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Recent advancements in canine chemotherapy have turned what used to be a terminal cancer diagnosis into viable treatment paths for veterinarians and a glimmer of hope for pet owners. In the unfortunate instances when the chemotherapy takes more of a toll on the dog’s health than the cancer itself, and treatment has to be paused or stopped, other options are available to you. These treatment tips from experts in the world of veterinary oncology can help you combat adverse effects to keep your patients on their chemo regimens and hopefully bring them back to full health as soon as possible.
Adverse reactions to chemotherapy are common. Eighty percent of dogs undergoing treatment experience at least one side effect and 32% suffer from serious reactions. Specific symptoms usually depend on the drug being used and how aggressive the treatment is, along with the age and health of the dog. While most side effects are mild and require only monitoring or light treatment, some can be life threatening and result in hospitalization, and possibly an end to the cancer regimen. Not only is this devastating to the patient’s recovery outlook, but having to rescue the dog from a severe episode can be both financially and emotionally draining for your clients.
Your goal as the oncologist is to keep the dog on its chemo treatment until recovery with as little discomfort as possible. Chemotherapy-induced side effects can be a massive detriment to this goal, but there are treatments that allow you to manage these issues, improving the dog’s overall health and chance at beating cancer. Here are the three main areas where adverse effects of chemo can occur and advice on how to get ahead of disruptive symptoms.
Hair loss may be the least dangerous to a dog’s health of the three main chemo-induced health issues, but witnessing a pet’s hair thinning or coming out can be jarring to the pet’s owners. Alerting clients to the possibility that their dog may lose whiskers or even parts of their coat will ease the shock if alopecia becomes noticeable. Unlike other side effects, coat thinning is relatively breed-specific, hitting hardest in dogs with hair such as Poodles and Schnauzers. Vets should keep this in mind when talking about effects of chemo with clients and take extra care to bring up the topic to owners of dogs with this type of hair.
Treating hair loss brought on by chemo in dogs is fairly straightforward. Regardless of the severity of the thinning, the dog will likely need a haircut to even out its coat. If shedding or patching are bad enough to impact the aesthetic or cause discomfort for your clients, shaving may be the best option. Ultimately, the decision is up to the owner, but you can help by keeping an eye on the hair-loss progression and advising owners in the best interest of the dog.
Bone Marrow Suppression
Since bone marrow is the body’s “factory” for new blood cells that grow at a similar speed to cancer, it is often targeted by chemo drugs that cannot distinguish cancerous from noncancerous rapidly growing cells. According to Michael K. Guy, DVM, MS, Ph.D., “Complete blood cell counts should be performed early and often after chemotherapy treatment has begun to monitor for myelosuppressive effects. A mild decline in both white and red blood cells is expected after beginning chemo and likely will not require treatment.”
In any case, Guy emphasizes that monitoring is the most important step to take in keeping blood cells at a healthy amount. It is recommended that veterinary oncologists include testing as a regular part of the treatment plan. Guy encourages vets to prescribe antibiotics as a boost to the immune system if white blood cell counts begin to dip. If red blood cell levels are looking low, the patient may require a blood transfusion to prevent more serious issues and potential hospitalization.
Gastrointestinal problems are the most common side effects to chemotherapy in dogs. These issues are caused by chemotherapy’s disruption to the balance of chloride ions and fluid in a dog’s intestines, causing discomfort and a variety of issues ranging from anorexia to vomiting and chemotherapy-induced diarrhea (CID).
As with blood cell counts, the most important step in managing digestive issues caused by chemotherapy is monitoring. Cooperation between vets and owners and open communication about patterns in appetite and stool are critical. If an owner mentions that their dog is experiencing a decrease in appetite, encourage them to pursue new options in making the dog’s food more appealing. VCA Animal Hospitals recommend heating food to body temperature in the microwave or enhancing the dog’s diet with low-sodium broth or home-cooked alternatives. Appetite stimulants are available to prescribe, and you should consider this option in cases where the problem persists.
Since the animal is already weakened by cancer and chemotherapy treatment, anorexia can quickly turn dangerous and require hospitalization. In drastic situations, a dog may require a feeding tube or IV to avoid starvation.
Vomiting and CID are both common and important to stay on top of as both symptoms can lead to potentially deadly dehydration and halt the chemo regimen. There are effective anti-emetic (anti-vomiting) medications that are fast-acting and crucial for certain chemotherapy protocols. Vomiting can happen quickly after the chemotherapy dosing starts, but sometimes dogs need to be on anti-emetics even at the time of chemo treatment to be sure it can occur without the dog having a reaction. Keep track of a dog’s history of nausea and reactions to medication and decide if providing anti-nausea medication before chemo would be the best option.
Unlike vomiting, which happens immediately, CID can occur hours or days following a chemo dose. Owners will need to monitor their pets and make sure that if the dog is exhibiting CID, the animal is drinking extra water to compensate. You can also prescribe a new plant-based medication with the active ingredient crofelemer that normalizes fluid influx in the GI tract. Both methods are great steps to diminish likelihood of a trip to the hospital for rehydration via IV.
Improving a dog’s health after a cancer diagnosis is a constant battle for both you and the owner. Even the best possible treatment plan can cause adverse symptoms. However, having a solid plan that involves treating both the cancer and any potential side effects can save money, stress and, in many cases, a dog’s life. +