Ovarian Tumors in Dogs

Although veterinarians may disagree about whether oophorectomy or ovariohysterectomy are the best options to treat a dog with ovarian tumors, both are possibilities to potentially get rid of the tumors for good. Although ovarian tumors are rare in dogs, the possibility is still there, specifically for English Bulldogs, German Shepherds, and Yorkshire terriers.

In most cases, there are no symptoms leading up to the tumors unless they grow to be noticeably large. Hormonal dysfunction and carcinogenic fluid in the abdomen are two signs of tumors. Sex cord stromal tumors are reportedly most likely to grow larger.

Other notable signs include:

• Aplastic pancytopenia (red blood cells not developing correctly near bone marrow)
• Excessive infiltration of endometrium cells
• Lack of a “going into heat” period
• Loss of hair on the body and head (alopecia)
• Overproduction of steroid hormones (estrogen, progesterone)
• Persistent estrus
• Red discharge in the vulva
• Too much attention from other female dogs, primarily due to higher testosterone, which may make the dog give off male dog traits
• Uncomfortable with being petted or touched
• Vulvar enlargement

Types

Although ovarian tumors are uncommon in dogs, epithelial tumors and sex cord stromal tumors are the primary results of a tumor diagnosis for 80 to 90 percent of all canine ovarian tumors.

Additional tumor types include:

• Germ cell tumors
• Mesenchymal tumors (primary ovarian hemangiosarcoma and fibromas)

Tumors appear to be most likely related to Boxers, English Bulldogs, German Shepherds, and Yorkshire terriers. The age ranges vary, as young as four years and as old as 16 years.

Although ovarian cancer is not very common, it does tend to affect older dogs more often, especially dogs that have not been spayed already. Detecting symptoms in the early stages may help the dog avoid cancerous tumors spreading throughout the body. Unfortunately, not all tumors are obvious from just viewing the dog.

Considering the symptoms for tumors are not always as noticeable as other illnesses may be, here are common ways to recognize their size and whether they are benign or cancerous:

• Cytologic evaluation of abdominal or pleural effusions
• Histopathological exam - mandatory test used to examine resected tissue while radiographs look for signs of a teratoma and is mandatory
• Intravenous pyelography - used to examine renal masses from ovarian masses
• Thoracic radiographs - used to establish whether there are signs of metastasis
• Transabdominal needle biopsies - used to examine the ovaries
• Ultrasonography - helps in establishing the size of the tumors
• X-rays - used to examine the urinary system for ovarian masses, separate from potential renal masses

Because sex cord stromal tumors tend to grow larger, those are one of the more obvious to examine. Although any sign of a tumor will be acknowledged, small lesions are usually diagnosed as benign. It's the larger ones that alert a veterinarian to the possibility of cancer.

Although chemotherapy is an option, there is no standard protocol for whether chemotherapy should be used in each instance. Other treatment options include:

• Intracavitary administration of cisplastin - used to control malignant effusions
• Oophorectomy - an alternative to ovariohysterectomy, in which only the ovary/ovaries are removed
• Ovariohysterectomy - removing female dog's reproductive organs to get rid of ovarian tumors

Pet owners, specifically in North America, may find that some veterinarians will debate which way is the better treatment: oophorectomy or ovariohysterectomy. While both procedures are meant to remove tumors, one is a less common procedure. Uterine disease also becomes a topic of concern if only oophorectomy is completed.

There are both pros and cons of removing both ovaries in a female dog with ovarian tumors.

• Pros
• Eliminates hormones (activin, estrogen, follistatin, inhibin, progesterone)
• Improve the survival rate after mammary cancer diagnosis
• Reproductive sterility
• Prevents genetic diseases (diabetes, epilepsy, demodecosis)
• Cons
• Uterine neoplasia is still a possibility

If the entire growth is removed, then recovery time may be faster and less difficult. However, if the tumor goes untreated and continues to spread, then the more surgery needed, the longer it will take for the dog to recover afterward. Chemotherapy or radiation treatment are possibilities to get rid of and kill cancerous cells, so they don't return. Although antibiotics are recommended after the surgery, using antibiotics may lead to exposure of other illnesses, including:

• Diarrhea or vomiting
• Loss of appetite
• Skin irritation (allergies, hives, rashes)
• Yeast infections

Pet owners should ask for help in deciphering between side effects and a possible new illness, considering some of these side effects are also the same as what would happen from tumors.

The survival rate after removing tumors is estimated at four to six years.