What are Bladder Stones?
Clinical signs depend on the severity of the blockage. Dogs that have a partial obstruction may:
- urinate small amounts frequently
- take a long time urinating
- strain to urinate
- have blood in the urine
- urinate in drips instead of a strong stream
- urinate in inappropriate places (on the carpet or on their bedding)
If the urethra is completely blocked, your dog will strain without producing any urine. He/she will be in pain and be lethargic, lose their appetite, and possibly start vomiting. An overly large urinary bladder will be easily felt in the back half of the belly. (Caution: it may be painful when touched). The urinary bladder may rupture and spill urine into the dog’s abdomen with complete obstruction. Dogs with total urethral obstruction will die within days if the obstruction is not relieved. Your pet should be seen by a veterinarian immediately if he/she is unable to urinate.
Urinary tract calculi are the most common cause of urethral obstruction in dogs, anything that causes stone formation will increase the risk of urethral blockage (see urinary stones). For example, Yorkshire Terriers and Schnauzers with liver shunts (see portosystemic shunts) and Dalmatian dogs are prone to forming urate calculi. Kidney, bladder, and prostate infections can increase the risk of struvite calculi formation.
What is a Cystotomy?
If the obstruction is caused by urinary tract calculi, your veterinarian will try to flush the stones back into the bladder, where they can either be removed surgically, dissolved with medical management (depending on the type), or broken up with lithotripsy (smashing of stones with ultrasonic waves or lasers). If your dog is very sick, surgery may be delayed, and a urinary catheter left in the urinary tract to drain urine from the bladder for a day or two, until medical conditions have improved and your pet is stable for general anesthesia and surgery.
To remove stones from the bladder surgically, a cystotomy procedure is performed. In this procedure, the dog is under general anesthesia. The bladder is accessed through a small abdominal incision. Then the bladder is opened, stones are removed, and the urinary tract is flushed thoroughly to make sure no stones are left behind. If stones in the urethra cannot be flushed into the bladder for removal, a separate incision into the urethra may be necessary. Stones removed at surgery are submitted for chemical analysis and in some cases, for culture as well. Biopsy of any abnormal bladder tissue may be collected as well.
Dogs which have a urethral obstruction that cannot be unblocked, have a tumor of the penis, or are recurrent stone formers may require surgery to form a new permanent opening to the urethra, called a scrotal urethrostomy. Scrotal urethrostomies may be required because calculi in the urethra may become trapped in scar tissue and therefore cannot be removed. A scrotal urethrostomy allows urine to exit behind the os penis where the urethra is wider. An opening is created that small stones may pass through. Patients with a scrotal urethrostomy may still get urinary obstruction by very large stones in the bladder or upper urethra. For most dogs having a scrotal urethrostomy, the penis is left in place, so your male dog will look the same when he is walking down the street. However, he will urinate from the new opening in the location where his scrotum used to be. In dogs with penile tumors, a scrotal urethrostomy is performed and the penis is removed. Because the surgery site is in the area of the scrotum, dogs are castrated (aka neutered) during the procedure.