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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 reasonably rare, often benign, neoplastic tumor of the testes that can either occur unilateral or single in the male dog. (In rare cases, malignant forms have been reported.)  When it does happen, it usually only affects dogs over the age of four, and even though it is rare, it is 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 challenging to identify. This is why we wanted to take a moment and discuss exactly what a seminoma is so that if your vet has recently told you that your dog 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 (tumors) comprise the overgrowth of abnormal cells (neoplastic cells) from the inner layer of the testicles or the spermatic germinal epithelium, where spermatocytes are generated.

The excellent 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. When left untreated, there is a chance 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. In some cases, dogs have shown pain due to the pressure the growing tumor causes. , A cancer, or testicular mass, can be palpated at several points. (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 spread to other body parts.

Now, if your dog…

If he exhibits 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 pain 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.

Also, suppose you notice your male dog squatting to urinate and having a reduced sex drive around females in heat. In that case, it may indicate excessive estrogen levels, which can signify 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 is called the Leydig cells, which is generally a benign tumor.


  • Cells that typically generate sperm make up these tumors.
  • Whether benign or malignant, these tumors 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 that 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 suffer from symptoms if they develop signs that could indicate a seminoma. This is why we always advise folks to take their pet to the vet once they suspect something is wrong with their animal.

Which brings us to…

We want to remind folks that we at IndulgeYourPet are not doctors, veterinarians, or medical professionals. We are all a bunch of folks passionate about animals and only want what’s best for them. If you feel your pet may have seminoma (or any other health issue), you’ll want to have them checked out by a vet ASAP!

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

Commonly Affected Breeds

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

Cause of seminomas in dogs

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

  • Old age
  • Chemical exposure
  • Infections
  • Radiation exposure
  • Undescended Testicles (cryptorchid testicles)
  • Dogs with cryptorchidism (undescended testis) have a ten times greater chance than normal dogs to get testicular cancer and tumors on the undescended testicles; 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, followed by a thorough 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 probably have the following:

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

Where there is an increase in estrogen, it 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…

You 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 piece is withdrawn for microscopic examination) to determine the cause of the testicular tumor and whether it I benign or malignant. Lastly, your veterinarian…

You may also want to take an ultrasound of the abdomen and testicles to get a better idea of the size and placement, along with the actual shape of the testes inside 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 surgically removing 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.


If the tumor has spread, your veterinarian may recommend radiation therapy and chemotherapy to kill off remaining tumor cells. As we’re sure you can imagine, this can become expensive fast! This is why we here at IndulgeYourPet also recommend that any new pet owner take a moment and see what it might cost to purchase a pet insurance policy for your new animal.

Now, will a pet insurance policy be suitable 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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