Question from Pam Gilmour Hi my chi(huahua) is 6 months , he only has one testicle. I will be having him done, what would be the best age to wait to see if it will come down? Answer from Shanika (online vet) Hi Pam and thank you for your Question regarding the best age to have a dog castrated which has a retained testicle. I will start by explaining a little about the testicles, what they are, where they develop and what can go wrong along the way. The testicles are two oval shaped structures normally found in the scrotum (loose sac of skin near your dog’s bottom). Testicles are male sexual glands and produce the hormone testosterone along with sperm and various other secretions which assist in reproduction. The testicles start developing while the puppy is inside the mother’s uterus (womb); they are at first located inside the abdomen (tummy) and just behind the kidneys. A few days after your puppy has been born the testicles should be in the scrotum, they travel from their starting point down through the abdomen and through an opening called the inguinal ring in order to get to the scrotum. When you take your puppy to the vets to have his first examination they will check for the presence of two testicles in the scrotum, if these cannot be felt then this will be checked again on future visits. If both testicles are not present this condition is referred to as cryptorchidism (retained testicles), either one (unilateral cryptorchid) or both (bilateral cryptorchid) of the testicles may be missing from the scrotum. In very rare cases on or both of the testicles has not actually developed at all. What should you do if your dog has cryptorchidism? Your vet is likely to suggest that you wait to see if the missing testicle comes down into the scrotum at a later date, this would usually be by 6 months of age but in some cases can occur up to 1 year of age. What to do if the testicle does not appear? Your vet will discuss a castration procedure with you in which both testicles are removed, it is a simple procedure to remove under general anaesthesia the testicle present in the scrotum, the retained one has to be located in your dog’s abdomen, and this can take some time. The surgical procedure to find and remove the testicle from the abdomen can be tricky as the testicle which has not found its way to the scrotum is often smaller and therefore not so easy to locate in amongst the contents of your dog’s abdomen. Why should I have my dog castrated if he has cryptorchidism? If the testicles are not in their correct location in the scrotum there is an increased chance of them becoming diseased, such as developing into cancerous tissue. Also a dog with cryptorchidism is likely to have reduced fertility and would not be an ideal candidate for breeding. I hope that I have managed to answer your question regarding the timing of castration in a cryptorchid dog and have managed to explain some of the reasoning behind why it happens and what the best plan of treatment is. Shanika Winters MRCVS(online vet) If you are worried about your dog please book an appointment with your vet or use our online symptom checker.