Toxoplasmosis in ring-tailed lemurs (Lemur catta) and a peahen (Pavo cristatus) in a zoological collection caused by the common toxoplasma genotype in wild animals in the US.

Toxoplasmosis is caused by the ubiquitous Apicomplexan protozoan Toxoplasma gondii. This pathogen affects domestic and wildlife species, but prosimians including ring-tailed lemurs (Lemur catta) are highly susceptible to infection with high mortality rates. Avian species are considered resistant to infection and are often used in surveillance efforts to determine genotypes of T. gondii present in geographical areas. This study describes the gross and histologic lesions of an outbreak of toxoplasmosis in a university-run zoological collection involving three ring-tailed lemurs and a peahen (Pavo cristatus). DNA was extracted from the liver of the lemurs and peahen to determine the genotype of T. gondii by polymerase chain reaction restriction fragment length polymorphism (PCR-RFLP), which revealed that all samples were ToxoDB PCR-RFLP genotype #5 (haplogroup 12) that is common in wildlife in North America.

Pancarditis as the sole clinical manifestation of protothecosis in a Boxer dog.

A 4.2-year-old, male castrated Boxer was diagnosed with a dilated cardiomyopathy phenotype, complex arrhythmias and left-sided congestive heart failure, but died suddenly shortly after initial diagnostics were complete. Ultrasensitive cardiac troponin I was markedly elevated (9.345 ng/mL [reference range: 0-0.06 ng/mL]), and a Trypanosoma cruzi immunofluorescent antibody titer was positive at 1:80. Necropsy revealed a severe, necrotizing, histiocytic, lymphoplasmacytic pancarditis with intralesional algae consistent with protothecosis, as well as evidence of left-sided congestive heart failure. Algal organisms were found only in the heart. Acute Chagas disease was not thought to play a role given the lack of T. cruzi amastigotes on postmortem and negative reverse transcription polymerase chain reaction testing on formalin fixed, paraffin embedded myocardium, however a possible contribution of chronic Chagas disease to the clinical picture could not be ruled out. Canine protothecosis is typically a disseminated disease. This case represents the first report of canine protothecosis limited solely to the heart.

Histologic comparison in two Doberman pinschers with a dilated cardiomyopathy phenotype.

Idiopathic dilated cardiomyopathy (DCM) is a common acquired cardiac disease in large breed dogs with a high prevalence in Doberman pinschers. It is characterized histologically by attenuated wavy fibers and fatty infiltration with degeneration. The phenotypic appearance of DCM includes ventricular dilation with systolic dysfunction and ventricular arrhythmias. These changes can be caused by other etiologies, including infectious, toxic, metabolic, and nutritional deficiencies. Chagas disease is the result of an infection with the protozoal parasite, Trypanosoma cruzi, transmitted by an insect vector. Histopathology of the myocardium is characterized by inflammation, fibrosis, and pseudocysts containing T. cruzi amastigotes. Differentiating idiopathic DCM from infectious myocarditis can be challenging when the clinical presentation and diagnostic test results are similar in affected dogs. We present thoracic radiographs, echocardiography, and post-mortem histopathology images obtained from two Doberman pinschers with similar signalment, clinical presentation, and electrocardiographic and echocardiographic appearance but with different appearing radiographs and different etiologies for their heart disease, one with idiopathic DCM and one with myocarditis attributed to Chagas disease, to highlight the value of considering alternative etiologies for DCM to guide additional clinical evaluation and owner counseling.

Granulomatous Rhinitis in a Horse due to Mycobacterium intracellulare Infection.

Mycobacterial infections in horses are uncommon, but are caused most frequently by Mycobacterium bovis of the Mycobacterium tuberculosis complex or Mycobacterium avium of the M. avium complex. Disease caused by Mycobacterium intracellulare, the second most common species within the M. avium complex, has not been reported in horses to date. Mycobacteriosis in horses most often presents as enteric, pulmonary or, rarely, systemic disease. Here we report a case of M. intracellulare infection in a horse presenting as a granulomatous nasal mass.

Immunohistochemical Characterization of Immune Cell Infiltration in Feline Glioma.

The relationship between inflammatory cells and tumour biology has been defined in many human intracranial neoplasms, but it is relatively poorly characterized in veterinary medicine. The aim of this study was to define the immune cell infiltration in cases of feline glioma and its possible association with tumour morphology and type. A retrospective search identified 18 gliomas that met inclusion criteria. Tumours were subjected to immunohistochemistry (IHC) for CD3, CD20, Iba1, MAC387 and factor VIII-related antigen. For each antibody, the number of labelled cells was counted in 10 high-power (×400) fields and a cumulative score for each antibody was generated. Intratumoural and peritumoural CD3+ T lymphocytes were observed in all cases and occurred primarily within perivascular spaces and rarely around areas of necrosis or leptomeningeal spread. Perivascular CD20+ B lymphocytes were detected in 12/18 (67%) cases and occurred within and around tumours and near areas of leptomeningeal spread. MAC387 immunoreactivity highlighted intravascular monocytes in 9/18 (50%) cases, but failed to highlight tumour-associated macrophages. Intratumoural and peritumoural Iba1 immunoreactivity was observed in all cases, with increased overall intensity around areas of necrosis and leptomeningeal spread. Intratumoural and peritumoural factor VIII-related antigen immunoreactivity was also detected in all cases and was concentrated in areas of microvascular proliferation and necrosis. No significant associations were found between IHC scores for immune cells (i.e. lymphocytes and macrophages) and tumour morphology and type. Average factor VIII reactivity was higher in astrocytomas than oligodendrogliomas (P = 0.003).

Interobserver Agreement Using Histological Scoring of the Canine Liver.

BACKGROUND: Grading schemes for the assessment of hepatic fibrosis and necroinflammatory activity in humans previously have been applied to dogs with chronic hepatitis. Interobserver agreement is a desirable characteristic for any histological scoring scheme. HYPOTHESIS/OBJECTIVES: To assess interobserver agreement associated with pathologists using a previously published histological scoring scheme to assess hepatic fibrosis and necroinflammatory activity in dogs and to compare fibrosis scores assigned to serial sections stained with hematoxylin & eosin (H&E) and picrosirius red. ANIMALS: Histological sections of liver from 50 dogs with variable degrees of hepatic fibrosis and necroinflammatory activity were selected from institutional tissue archives. METHODS: Six board-certified veterinary anatomic pathologists assigned fibrosis and necroinflammatory activity scores to the histological sections. The multiuser kappa statistic was calculated to assess interobserver agreement. Fibrosis stage assigned to serial sections stained with picrosirius red and H&E was compared using the Wilcoxon signed-rank test. RESULTS: Multiuser kappa statistics for assessment of fibrosis and necroinflammatory activity from H&E-stained sections were 0.35 and 0.16, respectively. There was no difference in median fibrosis scores assigned to serial section stained with H&E and picrosirius red (P = .248). CONCLUSIONS AND CLINICAL IMPORTANCE: There was fair interobserver agreement when pathologists assessed fibrosis and poor agreement when they assessed necroinflammatory activity. This suboptimal agreement must be taken into account by clinicians making decisions based on histology reports of the liver and in the design of studies evaluating these findings. To decrease this variability, ideally >1 pathologist should evaluate each section.

Pancreatic neuroendocrine tumors in twelve baboons (Papio spp.).

BACKGROUND: Pancreatic neuroendocrine tumors (PNETs) are rare in nonhuman primates and in humans. METHODS: Twenty-one PNETs from twelve female baboons (Papio spp.) from the Southwest National Primate Research Center were evaluated using histopathology and immunohistochemistry. RESULTS: Histologically, all tumors were benign and had neuroendocrine packeting. Immunohistochemical staining for synaptophysin and chromogranin was positive in all tumors evaluated (17/17). Insulin was positive in 16 of 21 tumors. Somatostatin was positive in 9 of 20 tumors. Multifocal staining for glucagon and pancreatic polypeptide was evident in a minority of tumors (6/20 and 2/17, respectively). Gastrin and vasoactive intestinal peptide were negative in all tumors evaluated. Nine tumors expressed more than one hormone marker. CONCLUSIONS: This is the first detailed pathologic study of pancreatic endocrine tumors in the baboon. The findings suggest that these tumors are generally benign and have similar morphologic and immunohistochemical features as those described in people, including the ability to express multiple hormones.

Meningoencephalitis in a dog due to Trichosporon montevideense.

Meningoencephalitis due to infection with Trichosporon montevideense was diagnosed in a 4-year-old dog with a brief clinical history of rapidly progressing neurological signs that culminated in a comatose state. No significant gross lesions were found at post-mortem examination. Microscopically, a few scattered areas of pyogranulomatous inflammation with a few small, non-pigmented fungal hyphae were found within the cerebrum surrounding the lateral ventricles. A Trichosporon sp. was identified through culture of the brain and species was determined via sequence analysis of the internal transcribed spacer region of the Trichosporon rRNA gene. DNA in-situ hybridization confirmed the diagnosis. This is the first reported case of Trichosporon-associated meningoencephalitis in a dog.

Necrotizing meningoencephalitis in atypical dog breeds: a case series and literature review.

BACKGROUND: Canine necrotizing meningoencephalitis (NME) is a fatal, noninfectious inflammatory disease of unknown etiology. NME has been reported only in a small number of dog breeds, which has led to the presumption that it is a breed-restricted disorder. HYPOTHESIS/OBJECTIVES: Our objective was to describe histopathologically confirmed NME in dog breeds in which the condition has not been reported previously and to provide preliminary evidence that NME affects a wider spectrum of dog breeds than previously reported. ANIMALS: Four dogs with NME. METHODS: Archives from 3 institutions and from 1 author's (BS) collection were reviewed to identify histopathologically confirmed cases of NME in breeds in which the disease has not been reported previously. Age, sex, breed, survival from onset of clinical signs, and histopathologic findings were evaluated. RESULTS: Necrotizing meningoencephalitis was identified in 4 small dog breeds (Papillon, Shih Tzu, Coton de Tulear, and Brussels Griffon). Median age at clinical evaluation was 2.5 years. Histopathologic abnormalities included 2 or more of the following: lymphoplasmacytic or histiocytic meningoencephalitis or encephalitis, moderate-to-severe cerebrocortical necrosis, variable involvement of other anatomic locations within the brain (cerebellum, brainstem), and absence of detectable infectious agents. CONCLUSIONS AND CLINICAL IMPORTANCE: Until now, NME has only been described in 5 small dog breeds. We document an additional 4 small breeds previously not shown to develop NME. Our cases further illustrate that NME is not a breed-restricted disorder and should be considered in the differential diagnosis for dogs with signalment and clinical signs consistent with inflammatory brain disease.

Neurological disease in lambs associated with exposure to high environmental temperature and humidity.

BACKGROUND: We detected a pattern of lambs presenting with hyperthermia and neurological signs during the summer. OBJECTIVES: The main objectives of this study were to compare clinical findings and results of diagnostic testing and to identify a potential etiology. ANIMALS: Fifteen clinical cases of lambs less than 12 months of age presenting with neurological signs, tachypnea, and hyperthermia over 4 summers. METHODS: Retrospective case series. Medical records were searched for lambs less than 12 months of age that presented with neurological signs including the following: kyphosis, pelvic limb hyperextension, treading of feet, muscle tremors and recumbency, and hyperthermia of greater than 104°F. A grading system was established to describe severity of presenting neurological signs. Weather data were collected from weather stations near the farm of origin for 3 days prior to presentation. RESULTS: The lambs were from 7 flocks in central Texas. All cases occurred between July and September, with a median heat index of 90.5 for the 3 days before presentation. Complete blood count, serum chemistry, necropsy examination, rumen content, virology, brain MRI, liver copper, selenium, and vitamin E failed to identify a consistent etiology for the signs presented. The only common factor was high heat and humidity. Histopathological examination identified axonal degeneration and skeletal muscle necrosis in some lambs. CONCLUSIONS AND CLINICAL IMPORTANCE: These clinical cases appeared similar to the Australian disease humpyback and indicate that lambs exposed to high environmental temperatures and humidity might be at risk of developing the described clinical presentation.

Intracranial migration of Eucoleus (Capillaria) boehmi in a dog.

A 4-year-old, spayed-female great Dane was referred for surgical treatment of a suspected meningioma, diagnosed on magnetic resonance imaging 10 days prior to presentation. The suspected meningioma was removed via image-guided stereotactic craniotomy. Histopathological diagnosis was severe, locally extensive, chronic meningoencephalitis with an intralesional nematode egg. The egg was morphologically consistent with Eucoleus boehmi, and aberrant migration into the cranial cavity was the presumed cause of this lesion. Three faecal samples were collected and revealed 4+ E. boehmi eggs. Treatment involved 110 mg/kg fenbendazole (Panacur, Intervet) orally twice daily for 14 days. Nematodes including E. boehmi are a previously un-recognised source of intracranial disease in dogs, and should be considered as a differential for mass-like lesions visualised by magnetic resonance imaging.

Broadly reactive polymerase chain reaction for pathogen detection in canine granulomatous meningoencephalomyelitis and necrotizing meningoencephalitis.

BACKGROUND: Granulomatous meningoencephalomyelitis (GME) and necrotizing meningoencephalitis (NME) are common inflammatory conditions of the central nervous system of dogs. Infectious pathogens, particularly viruses, are suspected to contribute to the etiopathogenesis of GME and NME. HYPOTHESIS: Broadly reactive PCR might aid in the identification of infectious agents in GME and NME. ANIMALS: Sixty-eight client-owned dogs evaluated by necropsy at 1 university referral hospital. METHODS: A mixed prospective/retrospective case-control study was performed. Brain tissue prospectively collected at necropsy from GME, NME, and control cases was evaluated by broadly reactive polymerase chain reaction (PCR) for adenoviruses, bunyaviruses, coronaviruses, enteroviruses, flaviviruses, herpesviruses, paramyxoviruses, and parechoviruses. In addition, these tissues were retrospectively evaluated for the presence of mycoplasmas by PCR, culture, and immunohistochemistry (IHC). RESULTS: Brain tissue was collected from 11 GME and 27 NME cases and 30 controls. Viral nucleic acids were not identified in the 6 GME cases, 25 NME cases, and 2 controls evaluated by viral PCR. Mycoplasma canis was identified by Mycoplasma genus PCR in 1/5 GME and 4/25 NME cases and subsequently was cultured from 4/5 GME and 4/8 NME cases as well as 2/9 controls. The IHC did not detect M. canis in any of the 11 GME and 27 NME cases or 14 controls evaluated with strain PG14 polyclonal antiserum. CONCLUSIONS AND CLINICAL IMPORTANCE: The negative results suggest that viral pathogens are not common in the brain tissue of dogs with GME and NME. Further investigation is warranted to determine the importance of M . canis in cases of GME and NME.

Natural Heterobilharzia americana infection in horses in Texas.

The schistosome Heterobilharzia americana infects dogs, raccoons, and other mammals in the southeastern United States. Migration of eggs into the liver results in parasitic granulomas with varying degrees of fibrosis and inflammation. Recently, hepatic parasitic granulomas in horses were shown to be caused by H. americana infection. In the present study, samples of liver from 11 of 12 horses with hepatic granulomas identified at necropsy (n = 11) or surgical biopsy (n = 1) were used for DNA extraction, polymerase chain reaction amplification and sequencing using primers specific for a portion of the H. americana small subunit ribosomal RNA gene. A polymerase chain reaction amplicon of the correct size was produced from the extracted DNA in 8 of the 11 horses. Amplicons from 5 of the 8 positive horses were sequenced and had 100% identity with H. americana. In all but 2 of the 12 horses, Heterobilharzia was not responsible for the primary clinical disease, and the hepatic granulomas were considered an incidental finding.

Sclerosing cholangitis in baboons (Papio spp) resembling primary sclerosing cholangitis of humans.

Primary sclerosing cholangitis is a chronic and progressive cholestatic liver disease that has been extensively documented in the human literature. Although it shares many features in common with chronic lymphocytic cholangitis in cats, primary sclerosing cholangitis has never been reported in a nonhuman primate. Primary sclerosing cholangitis is characterized by the presence of intrahepatic and/or extrahepatic inflammation and concentric fibrosis of bile ducts, eventually leading to cirrhosis and hepatic failure. The pathogenesis and cause remain unknown, but the disease likely involves a multifactorial mechanism with genetic- and immune-mediated components. The authors report 2 cases that histologically resemble the condition in humans; they consist of 2 adult male baboons with a clinical history of chronic elevated liver enzymes. In both cases, the liver was histologically characterized by thick bands of fibrosis and mild lymphoplasmacytic periportal cholangiohepatitis with concentric periductal fibrosis, resulting in atrophy and loss of bile ducts. Immunohistochemical analysis revealed positivity of hepatocytes to cytokeratin 7. Masson stain demonstrated marked biliary fibrosis. This is the first report that resembles sclerosing cholangitis in a nonhuman primate, and it suggests that the baboon may provide a useful animal model for this condition in humans.

Equine rhabdomyolysis.

A 1.5-year-old Quarter Horse gelding with a history of chronic nasal discharge and leukocytosis presented with signs of increased lethargy and muscular pain. The horse quickly became recumbent and unable to rise and was euthanized due to a poor prognosis. At necropsy, severe bilateral guttural pouch empyema was observed, as well as numerous well-demarcated areas of pallor within the skeletal muscles of all major muscle groups. Polymerase chain reaction testing of the guttural pouch exudate confirmed an infection with Streptococcus equi subsp. equi, and an S. equi-associated immune-mediated rhabdomyolysis was initially considered to be the most likely diagnosis. This report briefly discusses the various etiologies that should be considered in cases of equine myopathy, and it demonstrates the complexity of these poorly understood muscular disorders.

Intracranial meningioma in a baboon (Papio spp.).

Meningioma is the most common intracranial non-glial tumour of cats, dogs and man. Few spontaneously arising brain tumours have been reported in non-human primates. This report describes a meningioma in a captive baboon. Clinical signs exhibited by the animal included head pressing, visual impairment and vestibular disease. The tumour arose from the ventral aspect of the cranial cavity and compressed the overlying left side of the cerebellum and brainstem. Microscopically, the mass was characterized by pleomorphic spindle-shaped to polygonal cells arranged in sheaths, vague whorls and occasional papillary structures on vascular cores. Nuclear cytoplasmic invagination, syncytial-like cells and areas of mineralization were also evident. Immunohistochemically, the neoplastic cells expressed vimentin and S-100 protein, but not pancytokeratin, glial fibrillary acidic protein or epithelial membrane antigen. The features of this tumour are similar to those of meningiomas in other species.

Coccidioidomycosis presenting as a heart base mass in two dogs.

Two atypical cases of canine coccidioidomycosis presenting as heart base masses are described. An echocardiogram performed in one of the two dogs revealed a large mass at the base of the heart and a computed tomography scan showed that the mass compressed the bronchi, left atrium, aorta and pulmonary arteries. A firm, white or pale yellow mass was found at the base of the heart at necropsy examination in both cases. Microscopical examination of the masses revealed severe, chronic, locally extensive granulomatous or pyogranulomatous inflammation with intralesional spherules consistent with Coccidioides spp. The diagnosis was further confirmed by immunohistochemistry and in-situ hybridization. Coccidioides spp. have been reported to cause pericarditis in dogs, but this is the first description of coccidioidomycosis mimicking a heart-based tumour in dogs.

Granulomatous encephalomyelitis and intestinal ganglionitis in a spectacled Amazon parrot (Amazona albifrons) infected with Mycobacterium genavense.

An approximately 30-year-old male spectacled Amazon parrot (Amazona albifrons) was presented with a 2-week history of ataxia, head shaking, weight loss and seizures. Gross findings on necropsy examination included atrophy of the musculature, ruffled feathers and minimal epicardial and abdominal fat. Microscopically, there were perivascular cuffs of macrophages with fewer lymphocytes in the grey and white matter of the brain and spinal cord. These lesions were accompanied by gliosis and mild vacuolation of the white matter. In the small intestine, up to 70% of the intestinal ganglia were effaced by infiltrates of macrophages and fewer lymphocytes. The intestinal lamina propria contained multiple inflammatory aggregates of a similar nature. Ziehl-Neelsen staining revealed the presence of numerous bacilli within the cytoplasm of macrophages in the central nervous system (CNS) and enteric ganglia. Amplification of the DNAJ gene confirmed a mycobacterial infection and subsequent polymerase chain reaction (PCR) using a species-specific primer confirmed the aetiology as Mycobacterium genavense. Infection of the CNS with Mycobacterium spp. is uncommon and has not been previously reported in a parrot. This case is unusual in that the organism exhibited tropism for neural tissue.

Giant cell glioblastoma in the cerebrum of a Pembroke Welsh corgi.

A 6-year-old, neutered female Pembroke Welsh corgi was presented with a 1-month history of ataxia and panting. The clinical signs progressed until the dog became anorexic, obtunded and exhibited circling to the left. At necropsy examination, a mass was detected in the left forebrain, impinging on the cribriform plate. Microscopically, the mass was composed of sheets of round to pleomorphic neoplastic cells with vacuolated cytoplasm. Nuclear atypia, anisocytosis and anisokaryosis were common. Numerous bizarre, multinucleated giant cells containing 60 or more nuclei and giant mononuclear cells were present. The matrix contained abundant reticulin. Immunohistochemistry revealed the neoplastic cells uniformly to express vimentin, and a small number of neoplastic cells expressed glial fibrillary acid protein. A diagnosis of giant cell glioblastoma was made. Although well recognized in man, this tumour has been documented rarely in the veterinary literature.

Pathology of GM2 gangliosidosis in Jacob sheep.

The G(M2) gangliosidoses are a group of lysosomal storage diseases caused by defects in the genes coding for the enzyme hexosaminidase or the G(M2) activator protein. Four Jacob sheep from the same farm were examined over a 3-year period for a progressive neurologic disease. Two lambs were 6-month-old intact males and 2 were 8-month-old females. Clinical findings included ataxia in all 4 limbs, proprioceptive deficits, and cortical blindness. At necropsy, the nervous system appeared grossly normal. Histologically, most neurons within the brain, spinal cord, and peripheral ganglia were enlarged, and the cytoplasm was distended by foamy to granular material that stained positively with Luxol fast blue and Sudan black B stains. Other neuropathologic findings included widespread astrocytosis, microgliosis, and scattered spheroids. Electron microscopy revealed membranous cytoplasmic bodies within the cytoplasm of neurons. Biochemical and molecular genetic studies confirmed the diagnosis of G(M2) gangliosidosis. This form of G(M2) gangliosidosis in Jacob sheep is very similar to human Tay-Sachs disease and is potentially a useful animal model.