It is the kidney’s job to filter toxins from the blood, and each kidney contains thousands of microscopic filtration units called nephrons. Like all cells, nephrons have a finite lifespan. They cannot regenerate — your pets (and you) are born with an absolute number of nephrons, and once they’re gone, they’re gone.
Most pets have plenty of wiggle room in the nephron department — the kidneys function just fine even if they drop down to a fraction of healthy nephrons. In fact, it’s not until the kidneys are down to about a third of their filtering ability that signs of kidney disease occur.
Chronic renal failure, or chronic kidney disease, is common in older pets (especially cats). Kidneys filter out toxins and excrete them with water into the urine. When the kidneys start to slow down, they use more and more water to dilute the blood’s toxins. This leads to larger volumes of urine, which leads to increased thirst and water intake. Most pets with chronic kidney disease display increased thirst well before other symptoms emerge.
Eventually, the kidneys will not be able to adequately do their job, and toxins begin building up in the bloodstream. These toxins (as well as chronic dehydration) lead to clinical signs like inappetence, nausea, vomiting, weight loss and constipation. If you notice any of these signs, schedule a visit with your veterinarian for blood work.
Your veterinarian may offer several things you can do at home to maintain or improve quality of life for a pet with chronic kidney disease, including:
- water down: Encourage your pet to drink more. For cats, this may mean leaving cups of water around the house or perhaps investing in a recirculating water fountain.
- try a different diet: Switch to canned food, which has higher water content, and ask your vet about a special prescription diet to ease the burden on the kidneys.
- learn to administer fluids subcutaneously (under the skin): There will come a point when your pet simply cannot drink enough water to keep up with her losses, and administering fluids at home can help your pet avoid a hospital stay.
- watch closely for signs of progression: Pets with chronic kidney disease are at risk for dehydration, anemia, high blood pressure, blindness and severe electrolyte imbalances. Get in touch with your veterinarian right away if your pet develops new symptoms.