Rabbit Journal Summaries

Rabbit Retrospective Study of Neurological Disease in 118 Rabbits: 78 animals (66.1%) had inflammatory lesions of the CNS. Encephalitozoonosis was diagnosed in 69 (58.5%) of these rabbits and 2 animals had herpes simplex virus encephalitis. Cystic Mammary Adenocarcinoma Associated with a Prolactinsecreting Pituitary Adenoma in a New Zealand White Rabbit ( Oryctolagus cuniculus ). Vol 58, No 3 June 2008. Histologic evaluation confi rmed the presence of a pituitary adenoma, mammary hyperplasia, dysplasia, and cystic mammary adenocarcinoma. Immunohistochemical staining confi rmed the presence of abundant prolactin secreting cells in the pituitary adenoma. Solitary Biliary Hamartoma with Cholelithiasis in a Domestic Rabbit (Oryctolagus cuniculus). Vet Pathol 44:92–95 (2007). network of large varying sized cystic structures lined by simple cuboidal to columnar epithelium within an abundant fibrous stroma. Within many of the cyst lumina were varying sized, pale white to greenish hard concretions identified as choleliths and were analyzed and found to be composed of calcium carbonate. (human synonym=von Meyenburg Complexes). Effects of Autologous Stem Cells on Immunohistochemical Patterns and Gene Expression of Metalloproteinases and Their Tissue Inhibitors in Doxorubicin Cardiomyopathy in a Rabbit Model. Vet Pathol 44:494–503 (2007). In conclusion, chronic doxorubicin cardiomyopathy was characterized by increased MMP and decreased TIMP-3 expression. MSCs injection into the LV resulted in marked differences of collagen content and MMP/TIMP expression in the whole heart. After MSC injection, MMP-1, MMP-2, and TIMP-3 expression was higher. Testicular Interstitial Cell Tumor and Gynecomastia in a Rabbit. Vet Pathol 44:513–517 (2007). Neoplastic interstitial cells exhibited diffuse, granular cytoplasmic staining with Melan A. Multiple subcutaneous masses in the caudal abdomen were associated with enlarged nipples and consisted of hyperplastic mammary gland tissue with proliferation of ducts and alveoli, marked lobule formation, and pseudolactational hyperplasia. Many epithelial cells lining the hyperplastic ducts and alveoli exhibited intense nuclear expression of progesterone receptor antigen, whereas myoepithelial cells showed strong nuclear staining for p63 antigen. Cutaneous Neoplasms in Pet Rabbits: A Retrospective Study. Vet Pathol 44:579–588 (2007). The most common diagnoses were trichoblastoma, collagenous hamartoma, and Shope fibroma. Viral-induced tumors were Shope fibroma (19) and Shope papilloma (2). Common nonviral epithelial tumors included trichoblastoma (59), squamous cell carcinoma (5), squamous papilloma (4), trichoepithelioma (3), and apocrine carcinoma (3). Common mesenchymal tumors were lipoma (10), liposarcoma (3), myxosarcoma (9), malignant peripheral nerve sheath tumor (8), fibrosarcoma (7), and leiomyosarcoma (4).

Spontaneous Osteosarcoma in a Rabbit (Oryctolagus cuniculus). Vet Pathol 44:691– 694 (2007). Proliferative and destructive lesions of bone were observed. On histologic examination, the tumor was composed of proliferating neoplastic cells that resembled histiocytes, with abundant osteoid production. A large number of multinucleated giant cells were found throughout. Spontaneously Occurring Alimentary Osteofluorosis Associated with Proliferative Gastroduodenopathy in Rabbits. Vet Pathol 44:703–706 (2007). Painful thickenings of the extremities, multiple osseous proliferations of extremities and mandibles and a mild to severe proliferative gastroduodenopathy. Histologically, periosteal and endosteal hyperostosis and a mild to severe proliferation of the gastric and duodenal mucosa were noted. Major clinical manifestations of chronic fluoride intoxication are dental fluorosis and osteofluorosis. Dental fluorosis is characterized by enamel mottling and hypoplasia, and osteofluorosis by periosteal hyperostosis displaying a roughened irregular surface. Granular Cell Tumor in the Testis of a Rabbit: Cytologic, Histologic, Immunohistochemical, and Electron Microscopic Characterization Vet Path 2008 Jan: GCT may occur in the genital tract, including the vulva, clitoris, vagina, cervix, and/or uterus of cats, rodents. The tumor cells were vimentin, Melan A, NSE and Ki67 positive. DDx is leydig cell tumor

Choriocarcinoma with Metastasis in a Rabbit Vet Path 2008 Jan: uterine mass consisted of 3 different (trophoblastic, syncytiotrophoblastic, and cytotrophoblastic); positive cytokeratin in all 3 cell types, and the syncytiotrophoblasts were positive also for human chorionic gonadotropin. Choriocarcinoma is a highly malignant neoplasm of trophoblastic cells arising in placental tissue, ovary, testis, or sequestered remains of totipotential cells in the mediastinum or abdomen The Immunohistochemical Evaluation of Estrogen Receptor-{alpha} and Progesterone Receptors of Normal, Hyperplastic, and Neoplastic Endometrium in 88 Pet Rabbits Vet Path 2008 Mar: 59.3% normal and 68.4% of hyperplastic uteri stained positive with both ER- and PR. Papillary adenocarcinoma infiltrated the myometrium late in the disease, with thinning of myometrium and 80.8% were both ERand PR negative. Tubular/solid adenocarcinoma invaded into the deep myometrium early in the disease and 93.8% were positive for ER- , PR, or both, suggesting that there may be 2 different developmental pathways for uterine adenocarcinomas in the rabbit. An Outbreak of Fatal Herpesvirus Infection in Domestic Rabbits in Alaska Vet Path 2008 May: Clinical signs included conjunctivitis and periocular swelling, ulcerative dermatitis, progressive weakness, anorexia, respiratory distress, and abortion. Hemorrhagic dermatitis and panniculitis were associated with epidermal microvesicular degeneration, dermal and subcutaneous vascular necrosis, and thrombosis. Eosinophilic intranuclear inclusions consistent with herpesvirus were found within the epidermis and superficial follicular epithelium and within mesenchymal cells within the dermis and subcutis. Syncytial cells containing viral inclusions occurred within the epidermal and superficial follicular epithelium. Other findings were hemorrhagic necrosis of the myocardium with rare intranuclear inclusions within stromal cells, multifocal pulmonary hemorrhage, hemorrhage with sinus erythrophagocytosis in lymph nodes, and massive necrosis and fibrin deposition within red pulp of the spleen.

Spinal lymphoma and pulmonary filariasis in a pet domestic rabbit (Oryctolagus cuniculus domesticus). J Vet Diagn Invest 21:253–256 (2009). Spinal lymphoma and concurrent pulmonary filariasis are reported in a pet rabbit. The rabbit presented for pelvic limb paralysis resulting from extradural spinal lymphoma, presumably rising from the body of the sixth lumbar vertebra. The neoplasm was subsequently immunophenotyped as a B-cell lymphoma. Pulmonary filariasis was an incidental finding at necropsy. Spontaneous Deciduosarcoma in a Domestic Rabbit (Oryctolagus cuniculus). Vet Pathol 43:377-380 (2006 may) Deciduosarcoma - Hormonally dependent malignancy - Reported only in rabbits in toxicology studies involving estrogens with or without progestins - Induced in female rabbits and in the spleens of castrated male rabbits given estrogen CASE described: - spindloid cells and large epithelioid cells - Giant cells with large, bizarre, hyperchromatic nuclei were common - Positive for vimentin and progesterone and estrogen receptors - Negative for pancytokeratin (AE1/AE3), cytokeratin 18, desmin, alpha-smooth muscle actin (SMA), and CD10 (marker for nondecidualized endometrial stroma) Intraocular sarcomas in two rabbits J Vet Diagn Invest 21:547–551 (2009). pleomorphic, poorly differentiated, invasive, intraocular spindle cell neoplasm closely associated with lens and lens capsular fragments. strong, diffuse expression for vimentin; however, staining for smooth muscle actin, cytokeratin, S100, and desmin were negative. The histologic features of these intraocular neoplasms closely resemble posttraumatic ocular sarcomas in cats. Capillaria hepatica infection in Lab Rabbits: Tox Path 37 2009: Dilated bile ducts with luminal debris and fibrosis. Macrogranulomas in portal areas with eggs, macrophages, and eosinophils, and lymphocytes. Microgranulomas with epithelioid macrophages with eosinophils and lymphocytes. C hepatic eggs in lumen of bile ducts and gall bladder. Adults were not seen, but liver in liver. Granulomatous Pneumonia Caused by Mycobacterium genavense in a Dwarf Rabbit (Oryctolagus cuniculus). Vet Pathol 46:1000–1002 (2009). The main macroscopic findings were a watery red pleural effusion and some whitish striated foci in the lungs. severe granulomatous pneumonia with detection of acid-fast bacilli, in the kidneys, an interstitial chronic lymphoplasmacellular nephritis with interstitial fibrosis, and in the brain, a multifocal granulomatous and partly necrotizing encephalitis with detection of spores, suggestive of encephalitozoonosis Reversible Fibroadenomatous Mammary Hyperplasia in Male and Female New Zealand White Rabbits Associated with Cyclosporine A Administration. Vet Pathol 46:1144–1148 (2009). glandular hyperplasia with mild cellular atypia and ductal ectasia

separated by abundant hypercellular fibrous stroma, consistent with fibroadenomatous mammary gland hyperplasia. The hyperplasia resolved within 2 weeks of cessation of cyclosporine, and at necropsy identifiable mammary masses were not found.