Photodynamic Therapy in Dogs

Photodynamic therapy is a new and mostly experimental procedure used to treat certain types of cancer or other tumors in dogs, cats, and humans. This therapy is often a good alternative for treating superficial and small tumors as it has few side effects compared to procedures such as chemotherapy and doesn’t involve any invasive surgeries. Given that the procedure is fairly new, some pet owners may be unable to locate a veterinarian who is able to administer the treatment. Additionally, given the limitations of the procedures, not all dogs will be candidates for photodynamic therapy. 

Photodynamic therapy is a simple procedure that can either be performed on its own or in combination with other more traditional cancer therapies such as chemotherapy or surgical removal of tumors. Unfortunately, once cancer has metastasized, your dog is no longer a good candidate for this therapy.

Depending on your dog’s disposition, they may need only a mild sedative in order to undergo photodynamic therapy. Some animals may need to be anesthetized in order to allow for precision treatment. In these cases, the vet will want to order full bloodwork to confirm there are no underlying conditions that may create complications while your dog is under anesthesia.

Photodynamic therapy is administered through the injection of a photosensitizing drug directly into the tumor. This drug will accumulate within the malignant cells. Next, a special laser light is directed at the location of the tumor. Light is emitted in a wavelength designed to specifically interact with the drug. The light then reacts with the compound, causing the destruction and death of the cells in the area where the drug has accumulated.

This therapy is typically administered as an outpatient procedure. This means your dog will be able to arrive and go home the same day and will not require an extended stay at the veterinary office.

While still in early stages and not yet widely available, photodynamic therapy has proven effective for treating localized cancer tumors. In addition to destroying the tumor cells, it can also help shrink the tumor by destroying blood supply and other supporting tissues. This means that photodynamic therapy is also effective when used in combination with other more traditional tumor therapies. Like all therapies, there is potential for the tumor to reoccur if all of the cells are not removed or killed.

When compared with treatments such as chemotherapy or surgical removal, photodynamic therapy has a similar effectiveness for destruction of the tumor and prevention of regrowth. 

There is little impact to surrounding tissues during photodynamic therapy, which makes recovery time minimal with little to no side effects. Some dogs may see irritation to the surrounding tissue caused by the laser light, but this should be minimal and easily treated similarly to a burn or sunburn.

Given the experimental nature of photodynamic therapy and the fact that very few veterinarians are currently offering the procedure, the cost of this therapy can vary widely. In general, you should estimate that each treatment will cost between $300 to $500, with multiple treatments needed for complete efficacy. The cost of the procedure can vary depending on the size of the tumor, which will affect the amount of compound needed. In some cases, clinical trials may be available which will lower the price of the procedure.

Photodynamic therapy is an excellent choice for treating superficial cancer tumors. Unlike chemotherapy, photodynamic therapy does not cause damage to the surrounding tissues or overall immune system. Treatment is highly localized to the tumor in which the photosensitive compounds accumulate. 

Photodynamic therapy is only appropriate for a small number of tumors, given the fact that light can only penetrate so far through tissue. For these tumors, surgery, chemotherapy or other medications may be needed. 

Photodynamic therapy can also be used in connection with traditional therapies to help reduce stress to the surrounding tissues. For example, the therapy has been used to reduce the size of tumors prior to surgery or for treatment of larger tumors in between chemotherapy rounds, allowing your dog to recover and regain strength between treatments. 

While the cause of most cancers is unknown, there are many things you can do to prevent the types of cancers treated with photodynamic therapy. Small masses located near the surface of the skin are often melanomas or carcinomas that result from too much exposure to the sun. Both humans and dogs should avoid prolonged exposure to sun. Just like yourself, dogs with thin or close coats can benefit from a canine-safe sunscreen in order to help prevent skin cancer.