According to the Woodhaven Labradors breeding operation website, new owners of male dogs are commonly confused if not concerned when they notice two swollen lumps at the base of the penile shaft. The good news is this swelling of the bulbus glandis is a normal part of healthy dog arousal and reproduction. However, male dogs can suffer from tumors and other diseases that affect the penile region -- such conditions have different symptoms and should prompt a visit to a veterinarian.
Male dogs have several unique features about their reproductive anatomy, including the presence of the bulbus glandis at the base of the penis. When dogs become aroused, these two small glands swell and appear as lumps under the skin. This swelling is completely normal and goes away as the dog’s arousal fades. The bulbus glandis play an important role in the reproductive process.
When a male dog becomes aroused, the penile bone begins to emerge from its sheath. This bone -- another unique feature of male canine anatomy -- allows the dog to penetrate the female’s vagina. The contact between the penile bone and the inside of the female dog’s vagina causes the male to gain a full erection. Once the penis is fully inserted, the swollen bulbus glandis prevent the penis from exiting her vagina. In this way, the bulbus glandis are responsible for the copulatory tie that connects the two dogs until the mating and ejaculation are complete. The process can take up to an hour, during which time the dogs cannot physically separate -- nor should they be separated by force; both the male's and female’s reproductive organs can be damaged as a result.
Although swelling of the bulbus glandis during arousal is normal, male dogs can suffer from penile tumors that are not healthy. One example is called TVT. This condition occurs after a male dog comes in contact with a TVT tumor on another dog. The contact can involve mating, licking or smelling. Dogs who have TVT or other penile tumors tend to lick the area excessively to ease the irritation. These tumors can interfere with urination, cause bleeding and break off into smaller pieces -- all symptoms that are not associated with swelling of the bulbus glandis. Male dogs who exhibit these symptoms need to be examined by a veterinarian.
Owners who are concerned about their male dog's reproductive health should watch for symptoms that something may be wrong. Excessive licking of the area is a good indicator of a problem, including the presence of tumors, inflammation of the urethra, and balanoposthitis -- an inflammation of the surface of the penis or prepuce. Discharge from the penis can also be a sign of problems, including prostate disease and balanoposthitis. Swelling on the prepuce, the skin that covers the dog's penis before an erectionm, can signify a wound or dermatitis. This type of swelling differs from the swelling of the bulbus glandis primarily by placement. Whereas this swelling occurs on the skin covering the penis, swelling of the bulbus glandis is seen just behind the base of the prepuce.