Renal Dysplasia in Dogs

What is renal dysplasia?

Renal dysplasia is a developmental abnormality in which one or both kidneys do not form normally before a puppy is born. The affected kidneys contain immature or abnormally developed tissue and may be small, misshapen or unable to function normally.

Renal hypoplasia is a related condition in which one or both kidneys are unusually small because they have not developed fully.

The severity varies considerably. Some dogs have only mild changes and may show few or no symptoms for a considerable time. Severely affected puppies may develop kidney failure at a very young age.

What causes renal dysplasia?

Renal dysplasia is a congenital condition, meaning that the abnormal development occurs before birth. In some breeds, an inherited or familial component is suspected or has been identified.

Disruption to kidney development within the womb may also be associated with infection, inflammation or exposure to substances that affect developing tissues. However, in many individual cases, the precise cause cannot be confirmed.

Which dogs may be affected?

Renal dysplasia has been reported in many breeds. Breeds in which congenital or inherited kidney abnormalities have been described include:

• Lhasa Apso
• Shih Tzu
• Soft Coated Wheaten Terrier
• Standard Poodle
• Golden Retriever
• Cocker Spaniel
• Beagle
• Boxer
• Miniature Schnauzer
• Chow Chow
• Alaskan Malamute
• Bedlington Terrier
• Bernese Mountain Dog
• Shetland Sheepdog

The condition can also occur in breeds not included in this list.

When do symptoms appear?

The age at which symptoms become apparent depends on how much functioning kidney tissue the dog has.

Severely affected puppies may begin to show symptoms shortly after weaning. Dogs with less severe abnormalities may not become noticeably unwell until they are older.

Very young puppies normally produce more dilute urine while their kidneys are still developing. Excessive drinking and urination that persist beyond the normal early puppy stage should be discussed with a veterinary surgeon.

Possible symptoms

The symptoms resemble those of chronic kidney disease and may include:

• Drinking excessively
• Passing large quantities of pale or dilute urine
• Needing to urinate more frequently
• Poor growth or being unusually small for age
• Loss of appetite
• Weight loss or poor body condition
• Low energy, weakness or depression
• Vomiting or diarrhoea
• Dehydration
• A dull or poor-quality coat
• Pale gums caused by anaemia
• Bad breath
• Ulcers within the mouth
• Delayed or absent seasons in a female dog

Diagnosis

Your veterinary surgeon will consider the dog’s age, breed, symptoms, medical history and any known kidney problems within its family.

Investigations may include:

• Blood tests to assess kidney function and electrolyte levels
• SDMA testing
• Urine concentration and urinalysis
• Urine protein-to-creatinine ratio
• Urine culture to check for infection
• Blood-pressure measurement
• Ultrasound examination of the kidneys
• X-rays or other imaging where appropriate

An ultrasound may show that the kidneys are unusually small, irregularly shaped or have an abnormal internal structure. However, imaging alone may not always distinguish renal dysplasia from other forms of chronic kidney damage.

A kidney biopsy can confirm abnormal or immature kidney tissue, but it is not appropriate or necessary in every case. The possible benefit of obtaining a precise diagnosis must be considered alongside the risks of the procedure.

Treatment

There is no treatment that can make an abnormally developed kidney normal. Treatment is therefore aimed at supporting the remaining kidney function, controlling symptoms and maintaining quality of life.

Treatment may include:

• A carefully selected veterinary renal diet
• Medication to control nausea or vomiting
• Treatment for high blood pressure
• Treatment to reduce protein loss through the kidneys
• Phosphate binders where required
• Potassium or other supplementation if testing shows a deficiency
• Fluid therapy
• Treatment for anaemia
• Regular veterinary monitoring

Affected dogs should have unrestricted access to clean, fresh drinking water unless they are receiving specific instructions during hospital treatment.

Diet

Dietary requirements depend on the severity of the disease and the dog’s individual blood results. Veterinary renal diets generally contain controlled phosphorus, appropriate amounts of good-quality protein and adjusted levels of other nutrients.

Young dogs still require sufficient energy and nutrients for growth. A diet that is too restrictive or not properly balanced may lead to weight and muscle loss.

If a fresh, raw or home-prepared diet is preferred, it should be individually formulated with guidance from a veterinary surgeon or suitably qualified veterinary nutritionist.

Monitoring

Dogs with renal dysplasia require regular monitoring, which may include:

• Blood tests
• Urine tests
• Blood-pressure measurements
• Body-weight and muscle-condition checks
• Monitoring appetite, thirst and urine production

Treatment may need to be altered as the dog grows or if its kidney function changes.

Breeding considerations

Because renal dysplasia may have an inherited component in some breeds, an affected dog should not normally be bred from.

Owners and breeders should discuss the possible implications for parents, littermates and close relatives with their veterinary surgeon and breed health representatives. The availability and reliability of genetic testing vary between breeds and conditions.

Outlook

The outlook depends on how severely the kidneys are affected. Dogs with mild abnormalities and sufficient functioning kidney tissue may remain well for a considerable time.

Severely affected puppies may develop progressive kidney failure at a young age. Although damaged kidney tissue cannot be restored, appropriate treatment can help control symptoms and support quality of life.