Our canine companions share more similarities with us than we realise—even when it comes to health challenges. It is crucial for pet owners to look out for signs and symptoms that may indicate deterioration of their pet’s health- particularly regarding their kidneys. Just like in humans, a dog’s kidneys play a vital role in maintaining overall well-being by regulating electrolytes and filtering toxins from the bloodstream. Kidney problems can result in a myriad of other health issues- but by recognising warning signs early, we can take proactive steps to prevent serious illness from occurring in our furry friends.

One such disorder is cystinuria—an autosomal recessive metabolic disorder in which cysteine, an amino acid, does not get reabsorbed well enough into the kidneys. This results in the accumulation of crystals made up of cysteine being present in the urine, which leads to urinary tract obstructions that can cause significant discomfort.

What is Cystinuria?

Cystinuria will affect a pup's ability to filter cystine out from their urine. The tubules situated in the kidney usually reabsorb cystine, which then gets filtered out in urine. With dogs that have Cystinuria, the tubules fail to reabsorb the amino acid, leading to its accumulation in urine. Cystine, which is not easily dissolved in the acidic conditions of canine urine, crystallises and forms stones (also known as calculi).

This disorder has been observed in breeds such as the Newfoundland, Landseer, Labrador Retriever, Mastiff, Bullmastiff, French Bulldog, and Bulldog. Among these breeds, Newfoundlands exhibit a more severe type of the disorder. The disease is late mid- to late-onset, meaning that it usually only presents when a dog is between 4 to 5 years old. The exception to this is the Newfoundlands, which can present with symptoms earlier on from about 6 months to a year.

In some breeds, Cystinuria is caused by a mutation (c.586C>T) in the SLC3A1 gene. As it is a recessive disorder, the pup must inherit two copies of the causative gene to develop the disorder. Carriers, with a single copy of the mutation, do not exhibit symptoms but can genetically pass the mutation on to their offspring. If two carriers are bred, there is a 25% chance for each puppy to have Cystinuria.

What are the Symptoms?

Dogs with Cystinuria may be asymptomatic, even if they carry the mutation, until caliculi form. These stones will cause an obstruction and cause blockage in their urethra. Due to anatomical differences, males are more commonly affected than females, who may show fewer or no symptoms.

A few common symptoms to look out for include straining while urinating; frequently urinating in small amounts; urine containing blood; stomach pains and vomiting; as well as lethargy. Without medical intervention, a blockage in the urinary tract can be life-threatening. 

What are the treatment options?

If your dog is showing symptoms that indicate they might have Cystinuria, it would be best to consult your veterinarian, who will be able to advise you on the best therapeutic course to use to treat your pup. A urinalysis, which checks the pH level of urine, in conjunction with imaging techniques such as ultrasounds or x-rays can be done to confirm the diagnosis.

The right treatment can potentially minimise cystine levels in the urine through dietary and lifestyle changes. Changing your dog’s diet to include smaller amounts of protein or sodium, as well as adding more water to your pup’s meals helps raise the pH levels and dilutes the urine, may reduce the likelihood of stone formation.

In cases where stones have already formed, surgery will be the most effective removal method. Neutering can also be effective in preventing stone recurrence in males.

Early genetic testing can help identify carriers or affected dogs, enabling preventative measures to be taken before symptoms arise.

Where can I get genetic health tests done?

At ZooOmics, we provide both health and colour testing as well as DNA profiles for both canine and feline. We utilise innovative technology to perform mutation testing and provide certificates for all testing, which can be submitted to registrars and breed societies.

For inquiries about sample collection, shipping, processing, and services, please contact us at info@ZooOmics.co.za. Alternatively, visit our website at www.zooomics.co.za to download our sample submission form.