Monorchidism in dogs, also known as cryptorchidism, is a condition in which only one testicle descends and the other testicle is unable to descend into the scrotum. The descent of each testicle begins with each testicle moving through the abdomen into the inguinal area, then continued movement down and through the inguinal canal. Finally, the testicle reaches the scrotum from within the inguinal canal. When one of these processes is disrupted, the testicle stays within the abdominal cavity or in the inguinal area while the other drops down into the scrotum.

This entire process is stimulated by testosterone within a few weeks after birth. The process should be complete, with both testicles in the scrotum by two months of age. In some dog breeds, the process may take a bit longer, but typically the testicles should have dropped no later than six months after birth.

Monorchidism in dogs is usually genetic, and is dependent upon the INSL3 gene, or the Insulin-like 3, which is the protein that produces the hormone responsible for the development of the gonads, or gonadal tissue. Studies are being conducted to be sure this is the main cause of this disorder. The descent of the testicles is respondent to the effectiveness of this gene. Disruption of prenatal hormones may also play a role in the development of this condition.

Monorchidism in dogs results in one of the male dog’s testicles to remain up within the groin area and not descend. In typical male dogs that are not affected by this condition, both testicles are to descend at approximately the same rate.

A dog who is classified as having monochordism will most likely be asymptomatic. Some canines may show signs.

There are a few types of dog breeds that may be predisposed to this condition. These types of purebred breeds that may suffer from monorchidism include:

Studies of purebred dogs that have Monorchidism are still being conducted to further understand the role that genetics play in the development of this disorder. Causes may include:

If you suspect your dog has monorchidism, make an appointment with your veterinarian. The veterinarian will do a visual assessment of your dog’s scrotum and penile area. He will ask questions about his symptoms, his age, his breeding, and any other questions about his symptoms and overall health. If you have noticed any behavior changes in your young dog, such as licking of the area, it is important to tell your veterinarian. 

The medical professional will do blood testing, a urinalysis, and a biochemistry profile to check for any underlying disorders. He may also do specific testing on the testosterone levels of your dog, as dogs which suffer from monorchidism typically have low levels of this hormone. 

He will then feel your dog’s penile and abdominal area by palpitation of the scrotum and palpitation of the abdominal area. This will also give the veterinarian a great deal of information as to the whereabouts of the testicle. An ultrasound may also be conducted for further analysis.

Once your veterinarian has come to the conclusion of monorchidism, he will give you a few treatment options. Treatment methods include:

Your veterinarian will explain to you what hormone treatment entails. Although still being researched, studies show that the gonadotrophin releasing hormone, or GnRH, may be given to your dog to stimulate the descent of the testicle. This may be effective if the testicle is in the inguinal position, which is right above the scrotum and within the groin area. This is highly dependent upon your veterinarian’s outlook of your dog’s condition and the position of the testicle. It is also dependent upon the age of your young dog, as this procedure should only be conducted when the dog is four months of age or younger.

For most dogs with monorchidism, surgery is the best option. For purebred puppy owners that had the goals of showing the dog, this option will prevent this from occurring. However, for the health of the purebred dog, this may be the only option. Castration of both testes is recommended, even if one testicle is in the proper position. There is a risk of cancer if this treatment does not occur, and it is highly recommended that this surgery take place before your dog reaches four years of age to prevent any health repercussions.

If your dog has monorchidism and surgery was performed, he will need to wear an Elizabethan collar to keep him from chewing or licking the affected area. Once proper treatment is successful, the prognosis is good.

If you are giving your dog the hormone therapy, as recommended by your veterinarian, your dog will need repeated visits to the veterinarian to see how he is progressing. Hormone therapy is not guaranteed, but it may be an option if you want to show your dog. Although it may work for your dog, it is recommended that your companion not breed any puppies for profit, as they may have the condition as well.

Once your dog is home from treatment, the veterinarian will communicate to you the importance of monitoring your dog. He will want to see your dog again for a follow up visit or two to check the site of the surgery and to be sure he is recovering.

You will not be able to show your dog within the show ring due to the abnormality, but his health is very important and you, as well as he, will be happy being the purebred dog you are proud to own. He will be able to live a long and healthy life, even after a diagnosis of monorchidism.