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Ovarian Cysts in Dogs

There are three kinds dog ovarian tumors: epithelial tumors (skin/tissue), germ cell tumors (sperm and ova), and stromal tumors (connective tissue). The most common type of ovarian tumor in dogs is ovarian carcinomas. Granulosa cells are follicular cells (hollow cells) surrounded by theca cells (which form a surrounding sheath). Ovarian tumors are prone to metastasizing (spreading), and some are capable of producing hormones.

The tumors described in this medical article can affect both dogs and cats. If you would like to learn more about how this disease affects cats, please visit this page in the PetMD health library.

Symptoms and Types

1. Fluid build-up in the abdominal cavity
2. Fluid build-up in the chest cavity
3. Tumors producing steroid hormone:
   • Lack of sexual heat and menstruation
   • Persistent estrus (menstruation and heat)
   • Pyometra (pus-filled abdomen)
   • Gynecomastia (male animal exhibits feminine traits, like having enlarged nipples with leaking milk)
   • Bilateral, symmetrical baldness
   • Masculinization (excess testosterone)

Causes

This condition is often associated with non-spayed and non-neutered dogs.

Diagnosis

Your veterinarian will perform a thorough physical exam on your dog, including a blood chemical profile, a complete blood count, an electrolyte panel and a urinalysis. You will need to give your doctor a thorough history of your dog's health, with a description of the onset of symptoms. X-rays may reveal the spread of cancerous cells (metastases) by way of the blood vessels or lymphatic system.

Your veterinarian will also take X-rays and ultrasound images of the abdomen and chest to look for further evidence of tumors. Abdominal X-rays might show a unilateral or bilateral mid-abdominal mass near the kidney, or fluid build-up in the abdominal cavity. An ultrasound of the abdomen can reveal similar information, but with even greater sensitivity and detail. If there is excess fluid in the pleural (chest) lining, or fluid in the abdomen, your veterinarian will take a fluid sample for microscopic (cytologic) examination.

If the size of the tumor is minor, and the growth minimal, your veterinarian may recommend surgery to remove a solitary tumor, or to take a tissue sample (biopsy) of the tumor. Even if a tumor appears to be obviously malignant, and is metastasizing (growing), a biopsy can still be invaluable for the final, definitive diagnosis.

Your veterinarian may also want to perform a procedure called a histopathologic examination, for tracking changes in the tissue, to better understand the character of the growth.