All About Testicular Cancer in Dogs

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Testicular cancer dogs? Yeah, we also understand and freak out when we hear cancer around some places in the body. But can your dog really get testicular cancer? How common is testicular cancer in dogs?

Almost everyone is afraid of getting a diagnosis that says cancer. The fear, anxiety, money, and sickness process is something no one wants to go through. There are some places that you would never imagine cancerous cells to grow there, right? But cancerous tumors can grow anywhere. Let’s find out about one in our little male buddy, the testicles.  

Testicular Cancer

Testicular Cancer in Dogs

Dog testicular cancer can be defined as an abnormal, uncontrolled overgrowth of any or a mixture of the cells in one or both testicles of the dog. 

Tumors from a normally descended testicle are benign (less likely to spread), while tumors in undescended testes (cryptorchidism) are most likely to be malignant (can spread to other tissues). 

Testicular cancers produce many hormones, such as testosterone and estrogen, which affect other body structures and functions. 

Diagnosis is based on history and physical examination, and laboratory tests. Diagnosis can also be made using a fine needle aspirate to determine the kind of cells that are present. 

Can Neutered Dogs Get Testicular Cancer?

One mind-blogging question is, “can neutered dogs get testicular cancer?” Testicular cancer is prevalent in intact, unneutered dogs, so how about neutered dogs? 

Neutering has been shown to reduce, if not eliminate altogether, the chances of getting testicular cancer in dogs. However, it is important to neuter your dog after the necessary hormones for growth have been released and utilized. 

How Common is Testicular Cancer in Dogs?

Testicular cancer in dogs is more common than we can imagine. It is very common in adult intact / unneutered / non-castrated male dogs. However, the incidence of canine testicular cancer is not wide because most pet dogs are neutered in their puppy days. 

It is also widespread in cryptorchid dogs, both older and younger ones. Even though not all cryptorchid dogs develop testicular cancer, the risk is very high. 

Males of certain breeds, including German Shepherd Dogs (GSD), Boxers, Shetland Sheepdogs, Afghan Hounds, Labrador Retrievers, Maltese, Weimaraners, Golden Retrievers, and Collie Dogs, are predisposed to getting canine testicular cancer in their lifetime as compared to other breeds. 

The Causes of Canine Testicular Cancer

The leading cause of testicular cancer is unknown. Usually, cancer arises as a mixture of many risk factors. However, some elements have been shown to predispose or increase a dog’s chances of getting canine testicular cancer. 

These factors include:

  • Age (usually above ten years)
  • No neutering
  • Breed
  • Cryptorchidism (undescended testes)
  • Prostatic diseases
  • Hormonal imbalance
  • Genetic/hereditary 
  • Environment

Clinical Signs and Symptoms of Canine Testicular Cancer

Usually, clinical signs are based on the type of the tumor and its location. For example, signs and symptoms of testicular cancer in dogs can be broken down into early or warning signs and others or advanced signs. Most dogs do not show any clinical signs, however. 

Early signs of dog testicular cancer include:

  • Enlarged testicle (one or both)
  • Soft swelling in one or both testicles
  • Enlarged scrotum
  • Hair loss, especially around the scrotal region
  • Thin skin
  • Brittle hair
  • Darkened skin (skin pigmentation)
  • Slow hair growth (especially after grooming)
  • A red inflammatory reaction along the midline

Other signs include:

  • Squatting to urinate instead of raising a leg (hiking)
  • Elongated nipple
  • Anemia leading to lethargy (feeling unwell)
  • Atrophy of the non-cancerous testicle (reduction in size)
  • Atrophy of the penis
  • Atrophy of the prostate
  • Reduced libido (sex drive)
  • Enlarged mammary glands
  • Enlarged prostate
  • The attraction of other male dogs

Some of the signs are related to the other organs where the tumor had spread. These can include:

  • Vomiting
  • Weight loss
  • Decreased appetite
  • Difficulty in urinating or defecating
Male dog rolling on grass

Three Types of Canine Testicular Cancer

There are three main types of dog testicular cancer. These are seminomas, Sertoli cell tumors, and Leydig (Interstitial) cell tumors. In addition, there are other testicular cancers in dogs, such as hemangioma, teratoma, lipoma, chondroma, embryonal carcinoma, and fibroma. But these are rare.

Sertoli cell tumors and seminomas are more common in cryptorchid dogs. These cancers can spread to surrounding lymph nodes, even though they invade other tissues slowly. Leydig cell tumors are less likely to spread.

Seminomas arise from the cells that produce sperms (round cells in the seminiferous tubules). This tumor rarely shows any sign of ill-health and is found during a routine visit to the veterinarian. However, seminomas may lead to your dog exhibiting characteristics of a female. 

Leydig cells produce most of the male hormones, such as testosterone. Leydig cell tumors are microscopic, benign, and usually found on routine examinations by accident. They also do not show any signs of ill-health. 

Sertoli cells aid in the transport of matured sperms and also make the environment suitable for their survival. Tumors involving the Sertoli cells are very invasive and show the most visible signs. For example, there would be swelling of the scrotal or the testicular region.  

Amongst all the three types, the Sertoli cell tumor has the highest rate of spread.

Other cells in the testicles can become cancerous, but this is rare. 

How is Canine Testicular Cancer Treated?

The primary way to treat testicular cancer is by removing the affected testis surgically. However, your veterinarian may also decide to remove the unaffected testis, too, in addition. Alternatively, if the tumor has metastasized, chemotherapy and radiotherapy are employed. 

How Does Canine Testicular Cancer Progress?

Cancer progression implies the spread to other organs and the increased growth of a tumor. Testicular cancer has a low rate of spread compared to other forms of cancer. However, among these three types, Sertoli, Leydig tumors, and seminomas, Sertoli tumors have a 15% chance of spread, but Leydig tumors rarely spread. 

Abdominal ultrasound, CT scan, X-rays, urinalysis, bloodwork, and rectal examination can be used to stage testicular cancer and determine the spread. 

Sometimes, testicular cancer is a spread from another cancer in the body and needs to be checked by your veterinarian for appropriate actions to be taken. 

How to Prevent Testicular Cancer in Dogs

Now that we have seen the causes and symptoms, the next big question is: “How to prevent testicular cancer in dogs?” 

The main prevention of testicular cancer in dogs is to neuter them when they are of age and not use them for breeding. The best age, on average, to neuter a dog is between 6-9 months. However, the size of your dog matters as this affects the growth rate, and your veterinarian can help you make the right decision. 

Also, due to its genetic and hereditary risk factors, breeders should ensure that the breeding line is free from testicular cancer, and also cryptorchid dogs are not used for breeding.

The Prognosis of Testicular Cancer in Dogs

Prognosis or the outcome of testicular cancer is good if surgical intervention is done on time and if the tumor cells haven’t spread too much. 

Usually, Leydig cell tumors have excellent prognoses and Sertoli cell tumors also, if they haven’t metastasized. Non- hyperestrogenism seminomas (seminomas without excess estrogen) also have a good prognosis. 

The prognosis for testicular tumors that have spread is guarded (have chances) based on the degree of spread, the location of the spread, the type of tumor, and the treatment options. 

Testicular Cancer text


Although cancer is scary, Testicular cancer is actually not to worry about when caught early. Keeping a keen eye on your dog is best to detect any changes in its behavior. It can be treated, and the prognosis is good when detected early. 

However, if you are not using your pet to breed, we suggest you neuter it as every male dog is susceptible to developing canine testicular cancer regardless of the breed.  Testicular tumor dog should be on your list of family history when purchasing a dog, just as cryptorchism is on the list. 

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Currently a Veterinary House Officer at the University of Ghana, Akosua plays a pivotal role in disease diagnosis, treatment, and student supervision. Akosua's educational journey in veterinary medicine has been instrumental in shaping her commitment to public education and awareness. Her veterinary training equips her to communicate complex topics for public understanding. Her online presence on Instagram reaches a wider audience. She actively engages in public speaking, inspiring a deeper understanding of responsible pet care and the role of veterinary professionals in fostering a healthier coexistence between humans and animals.