Roger A. Hostutler

Antibiotic‐Responsive Histiocytic Ulcerative Colitis in 9 Dogs

Canine histiocytic ulcerative colitis (HUC) is characterized by colonic inflammation with predominantly periodic acid-Schiff (PAS)-positive macrophages. The inflammation results in colonic thickening, ulcerations, and distortion of normal glandular architecture. Resultant clinical signs consist of chronic large bowel diarrhea, tenesmus, and marked weight loss, and the disease frequently results in euthanasia. Conventional therapy consists of some combination of prednisone, azathioprine, sulfasalazine, and metronidazole. Nine dogs (8 Boxers and 1 English Bulldog) with histologic confirmation of HUC were treated with antibiotic therapy (either with enrofloxacin alone or in combination with metronidazole and amoxicillin). Clinical signs, physical examination findings, laboratory abnormalities, and the histologic severity of the disease were evaluated. Four of the 9 dogs had been treated previously with conventional therapy and had failed to respond favorably; then, these dogs were placed on antibiotic therapy (enrofloxacin, n = 1; enrofloxacin, metronidazole, and amoxicillin, n = 3) and had resolution of clinical signs within 3-12 days. Five dogs were treated solely with antibiotic therapy (enrofloxacin, n = 1; enrofloxacin and metronidazole, n = 1; enrofloxacin, metronidazole, and amoxicillin, n = 3), and clinical signs resolved in 2-7 days. Repeated biopsy specimens were obtained from 5 dogs after treatment, and all showed marked histologic improvement. The increase in body weight after treatment was statistically significant (P = .01). Three dogs currently are not on any treatment and have had resolution of clinical signs for up to 14 months. These observations suggest that an infectious agent responsive to antibiotics plays an integral role in the clinical manifestation of canine HUC, and they support the use of antibiotics in its treatment.

Suspected phenobarbital-induced pseudolymphoma in a cat

CASE DESCRIPTION A 4.5-year-old spayed female domestic shorthair cat was evaluated because of a generalized seizure disorder that developed after an anesthesia-related hypoxic event. CLINICAL FINDINGS Following administration of phenobarbital, the seizures stopped but the cat developed severe generalized lymphadenopathy. Results of a CBC and serum biochemical analysis were unremarkable. Cytologic examination of the lymph nodes revealed a reactive lymphocyte population. Differential diagnoses included neoplasia and infection, but results of related diagnostic tests were all negative. TREATMENT AND OUTCOME Treatment was changed from phenobarbital to levetiracetam. Ten days following discontinuation of phenobarbital, the lymph node enlargement resolved, and the cat remained free of seizures with levetiracetam as treatment. CLINICAL RELEVANCE Pseudolymphoma and anticonvulsant hypersensitivity syndrome are recognized potential sequelae to anticonvulsant administration in humans. However, a pseudolymphoma-like reaction to anticonvulsants in veterinary species has not previously been reported. This case highlighted a potentially serious yet reversible sequela to phenobarbital treatment that may have been mistaken for more severe illness such as neoplasia.

IMAGING DIAGNOSIS—MRI CHARACTERISTICS OF A FOURTH VENTRICULAR CHOLESTEROL GRANULOMA IN A DOG

A 2-year-old male American Bulldog experienced paroxysmal staggering, altered consciousness, and hyperesthesia. Magnetic resonance (MR) imaging enabled recognition of a fourth ventricular mass causing compression of the cerebellum and brainstem and obstructive hydrocephalus. The mass was uniformly T2-hyperintense and predominantly T1-hypointense. A fluid line was evident on the fluid-attenuated inversion recovery images. A thin rim of contrast enhancement was noted. Histopathologic diagnosis was a cholesterol granuloma. We were unable to identify any other reports of a cholesterol granuloma residing in the fourth ventricle of a dog. This case report documents the clinical, diagnostic imaging, and histopathologic findings of a canine intracranial cholesterol granuloma.

A Laboratory Diagnostic Approach to Hepatobiliary Disease in Small Animals

Routine biochemical tests generally include serum enzymes, proteins, and other markers useful for identifying hepatobiliary disease in dogs and cats. Obtaining results outside the reference intervals can occur with direct hepatocellular injury, enzyme induction by hepatocytes or biliary epithelium, or decreased hepatic function. However, detection of biochemical abnormalities does not necessarily indicate clinically significant disease. For a comprehensive approach to detection and treatment of hepatobiliary disease, the laboratory results must be correlated with the history and physical examination findings, diagnostic imaging results, and other assays.

Diagnosis of pneumocystis pneumonia in a 2‐year‐old King Charles Cavalier Spaniel using the polymerase chain reaction

A 2-year-old, female spayed, King Charles Cavalier Spaniel was presented for evaluation of dyspnea, inappetence, and lethargy. Thoracic radiographs revealed a moderate diffuse interstitial lung pattern affecting the perihilar and caudodorsal lung fields, and an echocardiogram revealed severe pulmonary hypertension. A bronchoalveolar lavage (BAL) was performed, and cytology revealed mixed inflammation with cysts and trophozoites consistent with Pneumocystis. Pneumocystis infection was later confirmed with PCR. To the authors knowledge, this report represents the first case of canine pneumocystis pneumonia diagnosed antemortem with PCR from a BAL sample. Pneumocystis represents an important, but uncommon cause of afebrile pneumonia in immunosuppressed dogs.