Larry G. Adams, DVM, PhD, DACVIM (SAIM)
Anorexia is a common clinical problem in cats with chronic kidney disease (CKD). It is important that cats with CKD maintain adequate caloric intake to avoid protein-calorie malnutrition and maintain body condition. A recent study in dogs with CKD comparing survival and body condition score (BCS) showed that dogs with low BCS have significantly shorter survival than dogs with normal BCS and those that were overweight.1 While a similar study has not been reported in cats, poor nutritional intake and low body condition score are likely to impact survival in cats with CKD, similar to other species such as dogs and humans.
Introduction of renal therapeutic diets may initially result in decreased food intake. The method of introduction of the diet is important. Gradual transition to the renal diet over 2–4 weeks resulted in excellent acceptance of the diet in cats with stage 2–3 CKD in one clinical trial.2 Cats with stage 4 CKD often fail to eat sufficient food voluntarily, regardless of the palatability or nutrient content. Monitoring for evidence of protein-calorie malnutrition should include monitoring for weight loss, hypoalbuminemia, anemia, poor hair coat quality, muscle wasting and declining body condition scores. Diet consumption may be encouraged by minimizing uremia by maintaining hydration and treating for uremic gastritis.
Cats with CKD have increased serum gastrin concentration, which contributes to the pathogenesis of uremic gastritis. Uremic gastritis contributes to anorexia in addition to vomiting. Famotidine (5 mg per cat PO q 24 h) is recommended for treatment of uremic gastritis secondary to CKD once the serum creatinine is above 250 mmol/L. For more severe uremic gastritis or during a uremic crisis, oral omeprazole (0.7 mg/kg PO q 24 h), IV pantoprazole (0.7–1 mg/kg q 24 h), ondansetron (0.5 mg/kg PO or IV q 12 h) or maropitant (Cerenia 0.5–1 mg/kg SQ or PO q 24 h) are more effective for reducing uremic gastritis and uremic-induced nausea. Maropitant is generally used once daily for up to 5 days, although current studies are evaluating longer-term administration for CKD patients.
During a uremic crisis with active vomiting, do not feed CKD cats orally and avoid force-feeding of renal diets because these approaches are likely to induce food aversions in cats. Once the vomiting has stopped and azotemia reduced, food is reintroduced as frequent small meals. It is better to introduce new renal diets once the cat is discharged rather than during hospitalization. For some cats, heating the food to room temperature, or adding small amounts of water, tuna water or clam juice to the diet may increase dietary acceptance. However, these may contain large amounts of sodium and may worsen hypertension.
For cats with stage 3–4 CKD, administration of subcutaneous fluids, such as Plasmalyte or LRS, daily or every other day may be beneficial. Subcutaneous fluids should not be implemented too early in the progression of CKD (stage 2 CKD) because the sodium content of isotonic fluids may contribute to development of hypertension in some cats with sodium-responsive hypertension. Subcutaneous (SQ) fluid therapy does not increase GFR above what the kidneys are capable of provided they are normally perfused. Subcutaneous fluids help keep the animal well hydrated and allow some increased elimination of BUN through increased tubular flow rates.
If therapy for uremic gastroenteritis and administration of SQ fluids fail to restore adequate caloric intake, administration of mirtazapine (1–3 mg PO q 72 hours) or cyproheptadine (1–2 mg PO q 12–24 hours) to stimulate appetite should be attempted. It is important to confirm that any apparent response sufficiently enhances food intake to meet nutritional needs (increasing or stable body weight and BCS). If food intake remains inadequate or BCS is low (≤ 3/9), assisted tube feeding should be considered.3 Long-term percutaneous endoscopic gastrostomy (PEG) or esophagostomy tubes are useful for delivering food, extra water and medications to cats with CKD. Tube feeding can reverse progressive weight loss associated with CKD and cats can have extended periods of improved quality of life. Tube feeding of CKD cats may be much easier than management with SQ fluids and numerous oral medications. Assisted tube feeding of cats with CKD is an important therapeutic approach that should be considered in any cat, when medical management does not effectively eliminate anorexia and for CKD cats with declining BCS.
1. Parker VJ, Freeman LM. Association between body condition and survival in dogs with acquired chronic kidney disease. J Vet Intern Med. 2011;25:1306–1311.
2. Ross S, Osborne CA, et al. Clinical evaluation of dietary modification for treatment of spontaneous kidney disease in cats. J Am Vet Med Assoc. 2006;229:949–957.
3. Elliott DA, Riel DL, et al. Complications and outcomes associated with use of gastrostomy tubes for nutritional management of dogs with renal failure: 56 cases (1994–1999). J Am Vet Med Assoc. 2000;217:1337–1342.