Two young adult dogs with gastrointestinal signs were each found to have an intra-abdominal mass based on physical examination and diagnostic imaging. On exploratory laparotomy, small intestinal masses and mesenteric lymphadenopathy were found in both dogs; a liver mass was also found in dog 1. Cytologic and histologic examination of intestinal and liver masses and mesenteric lymph nodes revealed 2 distinct lymphoid cell populations: lymphoblasts and atypical Mott cells. With Romanowsky stains, the atypical Mott cells contained many discrete, clear to pale blue cytoplasmic inclusions consistent with Russell bodies that were positive by immunohistochemistry for IgM and CD79a in both dogs and for IgG in dog 2. The Mott cells and occasional lymphoblasts stained strongly positive with periodic acid-Schiff. Using flow cytometric immunophenotyping in dog 1, 60% of peripheral blood mononuclear cells and 85% of cells in an affected lymph node were positive for CD21, CD79a, IgM, and MCH II, indicative of B-cells. With electron microscopy, disorganized and dilated endoplasmic reticulum was seen in Mott cells in tumors from both dogs. Antigen receptor gene rearrangement analysis of lymph node and intestinal masses indicated a clonal B-cell population. Based on cell morphology, tissue involvement, and evidence for clonal B-cell proliferation, we diagnosed neoplasms involving Mott cells. To the authors' knowledge, this is the second report of Mott cell tumors or, more appropriately, B-cell lymphoma with Mott cell differentiation, in dogs. More complete characterization of this neoplasm requires further investigation of additional cases. This lymphoproliferative disease should be considered as a differential diagnosis for canine gastrointestinal tumors.
OBJECTIVE- To determine clinical, histologic, and immunohistochemical findings for dogs with wart-like lesions involving the paw pads. DESIGN- Retrospective case series. ANIMALS- 24 dogs (18 Greyhounds and 6 dogs of other breeds). PROCEDURES- Medical records were reviewed for information on signalment, physical examination findings, concurrent disease processes, location of all lesions, and, when available, results of histologic examination of biopsy specimens. Available biopsy specimens (n = 11) were submitted for immunohistochemical staining and a PCR assay to identify viral inclusion bodies. RESULTS- In Greyhounds, most lesions involved the pads of the third and fourth digits, had a consistent histologic appearance without evidence of inflammation, were negative for papillomavirus, and had an unsatisfactory response to treatment. In other breeds, lesions often involved the pads of non-weight-bearing digits, had histologic evidence of inflammation, were positive for papillomavirus, and responded to surgical treatment. CONCLUSIONS AND CLINICAL RELEVANCE- Results suggested that wart-like lesions involving the paw pads of Greyhounds were a distinct clinical entity with features resembling porokeratosis plantaris discreta in humans. In Greyhounds, these lesions were not associated with an underlying viral etiology and, therefore, should not be considered plantar warts. Alternative treatments should be investigated because current treatments were generally unsuccessful in Greyhounds. Wart-like lesions of the paw pads in other breeds were often associated with papillomavirus, and surgical excision appeared curative.
The schistosome Heterobilharzia americana infects dogs, raccoons, and other mammals in the southeastern United States. Migration of eggs into the liver results in parasitic granulomas with varying degrees of fibrosis and inflammation. Recently, hepatic parasitic granulomas in horses were shown to be caused by H. americana infection. In the present study, samples of liver from 11 of 12 horses with hepatic granulomas identified at necropsy (n ¼ 11) or surgical biopsy (n ¼ 1) were used for DNA extraction, polymerase chain reaction amplification and sequencing using primers specific for a portion of the H. americana small subunit ribosomal RNA gene. A polymerase chain reaction amplicon of the correct size was produced from the extracted DNA in 8 of the 11 horses. Amplicons from 5 of the 8 positive horses were sequenced and had 100% identity with H. americana. In all but 2 of the 12 horses, Heterobilharzia was not responsible for the primary clinical disease, and the hepatic granulomas were considered an incidental finding.
A 25-year-old intact female orange-winged Amazon parrot (Amazona amazonica) presented for a 2-week history of straining to defecate, lethargy, open-beak breathing, decreased vocalization, and ruffled feathers. On physical examination, the parrot had a heart murmur, increased air sac and lung sounds, open-beak breathing, increased respiratory rate and effort, and coelomic distension. An ultrasound revealed intracoelomic fluid, and hemorrhagic fluid was aspirated from the coelom. Cytologic analysis indicated hemocoelom. Pericardial effusion was observed during the sonogram, and pericardiocentesis was performed. The bird was euthanatized upon the owner's request because of a poor prognosis. At necropsy, several masses that involved the ovary and oviduct were observed, as well as a thickened pericardium and a thickened, fibrinous epicardium. Results of a histopathologic examination of the masses that involved the reproductive tract revealed ovarian hemangiosarcoma, which was confirmed by immunohistochemical staining. To our knowledge, ovarian hemangiosarcoma has not been reported in a psittacine species, nor has immunohistochemistry confirmed ovarian hemangiosarcoma in avian species, specifically in an orange-winged Amazon parrot.
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