Kidney Problems in Dogs and Cats


All mammals have a pair of kidneys located in the abdomen, one either side of the spine and just tucked up under the ribs. Their main functions are to:

  • Eliminate waste products from the body
  • Help maintain fluid balance
  • Assist in regulation of blood pressure
  • Produce erythropoietin, a hormone involved in the production of red blood cells
  • Regulation of the calcium and phosphorus levels in the blood

Blood, carrying waste products, enters the kidneys through the renal arteries, which branch into smaller and smaller vessels within the kidney. These end as complex networks of capillaries, known as glomeruli, through which the blood is filtered.

The filtered material is collected and, as it passes along to the next stage, water and other vital substances are absorbed back into the bloodstream. This process of reabsorption is vital to good health. Under normal circumstances, some substances are completely reabsorbed, such as glucose, while others, such as urea (a waste product), are completely eliminated. Of all the fluid filtered out, some 99% is reabsorbed and as little as 1% ends up as urine which is passed into the bladder for storage.

The kidneys have a large functional reserve and can lose over 75% of their capacity before any symptoms of kidney disease can be seen. Despite this fact, kidney problems are fairly common in both dogs and cats.


There are basically two common forms of kidney failure:

  • Acute kidney failure

This is sudden in onset and caused by damage to the kidneys by infection, dehydration, poisoning or haemorrhage.

Symptoms include:

  • Vomiting
  • Diarrhoea
  • Lethargy
  • Dehydration
  • Anorexia (not eating)
  • Abdominal pain
  • Weight loss

The build-up of waste products, especially urea, leads to a situation known as uraemia, causing the breath to smell unpleasant. Treatment needs to be carried out promptly to limit damage.

  • Chronic kidney failure

This is more common, with a progressive deterioration of kidney function.

Symptoms include:

  • Increased thirst
  • Increased urination
  • Periodic vomiting
  • Picky appetite
  • Dehydration
  • Poor coat and general health
  • Ulceration of the mouth and gums
  • Bad breath
  • Anaemia
  • Weakening of the bones, due to imbalances in the calcium and phosphorus levels in the blood


It is important that you consult your vet if you suspect that your animal has kidney problems. The history and clinical signs may often be sufficient to arrive at a diagnosis, but your veterinary surgeon may decide to take blood samples to provide a more accurate picture of your pet’s condition. This will almost certainly involve measuring the levels of blood urea and creatinine. Based on the results, your vet will be able to determine the best course of treatment and to give you a prognosis.



The correct diet is of vital importance in the long-term management of kidney problems. The ideal diet should contain:

  • Reduced levels of protein.  It is a good idea to avoid excess protein, which has to be excreted by the kidneys. Chicken and egg are ideal protein sources and are often used as the basis of specialised kidney diets
  • Reduced levels of sodium (salt). Excess sodium can lead to an increase in blood pressure or retention of fluid within the body
  • Reduced levels of phosphorus

If you are unsure what to feed, your own vet is the best source of advice and may be able to provide you with specific prescription foods to help.


A number of drugs can now help with the management of renal problems. Of particular note are those in a group called ACE inhibitors (such as Fortekor), which help reduce blood pressure and so delay the progression of renal disease. Phosphate binders are now also used. These supplements are added to the diet to reduce the level of phosphorus in the blood reducing the health problems associated with raised blood phosphorus levels.



Herbal remedies can be used alongside diet to help deal with kidney disease. The following Denes products are useful:

These two combinations are formulated using medicinal herbal tinctures, to support the function of the kidneys. The cat version has added vegetable glycerine to improve palatability. Both can be easily added to food and contain the following herbs:

HAWTHORN (Crataegus oxycanthoides)
Tones the circulation, improving the blood flow through the kidneys, lowers high blood pressure which can be a problem with cats especially

BARBERRY (Berberis vulgaris)
Strengthens and cleanse the body generally

GOLDEN ROD (Solidago virgauria)
Improves kidney function generally

CLEAVERS (Galium aparine)
A mild diuretic, cleansing the body of toxins

PARSLEY (Petroselinum crispum)
Another diuretic herb, helping flush out toxins from the kidneys

RHUBARB (Rheum palmatum)
May slow the progression of chronic kidney disease

This herbal medicine is based on stinging nettles and can be used alongside Denes Kidney Support. Stinging nettles help by eliminating waste products and can help detoxify the body

This herbal supplement is useful in more severe cases. It is based upon two herbs classed as liver tonics, Dandelion and Milk Thistle. Both help by removing toxins and supporting and stimulating the function of the liver.

This is a herbal supplement that supplies a wide range of vitamins, minerals and trace elements. Animals with impaired kidney function normally benefit from extra supplementation. All-in-One Powder+ contains:

  • Seaweed, a good source of vitamins and minerals
  • Alfalfa to help assimilate nutrients
  • Spinach a good source of iron, excellent for helping with anaemia
  • Barleygrass Powder which is good for general health
  • Wheatgrass Powder, a rich source of nutrients


Omega 3 essential fatty acids have be shown to help reduce kidney inflammation, to slow the progression of renal disease by reducing blood pressure and by improving blood flow through the kidneys, helping to filter out waste products more effectively.


Homeopathy provides another way of supporting the kidneys. There are two remedies which may help:

Denes Kidney SupportDenes Greenleaf CapsulesMilk Thistle+ PowderAll-in-One+ Powder and Homeopathic Remedies can be used singly or in combination and are safe to use alongside any conventional treatment that your vet may prescribe.

Other Denes Fact Sheets to read