Sarcocystis neurona encephalitis in a dog

A 1.5-year-old male Feist dog was presented to a veterinarian for reluctance to stand on the hind legs. Treatment included dexamethasone and resulted in a favorable initial response, but posterior paresis returned and progressed to recumbency, hyperesthesia, and attempts to bite the owner. The dog was euthanized. The brain was negative for rabies by fluorescent antibody analysis. Multiple foci of encephalitis were found in the cerebrum and particularly in the cerebellum. Protozoa morphologically consistent with Sarcocystis sp. were identified at sites of intense inflammation and malacia. Additionally, multiple schizonts were identified in areas without inflammation. Immunohistochemistry using both polyclonal and monoclonal antibodies specific for Sarcocystis neurona was strongly positive. No reaction to polyclonal antisera for Toxoplasma gondii or Neospora caninum was found. Polymerase chain reaction confirmed that the protozoa were S. neurona. Additional aberrant hosts for S. neurona other than horses have been identified, but S. neurona encephalitis has not been documented previously in the dog.     

Sarcocystis calchasi encephalitis in a rock pigeon

A rock pigeon (Columba livia) caught in Akihabara, Tokyo, showed neurological symptoms, such as head tilt and circling. Pathological examinations revealed abundant Sarcocystic cysts in the skeletal muscle and myocardium with mild myositis, and numerous schizonts and sarcocysts with severe multifocal granulomatous T-lymphocytic infiltration in the central nervous system. A Sarcocystis calchasi-specific gene was detected in the muscle and brain. This case indicates S. calchasi was distributed in Japan and caused severe encephalitis to rock pigeons.     

Pineoblastoma in a cockatiel

Pineoblastoma, a primitive neoplasm of pineal gland origin, was diagnosed in a cockatiel based on gross, histopathological, and electron-microscopic findings.     

Sarcocystis neurona-like encephalitis in a Canada lynx (Felis lynx canadensis).

A 13-yr-old female Canada lynx (Felis lynx canadensis) died after a short clinical illness, and necropsy revealed multifocal, nonsuppurative encephalitis with protozoal schizonts present in cerebral vascular endothelial cells. The schizonts stained immunohistochemically with antiserum to Sarcocystis neurona. This is the first report of Sarcocystis encephalitis in the Canada lynx.     

Pancreatic carcinoma in a cockatiel

A female cockatiel was examined because of abdominal distention, decreased appetite, and weight loss. Although abdominocentesis, bacteriologic culture, radiography, and ultrasonography were performed, the diagnosis of pancreatic carcinoma was obtained only after exploratory laparotomy and histologic examination. The resected abdominal mass was pancreatic carcinoma. The bird survived for 56 days after surgery. Necropsy confirmed abdominal metastatic pancreatic carcinoma.     

Molecular characterization of Sarcocystis spp. as a cause of protozoal encephalitis in a free-ranging black bear

A free-ranging juvenile male black bear (Ursus americanus), found dead in Alberta, Canada, had severe nonsuppurative encephalitis. Lesions in the brain were most severe in the gray matter of the cerebral cortex, and included perivascular cuffs of lymphocytes and plasma cells, areas of gliosis that disrupted the neuropil, and intralesional protozoan schizonts. The left hindlimb had suppurative myositis associated with Streptococcus halichoeri. Immunohistochemistry and molecular analyses (PCR and sequencing of 4 discriminatory loci: 18S rDNA, ITS-1 rDNA, cox1, rpoB) identified Sarcocystis canis or a very closely related Sarcocystis sp. in the affected muscle and brain tissues. The main lesion described in previously reported cases of fatal sarcocystosis in bears was necrotizing hepatitis. Fatal encephalitis associated with this parasite represents a novel presentation of sarcocystosis in bears. Sarcocystosis should be considered a differential diagnosis for nonsuppurative encephalitis in bears.     

Listeriosis in a cockatiel (Nymphicus hollandicus)

Listeriosis was diagnosed in a 4-yr-old female cockatiel (Nymphicus hollandicus) that died after exhibiting clinical signs that included a fluffed-up appearance, weakness, and loss of weight of several days duration. Grossly, the bird was moderately emaciated, and the liver and spleen were enlarged. Microscopically, there was mild-to-moderate inflammation associated with rod-shaped, gram-positive bacteria in the liver, spleen, kidneys, adrenal glands, bone marrow, and esophagus. Listeria monocytogenes was isolated from the liver, trachea, and intestine. The isolate was identified as type 1 by agglutination with specific antisera, and it further identified as belonging to serovar group 1/2a, 3a by multiplex polymerase chain reaction assay. Listeria monocytogenes also was detected in affected tissues by immunohistochemistry.     

Goiter in a cockatiel (Nymphicus hollandicus)

Goiter in a 2-year-old male cockatiel with respiratory distress was characterized by bilateral enlargement of the thyroid glands. Microscopic lesions included features of both hyperplastic goiter and colloid goiter. There also was localized hemosiderosis due to hemorrhage in subcapsular space and in thyroid follicle lumens.     

Subcutaneous haemangiosarcoma in a cockatiel (Nymphicus hollandicus)

An ulcerated, 1 x 0.5 cm, subcutaneous mass on the craniolateral aspect of the right tibiotarsus of a 4-year-old male cockatiel was removed. Histologically, the neoplasm was non-encapsulated, infiltrative and composed of irregular vascular channels lined by branching and variably sized spindle-shaped cells with large vesicular nuclei, prominent nucleoli and rare mitoses. Surrounding these vascular channels were fibroblasts and mixed inflammatory cells. Neoplastic cells had diffuse immunoreactivity to factor VIII supporting a diagnosis of haemangiosarcoma.     

Abdominal hernia with formation of a urate concretion in a cockatiel

A female cockatiel had a 2-week history of abdominal distention, lethargy, and diarrhea. The cockatiel had a history of frequent egg-laying, and the owner suspected that she was egg-bound. A solid mass was removed through the cloaca and found to be a concretion of urates that had formed within a hernial pouch of the caudal abdominal musculature. Diagnosis was aided by contrast radiography, and surgery was performed. However, the abdominal hernias recurred 16 months later. The continual egg-laying probably predisposed this bird to hernia formation. Abdominal hernias in birds may be a consequence of continual egg-laying and associated hormonal effects leading to a weakening of abdominal musculature.     

Immunohistochemical characterization of a malignant intraocular teratoid medulloepithelioma in a cockatiel

A 3-year-old cockatiel was presented for evaluation of a buphthalmic right eye (OD). The history included a traumatic event 5 months prior to presentation, and the referring veterinarian diagnosed cataract and secondary glaucoma. Computed tomography of the bird's orbital region revealed a large right orbital soft tissue mass that extended lateral to the orbital rim with obliteration of the globe without bone involvement. There was also no evidence of metastatic disease within the lungs or any abnormalities within the celomic cavity, therefore enucleation was recommended to achieve a histopathologic diagnosis and prognosis, and to palliate the clinical signs. Final diagnosis was malignant intraocular teratoid medulloepithelioma.     

Myocarditis and encephalitis associated with Sarcocystis neurona infection in raccoons (Procyon lotor)

Sarcocystis neurona associated granulomatous encephalitis was found in 2 of 84 adult raccoons. Both raccoons also had an extensive nonsuppurative myocarditis and one had S. neurona schizonts and merozoites in the myocardium. Only the asexual stages (schizonts and merozoites) of S. neurona are found in tissues of naturally infected animals (horse, mink, raccoons, cats, skunk, pony, seals, sea otters) and since these have not been reported outside the central nervous system, the presence of concurrent myocarditis in raccoons with the presence of S. neurona in the current study is of interest. Pathologists should consider the possible association of S. neurona with myocardial inflammation in other S. neurona susceptible animals.     

Diarrhea associated with small-intestinal cryptosporidiosis in a budgerigar and in a cockatiel

Small-intestinal cryptosporidiosis has not been described in budgerigars or cockatiels. Organisms of the genus Cryptosporidium were found during histologic examination of segments of small intestine from a budgerigar with chronic weight loss and from a cockatiel that died acutely. Parasitism was accompanied by non-purulent inflammation (lymphocytes and plasma cells predominated). Bacterial and viral pathogens were not isolated. The death of the budgerigar was attributed to malassimilation interpreted to have been caused by Cryptosporidium. The cause of death in the cockatiel was inhalation pneumonia. Because the index of suspicion for cryptosporidiosis was low, samples for isolation of Cryptosporidium were not collected. In the future, cryptosporidiosis should be included as a differential diagnosis for weight loss and death in pet birds, and isolation and speciation of Cryptosporidium sp. should be attempted and reported.     

Egg binding in a cockatiel (Nymphicus hollandicus).

A 6-year-old cockatiel was diagnosed with egg binding based on clinical signs, physical examination findings, radiographs, and lack of oviposition. Medical management failed to induce oviposition, and surgical salpingotomy was used to remove the egg from the oviduct. Sterile egg yolk peritonitis was diagnosed based on histology. Postoperative management with leuprolide acetate and husbandary changes successfully prevented egg production for at least 2.5 months after the event.     

Polyostotic hyperostosis associated with oviductal tumor in a cockatiel

A 10-year-old female cockatiel in a thin and depressed condition and with a 1 X 2-cm soft abdominal swelling was hospitalized. Radiography revealed a well-circumscribed mass containing punctate areas of mineralization, displacing the gizzard cranially in the caudodorsal portion of the abdomen. There was bilateral, symmetric, generalized, increased medullary opacity of the radius, ulna, carpometacarpus, femur, tibiotarsus, and tarsometatarsus. These findings were compatible with polyostotic hyperostosis secondary to an estrogen-secreting tumor. Euthanasia and necropsy were requested. A small area of neoplastic cells in the oviduct was identified histologically, but most of the tissue mass consisted of necrotic cellular debris. There was no metastasis. Sagittal secretions of decalcified radiopaque bones revealed up to 60% filling of medullary cavities with bone spicules. Although clinical and radiographic findings were compatible with an estrogen-secreting tumor, osteopetrosis, metastatic neoplasia, hypertrophic osteopathy, and metabolic bone disease were included in the initial differential diagnosis. The absence of metastasis and the confinement of the tumor within the oviduct would have made surgical removal a possible approach to treatment.     

Ectopic egg yolk in the abdominal cavity of a cockatiel.

A mature cockatiel was presented to the teaching hospital with acute, severe dyspnea and a markedly enlarged abdomen. The bird died 2 hours after admission and was necropsied. A 3-cm egg yolk was present in the abdominal cavity and caused cranial displacement of the abdominal viscera. Death occurred acutely and was probably due to severe respiratory distress.