Dystocia in a rabbit (Oryctolagus cuniculus)

A 4-year-old female dwarf lop rabbit was presented with dystocia after mis-mating. Abdominal palpation, vaginal examination, and radiography confirmed that the doe was carrying 3 kits. Treatment for the dystocia consisted of gentle manual extraction of the fetuses and fetal membranes, and administration of oxytocin and calcium borogluconate.     

Demodex cuniculi in dwarf rabbits (Oryctolagus cuniculus)

Demodex cuniculi in a number of dwarf rabbits (Oryctolagus cuniculus) is reported. In contrast to previous reports the findings suggest that the mite should be considered as a normal resident of the epidermis and hair follicle of the rabbit.     

Spontaneous osteosarcoma in a rabbit ( Oryctolagus cuniculus)

A 6-year-old male cross-breed rabbit ( Oryctolagus cuniculus) was presented with lameness and severe swelling from the right shoulder to brachium. On 16-detector helical computed tomography images of the amputated right forelimb after being fixed in formalin, evident 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. This case was diagnosed as osteosarcoma by clinical, radiographic, and histologic findings. This is a rare case report of osteosarcoma in a rabbit consistent with canine predilection sites.     

Spontaneous deciduosarcoma in a domestic rabbit (Oryctolagus cuniculus)

Deciduosarcoma is a rare, hormonally dependent neoplasm with features of malignancy, previously reported only in rabbits enrolled in chronic toxicology studies involving estrogens with or without progestins. An exploratory laparotomy was performed on a 6-year-old pet Dutch dwarf rabbit following palpation of a 6-cm-diameter abdominal mass. Grossly, the mass was fleshy and nodular, adhered to but not appearing to originate from the small intestine, with a smaller mass of similar appearance involving the uterus, and an effaced mesenteric lymph node. Histologically, the mass was characterized by spindloid cells and large epithelioid cells with abundant pale eosinophilic vacuolated cytoplasm and an infiltrative pattern of growth. Giant cells with large, bizarre, hyperchromatic nuclei were common. Cells were positive by immunohistochemistry for vimentin and progesterone and estrogen receptors and negative for pancytokeratin (AE1/AE3), cytokeratin 18, desmin, alpha-smooth muscle actin (SMA), and CD10. Based on histologic and immunohistochemical findings, a diagnosis of deciduosarcoma was made.     

Extraskeletal fibroblastic osteosarcoma in a rabbit (Oryctolagus cuniculus)

A seven-year-old rabbit was presented with a non-painful mass in the right upper lip. Tissue samples from the mass at three different stages of the disease process were diagnosed sequentially as an osteogenic sarcoma, a fibroblastic tumour with rudimentary osteoid formation and, lastly, a fibrosarcoma. No bone involvement or metastatic disease was found. The final diagnosis was of an extraskeletal fibroblastic osteosarcoma, which is, to the authors' knowledge, the first reported such case in a domestic rabbit. Without the first two tissue samples, an incorrect diagnosis would have been reached; therefore, this disease may be underrepresented in the literature.     

Ossifying fibroma in a miniature rex rabbit (Oryctolagus cuniculus)

In humans and animals, ossifying fibroma is a benign neoplasm that most frequently affects the mandible, often resulting in cosmetic deformities and malocclusion. It is considered rare in animals and most frequently affects young horses. A surgical biopsy of a solitary mass located beneath the gingiva in the right maxillary region, which had overgrown teeth and expanded the adjacent hard palate from a 6-year-old miniature Rex rabbit was submitted for light microscopic examination. The submitted incisional biopsy specimen was pale pink, firm, and nodular. Histopathologically, the neoplasm was composed of fibroblastic cells separated by abundant collagen. The neoplastic cells were interwoven with osteoblasts surrounding islands of mineralized, bony matrix containing few, widely spaced, often empty, lacunae. Minimal inflammation was present. Based on the histopathologic features, the tumor was diagnosed as an ossifying fibroma. To our knowledge, this is the first report of an ossifying fibroma in a rabbit.     

Malignant mixed mullerian tumor in a rabbit (Oryctolagus cuniculus): case report with immunohistochemistry

A rabbit (Oryctolagus cuniculus) with a homologous malignant mixed müllerian tumor (MMMT) of the uterus with decidualization in the sarcomatous components is described. On histologic examination, the neoplasm was characterized by a carcinomatous and a sarcomatous component with invasion of the myometrium. The epithelial component was a well-differentiated carcinoma, and the nonepithelial component contained large amounts of intracytoplasmic glycogen. The changes in stromal cells were morphologically similar to changes usually found in decidual cells in the pregnant uterus or in deciduosarcomas in rabbits. Results of immunohistochemical analysis indicated that the epithelial components stained positive with cytokeratin (CK7, AE1/3) and the decidual-stromal cells stained positive for vimentin, but did not stain with alpha-SMA, actin, and desmin. This case fulfills all the criteria of an MMMT in having a carcinomatous and a sarcomatous component, but differs from cases of MMMT in women in that the sarcomatous component had decidualized. To the authors' knowledge, this is the first report of a malignant mixed müllerian tumor in rabbits.     

Solitary biliary hamartoma with cholelithiasis in a domestic rabbit (Oryctolagus cuniculus)

Hamartomas of the liver and biliary system are extremely rare entities in both animals and humans. Biliary hamartomas in humans are usually multiple and constitute the von Meyenburg complexes. This report describes the presence of a large solitary mass arising from the edge of the right medial liver lobe of a domestic rabbit. Histologically, the mass was composed of an extensive 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. This is the first known report of biliary hamartoma with cholelithiasis in rabbits.     

Fungiform papillae of the tongue in the rabbit (Oryctolagus cuniculus)

Examinations were conducted on four tongues of adult rabbits (Oryctolagus cuniculus). On the basis of observations in a scanning electron microscope (SEM) it was found that fungiform papillae in the rabbit are located on the dorsal surface of the apex and body of the tongue, in the front of the torus of the tongue and on the margins of the tongue. Moreover, fungiform papillae are located laterally in relation to the torus of the tongue and are arranged linearly. Fungiform papillae are distributed among filiform papillae and are separated from them by the interpapillary epithelium. The connective tissue core of fungiform papillae is formed from the body, narrow at the base and wider at the apex and 10-17 crest-like folds arranged around them. On the dorsal surface of the connective tissue core of fungiform papillae there are impressions of taste buds and occasionally traces of lymphatic nodules.     

Actinobacillus capsulatus septicemia in a domestic rabbit (Oryctolagus cuniculus).

A 5-year-old pet rabbit (Oryctolagus cuniculus) died after a 3-day history of anorexia and depression. At necropsy, the stomach was distended with dough-like ingesta and hair consistent with gastric stasis syndrome. The lungs had multifocal, raised red nodules with circumferential hemorrhage. Microscopic examination showed pulmonary hemorrhage with intravascular fibrin thrombi and bacterial colonies, which were present in lesser amounts in the kidney, heart, and liver. Bacterial culture of the lung produced a heavy pure growth of Actinobacillus capsulatus. Acute septicemia is a novel presentation for this pathogen. This is the first documented case of A. capsulatus disease in the contiguous United States and may represent an underdiagnosed to emerging disease of lagomorphs.     

Use of contrast‐enhanced ultrasonography in the diagnosis of a liver lobe torsion in a rabbit (Oryctolagus cuniculus)

A 1‐year‐old male French Lop rabbit (Oryctolagus cuniculus) was presented with a sudden onset of hyporexia. Physical examination revealed cranial abdominal discomfort. Liver enzymes were elevated on serum biochemistry profile. Abdominal radiographs showed diffusely gas‐dilated small intestinal loops. On abdominal ultrasound, a lobe in the right aspect of the liver was hypoechoic with rounded margins and was surrounded by hyperechoic fat and anechoic fluid. Contrast‐enhanced ultrasonography showed complete lack of perfusion in the abnormal right liver lobe. Exploratory laparotomy revealed torsion of the quadrate liver lobe. Diffuse coagulation necrosis was noted on histopathologic examination. The rabbit fully recovered after surgery.     

Intra-abdominal torsion of a neoplastic testicle in a rabbit (Oryctolagus cuniculus) with cryptorchidism

Background: Testicular torsion is a relatively common complication of cryptorchidism in domestic mammals but is currently unreported in rabbits. Case presentation: A 7-year-old Dutch rabbit was examined for sudden anorexia and lethargy. The rabbit was previously diagnosed with unilateral cryptorchidism 5 years earlier; however, the owner declined surgical treatment at that time. Transabdominal ultrasonography showed a structure consistent with an enlarged testis, with decreased echogenicity, and absent blood flow upon color Doppler ultrasonography. After induction of general anesthesia and during preparation for surgery, the patient had an episode of cardiac arrest. After successful resuscitation, bilateral cryptorchidectomy continued as planned. A ventral midline laparotomy was performed and confirmed presence of an enlarged, dark red left testicle torsed on its spermatic cord. The contralateral testicle was atrophic. Both testicles were removed after standard hemostasis. Recovery was uncomplicated. Histopathologic examination revealed a diagnosis of Sertoli cell tumor and extensive hemorrhage and necrosis in the torsed testicle. Conclusions and Clinical Relevance: Based on literature search, this is the first reported case of intra-abdominal torsion of a neoplastic testicle in a cryptorchid rabbit. Early elective cryptorchidectomy before the potential development of life-threating complications may be beneficial in rabbits as in other species.