What Is Hyperuricosuria?
Hyperuricosuria (HUU) means passing unusually high amounts of uric acid in the urine. In dogs it is usually caused by an inherited gene change that stops the liver from fully breaking down uric acid into a more soluble substance. The extra uric acid can form crystals and urate stones in the bladder or kidneys.
The Dalmatian story
Nearly all purebred Dalmatians carry two copies of the gene variant, which is why they are famous for urate stones.
Breeds at Risk
- Dalmatians (almost all affected)
- English Bulldogs, Black Russian Terriers, and smaller numbers of German Shepherds, Labrador Retrievers, Large Munsterlanders, Weimaraners and many other breeds
- Males develop blockages more often because their urethra is narrower
Urate stones can also form for non-genetic reasons, especially liver shunts; see portosystemic shunt.
Signs to Watch For
- Straining or frequent attempts to urinate
- Blood in the urine
- Accidents in the house or licking the genital area
- Small gritty stones in the urine
Emergency red flag
A dog straining to urinate with little or nothing coming out may have a stone blocking the urethra. This is an emergency; see a vet immediately.
Diagnosis and Testing
A urinalysis can show urate crystals, and X-rays or ultrasound look for stones (urate stones can be hard to see on plain X-rays). A simple cheek-swab DNA test identifies dogs that are clear, carriers or affected; see our guide to pet DNA testing. Breeders use the test to avoid producing affected puppies.
Management
- Low-purine diet: often a prescription urinary diet, limiting organ meats, game and some fish
- More water: wet food, water fountains and added water keep urine dilute
- Urine alkalinizers and allopurinol: prescribed in some dogs; allopurinol needs a matching low-purine diet to avoid other stone types
- Stone removal: some urate stones dissolve with diet and medication; others need surgery or other removal
Read more about stone types and treatment in bladder stones in dogs.
Frequently Asked Questions
Can hyperuricosuria be cured?
No, the gene change is lifelong, but stones can usually be prevented with diet, water and monitoring.
Do carriers get stones?
Dogs with one copy of the variant are carriers and are not expected to have high urinary uric acid. Dogs with two copies are at risk.
Should I DNA test my dog?
If your dog is a Dalmatian, Bulldog, Black Russian Terrier or another at-risk breed, or you plan to breed, testing is worthwhile.
Is your dog straining to pee or passing blood? Find a veterinary clinic near you for an exam.