutation using 14 FIS-affected, 17 obligate carriers, and 10 adults of unknown carrier status to a ∼1 Mb region (29.8 - 30.8 Mb) on chromosome (ECA) 26. A subsequent genome-wide association study identified two SNPs on ECA26 that showed genome-wide significance after Bonferroni correction for multiple testing: BIEC2-692674 at 29.804 Mb and BIEC2-693138 at 32.19 Mb. The associated region spanned 2.6 Mb from ∼29.6 Mb to 32.2 Mb on ECA26. Re-sequencing of this region identified a mutation in the sodium/myo-inositol cotransporter gene (SLC5A3); this causes a P446L substitution in the protein. This gene plays a crucial role in the regulatory response to osmotic stress that is essential in many tissues including lymphoid tissues and during early embryonic development. We propose that the amino acid substitution we identify here alters the function of SLC5A3, leading to erythropoiesis failure and compromise of the immune system. FIS is of significant biological interest as it is unique and is caused by a gene not previously associated with a mammalian disease. Having identified the associated gene, we are now able to eradicate FIS from equine populations by informed selective breeding.

Chronic equine wounds: what is the role of infection and biofilms?.

Wound research is an evolving science in the equine species. In particular, interest is growing regarding the role that microorganisms play in delaying both acute and chronic wound healing. Equine wounds, particularly lower limb wounds, frequently display delayed healing and infection is commonly the underlying reason. This review will summarize the current research and knowledge surrounding equine wound healing and wound care. Particular focus is placed on the role that microbes play in chronic equine wounds and the significance of associated bacterial biofilms. .

Primary intraocular primitive neuroectodermal tumor (retinoblastoma) causing unilateral blindness in a gelding.

A 14-year-old gray gelding was presented for investigation of a visible, pale-colored ocular mass in the right eye. An intraocular mass was identified clinically and ultrasonographically as originating from the superior nasal quadrant of the ciliary body and retina. The mass occupied the majority of the vitreous chamber and some of the superior anterior chamber of the eye. The affected eye was blind. Following exenteration, a primary intraocular primitive neuroectodermal tumor (i.e. a retinoblastoma/medulloepithelioma), a rarely described intraocular mass in adult horses, was identified by pathologic examination. The gelding returned to normal use following a short recovery period.

Discriminant and multiple regression analysis of anemia and opportunistic infection in Fell pony foals.

A condition resembling acquired immunodeficiency with anemia has been described in British Fell pony foals. The pathogenesis is unknown. The present study involved 322 foals of which 164 were of Fell breed and 12 were affected. Discriminant and multiple regression analyses were used to test the results of all clinical pathology parameters from these foals for statistical association with (1) breed origin and (2) presence of disease. Only hematocrit associated significantly with presence of disease. However, significant associations were found with Fell breed origin, including serum albumin concentration and lymphocyte count. The unexpected discovery of sporadic lymphocytosis in the breed indicates the value of this kind of analysis and may be evidence that Fell foal immunodeficiency is associated with retroviral infection.

Equine wound management: are there significant differences in healing at different sites on the body?

Abstract Trunk/body wounds heal rapidly with prominent Contraction while wounds on the limb commonly fail to heal or heal slowly by centripetal epithelialization. often with insignificant contraction. Chronic exuberant granulating wounds on the limbs heal well after grafting from donor sites on the trunk. Indolent wounds are less common but may granulate significantly following moist wound-healing management. Sarcoid transformation is an increasingly important cause of healing failure. Sarcoid transformations on the trunk are commonly verrucose while those on the limb are usually aggressive and fibroblastic. The primary objective of wound management should be to encourage rapid progression from acute inflammation to repair without intervention of chronic inflammation which is a significant factor in the pathophysiology of wound healing failure. Wounds fail to heal because there is disruption of the normal delicate balance of growth factors and inflammatory mediators. Wounds should be managed in such a way as to restore the balance of healing processes without damaging any of the cells involved in healing. Resumen Las heridas localizadas en el cuerpo o tronco curan rapidamente con contracción elevada, mientras que las de las extremidades no curan o curan lentamente por epitelización centrípeta, a menudo con contracción insignificante. Las heridas crónicas con tejido de granulación exhuberantes en las extremidades curan bien después de injertos a partir de áreas del tronco. Las heridas indolentes son menos frecuentes pero pueden granular significativamente después de un manejo húmedo de la curacion de la herida. La transformación sarcoidal es una causa cada vez más frecuente de fracaso de la curación. Las transformaciones sarcoidales en el tronco son generalmente de tipo verrucoso mientras que las de las extremidades son normalmente agresivas y fibroblásticas. El objetivo principal del manejo de heridas tendría que ser la estimulación de una progresión rápida de una inflamación aguda a la resolución sin intervención de inflamación crónica, que es un factor significativo en la patofisiología del fracaso en la curación de heridas. Las heridas no curan porque se produce una alteración en el fraegil equilibrio normal de factores de crecimiento y mediadores inflamatorios. Las heridas tendrian que ser manejadas de forma que se restaure el equilibrio del proceso curativo sin dañar ninguna de las células implicadas en la curacion. [Knottenbelt, D.C. Equine wound management: are there significant differences in healing at different sites on the body? (Manejo de heridas equinas: existen diferencias significativas en la curación en diferentes areas cutaneas?). Veterinar.): Dermatology 1997; 8: 273-290] Zusammenfassung Wunden am Rumpf heilen schnell und mit deutlicher Kontraktion, während sich Wunden an den Gliedmassen oft nur geringfügig zusammenziehen und entweder gar nicht oder nur langsam vom Rande her epithelisieren. Chronische, stark wuchernde Wunden an den Gliedmassen heilen nach Gewebetransplantation vom Rumpf zufriedenstellend. Indolente Wunden sind weniger häfig, können aber nach benetzender Wundversorgung deutlich granulieren. Sarkoide Transformation ist ein wichtiger Grund für Wundheilungstörungen. Sarkoide Transformationen am Rumpf sind gewöhnlich warzig, jene an den Gliedmassen üblicherweise aggressiv und fibroblastisch. Das wichtigste Ziel der Wundversorgung sollte es sein, eine schnelle Entwicklung von akuter Entzündung zur Heilung zu fördern, ohne in die chronische Entzündung einzugreifen, die ein massgeblicher Faktor in der Störung der Windheilung darstellt. Der Grund für eine nichtheilende Wunde ist eine Störung des enipfindlichen Gleichgewichts zwischen Wachstumsfaktoren und Entzündungsmediatoren. Wundversorgung soll das Gleichgewicht des Heilungsprozesses wiederherstellen, ohne Zellen zu beschädigen, die zur Wundheilung beitragen. [Knottenbelt, D.C. Equine wound management: are there significant differences in healing at different sites on the body? (Wundversorgung beim Pferd: Sind signifikante Heilungsunterschiede an verschiedenen Körperstellen vorhanden?). Veterinary Dermatology 1997; 8: 273-290] Résumé Les plaies affectant le tronc cicatrisent rapidement avec une contraction proéminente tandis que les plaies des membres cicatrisent ma1 ou lentement avec une épithélialisation centripète, et souvent avec une contraction insignifiante. Les plaies présentant une granulation chronique exhubérante sur les membres cicatrisent bien après greffe à partir d'un fragment prélevé sur le tronc. Les plaies atones sonl moins fréquentes, mais peuvent présenter un tissu de granulation significatif après application de pansements humides. La transformation en sarcoïde est une cause de plus en plus importante d'échec de cicatrisation. Les transformations en sarcoïdes sur le tronc sont fréquemment verruqueuses, alors que celles localisées sur les membres sont généralement agressives et fibroblastiques. Le but premier du traitement d'une plaie est de promouvoir la progression rapide d'une inflammation aigüe en cicatrisation sans passage par l'inflammation chronique qui est un facteur significatif dans la pathophysiologie de l'échec de cicatrisation des plaies. Les plaies ne cicatrisent pas parce qu'il y a un déséquilibre de la balance délicate entre facteurs de croissance et médiateurs de l'inflammation. Les plaies doivent être traitées de manière à restaurer l'équilibre des processus de cicatrisation sans altération des cellules impliquées dans l'inflammation. [Knottenbelt, D.C. Equine wound management: are there significant differences in healing at different sites on the body? (Traitement des plaies équines: y-a-t-il des différences significatives de cicatrisation en fonction de la topographie corporelle?). Veterinary Dermatology 1997; 8: 273-290].