Urethral diverticulum and urolithiasis in a female guinea pig (Cavia porcellus)

CASE DESCRIPTION A 5-year-old sexually intact female guinea pig was evaluated because of mild dysuria and a subcutaneous mass located cranioventral to the urogenital openings. CLINICAL FINDINGS Non-contrast-enhanced CT and surgical exploration of the distal aspect of the urethra revealed a urethral diverticulum with an intraluminal urolith. Analysis revealed that the urolith was composed of calcium carbonate and struvite. TREATMENT AND OUTCOME The urolith was surgically removed and ablation of the urethral diverticulum was attempted. Approximately 3 months later, the guinea pig was reevaluated for masses in the perineal region, and positive-contrast urethrocystography revealed 2 uroliths present in the same diverticulum. Uroliths were manually expressed with the patient under general anesthesia. Approximately 2 weeks later, urethroplasty was performed to create an enlarged stoma with the diverticulum, thereby preventing urine from pooling in the diverticulum and potentially reducing the risk of future urolith formation. The urethroplasty site healed well with no reported complications or evidence of urolith recurrence 6 months after surgery. CLINICAL RELEVANCE Urolithiasis is common in guinea pigs, and urethral diverticulum and intraluminal urolith formation should be considered as a potential differential diagnosis for a subcutaneous mass along the distal aspect of the urethra. Creation of a urethral stoma from a urethral diverticulum via urethroplasty achieved a successful outcome in this patient.

Ventral rhinotomy in a pet rabbit (Oryctolagus cuniculus) with an odontogenic abscess and sub-obstructive rhinitis

A rabbit was presented for severe dyspnea and was diagnosed with an odontogenic abscess obstructing the rostral nasopharynx using CT scan and oral endoscopy. The offending tooth was extracted intraorally, but due to persistent dyspnea, an endoscopic-guided ventral rhinotomy was performed. The dyspnea subsequently resolved, but the rabbit died 5 weeks later from a seemingly unrelated cause.

Maxillary Osteosarcoma in a Prairie Dog (Cynomys Ludovicianus)

To date, few tumors have been identified in prairie dogs, with odontoma being the most common. Osteosarcoma has been documented in a wide range of species, including a number of rodents. In this case, a locally invasive maxillary osteosarcoma was diagnosed in a prairie dog. Gross examination revealed a pale, tan, lobulated, sessile maxillary mass extending ventrally into the oral cavity from the hard palate and the gingiva surrounding the upper right cheek teeth. The mass invaded the right nasal cavity and retrobulbar space causing exophthalmia. Microscopically, the mass consisted of densely packed spindle-shaped cells with occasional multinucleated giant cells. Brightly eosinophilic osteoid was multifocally scattered in the tumor mass. To the authors' knowledge, this is the first documented report of maxillary osteosarcoma in a prairie dog.

Transurethral Cystoscopy and Endoscopic Urolith Removal in Female Guinea Pigs (Cavia porcellus)

Urinary diseases are commonly found in guinea pigs. Diagnostic workup includes clinical examination, blood testing, imaging studies, urine culture, and urinalysis. This article describes the use of transurethral cystoscopy in female guinea pigs as an ancillary tool to diagnose abnormalities within the bladder and urethra. In addition, the transurethral cystoscopic removal of uroliths measuring up to 5 mm and situated within the urinary bladder is described.

Enucleation for treating rodent ocular disease

Our standard of care for rodent corneal lesions previously included treatment of the primary lesion, application of topical NSAIDs, and systemic NSAIDs in severe cases. When intensive medical management was unsuccessful, animals were euthanized, leading to premature loss of valuable genetically modified animals and those on long-term studies. We investigated enucleation surgery as a treatment for 15 cases of rodent corneal disease that did not respond to medical management. Enucleation was performed under isoflurane anesthesia and involved removal of the globe, extensive hemostasis, and packing the orbital space with absorbable gelatin sponge. The lid margins were closed by tarsorrhaphy and tissue glue. Analgesia was provided by using buprenorphine preoperatively and carprofen chew tabs postoperatively. To date, we have a 100% success rate with this procedure (n = 20; 15 clinically affected rodents [2 rats, 13 mice], 5 healthy controls), which included a 60-d follow-up period. The single complication involved dehiscence of the tarsorrhaphy site and was repaired by trimming the lid margins to provide fresh tissue for closure. Histologic examination at both 1 and 3 mo after surgery revealed no evidence of infection of the enucleation site. Enucleation in rodents is a straightforward procedure that represents a refinement to our current standard of care for rodents, does not cause significant inflammation of remaining periocular structures, and has reduced the number of animals euthanized prior to study endpoint because of severe ocular lesions.

Atypical fibrosarcomas derived from cutaneous ganglion cell-like cells in 2 domestic Djungarian hamsters (Phodopus sungorus)

Androgen-dependent atypical fibromas are benign tumors derived from ganglion-cell-like cells that are particular to Djungarian hamsters (Phodopus sungorus). Masses excised from 2 hamsters were composed of pleomorphic ganglion cell-like cells supported by small to moderate amounts of collagenous matrix. Intracytoplasmic fibrils were present in silver-stained sections, and immunohistochemistry showed that the cells expressed vimentin, androgen receptor, and, in one case, estrogen receptor α. In contrast to previously reported atypical fibromas, these tumors had features of anaplasia and were locally invasive. We diagnosed the tumors as atypical fibrosarcomas and consider them an unusual malignant counterpart of atypical fibroma.

Two cases of vaginal bleeding in pet rats

Two unrelated rats were presented to the Western College of Veterinary Medicine emergency service for vaginal bleeding. Each was taken to surgery due to marked blood loss and suspicion of uterine pathology. Despite similar clinical presentation, gross and histopathologic examination revealed 2 different underlying disease processes, uterine dilatation with mild endometritis and vaginal polyp.

Bacterial pseudomycetoma in dwarf hamster, Phodopus sungorus

A case of a dwarf hamster with two progressively growing nodules on the right fore limb is described. These were excised following ineffective medical treatment and were submitted for histopathological examination, which revealed bacterial pseudomycetoma in both nodules. To the authors' knowledge this is the first reported case of bacterial pseudomycetoma in a dwarf hamster.

Exotic mammal renal disease: diagnosis and treatment

Knowledge of the renal anatomy and clinical pathology associated with renal disease can help the practitioner with interpretation of imaging procedures and urine, blood, and serum biochemical values. This article discusses specimen collection techniques, along with species variables in several clinical pathology parameters. Diagnostic tools and interpretations are discussed for the more common renal maladies affecting exotic mammals. Treatment guidelines are offered for general as well as specific exotic mammal renal diseases.

Subcutaneous Angiolipoma of Abdomen in a Golden Hamster (Mesocrietus auratus)

This is a single case report of an angiolipoma located in the subcutis of a 2-year-old golden hamster. The histological appearance of the tumour resembled that described in other species. The hamster died 1 month following removal of tumour and a necropsy was not performed. This is apparently the first recorded case of angiolipoma in a hamster.

Bile duct carcinoma and nasal adenocarcinoma in a guinea pig

A guinea pig with a low grade bile duct carcinoma and nasal papillary adenocarcinoma also had a collagen nevus or lipoma that was considered insignificant in the overall management of the case. The bile duct carcinoma was treated successfully through surgery. The clinical presentation of the adenocarcinoma, which was not treated, is described.

Orthotopic transplantation of rat ovaries as a tool for strain rescue

Spontaneous mutations in inbred strains provide valuable resources for new disease models. Unfortunately, these mutations may affect reproduction, which require considerable efforts in breeding management. We transplanted ovaries of such mutant rat strains orthotopically into ovariectomized premature coisogenic recipients. A reproductive cycle was established in each of the recipients within 5 to 6 weeks after transplantation. Moreover, one-third became pregnant and had litters an average of 3 months after transplantation. These experiments demonstrate that orthotopic transplantation of ovaries can be used in the management of subfertile rat colonies.

Ureterolithiasis and papilloma formation in the ureter of a guinea pig

A 5-year-old guinea pig with suspected urolithiasis was presented for radiology and ultrasound examinations of the abdomen. Radiographically, an irregular-shaped mineral opacity was detected in the area of the urinary bladder. Ultrasonographically, pyelectasia of the right kidney, hydroureter with an ureterolith cranial to a thickened ureter wall close to the ureterovesical junction, and a thickened urinary bladder wall were detected. Histopathologically, the thickened ureter wall was found to be a papilloma. The ureter calculus consisted of 100% calcite.

Mixed bone marrow or mixed stem cell transplantation for prevention or treatment of lupus-like diseases in mice

Scientific analyses fortified by interpretations of immunodeficiency diseases as 'experiments of nature' have revealed the specific immune systems to be comprised of T cells subserving cell-mediated immunities plus B cells and plasma cells which produce and secrete antibodies. These two separate cellular systems regularly interact with each other to produce a coordinated defense which permits mammals to live within a sea of microorganisms that threaten the integrity and the survival of individuals. We have shown that bone marrow transplantation (BMT) can be used as a form of cellular engineering to construct or reconstruct the immune systems and cure otherwise fatal severe combined immunodeficiency. When severe aplastic anemia complicated the first BMT which was performed to cure a fatal severe combined immunodeficiency, a second BMT cured for the first time a complicating severe aplastic anemia. Subsequently, BMT has been used effectively to treat some 75 otherwise fatal diseases such as resistant leukemias, lymphomas, inborn errors of metabolism, and genetic anomalies of the hematopoietic development such as sickle cell anemia, thalassemia, congenital neutropenias, and many other diseases. More recently, we have employed BMT in mice both to cure and cause autoimmunities, and, together, these experiments showed that autoimmunities actually reside in the hematopoietic stem cells. We have also found that mixed BMT or mixed hematopoietic stem cell transplantation (HSCT) can be used to prevent and cure the most complex autoimmunities such as those occurring in BXSB mice and in (NZW x BXSB)F1 W/BF1 mice. Untreated, the former develop fulminating lethal glomerulonephritis plus numerous humoral autoimmunities. Mice of the (W/B)F1 strain develop autoimmune thrombocytopenic purpura, coronary vascular disease with myocardial infarction, glomerulonephritis, and numerous autoantibodies. All of these abnormalities are prevented or cured by mixed syngeneic (autoimmune) plus allogeneic (normal healthy) BMT or mixed peripheral blood HSCT. Thus, the most complex autoimmune diseases can be prevented or cured in experimental animals by mixed syngeneic plus allogeneic BMT or HSCT which produce stable mixed chimerism as a form of cellular engineering.

Conjunctival dermoid in two guinea pigs: a case report

Clinical and histologic findings of conjunctival dermoids in two unrelated guinea pigs are described. The dermoids were treated surgically by resection with superficial lamellar keratectomy and corneal epithelial debridement. Histologically the dermis underneath a stratified squamous keratinized and variably pigmented epithelium consisted of multiple hair follicles, with clearly visible arrectores pilorum muscles, sebaceous glands and loose vascularized fatty tissue.

Malignant melanoma of the eyelid in a red squirrel (Sciurus vulgaris orientis)

A 6-year-old male red squirrel (Sciurus vulgaris orientis) developed bilateral tumors of upper and lower eyelids. The tumors in the left lid recurred despite surgical removal. Necropsy revealed metastasis to the lung. The neoplastic cells were epithelioid and highly pleomorphic, and only a few cells contained melanin granules. Occasionally melanoma cells were immunoreactive for S100, neuron-specific enolase and vimentin, and a small number of cells for cytokeratin. Ultrastructurally, the presence of premelanosomes was confirmed in the cytoplasm. Possible presence of cytokeratin-positive neoplastic melanocytes should be taken into account when differentiating a nonpigmented epithelioid melanoma from other tumors such as anaplastic carcinomas.

Lateral canthoplasty for facial nerve paralysis and exposure keratitis in a mouse

An 11-month old entire male mouse was presented with mucopurulent discharge and corneal scarring of the left eye. This mouse previously had a history of ear mites that responded to therapy, and had undergone surgery to remove a large discharging mass from the left side of the neck. The eye problem was noted prior to surgery, but after the ear mite infection. Examination revealed absence of a palpebral reflex in the left eye, and no spontaneous movements of the left ear or lip and whiskers. Examination of the left eye revealed extensive corneal vascularisation and pigmentation. Intraocular structures were not visible. A diagnosis of facial nerve paralysis and secondary exposure keratitis was made. Surgery was performed to close the lateral canthus and reduce corneal exposure. Following surgery the eye discharge ceased and corneal vascularisation resolved, however corneal pigmentation persisted.

Subcutaneous fibrosarcoma in an aged guinea pig

A 9-year-old, female guinea pig was diagnosed with a subcutaneous fibrosarcoma overlying the ventral thorax. The mass was invasive within the subcutis without extension into surrounding structures or organ systems. Other findings included cystic ovaries, renal cortical cysts, nodular hyperplasia of the liver, and myocardial fibrosis with pulmonary hypertension.

Granulosa cell tumor in a guinea pig

Abdominal distention is a common clinical sign in guinea pigs and may have many causes. Abdominal ultrasonography may be a useful diagnostic tool in differentiation of abdominal disorders in guinea pigs. Ovariohysterectomy is indicated for granulosa cell tumors and cystic rete ovarii in guinea pigs.

Obstructive respiratory disease in prairie dogs with odontomas

The clinical manifestations of odontomas in prairie dogs are described. Familiarity with this disease is important because it is common, and the signs of this disease mimic other respiratory disorders.

Ultrasonic diagnosis of ovarian cysts in ten guinea pigs

Ten guinea pigs with an ovarian cyst had clinical signs of anorexia, alopecia, or depression. Ultrasonographic features of the 2- to 3-cm diameter fluid-filled cysts included compartmentalization and connection to the ovary. In two animals, a unilateral cyst was present, and in two others, the cysts were bilateral. Diagnosis of the disease by plain radiography is difficult because of the similar opacity of ovarian cysts, abdominal neoplasms, and trichobezoars.

Effect of surgical removal of subcutaneous tumors on survival of rats

Mammary and other subcutaneous tumors were surgically removed from aged Sprague-Dawley rats in an attempt to extend survival. The surgical technique was straightforward, and survival following mastectomy was good (17/21). The number of mammary and pituitary tumors in sexually intact rats and those that had previously undergone ovariectomy were compared. The frequency of mammary tumors was significantly lower in ovariectomized vs sexually intact rats (2/47 vs 24/49), as was the frequency of pituitary adenomas (2/46 vs 27/41). Survival to 630 days of age was higher in ovariectomized than in sexually intact rats (42/47 vs 29/49), although tumors did not contribute significantly to mortality.

Effect of blood transfusion on survival in a mouse bacterial peritonitis model

Allogeneic blood transfusions can result in alloimmunization or immunosuppression. A previous study demonstrated a deleterious effect of allogeneic blood transfusion on tumor growth in mice that was dependent, in part, on the dose of tumor cells with which the host animal was inoculated. The current study examined the effect of a similar allogeneic blood transfusion protocol on survival in a mouse bacterial peritonitis model. C57Bl/6J mice were transfused with 0.2 mL of heparinized fresh whole blood from C57Bl/6J (syngeneic) or Balb/c (allogeneic) mice. Transfusions were given on Days -10 and -7. On Day 0, mice were injected intraperitoneally with 10(7) Escherichia coli. Survival at Day 7 was 61 percent in the allogeneic blood transfusion group and 55 percent in the syngeneic blood transfusion group (p = 0.52). Experiments using different strains of mice, different transfusion protocols, and different doses of bacteria also failed to demonstrate an effect of allogeneic blood transfusion on survival. The results demonstrate that blood transfusion does not influence survival after a septic challenge with bacteria. The data obtained in the present study, together with those obtained in the tumor model, suggest that the mechanisms by which the allogeneic blood transfusion impedes host defense against bacterial infections is different from the mechanisms involved in tumor growth.

A simple non-surgical method of intrabronchial instillation for the establishment of respiratory infections in the rat

A technique involving intubation of weanling rats for intrabronchial instillation of infectious material has been developed to produce a respiratory infection model suitable for experimental infection studies. The technique is performed simply with the use of a metal cannula and an intravenous plastic cannula, and dispenses with the need for illumination, laryngoscopy and extensive manipulation of the animal.

Veterinary care of rodents and lagomorphs

The species covered in this paper are the mouse, rat, golden hamster, gerbil (jird), guinea pig and rabbit, all of which are commonly kept as pets as well as for exhibition purposes, education and research. An understanding of the biology of these small mammals is necessary if they are to be satisfactorily restrained, examined and treated. They are susceptible to a range of infectious and non-infectious diseases. Small mammals have a high metabolic rate and a large body surface area. Anaesthesia and surgery may therefore present problems of hypoglycaemia and hypothermia. Various anaesthetic agents can be used and a range of surgical procedures may be safely and successfully performed.

Imperforate vagina in mice: per cent incidence and surgical repair

An inbred strain maintained at Nagoya University, Laboratory of Animal Genetics, produced high incidence of imperforate vagina as 12.21% of occurrence in females, herein designated as Imv strain. Selected females with imperforate vagina in this strain were surgically repaired and subsequently mated with their littermates. These matings produced a 12.76% incidence of imperforate vagina. A detailed description of the surgical technique is herein reported.

Heterotransplantation of feline malignant tumors in nude thymusless mice

The nude mouse was used to evaluate transplantation of feline tumors and subsequent doxorubicin chemotherapy. Three mammary gland adenocarcinomas and one salivary gland adnoecarcinoma were readily transplanted. All were successfully passed at least once. The two sarcomas, a fibrosarcoma and a malignant hemangioendothelioma, failed to grow when transplanted. Growth rates for the adenocarcinomas appeared to be specific for individual tumors. Generally, tumor weights increased five to eight times by days 40 to 50. Structural changes were not observed histopathologically in tumors transplanted several times. When doxorubicin was given intraperitoneally (1 mg/kg of body weight) weekly for 6 weeks to nude mice with transplanted feline mammary gland adenocarcinoma, there was no significant difference (P less than 0.05) in weights of tumors of experimental (n = 150 and control (n = 10) mice.