Cystine stones in dogs

Cystinuria is a genetic disorder affecting over 170 breeds of dogs. This disease causes uroliths (bladder or kidney stones) to form in the lower or upper urinary tract. Cystinuria has no permanent cure, but there are many ways to manage it [1]. 

Understanding the symptoms, causes, and treatments for cystine stones in dogs will help you provide the best care. 

What Are Cystine Stones in Dogs? 

Cystine is a naturally occurring amino acid found in many foods. Healthy dogs absorb cystine through the walls of the small intestine, circulate it through the body, and filter it through the kidneys [1].

Dogs with cystinuria have genetic mutations that prevent them from reabsorbing cystine and other amino acids, including lysine, arginine, and ornithine. These amino acids build up in the urine and may form bladder or kidney stones [2].

Cystinuria occurs in an estimated 1% to 3% of dogs in North America. Approximately 99% of affected dogs are male, and 1% are female [1].

Certain breeds have a higher risk of developing cystine stones, including [2].

• Staffordshire bull terrier
• Danish Swedish farmdog
• Chihuahua
• Shetland sheepdog
• French bulldog
• Mastiff
• Australian cattle dog
• Pitbull terrier
• Rottweiler

‍

Symptoms of Cystine Bladder Stones in Dogs 

Dogs are born with cystinuria but often don’t display symptoms unless cystine stones develop. Pet owners typically notice these signs [3]:

• Difficulty or pain when urinating 
• More frequent urination 
• Toileting in the house
• Bloody urine 

‍

In some cases, cystine stones block the urethra. Symptoms of urinary obstruction include a distended bladder, abdominal pain, lethargy, and vomiting [3].

A urethral blockage is a serious and potentially fatal medical emergency. Seek emergency veterinary care promptly if you suspect your dog has an obstruction [3].

Diagnosing Cystine Stones in Dogs

Veterinarians typically use urinalysis to detect cystine bladder stones in dogs. This test can reveal the presence of cystine crystals in the urine, though these formations aren’t continuously present [1].

Additionally, some dog breeds have genetic tests for cystinuria. These tests detect this condition before the dog develops symptoms [1].