Bladder Stones in Dogs

Bladder stones are a result of crystals that form from minerals in the urine. The crystals will form when there is a high salt concentration in the urine as well as a favourable pH (hydrogen ion concentration) level to facilitate crystallisation. If there is an excessive amount of crystal formation, these will then join and form calculi (stones). These stones can accumulate in the bladder causing discomfort and irritation. Stones can also become stuck in the urethra (the duct that carries urine out of the body) and cause an obstruction of urine flow. An obstruction is considered a veterinary emergency.

If your dog is encountering painful urination, you should act quickly. This situation can be life threatening and may be due to a number of issues, including bladder stones (medically recognised as urinary calculi). If your dog has urolithiasis, they may have blood in their urine and will urine quite frequently, with only a small amount each time.

The symptoms present depend on where in the urinary tract the stones have accumulated. Symptoms of bladder stones include:

• Straining to urinate
• Blood in urine
• Foul smell of the urine
• Increased frequency of urination
• Producing only small amounts of urine
• Incontinence or dribbling of urine
• Abdominal discomfort

If the stones have progressed from the bladder and into the urethra, causing an obstruction, dogs may display the following additional symptoms:

• Vomiting
• Loss of appetite
• Weakness
• Lethargy (lack of energy)

Types

There are several different types or varieties of urinary stones that will form dependent on their mineral composition. The bladder stones most commonly found in dogs accumulate from the following mineral and chemical compositions:

• Struvite
• Calcium Oxalate
• Urate
• Cystine
• Silicate

The definitive cause of bladder stone formation is not fully known. However, there are several factors that contribute to the formation of stones.

• Prevalence of a urinary tract infection
• Inflammation of the urinary bladder lining
• High dietary intake of certain minerals and proteins
• Reduced water intake
• Large amount of salts in the urine
• Optimal pH levels in the urine for stone formation
• Breed predispositions

Diagnosis of canine bladder stones is suspected from the above clinical symptoms. In order to form a definitive diagnosis, the veterinarian may perform several tests including urinalysis, radiography, and ultrasound.

Urinalysis involves a complete analysis of a urine sample. It features a dipstick test, a measure of urine specific gravity, and examination of the urine sediment under a microscope. The dipstick test measures values such as pH, protein content, glucose values, ketones, and traces of blood. The microscopic examination allows the veterinarian to look for the presence of red and white blood cells, epithelial cells, casts, bacteria, and most important, the crystals associated with bladder stones.

Radiographs are performed to determine the location and number of stones within the bladder or distal urinary tract. Many stones are radiopaque meaning that they will show up on the x-rays. Otherwise, a contrast agent can be introduced into the bladder to assist with visualisation. It is especially important to analyse the number and size of bladder stones in case a surgical removal of the stones is necessary.

Ultrasound is another tool that a veterinarian will use to visualise the stones; it is usually used to look for stones that do not show up on a plain x-ray. Ultrasound helps to determine the number of stones present, size, and location.

Once canine bladder stones have been diagnosed, treatment options include dietary management and medical dissolution, urohydropropulsion, surgical removal, and laser lithotripsy. The treatment choice will depend on type and size of bladder stones present.

Dietary management and medical dissolution can be effective depending on the types of stones identified and the likelihood of an obstruction due to size. Struvite is the most common composition of bladder stones in dogs and usually responds well to the dietary and medical treatment approach. The dog is fed a prescription veterinary diet that is specifically formulated to dissolve the crystals along with concurrent medications such as antibiotics to treat urinary infections. The patient will require a repeat urinalysis after two weeks to check that the crystals have dissolved adequately. After treatment, dogs are often switched to an ongoing preventive urinary diet.

Urohydropropulsion is a technique used to expel smaller stones from the bladder as well as dislodge stones stuck in the urethra. Urohydropropulsion involves placing a urinary catheter usually under sedation and flushing the bladder with sterile saline. The bladder is then compressed through palpation of the abdomen expelling the saline along with the smaller stones present.

Surgical removal is necessary with stones that do not respond to dietary and medical management due to their mineral composition and stones that are too big to pass through the urinary tract by urohydropropulsion. The surgical procedure performed is known as a cystotomy and there can be an anaesthetic risk, especially in older or compromised patients. Following surgery, preventative dietary adjustments should be made to prevent the reoccurrence of stones.

Laser lithotripsy is a technique that is currently only available in specialist veterinary centres. The laser is guided into the urinary tract with endoscopic equipment and breaks up the stones within the bladder so that they can be passed naturally. The procedure is less invasive compared to surgery and has a faster recovery time for the patient.

The best treatment method will be discussed by the veterinarian after a complete urinalysis and examination to determine the type of stones present.

Following treatment of canine bladder stones, a repeat urinalysis is performed several weeks later to check for reoccurrence of crystal formation. Once the stones are dissolved or removed from the bladder and the underlying bacterial infection is treated, the condition has a good prognosis.

Dietary dissolution and medical management is a less invasive approach but often takes a longer time to dissolve the crystals. Recovery from a cystotomy surgery is relatively quick, with the dog usually able to go home the following day. The surgical incision will take on average two weeks to fully heal and will need to be rechecked, which is usually when the repeat urinary sample is examined.

Dogs will often be placed on a urinary prescription diet on an ongoing basis. Such diets are specifically formulated to prevent future stone formation. Additionally, water consumption should be increased to help keep the urine diluted. The most common way to increase water consumption in dogs is to increase feeding of canned food as opposed to a sole dry food diet.

Following recovery, ongoing management is crucial to prevent the formation of bladder stones from reoccurring.

Treatment cost for bladder stones will depend on the optimal method for their removal.

If dietary and medical management is indicated, this will involve the purchase of a prescription diet and concurrent medications. A case of 12 Hill’s Prescription Diet S/D Urinary Care canned dog food is on average between $35 - $55. Medication costs will depend on what is prescribed by the veterinarian and can be between $30 - $85 for the duration of treatment.

Urohydropropulsion expenses involve sedation, urinary catheterisation, and irrigating fluids. Costs will vary depending on what drugs are used for sedation and the relative time it takes to perform the procedure. Urohydropropulsion including sedation can cost between $325 - $750.

Surgical expenses need to cover anaesthetic costs, IV fluids throughout surgery, surgical equipment, the surgeons time and expertise for the procedure, hospitalisation during recovery, postoperative medications, and additional analysis of stones and urine. The cost for a cystotomy can start at $1,300 for smaller breeds and increase to $2,200 for larger breeds as they require a bigger dose of induction drugs, fluids, gas anaesthetic, and use more surgical material.

Laser lithotripsy is considered a specialist procedure and is only performed at certain facilities. The cost is approximately $800 - $1,200 for the procedure, not including sedation or anaesthetics. The additional expenses for sedation or anaesthesia are dependent on the protocol used and can be between $500 - $1000.