Chronic Kidney Disease

Kidney disease in dogs and cats generally occurs as either acute, or chronic kidney disease.Acute kidney disease is usually caused by ingestion of a toxin or allergic disease causing sudden onset acute severe signs. Commonly accessible known toxins that we see regularly causing problems, are cats ingesting lilies, and dogs eating raisins and occasionally dried grapes. Affected animals can make a full recovery, with intensive care, medication and hospitalisation, however unfortunately some cases will die irrespective of the amount of treatment and medical intervention. Acute renal failure may cause a complete lack of urine production as the kidneys aren’t working at all.

Chronic kidney failure is quite different. It is usually the end stage of disease that has been going on for many years. It is thought in cats long term, lowgrade bacterial infection from dental disease or abscesses can lead to chronic kidney failure.

Chronic kidney failure is usually insidious in onset, with signs often appearing over months, or even years. Whilst the disease is incurable, it is very manageable with many patients living happy normal lives for months or years.

Unlike the acute form of the disease, affected animals often produce more urine than normal, and may be unable to make it through the night without needing to go to the toilet.

Clinical signs

Look for changes in behaviour such as needing to go to the toilet more often, general malaise, and increased water consumption. Other signs are:

• Weight loss
• Poor hair coat
• Increased drinking
• Increased urinating
• Inappetence
• Bad breath
• Lethargy
• Disorientation
• Blindness
• Vomiting

Diagnosis

Kidney disease is diagnosed by a combination of blood and urine testing. It is a common disease so is a normal component of screening blood tests. It is one of the reasons regular blood profiles are very important for older pets.

These tests can reliably tell if kidney disease is present. They are not good prognostic indicators. In other words very poor results can be caused by dehydration, and the long-term outlook may be good. Moderate elevations in blood result can be seen in animals with low body mass, even if the kidney disease is severe.

Blood pressure monitoring is also useful, as chronic kidney disease can lead to high blood pressure.

The kidneys may also be visualized by xray, or ultrasound, though this is more commonly of value for acute kidney disease rather than chronic.

Treatment

(1)Initial treatment
Some pets are very unwell at the time of diagnosis, as the early signs in your pet are easy to miss. If animals are very dehydrated, and inappetant, then they are usually hospitalised for a few days for fluid therapy.

This not only makes them feel better quickly, but can have a long-term impact. Protein plugs can form in diseased kidneys. Fluids can flush these out, much like using a high-pressure hose to flush a clogged showerhead. After fluids the kidney function can improve dramatically.

Unfortunately there is a minimum kidney mass required for life (about 10% of that they were born with). If they are under this limit pets cannot survive off a drip. Unfortunately we have no way of knowing what the remaining kidney mass is, so trial therapy is the only way to know if your pet will recover.

(2) Long term management
A number of factors can dramatically improve your pet’s quality of life, and life expectance, if they have kidney disease.

Diet
Animals with kidney disease have very specific protein requirements. They need limited amounts of high quality protein. Too much protein will make the clinical signs worse. Not enough protein and the kidney damage can actually be accelerated. This can also occur in animals without kidney disease that eat a restricted protein diet. This is not a diet that should be used in case there is a kidney problem. They are very specific diets to be used after proper diagnostic testing.

The diet also needs restricted amounts of phosphate (found in high levels in meat)

The diet is usually best managed using one of the specific diets made for treating kidney disease. These come in both canned and dry forms. We will advise you on what is the best option for your pet. In some instances a special homemade diet may also be used.

Phosphate binders
High phosphate levels are one of the key causes of inappetence in animals with kidney disease. Phosphate binders, such as iparkatine, which are added to the food, decrease levels of phosphate in the blood.

ACE inhibitors
These drugs are used primarily to control hypertension (high blood pressure). Whilst animals with kidney disease often have high blood pressure, these drugs have another important role.

They can specifically increase the blood flow through the kidney, in cats, improving kidney function. This effect may also occur in dogs. ACE inhibitors can have a dramatic effect on the long-term outcome, for animals with kidney disease.