Pulmonary angiocentric lymphoma (lymphomatoid granulomatosis) in a donkey

Multicentric lymphoma in a donkey with intestinal and bone marrow involvement

BACKGROUND

Lymphoma is a common neoplasm in horses but is reported much less commonly in donkeys. In this case report, we describe the macroscopic, microscopic and immunohistochemical features of a multicentric lymphoma with intestinal and bone marrow involvement.

CASE PRESENTATION

A geriatric female donkey with history of chronic lameness was found dead. Post-mortem examination revealed advanced emaciation, periodontal disease, left front foot laminitis and multiple, soft, white to yellow tan intestinal transmural masses, up to 12 cm in diameter. Cytology suggested a round cell intestinal neoplasm. The femur of the left hint limb was double the size of the normal contralateral, with suspected neoplastic infiltration and replacement of bone marrow and bone. Histologically we diagnosed a lymphoma in the intestine and left femur. Immunohistochemically, the neoplastic cells showed CD3 immunolabelling, supporting a diagnosis of a multicentric T-cell lymphoma.

CONCLUSIONS

To the authors' knowledge, this is the first time multicentric lymphoma is diagnosed in donkeys. Further studies of the genetic background, clinical, laboratory, histopathologic, and immunohistochemical, as well as the pathogenesis of lymphoma, is needed to better understand the uniquely low frequency of this neoplasm in donkeys.

Recent advancements in our understanding of equid gammaherpesvirus infections

Equid gammaherpesviruses are ubiquitous and widespread in the equine population. Despite their frequent detection, their contribution to immune system modulation and the pathogenesis of several diseases remains unclear. Genetic variability and the combination of equid gammaherpesvirus strains a horse is infected with might be clinically significant. Initial gammaherpesvirus infection occurs in foals peripartum with latency then established in peripheral blood mononuclear cells. A novel EHV-5 study suggests that following inhalation equid gammaherpesviruses might obtain direct access to T and B lymphocytes via the tonsillar crypts to establish latency. EHV-5 is associated with equine multinodular pulmonary fibrosis, however, unlike with EHV-2 there is currently minimal evidence for its role in milder cases of respiratory disease and poor performance. Transmission is presumed to be via the upper respiratory tract with periodic reactivation of the latent virus in adult horses. Stress of transport has been identified as a risk factor for reactivation and shedding of equine gammaherpesviruses. There is currently a lack of evidence for the effectiveness of antiviral drugs in the treatment of equine gammaherpesvirus infections.

Donkey Internal Medicine—Part II: Cardiovascular, Respiratory, Neurologic, Urinary, Ophthalmic, Dermatology, and Musculoskeletal Disorders

Cardiovascular diseases are scarcely reported in donkeys, probably linked to their limited athletic attitude and low frequency of poor performance-related examinations. Reports on treatments for cardiovascular pathologies are anecdotal in donkeys. Respiratory tract anatomy shows important differences between horses and donkeys. Donkeys and mules can act as reservoirs spreading many viral, bacterial, and parasitic infectious respiratory diseases. Mosquito and tick-borne encephalitis have been reported in these species in the later years, and even donkeys are being used as sentinels in some areas to detect these emerging diseases. Management and treatment of lithiases can be transferable from horses; however, the same assumption must still be demonstrated for acute and chronic renal diseases. Ocular pathologies are similar to horses, with corneal ulcers frequently observed. Lameness is a common problem in donkeys, with laminitis as the most reported cause followed by pedal abscess.

•

Donkeys are different to horses.

•

Numerous physiological and clinicopathologic idiosyncrasies are reported in horses.

•

Data published for horses should not be extrapolated for donkeys.

•

Specific reference ranges, doses, and protocols have to be used for donkeys.

Neoplasia in 125 donkeys (Equus asinus): literature review and a survey of five veterinary schools in the United States and Canada

A diagnosis of neoplasia was noted in 125 of 357 donkeys (35%) in our review of medical records from 5 veterinary schools in the United States and Canada. Equine sarcoid was the most common tumor in our study, accounting for 72% of all tumors and 82% of cutaneous tumors. Soft-tissue sarcomas were the second most common skin tumors. All other types of neoplasia were rare. Important differences in the occurrence of neoplasia in donkeys compared to horses included the rarity or absence of squamous cell carcinoma in any organ system and gray horse melanoma. Lymphosarcoma, the most common malignant tumor in horses, appears to be very rare in donkeys. We report several tumors in donkeys including melanocytoma, peripheral nerve sheath tumor, and gastrointestinal stromal tumor. Our data demonstrate commonalities as well as differences in neoplastic diseases of donkeys and horses. Understanding differences in carcinogenesis among these 2 closely related species can inform researchers pursuing pathogenic mechanisms of equine disease and inform veterinary diagnosticians regarding tumor prevalence.

Gammaherpesvirus infections in equids: a review

Although the first equine gammaherpesvirus was identified over 50 years ago, the isolation and characterization of other members of this virus group has been relatively recent. Even so, numerous clinical syndromes have been identified in equid species in association with these viruses. Equid gammaherpesviruses are a genetically heterogeneous viral subfamily, the function of which in host immune modulation and disease pathogenesis has not yet been elucidated. While they share similarities with gammaherpesviruses in humans, the role they play in their relationship with the host is the subject of continued interest and research. Their widespread presence in horses and other equid species provides a considerable challenge in linking them with particular clinical and pathological conditions and in defining their significance from a diagnostic and therapeutic viewpoint. The present review provides an update on the taxonomy, epidemiology, and clinical syndromes, especially respiratory, reported in association with gammaherpesvirus infection in horses, donkeys, and other equid species.