Urethrotomy in Dogs

Urethrotomy is a surgical procedure to create a temporary opening in the urethra of a male dog. The aim is to retrieve a lodged foreign body such as a bladder stone that has passed down into the urethra. 

Urethrotomy is performed on relatively infrequently because the anatomy of the canine urethra makes a similar procedure, urethrostomy, more viable. Urethrostomy is similar in many regards except the aim is to create a permanent opening into the urethra, to provide a means of bypassing the narrow urethra in the penis. 

The drawback to urethrotomy is that bladder stones tend to lodge in the penis itself where there is a natural stricture. Unfortunately, there is no surgical access to the urethra at this point which means operating 'upstream' where the urethra bends around the pelvis. 

However, the dog's scrotum and testicles are located at this spot, therefore castration and scrotal ablation are necessary in order to gain surgical access to the urethra. Once the surgeon has gone to substantial effort to dissect down to the urethra, it is as well to make a permanent orifice (urethrostomy) rather than a temporary one (urethrotomy.)

The patient is stabilized prior to surgery. This can involve draining urine from an obstructed bladder via cystocentesis, plus intravenous fluid therapy to correct electrolyte imbalances in the blood. 

Radiographs of the bladder and urethra are taken, so as to fully assess the number of stones and their location. If multiple stones are present in the bladder, then cystotomy may be required. 

Under general anesthetic, the dog lies on their back and the fur is clipped from the caudal abdomen. A urinary catheter is passed via the penile tip to the level of the blockage. If the obstruction lies in the urethra underneath the scrotum, then the dog is castrated and the scrotum removed, in order to give access to the urethra. 

An incision is made over the urethra and the stone removed. The urethra is either left open or fine absorbable suture used to repair it. The skin wound is repaired, leaving a small gap over the urethrotomy site. 

Anesthesia when a dog has a urinary obstruction carries a raised risk. This is because potassium retention can lead to an irregular heartbeat and even cardiac arrest. 

There are relatively few times when a urethrotomy (temporary opening) is preferred to a urethrostomy (permanent stoma). This is mainly because urethrotomy can only be performed where the urethra is accessible. This is also where the urethra is naturally wide, and therefore the chances of a stone edging in this location is reduced.

Urethrotomy is only worthwhile if the incision is made directly over the stone to remove it. Then, to stop recurrence of the stone at a later date, the dog's diet must be manipulated so the metabolism is deprived of the minerals to produce that particular stone. 

A urethrostomy, however, provides an alternative permanent  'port' through which the dog can pass urine. Thus, when it's not possible to remove stones from deep within the penis, the dog can still urinate via the permanent stoma. 

Urethrotomy is associated with heavy bleeding on urination for several days post surgery. This bleeding is less marked with urethrostomy, which makes it another reason the latter procedure is preferred. 

The dog must not lick the urethrotomy site until healing is complete two to three weeks later. 

Unfortunately, many dogs go on to grow new bladder stones and the urethrotomy needs to be repeated. Again, this is another indication for permanent urethrostomy instead, as a permanent solution. 

This is costly surgery that is often undertaken as an emergency, hence adding to the expense. It is not unusual for the surgery itself to be around $3,000, with the associated out of hours and nursing care charges in the postoperative period being an equivalent amount, making around $6,000 in total. 

A bladder stone lodged in the urethra is life-threatening, as it leads to urine retention and dangerous electrolyte changes in the blood. In these circumstances, the options are to operate or euthanasia. 

As already discussed, urethrotomy is a temporary procedure performed to remove a stone in an accessible location. However, it is more common for stones to lodge in the narrow penile tip, in which case urethrostomy is a better choice as it provides a permanent alternative means of urinating. 

Owners should be vigilant for signs of blood in the urine or straining to pass urine, (especially in male dogs) and seek urgent veterinary attention. Certain dog breeds such as Cairn terriers and Dalmatians, are prone to forming bladder stones. 

Urinary infections should be treated promptly, as shifts in pH associated with infection can encourage bladder stones to form. 

Likewise, when a stone has been removed it should be analyzed. This provides a breakdown of the constituent minerals, which then enables the owner to feed a diet that is low in those minerals, so as to minimize the risk of recurrence. 

When all else fails, the dog should be fed on canned food (because of the high water content) and encouraged to drink lots of water. This helps keep the urine dilute which makes it harder for stones to form.