Development of a reference interval for urinary ammonia-to-creatinine ratio in feline patients.

Background: Disruption of acid-base homeostasis can lead to many clinical problems. Ammonia excretion by the kidneys is critical to maintaining acid-base homeostasis through bicarbonate production. Measurement of ammonia excretion may help determine if the kidneys are properly functioning in maintaining acid-base balance.

A "down under" lesion on the muzzle of a dog.

A 10-year-old, castrated, male Labrador Retriever was presented to a local veterinary practice for investigation of a firm, deeply pigmented, alopecic, subcutaneous mass (8 mm in diameter) on the left side of the muzzle. A fine-needle aspirate of the mass was submitted for cytologic evaluation to the University of Florida. Microscopically, the preparation contained a predominant population of histiocytes that contained variable numbers of intracytoplasmic, negative-staining, filamentous structures consistent with Mycobacterium sp.