A quantitative study of the aorta of the New Zealand rabbit (Oryctolagus cuniculus L.)

Ten segments of the aorta of the rabbit were studied quantitatively. The thoracic and abdominal aorta of the rabbit were measured from proximal to distal and parallel to the reduced diameter, demonstrating a decreasing thickness of the tunica intima and tunica media that becomes physiologically apparent during adulthood in these commonly used laboratory animals. The ratio of intimal to medial thickness, multiplied by 100, was calculated and found to be between 2.56 and 3.74 for the thoracic aorta and 4.03 and 5.62 for the abdominal aorta of the rabbit. These findings are important for the better understanding of the development of atherosclerosis.     

Origin, course and distribution of the hypoglossal nerve in the New Zealand rabbit (Oryctolagus cuniculus L)

With 8 figures SUMMARY: This study aimed at revealing the origin, course and distribution of the hypoglossal nerve in 20 adult male New Zealand rabbits. In all the animals dissected, the hypoglossal nerve arose from the ventrolateral side of the medulla oblongata with two main roots and gave off a descending branch to the ansa cervicalis before reaching the division of the common carotid artery. This branch was not seen on the right side of only one case. At the lateral aspect of the hyoglossus muscle, the nerve then divided into the lateral and medial main branches, sent branches to the styloglossus, hyoglossus, genioglossus and geniohyoideus muscles and terminated in the intrinsic tongue muscles. A communicating branch was observed between the hypoglossal and accessory nerves in the right side of one animal and between the hypoglossal nerve and the ganglion nodosum in the right retropharyngeal area of another animal. An additional branch was observed innervating the stylohyoideus muscle in one animal only. A lateral lingual-hypoglossal communication was also seen between the lateral branch of the hypoglossal nerve and terminal branches of the lingual nerve.     

Antebrachial chondrodysplasia in New Zealand white rabbits (Oryctolagus cuniculus)

Rabbits obtained from a South African rabbit breeder exhibited deformities of the distal forelimbs. The clinical, radiological and histological presentation of mid-antebrachial valgus formation (a.k.a distal foreleg curvature) in these rabbits was consistent with an autosomal recessive trait associated with a chondrodystrophic lesion of the distal ulna epiphysis 1st described in the 1960s. The impact this might have on South African farming enterprises and laboratory facilities has not been established, but the heritability and welfare implications of this condition make it a concern. Mildly affected animals can adapt to the deformity with some housing adjustments, but severely affected animals may require humane euthanasia.     

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.     

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.     

Functional neuroanatomy of the domestic rabbit (Oryctolagus cuniculus).

This article reviews clinically relevant neuroanatomy of the central nervous system of the domestic rabbit (Oryctolagus cuniculus) that will help guide veterinarians in localizing neurological disease in this species. Although the vertebral column, spinal cord and brain of rabbits are similar to those of other mammals, features unique to the rabbit are emphasized where they exist.     

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.     

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.     

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.     

Safety and efficacy of oral mirtazapine in New Zealand White rabbits (Oryctolagus cuniculus)

BackgroundOne of the most common presenting complaints in rabbits is decreased food intake and/or fecal output. This can occur as a clinical consequence of pain, anesthesia and systemic or gastrointestinal disease. In conjunction with diagnosing and treating the underlying condition, veterinary care should aim to normalize food intake and fecal output. Mirtazapine is a tetracyclic antidepressant that has appetite stimulating effects in other species. However, studies in rabbits are currently lacking.MethodsNine six-month old, intact (4 male, 5 female) New Zealand White rabbits (Oryctolagus cuniculus) were used in a randomized, blinded, controlled, complete cross-over experiment. Each rabbit received a low-dose of mirtazapine (1 mg/kg), high-dose (3 mg/kg) and control treatment orally once a day for a total of 2 sequential days with a 5- day washout period between treatment groups. Fecal output, food intake and body weight were measured before, during and after treatment.ResultsFecal output was 25% higher (95% CI: 6.3%–46.9%, P= 0.01) on treatment days following high-dose mirtazapine treatment. Body weight was 1.5% higher (95% CI: 0. 5% to 2.6%, P= 0.006) for all groups on the 2 days following treatment compared to baseline. Body weight was reduced by 2.1% (95% CI: -3.6% to -0.6%, P= 0.011) the week following high-dose mirtazapine treatment. Mirtazapine did not have a statistically significant effect on food intake.Conclusions and clinical relevance:Oral administration of mirtazapine at 3 mg/kg once a day resulted in increased fecal output but not a concurrent increase in food intake. Overall, mirtazapine is well tolerated and may be a useful treatment to increase fecal output in rabbits. However, due to a mild reduction in weight following treatment, clinical monitoring is warranted.     

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.     

Pneumatosis cystoides intestinalis in a rabbit doe (Oryctolagus cuniculus).

Pneumatosis cystoides intestinalis (PCI) is an infrequent condition of animals characterized by the existence of numerous thin-walled, gas-filled cystic structures within the intestinal wall and adjacent lymph nodes. Microscopically, the cystic structures appear to be dilated lymphatics located in the lamina propria, submucosa, muscularis, subserosa, mesentery, and mesenteric lymph nodes. This report describes a case of pneumatosis cystoides intestinalis in a rabbit doe from an organic farm where 20 rabbit does were fed ad libitum with a natural diet consisting of whole barley, pea beans, alfalfa hay, and a pelleted vitamin-mineral blend. A combination of nutritional, bacterial, and other factors are hypothesized as possible predisposing factors in the development of PCI.     

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.