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Seminoma in Dogs… Symptoms, expectations and costs!

What is seminoma or spermatocytic seminoma? Well, the good news is that seminoma is a fairly rare, often benign, neoplastic tumor of the testes, that can either occur unilateral or single, in male dog. (In rare cases malignant forms have been reported.)

When it does occur…

It usually only affects dogs over the age of four and despite the fact that it rare, it is actually the second most common tumor that can affect the testes in dogs.

The problem is…

This tumor is usually less than 2 centimeters in diameter and often causes very few clinical symptoms in the affected male dog, thus making it difficult to identify.  Which is why we wanted to take a moment and discuss exactly what a seminoma is so that if you’ve recently been told by your vet that your do may be suffering from one, you’ll be better prepared for what to expect.

So, without further ado, let’s dive right in.

Seminoma Defined

Seminoma tumors (tumours) are made up of the overgrowth of the abnormal cells (neoplastic cells) from the inner layer of the testicles, or the spermatic germinal epithelium, which is where spermatocytes are generated.

The good news is…

That when this condition is caught early and castration surgery is performed there is a very high rate of survival for your buddy. The problem is, like we said before that this condition isn’t always the easiest to detect, and when left untreated, there is a chance with this that it may cause the production of estrogen to increase which could result in mammary enlargement and penile and testicular atrophy.

Symptoms of seminomas in dogs

Only rarely do male dogs that have seminomas exhibit any clinical symptoms, although in some cases dogs have exhibited pain which is due to the pressure that the growing tumor causes. In a small number of cases a tumor, or testicular mass, can be palpated.  (To palpate, is to examine, medically using the palm and fingertips to check for signs of a disease.  In rare cases the tumors have become malignant and have spread to other parts of the body.

Now if your dog…

Does exhibit any of the possible symptoms below, he needs to be seen by your veterinarian as soon as possible for obvious reasons.  Symptoms such as:

  • Blood in the peritoneal cavity or urine,
  • Enlarged Scrotum (swelling of the testicles),
  • Poor hair growth or hair loss (alopecia),
  • Thinning and darkening of the skin,
  • Infertility,
  • Unexplained growth or tumor on the testicles,
  • Brittle hair,
  • Changes in prostate size (Which folks won’t necessarily know about but might suspect by frequent urination),
  • Mammary enlargement,
  • Penile or testicular atrophy.


If you notice your male dog squatting to urinate and having a reduced sex drive around females in heat it may indicate that there is are excessive estrogen levels which can also be a sign of seminoma.

Types of seminomas

Some of the different cell types within the testes include:

  • Germ cells which make the sperm,
  • Sertoli cells which nourish the cells,
  • And Leydig cells which are the hormone producing interstitial cells.

The three main types of testicular tumors that can develop in an intact male dog’s testicles are:

Interstitial (Leydig) cell tumors

  • An overgrowth of testicular cells that produce testosterone, called the Leydig cells, which is generally a benign tumor.


  • Cells which normally generate sperm make up these tumors.
  • Regardless of whether these tumors are benign or malignant they often trigger male dogs to exhibit female characteristics.

Sertoli cell tumors

  • The cells that typically nurture the developing sperm make up these cancerous tumors.
  • While more common in dogs with undescended testes (one or both of the testes don’t descend into the scrotum and remain in the abdomen), called cryptorchidism, these tumors are more likely than the other testicular cancers to spread deeper into the dog’s body.

Some of the less common testicular cancers or growths which may affect a male dog’s testis include:

  • Embryonal carcinomas,
  • Gonadoblastomas,
  • Granulosa cell tumors,
  • Germ cell tumors,
  • Hemangiomas,
  • Lymphomas,
  • Mucinous adenocarcinomas,
  • Rete testis,
  • Sarcomas,
  • And Teratomas.

So, as you can see, there are a lot of “potential” causes for your dog to be suffering from symptoms if in fact he or she does develop symptoms that could indicated a seminoma.  Thich is why we always advise folks to take their pet to the vet once they begin to suspect something may be wrong with their animal.

Which brings us to…

Were we like to remind folks that we here at IndulgeYourPet are not doctors, veterinarians or medical professionals.  All we are is a bunch of folks who just happen to be passionate about animals and only want what’s best for them.

This is why…

If you feel like your pet may have seminoma (or any other health issue for that matter) the first thing that you’re going to want to do is have him or her check out by a vet ASAP!


The truth is, an early diagnosis will often lead to the “best” medical outcome for your pet regardless of what is bothering him or her, but beyond that diagnosing a medical condition early could save you a bundle in medical costs!

Affected Breeds

While all male dogs are susceptible to testicular tumors, there are some breeds that are predisposed to it, including the following;

Cause of seminomas in dogs

The cause is typically unknown but there are conditions that can increase your dog’s likelihood of developing testicular cancer, which can include;

  • Old age
  • Chemical exposure
  • Infections
  • Radiation exposure
  • Undescended Testicles (cryptorchid testicle)
  • Dogs with cryptorchidism (undescended testis) have a ten times greater chance than normal dogs to get testicular cancer and tumors on the undescended testicles and the subsequent tumors are more likely to be malignant.

Diagnosis of seminomas in dogs

Your veterinarian will need to get a complete oral history of your dog which will be followed up by a complete medical exam which will include searching for the testicular mass and seeing whether it is palpable.

With this…

Your veterinarian will likely want to perform some laboratory testing which will likely include:

  • A complete blood count,
  • A biochemistry profile,
  • A PLAP,
  • And a urinalysis to reveal whether the there is an underlying medical issue or whether there is a concurrent issue as well.

Where there is an increase in estrogen will help figure out whether the tumor is a Leydig cell tumor because Ledyg cell tumors do not increase the estrogen level.

Next your veterinarian…

May want to do a biopsy (obtain a tissue sample which will then be studied under a microscope) or a fine-needle aspiration or FNA (a hollow needle is inserted into the mass and a small sample is withdrawn for microscopic examination) to determine the cause of the testicular tumor and whether it I benign or malignant. Lastly, your veterinarian…

May also want to take an ultrasound of the abdamon and testicles to get a better idea as the size and the placement, along with the actual shape of the testes inside of the body. The total cost of diagnosing your dog with seminoma will usually run around $500 to $1250 dollars.

Treatment of seminoma in dogs

After your veterinarian has diagnosed your dog with seminoma they will look towards treating the cancer.  This is usually done simply by surgical removal of the testicular tumor since it doesn’t usually spread to other organs.  In cases like these, surgical castration tends to be relatively inexpensive considering the alternatives.


In the event that the tumor has actually spread your veterinarian may recommend radiation therapy and chemotherapy to kill off remaining tumor cells and as we’re sure you can imagine this can become really, expensive really fast!

Which is why…

We here at IndulgeYourPet also recommend that any new pet owner take a moment and see what it might cost for you to purchase a pet insurance policy for your new animal.

Now will a pet insurance policy be right for everyone?

No, probably not.  But until you fully understand what these policies “will” and “won’t” cover and how much these pet insurance policies cost, how will you know if one might be right for you?

For more information on who we feel currently offers the “best” pet insurance policies out there, we would encourage you to check out our Best Pet Insurance Policies article.

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