Canine Lymphoma Catherine MacLean, DVM

Canine Lymphoma

Catherine MacLean, DVM - Grantham, NH

Lymphoma is a type of cancer that can affect dogs of any age. It is estimated that it makes up about 24% of all canine cancers1,2. Golden Retrievers, Saint Bernards, Boxers, Scottish Terriers, Basset Hounds, and Mastiffs tend to be more prone to canine lymphoma, but it can affect any breed. Dogs that are immunocompromised with other health conditions are also at higher risk of lymphoma3 .

Dogs with canine lymphoma usually present with ambiguous signs in the beginning. They may have decreased appetite, decreased energy, vomiting, and just seem “off” to the owner. Bloodwork is usually unremarkable and on the physical exam, there is usually one lymph node that is enlarged.

Aspiration of one or more lymph nodes will help diagnose lymphoma. After a diagnosis of lymphoma has been made, staging needs to be done in order to determine if cancer has spread beyond the lymph nodes. Chest radiographs and abdominal ultrasounds are usually recommended for staging. Other specialized tests are also done to decide the phenotype of the lymphoma.

A diagnosis of cancer is scary and upsetting. Not everyone wants to put their pet through chemotherapy, radiation, etc. There are a lot of things to consider with a cancer diagnosis and treatment. Unfortunately, there are not a lot of oncologists in our immediate area, so travel is a factor. Cost is another factor, as well as your pet’s quality of life and your relationship with your pet.

The lymphoma phenotype (B cell vs. T cell) and staging influences the prognosis of canine lymphoma. Chemotherapy has been the treatment of choice. Depending what protocol is used, and what type of lymphoma your dog has, will determine which type of chemotherapy is used. Survival time with chemotherapy varies from four months to a year on average. Twenty-five percent of dogs using the CHOP protocol were alive at two years4 .

Many owners choose not to pursue Fall 2022

chemotherapy and elect for palliative care which involves high doses of steroids. Survival time with palliative care is 1-3 months.

Recently, two new drugs became available in the United States for the treatment of canine lymphoma. In 2021 a drug called Tanovea was approved by the FDA for the treatment of canine lymphoma. It involves a 30-minute infusion once every three weeks for up to five treatments. The median survival time is about 168 days.

The second new drug that has been conditionally approved by the FDA for the treatment of canine lymphoma is Laverdia-CA1. Laverdia-CA1 is an oral medication that can be administered by the owner at home and is given twice a week. It is used in patients where referral is not an option, but the owner wants to do more than steroids. It can also be used while waiting to get in for a referral if the patient hasn’t responded to chemotherapy or the lymphoma is atypical amongst other uses. Laverdia-CA1 is meant to stabilize the tumor and keep the pet more comfortable. No survival time information is available currently.

Cancer is scary, and just like in human medicine a lot of research is happening to try and find a cure. If your pet gets diagnosed with cancer you are not alone, and your veterinarian wants to help. We understand that going to an oncologist and pursuing advanced care is not for everyone. To me, the most important thing is for my client to be able to make an informed decision about the treatment options available for their pet, and for them to continue to have a good relationship with their pet. References

1. Kaiser HE. Animal neoplasms: A systemic review. In:

Kaiser HE, ed. Neoplasms: Comparative Pathology in Animals, Plants, and Man. Baltimore, MD:

Williams & Wilkins; 1981. 2. Molten JE, Harvey JW. Tumors of lymphoid and hematopoietic tissue. In: Moulton JE, ed. Tumors in

Domestic Animals. 3rd ed. Berkeley, CA: University of California Press; 1990. 3. Weiden PL, Storb R, Kolb HJ, et al. Immune reactivity in dogs with spontaneous malignancy. J Natl

Cancer Inst. 1974;53(4):1049-1056. 4. Withrow and McEwen’s Small Animal Clinical

Oncology. 4th ed. In: Withrow SJ, Vail DM, eds.

Philadelphia, PA: Saunders-Elsevier; 2007.

Dr. MacLean completed her Bachelor of Science from Penn State University, her Doctorate of Veterinary Medicine from Atlantic Veterinary College, and her pet acupuncture certification from Chi Institute. Her areas of special interest include general practice and acupuncture. She opened Sugar River Animal Hospital in 2013, and she has been practicing veterinary medicine since 2010. Dr. MacLean’s family consists of her husband Matt, her daughter Katarina, son Alexander and their three pets: Jack and

Misty, two cats, and Arrow, a dog. Fall 2022 www.4LegsAndATail.com 57