Nasal osteosarcoma and interstitial cell tumor in a Vancouver Island marmot (Marmota vancouverensis)

COMPARISON OF KETAMINE-MIDAZOLAM AND KETAMINE-MIDAZOLAM-BUTORPHANOL PREMEDICATION PRIOR TO SEVOFLURANE ANESTHESIA IN WOODCHUCKS (MARMOTA MONAX)

Cardiovascular disease is a frequent cause of death in the critically endangered Vancouver Island marmots (Marmota vancouverensis). This warrants the use of anesthetic protocols with minimal cardiovascular adverse effects. In this study, 12 adult male woodchucks (Marmota monax) were used as models for Vancouver Island marmots. The objective was to compare the physiological effects of two premedication protocols during induction and maintenance of anesthesia with sevoflurane. The two premedications were ketamine 10 mg/kg and midazolam 0.5 mg/kg (KM) or ketamine 10 mg/kg, midazolam 0.5 mg/kg, and butorphanol 1.0 mg/kg (KMB), administered intramuscularly prior to mask induction. Each marmot underwent three anesthetic events and protocols were assigned using a blinded randomized crossover design. Heart rate, respiratory rate, oxygen saturation, and body temperature were recorded throughout, and blood gases were assessed following induction. Resistance to induction was scored and time to induction was recorded. Although mask induction with sevoflurane was successful in all events (mean induction time of 2.1 min), KMB premedication resulted in a faster induction (mean induction time reduced by 1.2 ± 0.3 min) and lower resistance scores. Both protocols resulted in significant cardiovascular and respiratory depression; however, animals that received KMB were more hypercapnic than KM by 8.8 ± 2.8 mm Hg (P = 0.03) (mean venous partial pressure of carbon dioxide [PvCO2] for all: 79.9 mm Hg). In conclusion, if shorter induction times are desired, KMB premedication is preferred. However, cardiorespiratory variables including blood pressure should be monitored, and endotracheal intubation is recommended to allow for ETCO2 monitoring and provision of intermittent positive pressure ventilation.

Ovarian teratoma in a woodchuck (Marmota monax) with hepatocellular carcinoma: radiologic and pathologic features

Background

Teratomas are germ cell neoplasms composed of a wide variety of tissues. In the woodchuck, only one testicular teratoma has been described in the literature. The objective of this report was to describe the radiologic and pathologic findings in a female woodchuck (Marmota monax) with an ovarian teratoma consisting of mature tissues originating from all three germ layers.

Case presentation

A 2-year-old female woodchuck that had been infected at birth with woodchuck hepatitis virus and subsequently developed hepatocellular carcinoma was incidentally discovered to have a mobile 6.6 × 4.8 × 4.7 cm abdominal mass on computed tomography (CT) imaging. The tumor was predominantly solid and heterogenous on CT with soft tissue, fat, and areas of dense calcification. The teratoma did not enhance with intravenous contrast administration. On ultrasound, the tumor was solid with heterogeneous echogenicity, reflecting the fat content and areas of calcification. Sonolucent areas were present that may have represented cysts. There was heterogeneously increased signal on T1-weighted magnetic resonance imaging (MRI) and heterogeneous hyperintensity in T2-weighted imaging. Fat was evident within the tumor. At necropsy, the tumor was attached to the distal end of the right uterine horn. Histopathology showed mature tissue types representing all three germ layers.

Conclusions

Ovarian teratoma should be considered in the differential diagnosis of ovarian or abdominal masses in woodchucks. The tumor displayed mature tissue derived from all three germ layers. CT, ultrasound, and MRI findings were presented in detail and matched the typical imaging appearance of teratomas.

Risk Factors for Development of Canine and Human Osteosarcoma: A Comparative Review

Osteosarcoma is the most common primary tumor of bone. Osteosarcomas are rare in humans, but occur more commonly in dogs. A comparative approach to studying osteosarcoma has highlighted many clinical and biologic aspects of the disease that are similar between dogs and humans; however, important species-specific differences are becoming increasingly recognized. In this review, we describe risk factors for the development of osteosarcoma in dogs and humans, including height and body size, genetics, and conditions that increase turnover of bone-forming cells, underscoring the concept that stochastic mutational events associated with cellular replication are likely to be the major molecular drivers of this disease. We also discuss adaptive, cancer-protective traits that have evolved in large, long-lived mammals, and how increasing size and longevity in the absence of natural selection can account for the elevated bone cancer risk in modern domestic dogs.