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.     

Demodicosis in nine prairie dogs (Cynomys ludovicianus)

This case report describes the clinical signs and treatment of demodicosis in nine pet prairie dogs (Cynomys ludovicianus). Clinical records including history, clinical examination, microscopic evaluation and fungal culture of the skin lesions were available for all nine animals. In seven animals, blood was obtained for haematological and biochemical analyses. Clinical signs comprised bilaterally symmetrical alopecia extending from the middle part of the back down to the skin of the thighs and the dorsal and ventral parts of the tail. Demodex mites were found in skin scrapings from all cases. Treatment with amitraz at 250 p.p.m. resulted in resolution of lesions and hair regrowth. This is the first report of demodicosis in this species.     

No evidence for enzootic plague within black-tailed prairie dog (Cynomys ludovicianus) populations

Yersinia pestis, causative agent of plague, occurs throughout the western United States in rodent populations and periodically causes epizootics in susceptible species, including black-tailed prairie dogs (Cynomys ludovicianus). How Y. pestis persists long-term in the environment between these epizootics is poorly understood but multiple mechanisms have been proposed, including, among others, a separate enzootic transmission cycle that maintains Y. pestis without involvement of epizootic hosts and persistence of Y. pestis within epizootic host populations without causing high mortality within those populations. We live-trapped and collected fleas from black-tailed prairie dogs and other mammal species from sites with and without black-tailed prairie dogs in 2004 and 2005 and tested all fleas for presence of Y. pestis. Y. pestis was not detected in 2126 fleas collected in 2004 but was detected in 294 fleas collected from multiple sites in 2005, before and during a widespread epizootic that drastically reduced black-tailed prairie dog populations in the affected colonies. Temporal and spatial patterns of Y. pestis occurrence in fleas and genotyping of Y. pestis present in some infected fleas suggest Y. pestis was introduced multiple times from sources outside the study area and once introduced, was dispersed between several sites. We conclude Y. pestis likely was not present in these black-tailed prairie dog colonies prior to epizootic activity in these colonies. Although we did not identify likely enzootic hosts, we found evidence that deer mice (Peromyscus maniculatus) may serve as bridging hosts for Y. pestis between unknown enzootic hosts and black-tailed prairie dogs.     

Extensive lesions of monkeypox in a prairie dog (Cynomys sp)

Monkeypox with extensive lesions was diagnosed in a prairie dog that was involved in a recent human outbreak of monkeypox in the Midwestern United States. Gross lesions included oral ulcers, pulmonary consolidation, enlarged cervical and thoracic lymph nodes, and multifocal, small, white umbilicated plaques in the gastrointestinal wall. Microscopic lesions were extensive in the lungs and consisted of fibrinonecrotic bronchopneumonia with vasculitis and poorly defined eosinophilic intracytoplasmic inclusion bodies in cells thought to be alveolar epithelial cells, histiocytes, and fibroblasts. Multifocal necrotizing lesions, often accompanied by myxedema, were also present in most of the other examined organs. Aggregates of pox viral particles were observed within lesions by transmission electron microscopy. Monkeypox virus infection was confirmed by real-time polymerase chain reaction and virus culture at the Centers for Disease Control and Prevention. This report highlights the difficulties of rapid diagnosis of exotic or emerging diseases and further substantiates the prairie dog as an animal model of monkeypox.     

Hepatic calodium hepaticum (Nematoda) infection in a zoo colony of black-tailed prairie dogs (Cynomys ludovicianus).

Calodium hepaticum (syn. Capillaria hepatica), a nematode parasite commonly found in the liver of wild rodents, infects a wide variety of mammals, including humans. A retrospective study of black-tailed prairie dogs (Cynomys ludovicianus) at the Baltimore Zoo showed that 5 of 21 (24%) of the prairie dogs submitted for postmortem examination between 1981 and 2001 had hepatic capillariasis, with all the infections diagnosed during or after 1997. Affected livers contained multifocal granulomas containing numerous eggs and occasional adult nematodes. Asymptomatic wild rats in the zoo with a high prevalence of infection may have served as a reservoir for the disease. Wild rodent control is essential to minimize exposure of susceptible exhibition animals as well as humans to C. hepaticum.     

Traumatic Intervertebral Disc Herniation with Paraplegia in a Black-Tailed Prairie Dog (Cynomys ludovicianus)

A 2-year-old castrated male black-tailed prairie dog (Cynomys ludovicianus) was presented 48 hours after peracute onset of rear limb paraplegia secondary to a traumatic incident. The prairie dog was nonambulatory in the rear legs with absent deep pain; hematuria and pollakiuria were also observed. Diagnostic imaging revealed intervertebral disc herniation with compression of the spinal cord at the L1-L2 disc spaces. Hemilaminectomy at the L1-L2 disc space was performed. After 48 hours, the prairie dog regained anal tone, and a deep pain response was noted. Azotemia developed during the course of hospitalization likely secondary to neuromuscular damage causing an obstruction in the lower urinary tract but resolved with supportive care. The prairie dog recovered complete use of its hind legs and had normal excretory function at a 3-month recheck. Practitioners should consider intervertebral disc herniation secondary to trauma as a differential diagnosis for neurologic deficits affecting the rear limbs of prairie dogs. Surgical management of intervertebral disc herniation is a viable treatment option in appropriate cases.     

Original Rhinostomy Technique for the Treatment of Pseudo-odontoma in a Prairie Dog (Cynomys ludovicianus)

A 3-year-old, female black-tailed prairie dog (Cynomys ludovicianus) was presented for complications related to an earlier rhinostomy procedure and placement of a breathing tube for treatment of a pseudo-odontoma. The complaint by the owner was that the prairie dog would constantly remove the breathing tube. The breathing tube was replaced with a human earlobe retractor positioned (partially) under the nasal bones. The patient tolerated the procedure and location of the human earlobe retractor. This is the first reported case using a human earlobe retractor to function as a permanent rhinostomy device in a prairie dog.     

Prairie Dog (Cynomys ludovicianus) Influence on Forage Quantity and Quality in a Grazed Grassland-Shrubland Ecotone

Black-tailed prairie dogs (Cynomys ludovicianus) have high dietary overlap with livestock, which can cause forage-centric conflicts between agriculture and conservation. Research suggests prairie dogs can enhance forage quality, but trade-offs between quality and quantity throughout the growing season remain unclear, as well as the degree to which increased forage quality is caused by altered species composition versus altered plant physiology. To assess the effects of prairie dog herbivory on forage in a northern mixed-grass prairie, we collected samples on prairie dog colonies and at sites without prairie dogs during June, July, and August 2016 - 2017 for forage quality, and August 2015 - 2017 for herbaceous biomass. To isolate mechanisms affecting forage quality, we collected both composite samples of all herbaceous species and samples of western wheatgrass (Pascopyrum smithii [Rydb.] Á. Löve). Across years and plant sample types, crude protein, phosphorus, and fat were 12-44% greater and neutral detergent fiber was 6-10% lower on prairie dog colonies than at sites without prairie dogs. The effects of prairie dogs on forage quality persisted throughout the season for western wheatgrass samples (all treatment*time p-values ≥ 0.4). Across years, aboveground herbaceous biomass did not differ significantly between prairie dog colonies and sites without prairie dogs (on-colony: 933 ± 156 kg/ha, off-colony: 982 ± 117 kg/ha). The effects of prairie dogs on herbaceous biomass were significantly influenced by spring precipitation. In years with dry springs, herbaceous biomass was lower on colonies than sites without prairie dogs and this pattern was reversed in years with wet springs. Our results demonstrate season-long enhanced forage quality on prairie dog colonies, indicating that multiple mechanisms are shaping forage quality in this system, including altered species composition, phenological growth stage, and soil condition. Across years, enhanced forage quality may help to offset reductions in forage quantity for agricultural producers.     

Clinical Techniques: Surgical Removal of Elodontomas in the Black-Tailed Prairie Dog (Cynomys ludovicianus) and Eastern Fox Squirrel (Sciurus niger)

Acquired dental disease and the formation of elodontomas are often diagnosed in sciurids. The formation of the elodontoma may be preceded by a traumatic tooth injury or other initiating factors. The degree of disease severity varies based on individual presentation and the time of detection. Maxillary elodontomas in sciurid species cause airway obstruction that can prove fatal for these obligate nasal-breathing animals. A thorough understanding of rodent dental anatomy and a complete diagnostic workup are required for diagnosis, prognosis, and surgical planning of elodontoma presentations. This article highlights 2 successful surgical techniques for the removal of the maxillary incisors in sciurid patients with almost total occlusion of the nasal passage.     

Epitheliotropic cutaneous lymphoma (mycosis fungoides) in a dog

A seven-year-old castrated male Yorkshire terrier dog was presented for a recurrent skin disease. Erythematous skin during the first visit progressed from multiple plaques to patch lesions and exudative erosion in the oral mucosa membrane. Biopsy samples were taken from erythematous skin and were diagnosed with epitheliotropic T cell cutaneous lymphoma by histopathology and immunochemical stain. In serum chemistry, the dog had a hypercalcemia (15.7 mg/dl) and mild increased alkaline phosphatase (417 U/l). Immunohistochemistry was performed to detect parathyroid hormone-related peptide (PTH-rP) in epitheliotropic cutaneous lymphoma tissues but the neoplastic cells were not labeled with anti-PTH-rP antibodies. The patient was treated with prednisolone and isotretinoin. However, the dog died unexpectedly.     

Spontaneous acute erythroblastic leukaemia (AML-M6Er) in a dog

A five-year-old golden retriever was presented with anaemia, thrombocytopenia, anorexia and lethargy. Peripheral blood cytology showed abnormal cells similar to proerythroblasts with multiple nucleoli and strongly basophilic cytoplasm. Bone marrow cytopathology revealed that the blast cells accounted for more than 80% of all nucleated cells (ANC). These blast cells were confirmed as erythroblastic cells by cytochemistry, polymerase chain reaction for genetic clonality assessment of IgH and TCRγ, flow cytometry, and transmission electron microscopy. Based on these observations, the dog was diagnosed with acute erythroblastic leukaemia (AML-M6Er). Chemotherapy with cytarabine commenced on day 7 after initial presentation, but the dog died 2 days later. This is the first report of spontaneous AML-M6Er in a dog.     

草原练兵展警犬技术风采

八月的青城天高云淡,和风送爽.2010年8月24日上午,位于呼和浩特市大青山脚下的内蒙古自治区公安厅警犬基地内彩旗飞扬,嘉宾如云,犬声鼎沸.一场盛大的体现警犬技术风采的开幕式表演和以80名带犬民警、95头警犬为主角的警犬技术比赛开始了.     

Feasibility of Using Commercial Reagent Test Strips for Estimation of Blood Urea Nitrogen Concentrations in Captive Black-Tailed Prairie Dogs (Cynomys ludovicianus)

The black-tailed prairie dog (Cynomys ludovicianus) is a squirrel-like rodent (Sciuridae) that is used as an animal model for human gallbladder disease, as well as research on several viral and bacterial diseases. Prairie dogs are also prone to develop hepatobiliary diseases that can impair liver function. As a result, monitoring blood urea nitrogen (BUN) concentration or azotemia via low-volume blood samples with immediate test results can be clinically beneficial. In this study, blood samples were collected from captive black-tailed prairie dogs. The BUN analysis was performed in duplicate using a veterinary biochemistry analyzer and commercial reagent test strips. The indication of azotemia by the reagent test strips, when compared to plasma BUN results of prairie dogs with and without confirmed azotemia, had a sensitivity, specificity, positive predictive value, and negative predictive value of 100%, 95%, 71%, and 100%, respectively. Based on the results of this study, the reagent test strips provided a moderately accurate method of estimating the BUN concentration and high accuracy reporting both normal and azotemic black-tailed prairie dogs. Continued investigation into alternative point-of-care testing for prairie dogs is warranted, but standard blood chemistry analyzers should still be considered the most accurate method of BUN testing and azotemia determination for this species.     

Hepatocellular carcinoma in black-tailed prairie dogs (Cynomys ludivicianus): tumor morphology and immunohistochemistry for hepadnavirus core and surface antigens

From 1994 to 2002, tissues from 61 prairie dogs were submitted to Northwest ZooPath for histopathology. Of these, 12 (20%) had hepatocellular carcinoma (HCC). Three were pets submitted from private veterinary practices. The others were submitted from zoos in the United States. All were adults, ranging from young adult to 7 years of age, with average age of 5.1 years. The most common clinical signs were weight loss, lethargy, palpable abdominal mass, and respiratory difficulty. All tumors were well-differentiated HCCs in which four histologic patterns were recognized. The trabecular pattern was predominant in nine tumors, and the pseudoglandular pattern was predominant in two tumors. The pelioid pattern was also represented in eight tumors. A papillary pattern was present in one case. In seven cases vacuolar change resembling lipidosis was present in the neoplastic hepatocytes of both primary and metastatic tumors. Anaplasia was mild to moderate in most tumors, but a marked degree of anaplasia was noted in the metastatic foci of the case with papillary differentiation. Metastasis to lung was noted in five cases. One of these also had metastasis to the spleen, and another had metastasis to heart and mediastinum. In two cases there was concurrent hepatitis and in two cases, cirrhosis. All tumors and nonneoplastic liver stained negatively for woodchuck hepatitis virus surface and core antigens, and orcein and Victoria blue positive staining of hepatocytes typical of hepadnavirus infection in humans and woodchucks was not present. HCC is apparently common in captive prairie dogs. The hepatic neoplasia observed in prairie dogs was similar to that associated with hepadnaviral infection in humans, woodchucks, and ground squirrels, but no direct evidence of hepadnaviral infection was detected. The rate of metastasis in captive prairie dogs was higher than that reported in woodchucks.     

Cutaneous lymphomatoid granulomatosis (angiotropic lymphoma) in a dog: immunophenotyping analysis

Veterinary Research Communications -     

Spontaneous cholecystocutaneous fistula in a dog

The purpose of this case report was to describe the surgical correction of a cholecystocutaneous fistula in a dog. A 6 yr old Vizsla presented with a 2 mo history of a chronic draining wound on the right ventral thorax. Diagnostics revealed numerous fistulous tracts opening at a single site on the right ventrolateral chest wall, extending caudodorsally through the chest wall and diaphragm to the region of the right medial liver lobe. Exploratory laparotomy revealed the apex of the gallbladder adhered to the diaphragm with a tract of fibrous tissue extending along the diaphragm laterally to the right thoracic wall. Cholecystectomy was performed. The fistulous tract was incised to expose the lumen of the fistula, and the fistula was omentalized. Twenty-eight months after surgery, the dog had had no recurrence of the fistulous tract. Exploratory laparotomy allowed excellent visualization of the intra-abdominal path of the fistula and facilitated the ease of resection of the source. Cholecystectomy resulted in rapid and complete resolution of the fistula without the need for excision of the fistula. Although rare, gallbladder disease should be a differential for chronic fistulous tracts.     

Hepatosplenic lymphoma in a dog

We describe a case of a dog with hepatosplenic lymphoma, a disease characterized by infiltration of the liver, spleen, and bone marrow with gammadelta T cells, absence of peripheral lymphadenopathy, and an aggressive clinical course. Physical examination findings, hematologic and biochemical abnormalities, and clinical course of the disease in this patient were similar to those in humans. Immunophenotyping of liver and spleen aspirates supported an antemortem diagnosis of T-cell lymphoma consistent with hepatosplenic lymphoma. The diagnosis was confirmed postmortem by a combination of routine histopathology, showing a consistent pattern of organ involvement, and immunohistochemistry showing the infiltrating neoplastic lymphocytes to be T cells expressing the gammadelta T-cell receptor. To our knowledge, this is the first reported case of hepatosplenic lymphoma in a dog.