Clinical Case Challenge

feline photo

A 15-year-old castrated male domestic shorthair cat presented for evaluation of polyuria/polydipsia and weight loss despite a good appetite. He weighed 9 pounds (4.1 kg) with a body condition score of 4/9. Moderate atrophy of the epaxial muscles was noted. Physical examination was otherwise unremarkable. A CBC revealed a mild, non-regenerative anemia (Hct, 25%; reference range, 31-46%).The biochemistry profile revealed hyperglycemia (glucose, 583 mg/dl; reference range, 70-120 mg/dl) and azotemia (BUN, 99 mg/dl; reference range, 15-33 mg/dl; creatinine, 3.2 mg/dl; reference range, 0.9-2.1 mg/dl). Urinalysis revealed a specific gravity of 1.015 with 4+ glucose and no proteinuria. T4 was within the reference range. A complete diet history revealed that the cat was eating ½ cup over-the-counter (OTC) dry adult maintenance cat food plus two 3 oz. cans of cat food per day (both made by good quality major manufacturers – specific varieties and flavors were included in the diet history). The cat did not receive any cat treats, table food, or dietary supplements.

How can you explain this cat’s PU/PD and weight loss?
This cat likely has multiple disease processes. The hyperglycemia and glycosuria strongly suggest the presence of diabetes mellitus (DM); this could be confirmed with a fructosamine level. The azotemia and lack of appropriate urine concentration suggest the presence of chronic kidney disease (CKD). However, because DM may cause pre-renal azotemia and isosthenuria, it is important to monitor urine specific gravity and kidney values to ensure that the abnormalities persist after treatment of the DM. Anemia is likely due to CKD, i.e.,  anemia of chronic disease. Both DM and CKD likely contributed to this cat’s weight loss and muscle loss.

What nutritional intervention(s) should be instituted?
Insulin is central to the treatment of feline DM. However, nutrition is a key component of optimal medical therapy for cats with either DM or CKD. There is some evidence that decreased dietary intake of carbohydrate and increased protein may improve diabetic control. For CKD, a protein and phosphorus-restricted, non-acidifying diet is optimal to prolong survival and reduce the risk of uremic crises. In this cat, a diet with the following properties is desired:
– Reduced in protein, phosphorus, and sodium
– Non-acidifying for the kidney disease (most OTC cat foods are acidifying)
– Reduced carbohydrate

Royal Canin Renal LP Modified canned food was selected. The 6-oz pâté variety of this diet was chosen as the 2.5-oz morsels in gravy variety are high in carbohydrate.

In cases where multiple disease processes are present with disparate nutritional goals, we must consider the relative impact of each disease on the patient’s survival and quality of life. Obtaining a thorough diet history is important to assess baseline nutritional status and thus allow for appropriate dietary recommendations.

The cat was regulated on 1 Unit PZI insulin SQ q12h and a consistent diet of Royal Canine Renal LP canned food. Body weight improved and was carefully monitored to avoid obesity. Renal values stabilized at IRIS stage II CKD.