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 Prolactin-secreting Pituitary Adenoma in a New Zealand White Rabbit (Oryctolagus cuniculus). Vol 58, No 3 June 2008.  Histologic evaluation confirmed the presence of a pituitary adenoma, mammary hyperplasia, dysplasia, and cystic mammary adenocarcinoma. Immunohistochemical staining confirmed 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 inDoxorubicin 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 thegenital 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-{alpha} and PR. Papillary adenocarcinoma infiltrated the myometrium late in the disease, with thinning of myometrium and 80.8% were both ER-{alpha} and PR negative. Tubular/solid adenocarcinoma invaded into the deep myometrium early in the disease and 93.8% were positive for ER-{alpha}, 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 post-traumatic 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 hepatica 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 AAdministration.  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.

A case of interscapular fibrosarcoma in a dwarf rabbit (Oryctolagus cuniculus). J Vet Diagn Invest 21:900–905 (2009). vaccinated against myxomatosis and rabbit viral hemorrhagic disease. a localized reaction appeared in the same anatomic site within a few days. the swelling apparently disappeared in 3 months. July 2006 a sudden appearance of a nodular, 4.5 cm 3 3.5 cm 3 2.0 cm, subcutaneous mass located over the interscapular space. The neoplastic tissue exhibited fascicles composed of malignant spindle-shaped cells with elongated to oval hyperchromatic nuclei and scant cytoplasm. Occasional multinucleated cells were also observed. The neoplastic cells were immunoreactive for vimentin but did not stain for smooth muscle actin, desmin, myoglobin, and cytokeratins (AE1/AE3). Moreover, the histochemical stain for aluminum was positive. The histologic features of this neoplasm were remarkably similar to feline injection-site sarcoma.

Histopathological Features of Capillaria hepatica Infection in Laboratory Rabbits. Toxicologic Pathology, 37: 661-666, 2009. Adult worms inhabit the liver. Histopath: portal tracts- dilated bile ducts with luminal debris, and fibrosis. Large granulomas (macrogranulomas) were evident in portal areas and involved the bile ducts. Macrogranulomas contained collections of characteristic C. hepatica eggs, macrophages, eosinophils, and lymphocytes. Small granulomas (microgranulomas), characterized by epithelioid macrophages surrounded by lymphocytes and eosinophils, were also identified. C. hepatica eggs were also observed in the lumina of the bile ducts and gall bladder. No adult C. hepatica worms were identified.  In some cases, linear deposits of eosinophilic, hyaline (amyloid-like; congo red negative) material were present immediately beneath the biliary epithelium.

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