Lymphosarcoma, also known as lymphoma, is a malignant cancer that frequently occurs in cats and dogs. Lymphoma is classified according to where it is located within the pet’s body, as well as by high grade or low grade. The most common types of lymphoma are:
Multicentric: This type of lymphoma occurs in multiple locations within your pet’s body, and is the most common type to afflict dogs.
Extranodal: Involving organs such as the skin, kidney, heart, or eye, this type of lymphoma can also affect the central nervous system.
Mediastinal: This variant occurs in a pet’s chest cavity.
Gastrointestinal: Also known as alimentary lymphoma, this type occurs within the gastrointestinal tract, including the stomach and intestines. Cats are most likely to experience this form of the disease.
Cutaneous: This type of lymphoma is found on a pet’s skin. While there is no cure for lymphosarcoma, treatment can help extend your pet’s life and alleviate discomfort.
For dogs, the causes of lymphoma are largely unknown -- the cancer typically occurs in middle aged or young dogs, but there are no known environmental factors leading to the disease. Some breeds do seem to get the cancer at a higher rate, including Golden Retrievers, but also Boxers, Rottweilers, Poodles, Beagles, Basset Hounds, and Bulldogs, among others. For both cats and dogs, occurrence is evenly split amongst the sexes.
Cats have an increased risk of lymphoma if Feline Leukemia Virus (FeLV) or Feline Immunodeficiency Virus (FIV) are contracted. These two diseases are most common in young cats, so it makes sense to test for them if a younger cat is suspected to have lymphoma. For middle aged and older cats, the more common form of lymphoma is alimentary, occurring in their stomach or intestines.
The basic symptoms of lymphoma are a loss of appetite, weight loss, fever, and potentially a loss of fur. Depending on the type of lymphoma your pet has, other symptoms may occur. With multicentric lymphoma, your pet may have enlarged lymph nodes which can typically be felt under your pet’s mouth, by knees and joints, as well as in the groin area. It can also cause your pet’s stomach to become distended.
Mediastinal lymphoma causes fluid in the lungs, which can lead to breathing issues and coughing. You may notice your cat breathing with an open mouth with this form of cancer. Gastrointestinal lymphoma brings with it stomach-related symptoms, such as vomiting, diarrhea, constipation, or bloody stools.
While the symptoms of lymphoma are often more severe in cats than dogs, both cats and dogs are prone to developing hypercalcemia, or high blood calcium levels, as a result of lymphoma. You may notice your dog drinking more water and then correspondingly urinating with greater frequency.
Diagnosis and Treatment:
As well as taking a medical history, your vet will need to take x-rays, a complete blood count, and perform either a fine needle aspirate or a biopsy of the affected area. As well, cats should be tested for feline leukemia and feline immunodeficiency virus, since those two diseases are very often contributing factors to lymphoma in cats. After tests, it will be clear what stage, from one to five, of lymphoma your pet has. As with human cancers, the stage of the disease has an impact upon treatment and prognosis, with the prognosis growing progressively worse with every stage.
Sadly, there is no cure for lymphoma, although remission is possible. Treatment is aimed at reducing your pet’s pain, and hopefully extending the life of your cat or dog. Generally speaking, chemotherapy is used; the most common drugs are Prednisone, Vincristine, Cyclophosphamide, Doxorubicin, and L-asparaginase. These drugs can be given through shots, intravenously, or orally. Radiation and surgery can also be a treatment option, particularly for lymphosarcomas that are focused in one spot. These treatment options can help exceed your pet’s lifespan by months, and potentially even up to a couple of years.
This information is for informational purposes only and is not meant as a substitute for the professional advice of, or diagnosis or treatment by, your veterinarian with respect to your pet. It has, however, been verified by a licensed veterinarian for accuracy.
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