Multilobular tumor of bone on the forehead of a guinea pig.

Multilobular tumor of bone (MLTB) is an infrequent, slow-growing, bone neoplasm formed predominantly on the head. These tumors can behave as malignant neoplasms clinically and pathologically and can metastasize occasionally. No cases of MLTB in rodents have been reported, to our knowledge. We describe a novel case of an MLTB in a guinea pig. An adult guinea pig had an exophytic mass fixed on the frontal bone, maxilla, and nasal bone. On radiography, the mass had a spherical contour and variable density and was formed on the surface of the cranial bones. The mass was excised surgically. The cut surface was light-yellow to milky-white and had a granular texture with fine fibrous septa. Histologically, the neoplasm had a multilobular pattern, which consisted of many islands of bone and/or cartilage matrix surrounded by small cells and separated by fibrous septa, which closely resembles the equivalent neoplasm in dogs.

[Gastric dilatation-volvulus syndrome in guinea pigs (Cavia porcellus)]. / Magendrehung (Dilatatio et Torsio ventriculi) beim Meerschweinchen (Cavia porcellus).

AIM: The aim of this study was to present an overview of the gastric dilatation-volvulus syndrome in guinea pigs. MATERIAL AND METHODS: Four cases of gastric dilatation-volvulus syndrome in guinea pigs were evaluated. Its clinical presentation, diagnostic options, therapeutical approach and possible alternatives thereof were discussed. Furthermore, risk factors for the disease as well as pathophysiology and etiology were discussed and compared to the situation in other species. RESULTS: The presented cases indicate that in addition to anamnesis and clinical examination, radiography is the means of choice to diagnose a gastric dilatation-volvulus syndrome in guinea pigs. All four patients underwent surgery. One animal was euthanized during surgery, the other three guinea pigs died postoperatively. CONCLUSION AND CLINICAL RELEVANCE: Gastric dilatation-volvulus syndrome in guinea pigs is considered to be an emergency and, therefore, immediate stabilization is necessary, as well as surgery in almost all cases. The prognosis of this disease is guarded to poor.

Review of gastric torsion in eight guinea pigs (Cavia porcellus).

The authors present eight cases of gastric dilatation and volvulus (GDV) in guinea pigs from the Department and Clinic of Exotic Animal and Wildlife Medicine, University of Veterinary Medicine, Budapest, Hungary between 2012 and 2016. Seven animals were operated on and two survived. Gastric torsion has been noted in many mammalian species. Gastric volvulus has a high morbidity and high mortality rate with a guarded to poor prognosis in all of these species. How GDV develops is still not widely understood. Postmortem examinations, in both our cases and previously reported cases, have failed to reveal the exact causes of the gastric torsions. The aetiology of gastric torsion in guinea pigs is probably multifactorial. Feeding fewer meals per day, eating rapidly, decreased food particle size, exercise, stress after a meal, competition, age, and an aggressive or fearful temperament, are all likely and potential risk factors for GDV development in a similar fashion to dogs. Sex, breeding, dental diseases, anatomical abnormalities, pain and pregnancy may also be contributing factors.

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.

[Renal pleomorphic sarcoma in four guinea pigs (Cavia porcellus)]. / Renale pleomorphe Sarkome bei vier Meerschweinchen (Cavia porcellus).

OBJECTIVE: Renal tumours apparently are rare not only in cats and dogs, but also in guinea pigs and can be difficult to diagnose. The aim of this study is to describe the clinical, pathological and immunohistochemical findings in guinea pigs with renal tumours. Furthermore, the symptoms, diagnostic possibilities and therapy are compared with renal tumours in other small animals, including cats and dogs. MATERIAL AND METHODS: During a period of 4 years and 4 months the data of guinea pigs that had been presented in the clinic were retrospectively analysed. The analysis comprised guinea pigs that underwent a macroscopical and histopathological postmortem examination, and were diagnosed to have a renal neoplasm. RESULTS: Four guinea pigs had a renal tumour. The percentage of renal neoplasms in relation to the overall necropsied carcasses and the number of organs originating from guinea pigs was 4.7 % and the percentage of renal neoplasms in relation to the overall diagnosed tumours of the abdominal and pelvic cavities was 30.7 %. Histology and immunohistochemistry revealed the presence of renal pleomorphic sarcomas in all four cases. In two of the four guinea pigs, the classical triad, as described for cats and dogs with renal tumours (weight loss, abdominal mass and haematuria), was observed. During clinical examination, a prominent, apparently painful abdominal mass in the region of the kidneys was palpable in all four cases. Applying radiography, the suspected diagnosis of a mass in the area of the kidney was confirmed in three cases, and in two animals the renal origin of the masses was determined by ultrasound examination. CONCLUSION AND CLINICAL RELEVANCE: Because a renal neoplasm is a pain-inducing disease with a high risk of metastases in domestic animals, a prompt nephrectomy should be performed when azotaemia is absent.

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.

Rhinotomie ventrale chez un lapin de compagnie(Oryctolagus cuniculus)atteint d'un abcès odontogène et d'une rhinite causant une subocclusion. Un lapin a été présenté pour une dyspnée grave et a été diagnostiqué avec un abcès odontogène bloquant le nasopharynx rostral par tomodensitométrie et endoscopie orale. La dent en cause a été extraite intra-oralement, mais, en raison d'une dyspnée persistante, une rhinotomie ventrale guidée par endoscopie a été réalisée. La dyspnée s'est subséquemment résorbée, mais le lapin est mort 5 semaines plus tard d'une cause apparemment non reliée.(Traduit par Isabelle Vallières).

Treatment and re-characterization of mouse obstructive genitourinary syndrome.

We aimed to characterize and to explore a treatment for a condition in which male mice exhibited a solid bulge in the preputial area and an inability to breed. Twenty-seven mice from several animal housing institutions in Spain were included in this study for microbiological and pathological characterization of this condition. The condition mostly affected breeding animals and was associated with the C57BL/6J genetic background. A solid, yellowish-white substance was found inside the prepuce, which displaced the penis cranially, preventing its externalization and limiting the animal's capacity to breed. This pattern was almost identical to that of post-coital vaginal plugs, suggesting that the blocking substance originated from ejaculate. Opposite to what was suggested in previous publications, the penis was completely intact in all of the cases, with no signs of mutilation or wounds. Based on our findings, we developed a surgical technique to clear the prepuce and recover breeding performance, which we tested in 15 other mice with the condition. We eliminated the blocking substance and recurrence of the condition by surgically opening the prepuce, and most of the animals recovered fertility.

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.

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.

Atypical fibrosarcoma in the skin of a Roborovski hamster (Phodopus roborovskii).

A 2.5-year-old intact male Roborovski hamster (Phodopus roborovskii) was presented with a large subcutaneous mass overlying the abdomen, affecting the animal's ambulation and access to different compartments of the cage through narrow tubing. Ultrasound examination delineated a well-circumscribed mass in the subcutis of the caudoventral abdominal region. The mass was surgically excised and on cytologic examination showed, in a background of blood, a small population of individually arranged oval to spindle-shaped cells that exhibited a moderate degree of anisokaryosis, coarsely stippled chromatin, one or more prominent nucleoli, and lightly basophilic well-defined cytoplasmic processes. Histologically, the mass was composed of interlacing streams and bundles of pleomorphic spindle cells (ganglion-like cells) with variable amounts of collagenous stroma. The neoplastic cells exhibited moderate features of malignancy. These cells stained intensely with vimentin, but not with any other markers, including antibodies to cytokeratin AE1/AE3, S100 protein, desmin, smooth muscle actin, synaptophysin, neurofilament, and androgen receptor. Based on histologic features, the mass was diagnosed as an atypical fibrosarcoma. This is the first report of an atypical fibrosarcoma in a Roborovski hamster and one of few reports of atypical fibrosarcoma in domesticated hamsters overall.

Intraocular signet-ring cell melanoma in a hamster (Cricetulus griseus).

A two-and-a-half year-old male Chinese hamster (Cricetulus griseus) was referred for evaluation of an intraorbital mass involving the right eye. Based on ophthalmic examination and ultrasonography, a diagnosis of intraocular neoplasia was made. Enucleation of the affected eye was performed. The mass was histologically diagnosed as a primary malignant intraocular signet-ring cell melanoma. No signs of recurrence were detected, and the hamster remained clinically healthy until it died 6 months after surgery. This case report attempts to contribute to the limited body of knowledge available in the literature on primary intraocular neoplasms in hamsters.

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.

Claudin-5-positive angioleiomyoma in the uterus of a degu (Octodon degus ).

A 5-year-old female degu (Octodon degus ) showed the clinical sign of metrorrhagia. During ovariohysterectomy a circumscribed tumoural lesion was found in the right uterine horn. The histopathological diagnosis of this soft tissue mass was primary benign cavernous angioleiomyoma of the uterus. During immunohistochemical analysis the neoplastic endothelial cells of this mixed mesenchymal tumour showed strong membrane positivity for the endothelial marker claudin-5 but were negative for CD31 (another endothelial marker). The endothelial cells of the internal positive control tissues such as intact peritumoural vessels were positive for claudin-5 but negative for the CD31 endothelial marker. As it has been described also in other species, it seems that claudin-5 is a better endothelial marker than CD31 for the detection of normal and neoplastic endothelial cells in different tissues of degus.

Gastric dilatation-volvulus in a guinea pig (Cavia porcellus).

A 3-year-old, intact female guinea pig (Cavia porcellus) was presented for anorexia and abdominal distention of 24 hours' duration. Radiographs revealed a severely distended stomach, suggestive of severe gastric dilatation or gastric dilatation-volvulus (GDV). Exploratory surgery was recommended, but the owners elected euthanasia. On necropsy, the guinea pig was found to have GDV. No underlying conditions were identified that could have predisposed this guinea pig to the development of GDV.