Several reproductive diseases can affect male dogs. This section discusses the most common of these disorders.
Cryptorchidism is a failure of one or both testicles to descend into the scrotum. It is the most common disorder of sexual development in dogs. The condition has a genetic basis and can be inherited from either parent. If both testicles are affected, the dog is sterile. Because the retained testicles still produce male hormones, these animals have normal mating behavior and sexual characteristics. If only one testicle is retained (unilateral cryptorchidism), the dog can still mate normally, as the one normal testicle will produce normal sperm. Because the condition is inherited, cryptorchid dogs should not be used for breeding. This condition occurs in all breeds but is commonly seen in the Toy and Miniature Poodle, Pomeranian, Dachshund, Chihuahua, Maltese, Boxer, Pekingese, English Bulldog, Miniature Schnauzer, and Shetland Sheepdog. Affected animals should be neutered due to an increased risk of developing testicular cancer.
Short-term inflammation of the testis or epididymis may be caused by injury, infection, or twisting (testicular torsion). Signs are pain and swelling of the testes, epididymides, or scrotum. There may be wounds or other abnormalities in the scrotal skin. The disease is diagnosed by physical examination, ultrasonography, and laboratory tests. Because the condition is painful, sedation or anesthesia may be necessary for diagnosis. Treatment is difficult unless the cause of the inflammation can be identified. The outlook is unknown, even with prompt treatment, because inflammation can cause permanent damage. Application of cool water packs may decrease testicular damage caused by inflammation. If there is a bacterial infection, antibiotics will be administered. If the cause is an immune disorder, medications that suppress the immune system may be administered but are often unsuccessful and can perpetuate infertility. When maintaining fertility is not important, castration is a reasonable treatment choice for inflammation of the testes or epididymes due to any cause.
Longterm inflammation of the testis or epididymis may follow short-term inflammation, although in some cases there is no history of testicular inflammation. Tumors may also be present. Many dogs do not have any signs of the disease except for infertility; however, decrease in size or softening of the testes may be present. Non-inflammatory causes of this disease include previous exposure to excessive pressure, heat, cold, or toxic agents. Hormonal causes are also possible. The diagnosis and treatment is as described above for the short-term condition. The outlook with longterm inflammation is poor.
Balanoposthitis is inflammation of the penis or preputial cavity (the skin on the dog’s belly that covers the penis). Mild balanoposthitis is present in many sexually mature dogs and it resolves spontaneously without any treatment. There are several causes of more severe balanoposthitis, including allergies, trauma, foreign objects, bacterial infection, cancer, urinary tract stones, and phimosis (a condition in which the prepuce cannot be drawn back to expose the penis). The most common sign is yellow-green discharge at the tip of the penis or prepuce. Excessive licking of the prepuce may also be seen. Swelling of the prepuce and pain are rarely present except in cases of trauma or foreign objects. The disease is diagnosed by physical examination and laboratory tests. Sedation or anesthesia may be necessary. Treatment includes correcting any predisposing factors, clipping long hair away from the opening of the prepuce, and thorough flushing of the preputial cavity with a mild antiseptic or sterile saline solution. In the case of a bacterial infection, your veterinarian may prescribe an antibiotic. Neutering will diminish, but not eliminate, preputial secretions.
Paraphimosis, or the inability to completely retract the penis into the preputial cavity, usually occurs after erection. It is seen most often after semen collection or breeding. The skin at the preputial opening traps the extruded penis, impairing blood circulation. Other causes of paraphimosis include a constricting band of hair at the preputial opening, a small preputial opening, foreign material around the penis, or other trauma to the penis. Paraphimosis is a medical emergency because the exposed penis quickly becomes swollen (due to accumulation of fluid), dry, and painful. If recognized early, before severe swelling and pain develop, paraphimosis is easily treated. The treatment consists of gentle cleansing and lubrication of the exposed penis. The penis is replaced inside the prepuce and the swelling resolves once circulation is restored. More advanced cases of paraphimosis may require additional treatments or surgery to correct.
Priapism is a persistent erection that is not due to sexual stimulation. It is diagnosed by physical examination. Partial paraphimosis can also result. Priapism can be caused by neurologic dysfunction, drugs, blood vessel abnormalities, masses on the penis, trauma, or an unknown cause. If blood circulation is blocked, it is a medical emergency. Some medications may help, but neutering does not,
Phimosis is the inability to expose the penis and may be due to an abnormally small preputial opening. It may be hereditary or acquired as a result of trauma, inflammation, or bacterial infection. The signs are variable. Usually, the problem is unnoticed until the dog attempts to mate and is unable to copulate. Diagnosis is established by physical examination of the prepuce and penis. Treatment depends on the severity of the phimosis and the intended use of the dog. If the dog is not used for breeding, treatment probably is not needed, although neutering could be considered to prevent arousal. Surgery to enlarge the opening of the prepuce can be performed for breeding dogs or those that have inflammation or difficulty urinating.
The prostate gland is located within the pelvis behind the bladder. The prostate gland is not required for sperm production, but it is important for successful breeding. The prostate gland provides the major part of the fluid in the ejaculate and is important in nourishing the sperm cells and increasing their movement.
Diseases of the prostate gland are common in dogs that have not been neutered, especially enlargement of the prostate (benign prostatic hyperplasia). Other prostate diseases, including bacterial infection, abscesses, cysts, and tumors, are less common and can be seen in neutered males. These disorders cause enlargement of the prostate gland and can cause straining when defecating, blood in the urine, repeated urinary tract infections, and pain. Additional signs, such as fever, malaise, poor appetite, stiffness, and pain in the belly, are often due to bacterial infections or presence of tumors. Prostatic diseases are diagnosed by physical examination, rectal examination, x-rays, ultrasonography, and blood and semen tests.
Enlargement of the prostate is the most common prostatic disorder. It is caused by male hormones. It is found in almost all unneutered dogs over the age of 6 years. There may be no signs, or straining to defecate, blood in the urine, or preputial discharge may occur. Neutering is the preferred treatment. Reduction in the size of the prostate usually follows within a few weeks of the surgery. In dogs used for breeding, medication to decrease the size of the prostate may be helpful.
Prostatitis is inflammation of the prostate gland. It is usually due to bacterial infection and can result in an abscess. Longterm inflammation can also occur because of prostate enlargement (see above). Sudden prostatitis (acute prostatitis) often causes malaise, pain, and fever. Dehydration and shock may occur in severe cases of prostatic abscesses. The disease is diagnosed by physical examination, x-rays, blood and urine tests, and examination of prostatic fluid. Longterm bacterial prostatitis may cause no signs except for recurrent urinary tract infection. Sudden prostatitis is treated by administration of antibiotics and may require prolonged treatment. Intravenous fluids may be necessary in severe cases. Neutering should be considered after treatment for sudden disease. Longterm prostatitis will only resolve with treatment of benign prostatic hyperplasia, which involves neutering or medication to shrink the prostate. Antibiotics alone are usually ineffective for longterm cases.
Large cysts are occasionally found within or near (paraprostatic) the prostate gland. The signs are similar to those seen with other types of prostatic enlargement and usually become apparent only when the cyst reaches a size sufficient to cause pressure on other organs. Large cysts may result in abdominal distention. Drug treatment is ineffective. The treatment of choice for large cysts is surgical removal. Neutering alone is unlikely to provide sufficient benefit but may be recommended after the cyst has been removed.
Prostate cancer is a serious, yet uncommon, disorder in dogs. Neutering does not protect against future development of prostate cancer in dogs. The signs are similar to those of other prostatic diseases. Pain and fever may be present. Furthermore, the cancer frequently spreads to other tissue and organs (metastasis). If the cancer invades the urethra, urination can be difficult or urine outflow can be blocked. Diagnosis is made using rectal examination, ultrasonography, biopsy, and other tests (such as x-rays) to look for evidence of metastasis. There is no effective curative treatment, but some medications may prolong survival time. Consultation with a veterinary oncologist (cancer specialist) is recommended.
Also see professional content regarding reproductive diseases of male dogs Reproductive Diseases of the Male Small Animal read more .