Disseminated Halicephalobus gingivalis infection in a horse.

A 19-y-old American Saddlebred gelding was evaluated for epiphora of the right eye and generalized cachexia. Initial examination revealed anterior uveitis without ulceration, for which treatment was initiated. Despite the initial response to treatment, the signs progressively worsened to blindness. Histologic examination of the enucleated eye revealed granulomatous panuveitis and optic neuritis with intralesional nematode larvae identified as Halicephalobus gingivalis. Over time and despite anthelmintic treatment, blindness developed in the left eye along with neurologic signs, and the horse was euthanized. Disseminated halicephalobosis was diagnosed on postmortem examination, involving the heart, spleen, kidneys, oral cavity, tongue, left eye, lungs, CNS, adrenal glands, liver, and lymph nodes. Splenic involvement has not been reported previously, to our knowledge. Halicephalobosis is a sporadic parasitic disease that affects equids mostly and for which prognosis is poor despite aggressive systemic anthelmintic treatment. Parasitic granulomatous disease should be included as a differential diagnosis in equids with ocular or neurologic disease.

Pathology in Practice.

In collaboration with the American College of Veterinary Pathologists.

Malakoplakia in the Urinary Bladder of 4 Puppies.

Malakoplakia in humans most often affects the urinary bladder and is characterized by inflammation with von Hansemann-type macrophages, with or without Michaelis-Gutmann bodies, and is frequently associated with Escherichia coli infection. We describe the microscopic features of malakoplakia in the urinary bladder of 4 puppies. In all cases, the lamina propria of the urinary bladder was markedly expanded by sheets of large, round to polygonal macrophages with intracytoplasmic, periodic acid-Schiff-positive granules and granular inclusions, and rare Prussian blue-positive inclusions. Macrophages were positive for CD18 and Iba1. In 2 cases, Michaelis-Gutmann bodies were detected with hematoxylin and eosin stain and were best demonstrated with von Kossa stain. E. coli infection was confirmed in 2 cases with bacterial culture or polymerase chain reaction (PCR) and sequencing of the bacterial 16S ribosomal RNA gene. Transmission electron microscopy of one case demonstrated macrophages with abundant lysosomes, phagolysosomes, and rod-shaped bacteria. Microscopic features were similar to human cases of malakoplakia. In dogs, the light microscopic characteristics of malakoplakia closely resemble granular cell tumors and histiocytic ulcerative colitis.

Diagnosis of Collagen Type III Glomerulopathy Using Picrosirius Red and PASH/Masson's Trichrome Stain.

Canine collagen type III glomerulopathy (Col3GP) is a rare juvenile nephropathy in which irregular type III collagen fibrils and fibronectin accumulate in glomerular capillary walls and the mesangium. Necropsy findings were reviewed from 5 puppies diagnosed with Col3GP at 6 to 18 weeks of age. Histologically, with hematoxylin and eosin stain, the glomerular capillary walls and mesangium were diffusely and globally expanded by homogeneous pale eosinophilic material. Ultrastructurally, the subendothelial zone and mesangium were expanded by fibronectin and cross-banded collagen type III fibrils, diagnostic of Col3GP. Two additional stains were employed to identify the material within glomeruli as fibrillar collagen using light microscopy. In all 5 cases, the material was red with picrosirius red and birefringent under polarized light, and was blue with periodic acid-Schiff/hematoxylin/trichrome (PASH/TRI), thereby identifying it as fibrillar collagen. Based on these unique staining characteristics with picrosirius red and PASH/TRI, Col3GP may be reliably diagnosed with light microscopy alone.

Disseminated Rhodococcus equi in an Anglo-Nubian goat.

Disseminated Rhodococcus equi infection was diagnosed in an Anglo-Nubian goat presenting for non-weight bearing lameness of the right pelvic limb. Radiographs showed a moth-eaten osteolytic lesion in the proximal tibia suggestive of an aggressive bone lesion. Two pulmonary nodules were also present on thoracic radiographs. Initial antemortem cytology of the tibial lesion was suggestive of Rhodococcosis and the goat was sent to necropsy. Necropsy and bacterial culture confirmed the diagnosis of disseminated R. equi infection in the right tibia, lungs, and liver.

A case of hypercalcemia in a heifer presumably due to mammary carcinoma bovine hypercalcemia of malignancy.

Mammary carcinoma is rare in cattle with only a handful of cases found in the literature, and none have reported an associated hypercalcemia. An 8-year-old Holstein-Friesian heifer was presented to the Purdue University Veterinary Teaching Hospital's Large Animal Hospital with a 3-month history of lethargy. Laboratory abnormalities included ionized hypercalcemia and hypophosphatemia (2.28 mmol/L and 1.8 mg/dL, respectively). Physical examination revealed a mammary mass that was cytologically described as a suspected mammary carcinoma, which was later confirmed by histologic evaluation. On surgical removal of the mass, calcium initially decreased rapidly, and within a few days was within the RI, further supporting a diagnosis of hypercalcemia of malignancy in a heifer. However, attempts to confirm this using hormone profiles (parathyroid hormone [PTH], parathyroid hormone-related protein [PTHrp], and calcitriol) were inconclusive due to the lack of validated assays and RIs for cattle. Immunohistochemical staining for PTHrP showed scattered cytoplasmic staining among the neoplastic cells, suggesting PTHrP production by these cells.