Canine kidney stones are much like the formation of a pearl inside an oyster. A stone forms from a single irritating particle called a nidus, which consists of a tiny particle such as a mineral crystal. Other minerals are deposited on its surface, and over time it grows larger and forms a stone. These stones can travel throughout the urinary system, through the ureters into the bladder and through the urethra and out of the body. Problems occur when they get stuck somewhere along the way.
When stones form in the kidneys, they often block the openings to the ureters. This causes a condition called hydronephrosis, in which the kidney becomes swollen with pressure from backed up urine. It can cause serious kidney damage and can be life-threatening if not treated in a timely manner.
There are risk factors for older castrated dogs, obese dogs and small breeds, particularly the Miniature Schnauzer.
Canine Kidney Stones Symptoms
Symptoms of dog kidney stones include frequent urination, often in small amounts, and often in unusual places. Your housebroken pet may begin peeing in the house. Symptoms include dribbling urine, straining to urinate, and blood in the urine. Other symptoms include weakness, depression, loss of appetite, vomiting, and abdominal pain. In severe cases, your dog may not be able to urinate at all.
If your dog has kidney stones symptoms, he needs to see a vet. Kidney stones are a serious medical condition that requires prompt medical treatment.
Canine Kidney Stones Diagnosis
If kidney stones are suspected, your vet will take x-rays. The stones will usually show up white on the x-ray. Some kinds of stones don't show up on x-rays and can only be seen by ultrasound. Your vet will look for stones elsewhere in the urinary tract as well.
Your vet will also test your dog's urine to see if he has a bladder infection. Bladder infections are very common in pets with kidney stones.
Canine Kidney Stones Treatment
Dog kidney stones must usually be removed surgically. In some cases, the kidney has been damaged to the point that it must be removed. Your dog can live with just one functioning kidney if this is the case.
Special diets can also be used to prevent and treat kidney stones. The S/D diet produced by Hills can actually cause stones to dissolve. Purina also makes a special diet for dogs with kidney stones. These diets work because they contain lower than usual amounts of protein, magnesium, and phosphorus, which are things that contribute to the formation of kidney stones.
Recent studies recommend a canned diet because it has higher moisture content. If your dog will not eat canned food, consider adding water to dry food to moisten it the best that you can. Your veterinarian may retest your dog's urine after dietary change to recheck the sediment in the urine. If your dog will not tolerate a dietary change, then other approaches might be tried to increase the intake of water.
Dietary supplements may also help avoid kidney stones. Magnesium, citrates and phosphates are believed to inhibit stone formation. A moderate to slightly increased protein content may also be beneficial in the prevention of urolithiasis, the formation of stones in the urinary system.
Foster, Race DVM and Smith, Marty DVM
Holt, P. E.
Canine and Feline Calcium Oxalate Urolithiasis in Dogs and Cats
University of California, Davis School of Veterinary Medicine