Chronic renal insufficiency
Chronic renal insufficiency occurs in three times as many geriatric cats as geriatric dogs. Stabilized cats can live for many
years with chronic renal insufficiency, so develop a comprehensive management plan for these patients. Your goal is to help
cats enjoy longer, higher-quality lives by lessening clinical signs and systemic complications and preventing further renal
function deterioration. Chronic renal insufficiency complications in cats include renal secondary hyperparathyroidism, hypertension,
hypokalemia, proteinuria, anorexia, and anemia.
Cats and owners benefit when you teach owners to administer subcutaneous fluids at home. Administering about 100 ml of crystalloid
fluids daily subjectively appears to improve quality of life. Offering water flavored with low-sodium chicken broth or clam juice and using recirculating water fountains may also increase cats' water intake.
Don't restrict dietary protein for cats experiencing mild to moderate chronic renal insufficiency (creatinine 1.6 to 2.8 mg/dl,
140 to 250 μmol/l) because it can lead to protein malnutrition. These cats require adequate protein and calories to maintain
body weight and to avoid muscle wasting and anemia. Protein restriction decreases hemoglobin production, promoting anemia,
and decreases plasma protein levels, causing muscle wasting. Cats with moderate to severe chronic renal insufficiency (creatinine
>2.9 mg/dl, 251 μmol/l), however, will benefit from dietary protein and phosphorus restriction to avoid uremia complications.
The signs of uremia in cats include lethargy, depression, anorexia, and vomiting due to gastritis. Choose a palatable diet,
preferably canned, with protein of high biological value.
Never try to force an anorexic patient with chronic renal insufficiency to eat a protein-restricted diet. Instead, concentrate
on encouraging anorexic patients to eat. Controlling uremic gastritis with H2 receptor blockers such as famotidine (0.5 mg/kg orally every 24 to 48 hours) or ranitidine (2 mg/kg orally every 12 hours)
may help inappetent cats eat more.
Nauseated cats may benefit from metoclopramide (0.2 to 0.4 mg/kg orally every eight hours) given 30 minutes before feeding.
Use cyproheptadine (1 to 2 mg/cat orally) as needed to stimulate the cat's appetite. About 20% to 30% of patients with chronic renal insufficiency are hypokalemic at
presentation (Figure 3), so monitor serum potassium and supplement with potassium gluconate (2 to 4 mEq orally every 12 hours) as necessary. Correcting
hypokalemia improves the patient's well-being and appetite.
Figure 3. Cervical ventroflexion is a common clinical sign in cats with severe hypokalemia, often associated with chronic
Renal secondary hyperparathyroidism occurs in 80% or more of patients with chronic renal insufficiency. To maintain normal
serum phosphorus concentrations, use intestinal phosphate binders such as aluminum hydroxide (90 to 100 mg/kg/day orally, divided doses with food, increase as needed). A new phosphate binder that may be useful for cats that do not tolerate aluminum
hydroxide is sevelamer hydrochloride (Renagel—Genzyme Corp.; suggested dose 200 mg orally every eight to 12 hours with food),
although it requires further investigation to define its benefits and a definitive dose for cats.
Calcitriol (2 to 3 ng/kg orally every 24 hours) may help prevent and treat elevations in parathyroid hormone (PTH) concentrations
associated with chronic renal insufficiency. Controlling PTH may reduce PTH toxicosis, slowing chronic renal insufficiency progression and improving appetite and well-being. It is only administered when phosphorus concentrations are normal and the calcium × phosphorus product is under 60. It's important to educate clients and ensure compliance when you use calcitriol
because you must monitor patients' PTH and ionized calcium concentrations regularly. Serum calcium must be monitored at one
and two weeks after the start of calcitriol therapy and every six months thereafter. PTH levels should be monitored monthly