Testicular cancer in male dogs

Testicular cancer in male dogs

Health & Safety

Male dogs that are not neutered (castrated) run the risk of developing a few different conditions that neutered dogs cannot contract, due to the fact that their testes and so, testosterone production remain present throughout their lives. Tumours of the testes, or testicular cancer is one of the most common of these, and in un-neutered male dogs that have reached maturity, tumours of these types are relatively regularly seen in veterinary practices.

If you own an un-neutered dog and are wondering about the risks of testicular cancer, read on for more information.

What type of dogs can develop testicular cancer?

The good news is, if you own a bitch or a neutered male dog, your dog is safe from this particular type of cancer! Testicular cancer occurs only in un-neutered male dogs, and is generally found only in adult and mature dogs over the age of four. There are no breed-specific risk factors for testicular cancer, and it affects all breeds equally.

However, dogs that are considered to be cryptorchid (one or both of the testes does not descend properly and is not visible outside of the body) are more than ten times more likely to develop the condition in the testes that has failed to descend than dogs with normal testes development.

What types of testicular cancers can dogs develop?

There are three different types of common testicular cancers that can affect dogs, each of which have slightly different symptoms and appearances. However, as they are all generally treated in the same fashion, as a whole, the three different types of testicular cancer are usually simply grouped together for treatment purposes.

Sertoli cell tumours

Sertoli cell tumours cause swelling of the scrotum and testes, or, for cryptorchid dogs, within the abdominal or inguinal area where the testicle is retained. The presence of sertoli cell tumours leads to oestrogen production, and up to 50% of affected dogs will test positively for hyperoestrogenism, or high levels of oestrogen in the body. The other indications of a sertoli cell tumour may include an enlarged prostate gland, hair loss, anaemia, and swollen nipples and an enlarged mammary gland.

Left unchecked, sertoli cell tumours may metastasize to the lungs, brain and abdomen, but this is relatively rare.


Seminomas lead to a generalised swelling of the testicles, scrotum and abdominal/inguinal area. While seminomas can potentially also produce oestrogen and have the ability to metastasize, this happens in less than 5% of all cases.

Interstitial cell tumours

Interstitial cell tumours are usually only found by accident, as they do not display any obvious symptoms, and do not metastasize or produce oestrogen. Interstitial cell tumours are generally considered to be low risk, and not hugely problematic.

How does the vet diagnose testicular cancer?

Examining the history of your dog, making a thorough physical examination and taking a biopsy of the affected area for examination is the usual means of definitive diagnosis, but your vet may also run a blood panel and take chest and abdomen x-rays to ensure that the tumours have not metastasized.

How is testicular cancer in dogs treated?

Testicular cancer in dogs is thankfully easy and quick to treat, as it involves castration of the affected dog to remove the problematic testes. As testicular cancer in dogs very rarely metastasizes, this is usually all that is required!

However, if the cancer has metastasized, chemotherapy may be used either instead of or as well as castration. If the dog is not deemed to be a good candidate for surgery, your vet may decide to treat the dog using chemotherapy alone, without castration.

What is the prognosis after treatment?

Generally, dogs that are treated for testicular cancer via castration have an excellent prognosis, and an almost 100% survival rate. Testicular cancer in dogs is relatively easy to resolve, as the testes are outside of the body, and can simply be removed with a short surgical procedure.

Occasionally, when the cancer has metastasized, the treatment required needs to be more aggressive, and the prognosis more guarded, with a longer recovery time for the affected dog.

In cases where the presence of the cancer has caused the dog’s body to produce high levels of oestrogen, the oestrogen levels within the body will usually return to normal on their own after castration. However, in severe cases of hyperoestrogenism, anaemia may accompany the condition, which can necessitate aggressive treatment to raise the red blood cell count, and possibly even blood transfusions.

Can testicular cancer in dogs be prevented?

Testicular cancer in dogs is totally preventable and really easy to achieve; simply have your dog castrated when they are old enough to undergo the procedure! This is particularly important for male dogs that are cryptorchid, or have an un-descended testicle, as the rate of testicular cancer in cryptorchid dogs is exponentially higher.

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