Merogonic stages of Theileria cervi in mule deer (Odocoileus hemionus).

In February 2012, 12 farmed mule deer (Odocoileus hemionus) were moved from a facility in southwestern Oklahoma to a facility in southeastern Oklahoma that housed 100 farmed white-tailed deer (Odocoileus virginianus). Between the third and fifth weeks, 9 of the 12 mule deer had died, 4 of which were submitted for necropsy. The deer were heavily infested with Amblyomma americanum (lone star ticks). Hematologic data from 1 deer revealed severe anemia, leukocytosis, and intraerythrocytic hemoparasites consistent with Theileria spp. Microscopically, the liver, lymph nodes, and spleen contained multifocally distributed, enlarged monocytic cells whose cytoplasm was replaced by developing meronts in various stages of merogony. It appears that, upon arrival, the Theileria cervi-naïve mule deer became infested with large numbers of Theileria-infected lone star ticks leading to massive exposure of the mule deer to sporozoites of the protozoan, resulting in an acute hemolytic crisis and fatalities. The merogonic stages of T. cervi are also described. The lack of earlier reports of merogony may be due to the fact that only a single, short-lived, merogonic cycle follows exposure to sporozoites and thus merogonic stages are demonstrable for only a short period. Polymerase chain reaction testing of paraffin-embedded tissue yielded a 507-bp amplicon sequence that was 100% identical with the sequence of T. cervi previously reported from white-tailed deer in Oklahoma and from elk in Wisconsin and Indiana.

Gastric pneumatosis with associated eosinophilic gastritis in four black and white ruffed lemurs (Varecia variegata variegata).

Pneumatosis cystoides intestinalis (PCI) with associated eosinophilic inflammation was documented in the gastric tissues of four black and white ruffed lemurs (Varecia variegata variegata). Pneumatosis cystoides intestinalis is an uncommon disease described in humans and characterized by multilocular gas-filled cystic spaces located within the wall of the gastrointestinal tract. These cystic spaces can occur in any location along the gastrointestinal tract as well as within the associated connective and lymphatic tissues. The exact cause of this disease is unknown. The four black and white ruffed lemurs described in this case series were captive born and had been housed in zoological institutions at two separate locations. Three of the four cases were female lemurs, and two of the affected lemurs were directly related. The individual disease presentations spanned a 5-yr time period. Two lemurs presented dead with no premonitory signs, whereas the other two lemurs presented with clinical signs of gastrointestinal disease and nonspecific signs of weakness. Gastric pneumatosis, diagnosed either grossly or histopathologically in each of these four lemurs, is described as a subset of PCI in which cystic spaces are localized to the stomach wall. Significant eosinophilic inflammatory infiltrate was identified on histopathology of gastric tissues and found to be associated with the cystic lesions in each lemur. No classic etiology, such as a fungal infection or a parasitic infection, was identified as the cause of the eosinophilic gastritis. This case series demonstrates that gastric pneumatosis with associated eosinophilic gastritis may be a significant gastrointestinal disease in black and white ruffed lemurs.

Pseudorabies virus infection in Oklahoma hunting dogs.

Pseudorabies is caused by Suid herpesvirus 1, a member of the Alphaherpesvirinae subfamily. Although pigs are the natural host of Pseudorabies virus (PRV), the virus has a broad host range and may cause fatal encephalitis in many species. The United States obtained PRV-free status in 2004 after the virus was eradicated from domestic swineherds, but the virus is still present in feral swine populations. The current report describes PRV infection in 3 dogs that were used to hunt feral swine. The dogs developed clinical signs including facial pruritus with facial abrasions, dyspnea, vomiting, diarrhea, ataxia, muscle stiffness, and death. Two were euthanized, and 1 died within approximately 48 hr after onset of clinical signs. The salient histologic changes consisted of neutrophilic trigeminal ganglioneuritis with neuronophagia and equivocal intranuclear inclusion bodies. Pseudorabies virus was isolated from fresh tissues from 2 of the dogs, and immunohistochemistry detected the virus in the third dog. Virus sequencing and phylogeny, based upon available GenBank sequences, revealed that the virus was likely a field strain that was closely related to a cluster of PRV strains previously identified in Illinois. Though eradicated from domestic swine in the United States, PRV is present in populations of feral swine, and should therefore continue to be considered a possible cause of disease in dogs and other domestic animals with compatible clinical history and signs. Continued surveillance is necessary to prevent reintroduction of PRV into domestic swine.

Severe zinc responsive dermatosis in a litter of Pharaoh Hounds.

A litter of 3-month-old Pharaoh Hound puppies presented to the referring veterinarian with severe generalized erythematous-crusted papules with pruritus, accompanied by exfoliation and erythema of footpads, inappetence, lethargy, and retarded growth. Three of 5 puppies (2 male and 1 female) were affected. Representative areas were biopsied from 1 affected male puppy and were routinely processed. Histologically, there was marked epidermal hyperplasia with a disorganized appearance of the epidermis and massive parakeratotic hyperkeratosis, compatible with zinc-responsive dermatosis. Low serum zinc concentrations were documented, and the affected animals partially responded to intravenous zinc supplementation but did not respond to oral supplementation. One male puppy died as a result of unrelated causes and was necropsied. The remaining 4 puppies were followed over 2 years. Growth was stunted, and enamel hypoplasia of permanent dentition developed compared with unaffected littermates. Intravenous zinc supplementation at 3-4 week intervals was required to prevent further skin lesion development. One dog died at 3 years of age of renal failure.

Successful treatment of a Vietnamese potbellied pig with an ovarian leiomyoma.

CASE DESCRIPTION: An adult sexually intact female Vietnamese potbellied pig was examined because of abdominal distention of 5 months' duration. CLINICAL FINDINGS: The pig was moderately anemic, and its abdomen was greatly distended. A freely movable abdominal mass was detected during palpation and ultrasonographic examination of the abdomen. Examination of abdominal and thoracic radiographs revealed faint, ill-defined, linear and curvilinear mineralized opacities in the region of the mass and that the gastrointestinal tract was displaced craniodorsally. Results of radiographic examination suggested that the cause of distention was a single abdominal mass (possibly a neoplasm). TREATMENT AND OUTCOME: Surgery was performed, and the mass, which was identified as the right ovary, was removed. The left ovary had a normal appearance, but it was also removed during surgery. The pig was administered a transfusion (314 mL of plasma and 296 mL of packed RBCs) before and during surgery. The mass, which accounted for approximately one-third of the pig's body weight, was identified histologically as an ovarian leiomyoma. CLINICAL RELEVANCE: Pigs can safely be administered a transfusion of RBCs and plasma. Ovarian tumors can be removed from Vietnamese potbellied pigs, which allows them to be used as pets or for reproduction when only 1 ovary is affected. Uterine masses in older sexually intact Vietnamese potbellied pigs are more common than are ovarian tumors; thus, complete ovariohysterectomy should be considered when the primary purpose of the pig is to serve as a pet.

Disseminated cutaneous mast cell tumors with epitheliotropism and systemic mastocytosis in a domestic cat.

A 15-year-old female domestic, medium-haired cat presented to the referring veterinarian with a 2-month history of multiple, raised, disseminated, nodular skin lesions. A biopsy of 1 of the lesions was submitted to the Oklahoma Animal Disease Diagnostic Laboratory for evaluation. Histologically, there were multiple dermal nodules composed of sheets of neoplastic round cells. Multifocally, the neoplastic cells formed multiple small clusters of 3 to 5 cells within the epidermis. Distinct cytoplasmic granules were evident within the neoplastic cells with toluidine blue and Giemsa stains. The neoplastic cells were immunoreactive for c-KIT and lacked immunoreactivity for cluster of differentiation 3 with immunohistochemistry. Based on these findings, multiple epitheliotropic cutaneous mast cell tumors were diagnosed. The cat's health declined rapidly despite aggressive treatment, and the animal was humanely euthanatized. A complete necropsy revealed sheets of similar neoplastic mast cells within the spleen, liver, and individual cells scattered within the bone marrow. Exon 11 of the c-KIT messenger RNA from 1 of the cutaneous masses and the spleen was amplified with reverse transcription polymerase chain reaction, sequenced, and compared with the published c-KIT messenger RNA sequence from fetal cat tissues. The maximum identity was 100% for both tissue samples. To the authors' knowledge, the present report is the first to describe disseminated cutaneous mast cell tumors with epitheliotropism and systemic mastocytosis in a domestic cat.

Getting the most from dermatopathology.

Dermatohistopathology is one of the most powerful diagnostic tools in clinical dermatology. It is a process in which the veterinary clinician and the veterinary pathologist must consider themselves a team in patient care. The veterinary clinician must know when biopsies are indicated; be able to select lesions to biopsy that are likely to yield diagnostic results; skillfully procure the biopsy samples; and provide the pathologist with an accurate history, clinical description, and clinical differential diagnosis. The pathologist should have particular interest and expertise in dermatohistopathology, be readily accessible to the clinician, and be vigilant in the pursuit of an accurate histologic description and diagnosis.