CBD for Dogs with Cancer

Although the effects of cancer in dogs can vary, one thing is certain: cancer seriously hurts your dog’s well-being. Whether from tumor growth and spread, or nausea and pain from common treatments, cancer is always scary and damaging, even in less severe cases.

In light of the recent increase in research exploring the potential effects of cannabidiol (CBD) on cancer and humans living with cancer, there has been a rise in pet parents using CBD as well. But just how can CBD work to help treat cancer in dogs?

To be clear, CBD is not a cure for cancer, and should not replace conventional treatments like surgery or radiation. Implying otherwise is dishonest and irresponsible. However, there is growing evidence that CBD, as part of a larger cancer treatment plan, may be able to help dogs with cancer in two ways. First, by helping slow down cancer cell growth, and second, by improving quality of life during conventional treatment (which often comes with severe side effects).

This article is intended to give you a complete, thoroughly researched and up to date guide on using CBD to help your dog while they are fighting with cancer.

Cancer in Dogs – What is it?

Cancer involves the new growth of abnormal cells, which are often consolidated into a mass, called a tumor. While various types of cancer can appear very differently, the common characteristic of all cancer growths is that they lack normal regulation for growth and development.

Normal cells reproduce and grow only when old cells die, and/or while the animal as a whole is growing (ie. when your pup is young). But cancer cells continuously grow and reproduce when new cells are not needed, and may even damage or kill nearby healthy cells.

Types of Cancer

As a category, tumorous growths can be either benign or malignant. Benign tumors grow to form a mass of cells, but do not spread to other parts of the body. They may need to be removed if they grow to a size that compresses the healthy tissues next to it.

On the other hand, malignant tumors are able to invade and harm nearby tissues, and can spread to other parts of the body (which makes them harder to treat). Typically, only malignant tumors are referred to as ‘cancerous.’

Theoretically, any tissue or organ in an animal’s body can develop cancer. However, in dogs, there are a select few cancers that are most commonly seen by veterinarians.
Skin cancer is a very common type of cancer in dogs. Although many skin tumors are benign, some are malignant, such as melanoma. Mast cell tumors are a type of skin cancer that affects the connective tissues close to the skin, particularly in the nerves and blood vessels, like the nose and mouth.

Leukemia is a cancer of the blood, while lymphoma is a cancer of a specific blood cell and the lymphatic system. Neither of these cancers form mass like growths (at least initially), instead they crowd out other, healthy cells in the bloodstream and in bone marrow.

Bone cancer (or osteosarcoma) is another common type of cancer in dogs. Sarcomas form when cancerous cells develop into growths on muscles, bones and connective tissues like tendons and ligaments.

Statistically, younger dogs have less risk of developing cancer than do older dogs, but cancer can affect dogs of any age.

Common Signs and Symptoms

According to the Veterinary Cancer Society, about 25% of all dogs are diagnosed with cancer at some point in their lives, and that number rises to 50% for dogs who make it beyond the age of 10. Put another way, this is approximately 6 million new cancer diagnoses in dogs each year, in the U.S. alone.

Thankfully, many types of cancer in dogs are treatable, especially if the disease is discovered in an early stage. With that in mind, keeping an eye out for possible early warnings signs or symptoms can be paramount to ensuring the health of your pet.

Some symptoms are easier to catch than others, and may include visual clues, like any new abnormal or growing cysts or swellings on your dog’s skin or in their mouth. Another example would be sores that do not seem to be healing, or bleeding and other liquid discharge from openings in the body like the anus.

Other symptoms may be harder to spot, and can be physiological or behavioral. Physiologically, they may have difficulty moving their bowels or urinating. Or you may notice they are having trouble swallowing, chewing or breathing. Similarly, any pain from tumors in the mouth or GI tract from eating can lead to avoiding eating, which can also lead to weight loss.

Alternatively, lethargic behavior or general weakness can be behavioral warning signs. Other signs, like a reluctance to move around, low energy levels, tense or aggravated behavior, or restlessness, might indicate that your pup is in pain, which can be a symptom of cancer (but not in all cases, of course).

If you notice a change in your dog’s health – whether physical or behavioral – and you suspect cancer as a possibility, consult your vet as soon as possible. Early detection and treatment can seriously help your pet in their fight against this disease.

Treatment Options

Veterinarians will treat cancer in dogs on an individualized basis, and often with a detailed, multi-faceted treatment plan that can include more than one medicine. Common treatments include surgical intervention, radiation, and chemotherapy. Treatments will be chosen based on the type of cancer present, where it is located, and how quickly it has grown and spread.

The primary goal of treatment is, of course, to eliminate any and all cancer cells, in other words to ‘cure’ the cancer. At the same time, a secondary treatment goal is to reduce any pain and improve overall quality of life – this is especially important for dogs who must live with cancer and treatment for extended periods of time, or for whom a complete elimination of cancer is not possible.

How Can CBD Help Dogs with Cancer?

CBD May Help Reduce Tumor Size and Growth

CBD may act to directly limit the growth and spread of cancer cells. While this topic has yet to be explored in detail for dogs, CBD has been linked to helping mitigate cancer cell growth or even kill cancer cells in human and mice models of cancer.

Studies have demonstrated this link in leukemia, colon cancer, and breast cancer, among others. CBD acts to suppress cancer cell growth and kill existing cancerous cells through a variety of mechanisms, including protecting DNA inside cells from oxidative damage, which can lead to cancer cell formation.
Furthermore, CBD may also increase the efficacy of other cancer treatments when used in combination. A 2018 study showed that using radiation together with CBD was more effective for killing pancreatic and lung cancer cells in mice than using radiation alone. The corollary is that using CBD may allow veterinary oncologists to reduce the amount of radiation they give dogs with cancer, and thereby reduce the adverse effects on the healthy surrounding tissue, while still having the same effect on the cancer cells.

A further recent study showed that CBD helped augment chemotherapy treatment in mice with pancreatic cancer. Specifically, their data showed that the mice that were treated with a combination of CBD and gemcitabine (a chemotherapy drug) lived almost 3 times longer as those that were treated with the gemcitabine alone.

While further research is needed to establish the magnitude of these effects, different effective dosage levels, and to study the effect in dogs specifically, the existing research has given us good reason to believe that CBD might help to directly mitigate tumor size and growth for dogs with cancer.

CBD Helps Minimize the Harmful Side Effects of Other Treatments

In addition to helping to stop tumor growth, CBD can help dogs get through the difficult side effects of cancer treatments like chemotherapy and radiation. CBD will help to reduce pain and inflammation, as well as help with nausea and appetite.

Pups that are battling with cancer can experience pain and inflammation from tumors themselves, and/or from treatments like radiation therapy. Accordingly, reducing pain is almost always a part of a treatment plan for dogs with cancer.

Veterinarians often prescribe non-steroidal anti-inflammatory drugs (NSAIDs) or opioids to dogs in pain. However, these can have unintended consequences in some dogs. NSAIDs sometimes cause unwanted side effects, especially in the gastro-intestinal system, like vomiting and diarrhea, or even kidney and liver issues. And of course opioids can lead to addiction and withdrawal symptoms, or the building of a tolerance and potential for overdose.

Alternatively, research has shown that CBD helps reduce pain and inflammation in dogs. And other studies have shown that CBD can work with prescription pain medications to further decrease pain, compared to just using pills.

CBD can also help to reduce nausea and loss of appetite in dogs, both common side effects of chemotherapy. At its worst, nausea can lead to such a strong avoidance of food that the dog becomes anorexic. However, CBD has been shown to help prevent nausea and vomiting for chemotherapy patients, not only in humans, but also in several different animals.

Since we know that the endocannabinoid system (ECS) helps to regulate gut health and metabolism in dogs and other animals to maintain homeostasis, and we know that CBD interacts with this system, it’s easy to see how CBD might increase appetite and minimize nausea to help maintain balance in the body. The intestines are full of endocannabinoid receptors and transmitters, which help control feelings and functions like the vomiting reflex, sensation in the GI tract, and satiety (how full we feel).

Of course, always consult a veterinarian before starting on a new course of treatment, or when adding more treatments to an existing plan. But given that the existing research has shown that CBD is quite safe in dogs, there seems to be a strong case for making CBD part of a thoughtful cancer treatment plan, for a variety of reasons.