Moey is a sprightly 10 year old Poodle x Maltese who has been one of our regular patients for many years. He recently underwent a desexing procedure because his prostate had become enlarged. Prostatic enlargement can lead to a number of health problems including infection, difficulty urinating and constipation. Desexing is usually curative for these.
It was then somewhat of a surprise when Moey’s owner brought him in 4 weeks after his operation with urinary tract problems. Moey had been dribbling urine and was quite unwell. Our investigation needed to include an assessment of his entire urinary tract from his kidneys down to his bladder, prostate and finally his urethra and penis.
We knew from recent blood tests that Moey's body functions were all normal so we immediately did an ultrasound examination of his kidneys, bladder and prostate. These were all normal and so the next step was to pass a catheter to check his urinary passage (urethra). The catheter immediately met an obstruction just a short distance inside the penis. X-rays of this area showed that there were two small stones lodged inside the urethra at the level of the entrance to the penis (see x-ray image). These were preventing him from passing a good stream of urine and making him very uncomfortable.
This area of the urinary passage is a common place for obstruction to occur in male dogs. Stones can form in the urinary tract of dogs for a number of reasons. They nearly always form in the bladder which is unlike in people where the kidney is a common site. In the early stages these stones usually do not cause any problems or discomfort. They may be present for quite some time before they cause any signs that are noticeable. Sometimes they are found during routine investigations for other problems. In Moey’s case it is likely they had been present for many months. They only caused a problem when they began to be passed out. Stones that remain in the bladder can become very large. We have removed some greater than 7 cm in size!
Male dogs have a bone inside their penis and the urethra passes through a small slot in this bone before exiting at the tip. The slot is quite narrow and since most of the stones are spherical they lodge at the narrow segment. They can be clearly seen on the x-ray.
Removal of the stones requires an operation to open up the urethra and extract them. This procedure was performed immediately on Moey and went very well. He made a quick recovery and was passing urine comfortably the next day. Had there been stones in the bladder as well Moey would have needed a bladder operation as well to remove them. In this circumstance we sometimes attempt to flush any stones lodged in the urethra back up into the bladder so that we only have to operate in one place. This is not always successful and some patients need the two operations.
Moey’s stones were analysed so that a cause might be determined and steps taken to prevent a recurrence. The stones came back as Calcium Oxalate. These stones have a number of contributing causes including the breed of dog, diet, age and concurrent illnesses. Strategies to achieve a slightly alkaline and dilute urine are needed for prevention. This can be achieved with a special prescription diet from Hills. We have commenced this diet with Moey and he can now enjoy life without the risk of becoming blocked up again.