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.

Multisystemic eosinophilic epitheliotropic disease in three donkeys.

Multisystemic eosinophilic epitheliotropic disease (MEED) is a rare condition of equids characterized by eosinophilic infiltration of multiple organs. Clinical signs are variable depending on the affected organs. The most common clinical signs include chronic weight loss, diarrhoea and exfoliative dermatitis. Respiratory distress and raised liver enzymes are less frequently seen. The cause is unknown and the pathogenesis is poorly understood. There are less than 50 reported cases of horses with MEED. We now document the lesions in three donkeys with fluctuating or chronic loss of weight, lethargy, exfoliative dermatitis and peripheral eosinophilia. All three animals were euthanized due to poor prognosis and welfare concerns. Post-mortem examination revealed multiple white to tan, irregular masses composed of eosinophilic infiltrates, including eosinophilic granulomas in several organs, confirming the presence of MEED. To the best of our knowledge, MEED has not previously been reported in donkeys.

Treponema spp. spirochetes and keratinopathogenic fungi isolated from keratomas in donkeys.

Keratoma is an aberrant keratin mass thought to originate from epidermal horn-producing cells interposed between the stratum medium of the hoof wall and the underlying third phalanx. The cause is unknown, although the presence of keratomas is frequently associated with chronic irritation, focal infection, or trauma. A total of 167 donkeys with keratomas were presented in this study. The diagnosis of a keratoma was based on clinical signs, radiography, and histopathologic examination. Surgical excision was attempted on all donkeys with lameness unless euthanasia was advised. Histopathologic examination, including Giemsa, periodic acid Schiff, and Young's silver special histochemical stains, was performed and showed the presence of fungal hyphae and spirochete bacteria within the degenerate keratin. Polymerase chain reaction (PCR) for treponeme bacteria was performed on 10 keratoma lesions and 9 healthy pieces of hoof (controls). All healthy donkey tissues were negative for the 3 recognized digital dermatitis (DD) treponeme phylogroups, whereas 3 of 10 (30%) donkey keratoma samples were positive for one of the DD treponeme phylogroups. Routine fungal culture and PCR for fungi were performed on 8 keratoma lesions and 8 healthy pieces of hoof (controls). Keratinopathogenic fungi were detected in 1 of 8 (12.5%) keratomas, while only non-keratinopathogenic, environmental fungi were detected in 8 control healthy hoof samples. This is the first time the DD treponemes phylogroup and keratinopathogenic fungi have been detected in keratomas. Further studies are required to assess the significance of this finding.

Alzheimer-like pathology in the parietal cortex and hippocampus of aged donkeys.

Neurodegenerative disorders are gaining ever more importance in ageing populations of animals and people. Altered insulin signaling and type II diabetes have been linked to the development of Alzheimer's disease (AD) in humans and AD-like neurodegeneration in other long-lived animals. Donkeys are unusual amongst domestic species for their exceptional longevity and are additionally predisposed to abnormalities of insulin metabolism similar to those found in humans. In this study, the parietal lobe and hippocampus of 13 aged (>30 years) and 2 younger control donkeys were evaluated immunohistologically for the presence, distribution, and frequency of neurofibrillary tangles (NFT) and amyloid plaques (AP); the characteristic lesions of AD. AP were in parietal cortices of 9 donkeys, with a predilection for deep sulci, and NFT-like structures were observed in 7 donkeys, primarily within cortical areas. No changes were observed in the control donkeys. This represents the first identification of both AP and NFT in equids and is a stimulus for future work assessing their metabolic status in parallel.

Oesophageal Obstruction in a Donkey Due to Mediastinal Lymphadenitis Caused by Mycobacterium avium Complex.

Mycobacterial infections are rare in horses, donkeys and mules. Although there are a few reports in horses, mycobacterial disease is poorly documented in the donkey. Mycobacterial infection of equine species typically affects the alimentary tract, causing granulomatous enterocolitis resulting in diarrhoea and chronic weight loss, while lymph nodes and liver may also be affected. We now document recurrent oesophageal obstruction, secondary to cranial mediastinal lymphadenitis caused by Mycobacterium avium complex (MAC). To the best of our knowledge, this is the first report of MAC infection in a donkey in the UK.

Suspensory Ligament Desmitis Caused by Onchocerca sp. in Three Donkeys.

Three donkeys were presented with progressive lameness and distal suspensory ligament breakdown in multiple limbs. Treatment with nonsteroidal anti-inflammatory drugs was only partially effective and eventually the donkeys were euthanized due to further progression of the lameness and concerns for their welfare. At necropsy, the distal part of the suspensory ligaments in multiple limbs, including the suspensory ligament branches, was markedly thickened, enlarged, and mottled white and brown on cut section. In one case, adult Onchocerca sp. nematodes were grossly identified embedded within the suspensory ligaments. Histopathologic examination revealed chronic, multifocal to coalescing, moderate to severe, lymphoplasmacytic, eosinophilic, and fibrosing desmitis and tendinitis with intralesional, coiled adult nematodes of Onchocerca sp., accompanied by osseous and cartilaginous metaplasia. To the authors' knowledge, this is the first histopathologic description of suspensory ligament desmitis and tendinitis associated with Onchocerca sp. in donkeys.

First record of besnoitiosis caused by Besnoitia bennetti in donkeys from the UK.

BACKGROUND: The involvement of Besnoitia bennetti in skin pathologies was investigated in a series of 20 donkeys from the Donkey Sanctuary in England, in the 2013-2019 period. METHODS: The initial histopathological finding of Besnoitia cysts in skin lumps that were presumed to be sarcoids in 2013 triggered our cognisance of this parasite and resulted in identification of a total of 20 cases. Histopathological examination of surgical biopsy samples collected from 8 live donkeys and tissue specimens from 12 deceased donkeys at post-mortem examination revealed the presence of Besnoitia cysts in all 20 donkeys. The indirect fluorescent antibody test (IFAT) and immunoblotting analysis showed the presence of anti-Besnoitia antibodies in archived serum samples from 4 deceased donkeys. Additionally, infection was evidenced in one live donkey based on IFAT and immunoblot analysis of tissue fluid of a dermal mass containing Besnoitia cysts, and real-time (RT)-PCR analysis and microsatellite genotyping of DNA isolated from the tissue of the same dermal mass confirmed the infection specifically as B. bennetti. RESULTS: Both serological and microsatellite analyses confirmed the aetiology to be B. bennetti. Our findings suggested that in cases of skin masses such as sarcoids, the suspicion of B. bennetti infection should be borne in mind even when clinical and histopathology examination results are negative in order to avoid misdiagnosis. CONCLUSIONS: This case series documents, to our knowledge, the first report of B. bennetti infection in donkeys in the UK, indicating that donkey besnoitiosis has become noteworthy in the UK. Further investigations of the occurrence, epidemiological characteristics, and clinical manifestations of B. bennetti infection in donkeys and other equids are warranted.