Given that dogs are widely regarded as ‘man’s best friend’, it makes sense that we are constantly trying to find ways to improve canine health. One method that has been – and is still – being explored is the use of immunotherapy, which uses a dog’s own immune system to fight health problems, such as allergies and cancer.
Although immunotherapy for dogs still lagged a little behind compared to human immunotherapy it is still a major topic of interest in veterinary medicine and is a very advanced field, with a number of research studies being conducted around canine immunotherapy, particularly with regard to cancer treatment.
And it’s not just studies that are being conducted; There are already several immunotherapies commonly used by veterinarians, such as allergy shots to treat environmental allergies in dogs, and even vaccines to treat some types of canine cancer.
Fighting allergies in dogs with immunotherapy
The idea of using immunotherapy to treat allergies isn’t just limited to humans. Immunotherapy for dogs has been around for decades, and is generally considered a highly successful method, with around 75% of dogs showing symptom improvement, and some even making full recovery with the treatment.
Dog allergies generally fall into one of three categories: flea allergies, food allergies, or environmental allergies. Flea and food allergies, once identified, are fairly easy to treat; if your dog has fleas, then you will need to use a flea treatment to get rid of the fleas, and if your dog has a food allergy, you will need to try and avoid the food that caused the flare-up.
Environmental allergies, however – affecting between 10% and 20% of dogs – are more difficult to treat because they involve reactions to outside factors such as grass, pollen and insects, most of which cannot be eliminated from a dog’s natural environment.
This is where immunotherapy can be very helpful, and can help relieve your dog’s symptoms, the most common of which is localized or generalized intense itchy skin.
Treatment is given to dogs in the form of ‘allergy shots’ – formally called allergen-specific immunotherapy – in which a small portion of the identified allergen causing the reaction is given to the dog regularly, with a gradual increase in dose. over time, until the dog’s immune system finally stops overreacting to the allergen.
While the frequency of injections can vary from case to case, they are generally given daily at first, before reducing to once or twice a week, and it can be several months before your dog feels any benefit from the injections.
Against canine cancer: CAR-T cell vaccines and therapy
Apart from being used to treat allergies, immunotherapy can also be used to treat cancer in dogs, just like in humans.
“Immunotherapy to treat allergic disease in dogs has been around for decades now, but there has been a surge in interest and research aimed at harnessing the power of the immune system to treat cancer in dogs,” commented Kelly Diehl, veterinarian and senior director of communications science at Morris Animal Foundation. .
This is important because cancer is common in dogs, and it is estimated that more than 50% of dogs over the age of ten will develop some form of cancer. The most common cancers are melanoma and mast cell tumors – types of skin cancer, lymphoma and bone cancer.
According to Jethro Forbes, assistant clinical professor of emergency and critical care at Cornell University College of Veterinary Medicine, immunotherapy is currently being used to treat at least two different types of cancer in dogs. It is effective, showing a longer survival time compared to standard care.
One of these immunotherapies is for the treatment of osteosarcoma – a malignant tumor of the bone – and is available in the form of a cancer vaccine.
“Ostesarcoma tumor cells from each canine patient were harvested and made into a vaccine to stimulate the dog’s immune T-cell production. The T-cells are then harvested and expanded ex vivo for feeding to dogs. Other treatments of osteosarcoma with listeria-derived vaccines are also well established,” explained Forbes.
There is also a vaccine available for oral melanoma, which works by alerting the immune system to the presence of melanoma proteins to help it fight cancer cells. It is intended to be used in combination with surgery and radiation to treat the initial tumor.
Furthermore, after success in humans, CAR-T cell therapy does too being explored in veterinary medicine, and, although not yet approved as a treatment option, there are some ongoing clinical investigations, particularly for blood-based cancers, such as B-cell lymphoma and B-cell leukemia.
Limitations of using immunotherapy to treat cancer in dogs
Despite existing cancer vaccines and research around CAR-T cell therapy, there are some limitations to the use of immunotherapy to treat cancer in dogs.
One is that much of the information about immunotherapy in dogs has been drawn from human studies, meaning the canine immune system itself may not have been studied as extensively as is necessary to develop more successful canine immunotherapies.
For example, lymphocytes – a type of white blood cell that helps the immune system fight cancer and foreign viruses and bacteria – in a dog’s immune system have not been fully characterized, making it more difficult to predict which dog and which cancer. most likely to respond to immunotherapy treatment.
And, because canine cancer has not been as widely identified as human cancer in terms of appearance and genetics, this also makes it difficult to create unique and personalized immunotherapies suitable for individual canine tumors.
Targets autoimmune diseases
Although not that extensive, there has also been research conducted around the use of immunotherapy for dogs to treat certain autoimmune diseases.
“One of the many exciting immunotherapeutic techniques in the treatment of dogs involves removing immune-destroying effectors from the patient’s own red blood cells, a disease called Immune-Mediated Hemolytic Anemia. This autoimmune disease is mainly treated with drugs to suppress the immune system. However, some cases are severe or refractory to treatments and drugs take time to work,” said Forbes.
“Through the use of an extracorporeal (outside the body) therapy called therapeutic plasmapheresis (or plasma exchange), we can actually eliminate the autoantibodies responsible for the destruction of red blood cells through blood purification. We then return the blood to the patient.”
Forbes says they are currently offering this therapy at Cornell University School of Veterinary Medicine, and it can also be used to treat other immune-mediated conditions, such as myasthenia gravis.
More progress to come
In recent years, immunotherapy for dogs has approached human immunotherapy in terms of research, but much remains to be done to catch up.
As Forbes points out, development costs for dog treatment are not as well funded as human medicine, and the cost of actually receiving treatment is a major issue, as many dogs do not have insurance.
Because of this, it seems that more money is slowly being poured into research around immunotherapy for dogs. For example, as Diehl points out, in 2018, the Morris Animal Foundation stepped in by awarding a $775,000 grant to Dr. Nicola Mason at the University of Pennsylvania School of Veterinary Medicine to test a vaccine that could increase the longevity and quality of life of dogs. with osteosarcoma.
“I think we will see more immunotherapy-based treatments in dogs over the next decade. Partly, this is because more animal scientists are simply interested in this topic and partly because, I think, because the dog is being recognized as a good study model for some human diseases, there is more financial support and interest in studying therapies that have translational potential for humans. generate more funding for veterinary scientists,” said Diehl.