Canine Cryptorchidism          


This condition may be inherited or present from birth.  Cryptorchids should not be bred, because the problem is believed to be hereditary.  The testes start life within the abdomen, near the kidneys, and then drop down into the scrotum at around the time of birth.  Though newly weaned puppies sometimes have only one, or sometimes no testes present, usually two testes are present between two months and six months of age.  If they have not appeared by this stage, they are unlikely to drop. They may be just under the skin near the scrotum or in the abdomen and are known as retained testicles. A cryptorchid will often have no problems initially with his situation, showing no indications of being in pain or discomfort.  However, research has shown that retained testicles often run a greater risk of becoming cancerous and a malignant tumour is more common.  Being inside the abdomen, these tumours are also more likely to go undetected..  Some also feel that there is an increased risk of testicular torsion, which is very painful.  In some breeds dogs have lived very long lives without being castrated but these seem to be the exception rather than the rule.  When castrating, both testicles should be removed as, though they do not always produce sperm, they are more likely to develop testicular cancer.  For these reasons you should have your dog castrated.

What is Cryptorchidism?
Cryptorchidism (undescended testicles)
Counting to Two


What is cryptorchidism?
During development before birth, the testicles migrate from the abdomen into the scrotum. Normally this is complete by 10 days of age. Cryptorchidism means that one or both of a dog's testicles have not descended into the scrotum. If this does not happen by 8 weeks, the dog is generally diagnosed as cryptorchid, although the testicles may still descend up to 4 months or so.

How is cryptorchidism inherited?
Although the condition is of course seen only in male dogs, both males and females can carry the gene for cryptorchidism. Heterozygous males and females, and homozygous females, will be physically normal, but can pass the gene on to their offspring. Homozygous males are cryptorchid. Thus cryptorchidism is thought to be a sex-limited autosomal recessive trait

What breeds are affected by cryptorchidism?
This is a fairly common condition, which is seen most often in the toy and miniature poodle, pomeranian, Yorkshire and Cairn terrier, dachshund, Chihuahua, Maltese, boxer, Pekingese, English bulldog, miniature schnauzer, and Shetland sheepdog.

For many breeds and many disorders, the studies to determine the mode of inheritance or the frequency in the breed have not been carried out, or are inconclusive. We have listed breeds for which there is a consensus among those investigating in this field and among veterinary practitioners, that the condition is significant in this breed.

What does cryptorchidism mean to your dog & you?
Dogs that are cryptorchid have a much increased risk of testicular cancer (approximately 10 times). Castration will of course eliminate this risk.

Dogs with cryptorchidism can not be shown.

How is cryptorchidism diagnosed?
Your veterinarian will diagnose this condition when s/he examines your dog at the time of vaccination. Most affected dogs have 1 testicle that is not descended.

How is cryptorchidism treated?
The only treatment for this condition is removal of both testicles (neutering or castration). Dogs with cryptorchidism should be castrated for 2 reasons: if the testicles are not removed, there is an increased risk of testicular cancer, and if your dog is bred, the trait will be passed on to future generations.

Breeding advice
Affected dogs should be not be bred. It is best not to breed their parents as well, who carry the gene.


Copyright © 1998 Canine Inherited Disorders Database. All rights reserved.
Revised: December 05, 2001.
This database is a joint initiative of the Sir James Dunn Animal Welfare Centre at the Atlantic Veterinary College, University of Prince Edward Island, and the Canadian Veterinary Medical Association.

Permission to reprint granted by
Alice Crook, DVM Coordinator, Sir James Dunn Animal Welfare Centre
Atlantic Veterinary College University of Prince Edward Island

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Cryptorchidism: Undescended Testicles

  Race Foster, DVM and Marty Smith, DVM
Drs. Foster & Smith, Inc.

This article will help you better understand the developmental abnormality of cryptorchidism, or undescended testicles in male puppies. If your pet is showing any symptoms or signs of disease, please contact your veterinarian. We want you and your pet to be happy and healthy.

At birth, the testicles of a puppy are still within its abdomen. As the animal develops, the testicles slowly "descend" into the scrotum. In mammals, sperm development does not occur correctly at the high temperatures found within the body. The testicles are therefore held outside of the abdomen and within the scrotum to provide a cooler environment. The production of testosterone is usually not influenced by temperature.

Frequently, owners notice that the puppy they just purchased only has one or possibly no testicles within the scrotum. Although different dates are listed in some of the veterinary literature, both testicles are usually within the scrotum by the time the animal is six weeks of age and they should definitely be there by the time the puppy is eight to ten weeks of age. If one or both testicles are not present at that location by twelve weeks of age, they probably never will be and the animal is said to be suffering from cryptorchidism or "retained testicles." This is a disorder that may be passed from generation to generation.

What are the symptoms?
These animals rarely show any abnormalities because of this condition. They have normal activity levels, growth and behaviour. Although fertility may be affected, they will usually show normal breeding behaviour and frequently impregnate females, especially when one of the testicles has descended into the scrotum.

What are the risks?
Some researchers believe that dogs with cryptorchidism may have a higher incidence of other testicular diseases. Specifically, these would be cancer and torsion.

What is the management?
Cryptorchid dogs should never be allowed to breed. This is a well documented genetic trait, passed on to future generations. In addition, because of the potential for an increased incidence of torsion or cancer within the retained testicle, it is strongly recommended that all of these individuals be neutered. The surgery to remove a retained testicle is more involved than a routine neuter. The veterinarian must literally hunt for the testicle which may be located anywhere from the area around the kidney in the abdomen to the muscle near the groin.

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Counting To Two

by D. Caroline Coile, Ph.D.
First appeared in Dog World magazine

Human parents may rejoice at counting 10 fingers and 10 toes, but dog breeders need only count to two to be grateful: two testicles, that is.

At birth a male puppy's testicles are still within the abdomen, but they slowly descend into the scrotum by about 10 days after birth. They may be hard to locate at first, but by 6 to 10 weeks they should be easily located in the scrotum. If not, there is only a small chance they will descend. However, they are soft and can still move between the scrotum and inguinal canal, especially when the pup is cold or scared, so they may appear to come and go until the pup's inguinal rings close at about 6 months of age. At that time, a dog with only one descended testicle is termed a unilateral cryptorchid, and one with no descended testicles is a bilateral cryptorchid.

The reported incidence of cryptorchidism in dogs ranges from 1 to 10%, with many more almost certainly unreported. Unilateral cryptorchids occur more often than bilateral, and the retained testicle is usually the one on the dog's right side. Cryptorchidism is reported most often in Toy Poodles, Pomeranians, Yorkshire Terriers, Miniature Dachshunds, Cairn Terriers, Chihuahuas, Maltese, Boxers, Pekingese, English Bulldogs, and small or short-nosed breeds in general. In humans, about 3-6% of newborn males are cryptorchid, rising to 9-30% in premature males. Low birth weight, being one of a twin, and maternal exposure to estrogen during the first trimester all predispose a human male to cryptorchidism.

Hereditary factors are assumed to play an important role even in humans, where 7% of brothers of cryptorchids are also cryptorchids. Certain inbred families of dogs, notably Cocker Spaniels and Miniature Schnauzers, have increased rates of cryptorchidism. Some of the most telling data come from selective breeding in goats. Deliberate use of cryptorchid sires raised the incidence in a goat herd from 7% to 51%; then subsequently in that same herd strict selection against cryptorchids (using only entire sires, and using neither a parent of a cryptorchid nor offspring of a known carrier) decreased the incidence to 1%.

The genetics aren't known, although it's commonly speculated that the trait is a sex-limited (that is, can only be seen in males) autosomal (non-sex chromosome) recessive (takes two) trait, meaning that both males and females can be carriers. That means that if a breeder seriously wants to rid the trait from a line, then not only affected males, but sisters, mothers, and dams of affected males must be pulled from the breeding pool. This would create such a devastating blow to most gene pools that it's not reasonable. Another possibility is that cryptorchidism is a polygenic trait, that is, arises from the interplay of multiple genes. This would make it even more difficult to control.

Cryptorchid dogs can't be shown in conformation, and bilaterally cryptorchid dogs are sterile. A retained testicle is about 10 times more likely to become cancerous, and its spermatic cord is also more likely to become twisted causing testicular torsion, but the chances of both are still fairly low. Nonetheless, because of these potential problems a retained testicle should usually be surgically removed.

Breeders hoping to avoid these problems often turn to veterinarians for help in encouraging a reluctant testicle. In humans, surgical correction is the treatment of choice. The same procedure is possible in dogs, but because such treatment is considered a fraudulent change of appearance by the AKC, and because such dogs could then be used at stud and perpetuate the trait, veterinarians consider it unethical.

Drug therapies are often tried. Much controversy exists over whether such treatment is effective because few if any studies include control cases. Repeated doses of drugs such as human chorionic gonadotropin (HCG) or gonadatropin releasing hormone (GnRH) are given to stimulate androgen production, which in turn appears to influence testicular descent by affecting the testicular cord or cremaster muscle. In humans, no difference in efficacy has been found between 4 doses compared to 10 doses of HCG; nonetheless, it is commonly given twice a week for five weeks. Success rates in humans range from 6-21 % in randomized blind studies, and much higher in uncontrolled studies.

GnRH may give better results, and is available as a nasal spray instead of injection, but is only improved for treatment of cryptorchidism in humans in Europe. Success rates in controlled human studies range from 6-38%, and in uncontrolled studies from 13-78%. In a comparison of HCG and GnRH, the HCG had a success rate of 6% and the GnRH 19%. Some investigators advocate using both therapies.

These percentages only apply for humans. Little hard data is available for dogs, but one study in which HCG was given four times over a two-week period reported success in 21 out of 25 dogs, with better results when given to puppies less than 16 weeks old.

Some veterinarians and breeders consider even drug therapy unethical. However, side effects are minimal, and if medical treatment can reduce the need for abdominal surgery in a hunt for retained testicles, it would seem unethical not to try it. Retained testicles predispose dogs to some medical problems, but in many breeds the most serious threat it poses is euthanasia. The sad truth is that dogs in breeds in which pet homes are seldom available may be euthanized because they cannot be used for show. And while breeding such dogs may raise the probability of producing more cryptorchids, the condition is not as devastating as many other conditions dogs are routinely bred with.

Until the time a DNA test becomes more available, and the mode of inheritance and other possible factors are better understood, breeders will continue to make their best bet and then hold their breath and count to two. 

reprinted with kind permission from Caroline Coile
Author of German Shepherds for Dummies

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Chrytorchidism Left Testicle Undescended
Bosso's Story
Undescended Testes

chloebutton talabutton

The above information is simply informational. It's intent is not to replace the advice of a veterinarian nor to assist you in making a diagnosis of your pet. Please consult with your own veterinarian for confirmation of any diagnosis. Your pets life may depend on it