A challenging case: A German shepherd with a decreasing appetite and azotemia

Obtaining samples by using ultrasound guidance and re-reviewing results helped these clinicians identify a rare and easily overlooked disease.


Vital Stats
A 3-year-old castrated male German shepherd was referred to the Foster Hospital for Small Animals at Tufts University for evaluation of polyuria, polydipsia, and decreasing appetite.

History

The dog had been presented to the referring veterinarian five months earlier for evaluation of intermittent inappetence, polyuria, and polydipsia. The dog had a history of skin allergies, which had been treated with prednisone (0.5 mg/kg) intermittently and hyposensitization.

The results of a complete blood count and serum chemistry profile had been normal except for eosinophilia (2,048 cells/μl, reference range = 100 to 1,250 cells/μl). Urinalysis of a free-catch sample revealed isosthenuria with mild hematuria, pyuria, and bacteriuria. Cephalexin (22 mg/kg orally t.i.d. for 14 days) had been prescribed for a presumed bacterial urinary tract infection. No clinical improvement had been noted.

The dog had been brought back to the referring veterinarian three months later with the same presenting complaint. A complete blood count and serum chemistry profile performed at that time revealed persistent eosinophilia (2,125 cells/μl), hyperproteinemia (8.6 g/dl, reference range = 5.1 to 7.8 g/dl), hyperglobulinemia (5.4 g/dl, reference range = 2 to 4 g/dl), hypercalcemia (11.5 mg/dl, reference range = 8.5 to 11.3 mg/dl), and azotemia (blood urea nitrogen [BUN] 57 mg/dl, reference range = 7 to 27 mg/dl; creatinine 4.2 mg/dl, reference range = 0.4 to 1.8 mg/dl). The urinalysis results had been similar to those of the previous examination. The results of an aerobic bacterial urine culture, a serum total thyroxine measurement, and an abdominal radiographic examination had been normal. Phenylpropanolamine was prescribed at that time.

Physical examination and diagnostic tests

At presentation to Tufts University two months later, the dog weighed 93 lb (42.2 kg). It had lost 4.5 lb (2 kg) since the initial examination by the referring veterinarian. The dog's temperature, pulse, and respiration were normal, and the physical and ophthalmic examination results were unremarkable except for abdominal discomfort during palpation.

A serum chemistry profile revealed azotemia (BUN 47 mg/dl, reference range = 8 to 29 mg/dl; creatinine 5.6 mg/dl, reference range = 0.6 to 2 mg/dl), hypercalcemia (12.7 mg/dl, reference range = 9.4 to 11.6 mg/dl), and hyperkalemia (5.7 mEq/L, reference range = 3.8 to 5.4 mEq/L); the results were suggestive of renal disease. A complete blood count was not done at this time. Pending further diagnostic evaluation, the dog was treated with intravenous lactated Ringer's solution (170 ml/h) and ampicillin (22 mg/kg intravenously t.i.d.) for possible leptospirosis.

An ACTH stimulation test was performed to rule out hypoadrenocorticism as a cause of the polyuria, polydipsia, and eosinophilia. The results were normal (baseline cortisol = 3.1 μg/dl, reference range = 2 to 6 μg/dl; cortisol concentration an hour after cosyntropin administration = 13.8 μg/dl, reference range = 6 to 18 μg/dl). The dog was seronegative for antibodies to Leptospira species (serovars pomona, hardjo, icterohaemorrhagiae, grippotyphosa, canicola, and bratislava). Serologic testing for tick-borne diseases was not indicated based on the absence of such clinical signs as fever, lethargy, lameness, or lymphadenopathy.

Urinalysis of a sample collected by cystocentesis revealed isosthenuria (urine specific gravity 1.012), hematuria (20 to 30 red blood cells/hpf, 10 to 20 white blood cells/hpf), and many fungal hyphae. Aerobic bacterial and fungal urine cultures yielded no growth.