Water intake remains an important factor for the prevention of the formation of bladder stones.

Last week, I stopped to top up my car with fuel. The pump attendant recognised me as the vet who had operated his father’s dog for bladder stones a couple of months ago, so we stopped for a chat and an informal update as to the condition of his father’s dog.

Francesca, as he reminded me the dog is called, was a particular case. I had seen her as a weekend emergency. She was suffering from dysuria and stranguria, which are the medical terms respectively for difficult and painful urination.

When I had examined her, it was immediately obvious that she had a very full bladder and some kind of blockage in her urethra, the channel through which urine flows. The bottom line was that she had not been able to pee for the past 24 hours and was therefore in considerable pain.

What was particular about this case was that, due to the obvious differences between the male and female anatomy, where the urethral channel for males is much longer than it is for females, it is far more common for male dogs or cats to suffer from a blockage. In fact, I had difficulty recalling the same case occurring in a female patient. A common cause of blockages of this type is urolithiasis.

Urolithiasis is the term used for any type of stone which forms in the urinary tract, which includes the kidneys, the ureters, which are the tubes that take urine down to bladder, the urinary bladder itself and the urethra, the tube through which urine flows out of the body. In dogs, stones tend to form in the urinary bladder rather than in the kidney.

Stones form from an agglutination or clumping of crystals which may materialise due to a number of reasons. Various types may form, having varying shapes and sizes. Apparently, one of the largest ever encountered in a dog in the US weighed a massive 600g and was removed from the bladder of a border collie. This particular stone measured 12.5cm in length and at its widest part measured 7.5cm. That’s a lot of stone to carry around!

There is no specific age at which your dog or cat might start to form bladder stones. Symptoms that your dog might have bladder stones are increasingly frequent attempts to urinate, and may also have blood in the urine.

The increased frequency is due to the reduced volume of bladder space taken up by the presence of foreign bodies, the stones, and also to bladder irritation caused by the stones themselves. There is also the possibility of dysuria and stanguria due to urine blockage, especially in male dogs and also in Francesca’s case.

The composition of bladder stones can vary greatly. The most frequently occurring are composed of magnesium ammonium phosphate, commonly referred to as struvite, and calcium oxalate. Less common ones are urates, cystine, silica and composite stones.

If your dog is a lazy drinker, try to encourage it to drink more often

The predisposing factors for the formation of the commonly occurring struvite stones are urinary tract infections in patients with concentrated urine of alkaline pH. Calcium oxalate stones frequently occur in predisposing cases where not enough water intake takes place. This causes a higher concentration of urine. Foods that are very rich and dry, as well as dog treats, may contribute towards this type of stone formation.

Other types of stones may have different underlying causes, including breed prevalence. A typical example of this is the higher incidence of urate stones occurring in the Dalmatian dog due to a particular metabolic predisposition in this breed, which causes a higher concentration of uric acid in the urine.

If your pet is found to be suffering from bladder stones, your vet will normally recommend that they are surgically removed. Firstly to remove the source of pain from your pet and, secondly, to have them analysed. It is worth going that extra mile to have them analysed since the incidence of bladder stones tends to recur after a length of time if the underlying cause of their formation is not addressed. The formation of different types of stones occurs under different conditions and, knowing the composition of the stone, your vet will be able to draw up a plan of preventative treatment.

From your end, you can help your pet avoid a repetition of these painful episodes. Water intake remains an important factor for the prevention of the formation of bladder stones.

If your dog is a lazy drinker, try to encourage it to drink more often, even if it means giving it more wet food rather than dry food to increase water intake.

With Francesca, an X-ray and ultrasound exposed the cause of her problem. The bladder contained about five or six spherical stones of about 3-4mm in diameter. I could only presume that Francesca was unlucky enough that one of the stones was the perfect size of the opening of her urethra and had blocked the opening.

A catheter luckily managed to dislodge the implicated stone and the bladder was soon voided. Within 24 hours, she was operated upon. The bladder was opened up and all the stones were surgically removed. They were then sent for analysis.

Francesca’s stones were of the struvite type. Urinalysis also showed she was suffering from a bladder infection. After the stones were removed, she was given the appropriate treatment to clear the infection and a specific diet to prevent the formation of stones.

After having passed through such an ordeal, it was good to hear that Francesca was doing so well and I trust that with continued monitoring and medicated diet, she will avoid a recurrence of urolithiasis.

thisweekwiththevet@gmail.com

Dr Martin Debattista is a veterinary surgeon.