Phimosis is a reproductive problem that occurs when the opening in your dog's prepuce, the skin sheath over his penis, is not large enough. Dogs with phimosis often can't mate because the penis can't protrude from the skin. Phimosis is different from paraphimosis, a condition that occurs when your dog can't retract his penis back into the skin.
Phimosis and Paraphimosis
Your dog's penis is normally covered by a skin sheath, called the prepuce when it is not erect. When a normal, healthy male dog wants to mate, the erect penis protrudes from this skin sheath. Phimosis and paraphimosis are two different conditions with two different sets of causes.
Phimosis occurs when the orifice at the end of the prepuce is too constrictive, and prohibits your dog's erect penis from protruding during mating. Paraphimosis creates the opposite situation; it makes your dog's penis distended, so that your dog can't retract his penis back into the prepuce after mating.
Causes and Symptoms of Phimosis
Often, phimosis is a genetic condition. Golden Retrievers and German Shepherds are most vulnerable to congenital phimosis. Other causes of phimosis include injury to the prepuce, especially when it leads to the development of:
- scar tissue
- cancer
- inflammation of the penis or prepuce
- edema, or water retention, within the penis
Some dogs may suffer from a related condition called penile/preputial frenulum, in which a narrow band of skin attaches the penis to the prepuce, resulting in phimosis, even if the preputial orifice is technically large enough.
If your dog has phimosis, he'll have problems mating. His penis won't be able to protrude from the prepuce when it is erect. You may be able to see it as a sizable bulge beneath the skin.
Your dog may even hurt himself in his attempts to mate with phimosis, and may suffer permanent damage to the penis. Your dog may also have problems with urination. His urine may not be able to escape efficiently from the prepuce.
If this occurs, urine may accumulate inside the skin sheath, dripping out slowly over time. Urine contains caustic acids, and, if it's allowed to remain in constant contact with the skin, it can lead to a condition known as urine scalding, in which the skin becomes chronically irritated. Sores and infections can develop on urine scalded skin.
Treating Phimosis in Dogs
Your vet can easily treat phimosis with a simple surgical procedure. If your dog's preputial orifice is not large enough, your vet can surgically enlarge it. If your dog is suffering from penile/preputial frenulum, your vet can surgically sever the strip of tissue attaching your dog's penis to his prepuce. If you aren't planning to breed your dog, however, and his phimosis isn't causing problems with urination, you may choose to simply have him neutered, thus eliminating the need for the preputial opening altogether.
Though phimosis is sometimes a genetic condition, the condition is not considered serious enough to prevent breeding. Dogs with phimosis may still be bred.