Cancer in Guinea Pigs

Like all animals, guinea pigs can develop cancer, and it becomes more common as they get older. The term "cancer" refers to the uncontrolled growth of abnormal cells, which can form masses or tumors. These tumors can be benign (non-cancerous and do not spread) or malignant (cancerous and can spread to other parts of the body).

Any new lump or bump found on a guinea pig should be evaluated by a veterinarian. While some lumps may be harmless cysts or abscesses, it is impossible to know without a proper diagnosis.

Common Types of Cancer in Guinea Pigs

1. Skin Tumors:

   • Trichofolliculoma: This is the most common type of skin tumor in guinea pigs. It is a benign tumor of the hair follicle. It often appears as a firm, well-defined lump under the skin, frequently with a central pore. While benign, they can sometimes rupture and become infected, so surgical removal is often recommended.
   • Sebaceous Gland Tumors: These are tumors of the oil glands in the skin. They can be benign or malignant.

2. Lymphoma (Lymphosarcoma):

   • What it is: This is a cancer of the lymphocytes, a type of white blood cell. It is one of the most common cancers in guinea pigs, particularly in younger animals (around 1-3 years of age).
   • Signs: The most common sign is a significant enlargement of the lymph nodes, which can be felt as firm lumps under the jaw, in front of the shoulders, or in the armpits and groin. Other signs are non-specific and include lethargy, weight loss, and decreased appetite.
   • Prognosis: Lymphoma is an aggressive cancer, and the prognosis is generally poor.

3. Mammary Tumors:

   • What it is: These are tumors of the mammary (breast) tissue. They can occur in both male and female guinea pigs.
   • Signs: A noticeable lump or swelling in the mammary tissue, located on the underside of the guinea pig.
   • Action: About 70% of mammary tumors in guinea pigs are benign, but 30% are malignant. Surgical removal is always recommended to prevent the spread of cancerous tumors.

4. Uterine Tumors:

   • What it is: Tumors of the uterus are very common in unspayed female guinea pigs, especially as they age.
   • Signs: The most common sign is blood in the urine or a bloody discharge from the vulva. The abdomen may also become enlarged.
   • Action: The best treatment is to spay the guinea pig, which removes the cancerous tissue. This is also why spaying female guinea pigs when they are young is recommended as a preventative measure.

Diagnosis and Treatment

If you find a lump on your guinea pig, your veterinarian will likely recommend a few steps:

• Fine-Needle Aspirate (FNA): The vet will use a small needle to take a sample of cells from the lump. This is a quick and minimally invasive procedure that can often determine if the lump is a cyst, an abscess, or a tumor.
• Biopsy and Surgical Removal: For any suspected tumor, the best course of action is to surgically remove it. The removed tissue is then sent to a lab for a biopsy, which will determine exactly what type of tumor it is and whether it is benign or malignant.

For skin tumors, surgical removal is often curative. For internal or systemic cancers like lymphoma, the prognosis is more guarded, but treatments like chemotherapy may be an option in some cases.

Early detection is key. Performing regular health checks at home to feel for any new lumps or bumps can help you catch potential problems early and give your guinea pig the best chance at a successful outcome.