Merck Manual

Please confirm that you are a health care professional

honeypot link
Pet Owner Version

Caring for a Pet with Cancer


Manuals Staff

Reviewed/Revised May 2020 | Modified Nov 2022

Caring for a pet with cancer is always a team effort. The owner of the animal is central to the treatment and management of the disease. The veterinarian and other members of the veterinary care team provide information and recommendations and perform tests and many of the treatments, but these steps come in response to the owner’s decisions about the course of treatment. In addition, the owner, as primary care giver for the pet, will be directly and personally involved in the day-to-day care of the animal, including providing support, comfort, and delivery of medications. This is possible only when the owner works cooperatively with the veterinary care team and makes the effort to gain the knowledge and skills necessary to provide the needed decisions and care.

Supportive Care

All pets undergoing cancer treatment require supportive care. These tasks include giving prescribed medications, learning to recognize the signs of pain, and providing the nutrition your pet requires.

Giving Medication

Cancer treatment programs include medications for various reasons. If the animal is undergoing chemotherapy, there will be prescribed drugs to destroy the cancer cells. If surgery is included, pain medications are usually prescribed to control postoperative pain. If the cancer itself causes pain, medications to control that pain will also be provided. Other possible medications include ones to reduce the adverse effects of chemotherapy or radiation therapy.

Some of the medications described above will be administered by your pet’s medical team in a veterinary hospital or clinic. However, you may also have to give your pet medications at home. The timing of the medication is often critical to effective treatment. Thus, you play a vital role in making sure your pet receives the correct dose of medication at the prescribed times. As the primary care giver, you can also help your veterinarian by monitoring your pet’s behavior and activity and reporting how well the medication seems to be working. If your pet does not respond as expected to the medication, or if your pet responds in an unusual or unexpected way, your veterinarian needs to be notified promptly so that dosages or medications can be adjusted.

You also should learn to recognize the signs of pain in your pet (see below), so that pain-relieving medications can be prescribed as needed. Drugs that relieve pain are known as analgesics. Your veterinarian can prescribe any of several basic types of pain-relieving drugs. One type is known as nonsteroidal anti-inflammatory drugs (NSAIDs). These drugs block the production of inflammatory molecules that contribute to pain and swelling. Corticosteroids (cortisone, for example) are a second type of pain reliever. Like the NSAIDs, corticosteroids are anti-inflammatory drugs that reduce pain and allow your pet to be more comfortable. However, caution is needed in giving steroids because they may have unwanted side effects when used for an extended period of time. Opioids are a third type of pain medication for cancer. Opioids include morphine and codeine. These are prescribed when advanced cancers cause prolonged, severe pain. Other types of pain medications that may be used include local anesthetics and alpha2 agonists, although use of these medications is not as common as the use of other pain relievers.

Giving pain medication on a preset schedule is less difficult and more effective than providing pain medication “as needed.” If your pet is in pain, it is likely to be stressed, nervous, and upset. This makes the administration of the medication more difficult for both you and your pet. Also, higher dosages of the medication may be required in these situations. The higher dosages increase the risk of adverse effects. The best plan is to set up a pain medication schedule in cooperation with your veterinarian before treatment and then follow that medication schedule as closely as possible.

Recognizing Cancer Pain

Pain is a subjective experience and is difficult to measure accurately. Even if you have had your pet for a long time, recognizing and assessing pain during cancer treatment is challenging. Careful and close observation of your pet is needed.

Cancer pain is usually defined as the uncomfortable and disagreeable response of the body to the development and presence of cancer itself or the treatment for the disease. Some cancer-related pain may be acute. Acute cancer pain occurs when a tumor invades nearby tissues and expands. Acute pain may also occur in response to surgery, radiation therapy, or chemotherapy. Other cancer-related pain may be chronic. To assess your pet’s pain level, you may have to look for behavioral changes that are associated with both acute and chronic pain Types of Pain Pain serves a protective role that alerts an individual to injury from the environment or from within. For example, if a muscle strain or pull causes pain in a limb, not putting weight on that... read more .

For those who are not familiar with the normal behaviors of a particular species or an individual animal, assessing pain can be very difficult. The challenge is greater in some cases because many animals (such as birds) instinctively attempt to hide any behavior or sign that might show they are weak or in pain. These difficulties are complicated by the fact that the amount of pain caused by various cancer treatments can vary greatly. Furthermore, pain is not simply physical; it can be emotional and psychological as well.

In the face of these challenges to pain assessment, owners are much more likely than veterinary care givers to notice the small variations in behavior that indicate pain. This is because owners are familiar with their pet’s normal responses and movements, and their pet’s reactions to a variety of situations. You are in the best position to take primary responsibility for judging your pet’s tolerance for pain, for recognizing when your pet is in pain, and for taking the steps needed to reduce or eliminate it.

Nutritional Support

Every animal needs appropriate nutrition to live a healthy life. When cancer strikes, good nutrition is even more important. Although we do not yet fully understand the nutritional needs of animals with cancer, researchers have learned that animals undergoing cancer treatment may need different foods and different amounts of food than healthy animals.

Metabolism is the term that describes the physical and chemical processes used to build and maintain body tissues. Both cancer and cancer treatments can change your pet’s metabolism. Your pet’s usual diet may not provide sufficient nourishment while cancer is growing or while cancer treatments are being provided. Animals often lose their appetite during cancer treatment. If your pet does not eat enough to fuel its body, then tissues may be broken down to create the energy needed to survive. In these circumstances, your pet may “waste away” due to malnutrition. This occurs most frequently if the treatment continues for a long time. Another common risk is dehydration; pets with cancer may not drink enough water. Just as people can die more quickly from dehydration than starvation, so can animals. Drinking enough water is, therefore, as important as eating enough solid food.

Researchers are still studying the nutritional needs of animals with cancer. Some studies show that the high-carbohydrate and low-fat nutrition traditionally found in pet foods may not be the best for animals with cancer. Instead, these studies support the idea that animals with cancer need diets that are low in carbohydrates and high in fat. This type of diet may help address some of the changes in metabolism of pets with cancer.

If your pet is diagnosed with cancer, ask your veterinarian about changes you may need to make in your pet’s diet. During your conversation, also ask about appetite stimulants and other medications that reduce side effects, such as pain, that can discourage healthy eating. Once the nutritional plan has been developed, you may then need to adjust it to your pet’s individual likes and dislikes. The goal is to supply your pet with the nutrition needed to fuel the normal functions of the animal’s healthy organs and tissues.

Alternative ways of providing your pet with the needed nutrition may be required if the cancer or cancer treatment has caused changes that prevent your pet from consuming enough food and water. In some cases, special nutritional supplements may be needed or unusual feeding methods adopted. If, for example, part of the jaw has had to be removed due to mouth cancer, the pet will have to adapt to the new mouth shape. While recovering and adapting to the new shape, it may be necessary to feed your pet with a feeding tube. There are 3 common ways to provide nutrition through a feeding tube. A tube may be run through the nasal passages to the stomach (nasogastric tube), through the neck into the esophagus (esophagostomy), or directly into the stomach (gastrostomy). These tubes are removed once the animal recovers sufficiently to eat on its own.

The metabolic changes caused by cancer or cancer treatment sometimes continue long after the cancer has been cured. In these cases, you need to provide the most appropriate diet after the cancer has been removed or destroyed. Follow your veterinarian’s advice regarding the diet your pet needs following cancer.

Providing Comfort Care (Pet Hospice)

Not all cancers can be cured and not all cancer treatments are fully successful. The cancer may be decreased or eliminated temporarily (in remission) and then return later. The treatment needed to control the cancer may cause considerable pain or cause significant adverse effects without any hope of curing the cancer. If this is the case, you may need to decide whether the continuation of treatment is worth the decrease in your pet’s quality of life and consider stopping the treatments. The concerns to try to balance are length of life in pain versus a shorter life with less pain and discomfort.

When this point is reached, then the treatment focus shifts to one of providing as much comfort and nurturing care for the pet as possible in its final days or months. For situations where a cure is unlikely or not possible, where treatments have proved ineffective, or where the costs (especially any physical or emotional harm to the animal) outweigh the benefits, comfort care is the most appropriate answer.

The goal of comfort care, like the goal of hospice care for people, is to prevent pain and discomfort while providing emotional and physical support. This type of care allows you to focus on the quality of life for your pet rather than the quantity of life. A safe, stress-free environment in familiar surroundings helps your pet live out its life while you and your family emotionally adjust to your pet’s terminal illness and prepare to say goodbye. See also Pet Loss and Grief Pet Loss and Grief As with all relationships, when an animal companion dies or is ill, its family will likely feel stress, sorrow, and grief. The effects may be felt by not only family members but also by neighbors... read more .

In most cases, the best environment for comfort care is at home. This permits you and your family to spend more time with your ailing pet. It also permits you to be fully aware of its day-to-day needs. This will allow you to react more quickly when the animal’s needs change. Providing comfort care at home helps you prevent unnecessary pain, fear, and suffering as your pet approaches the end of its life.

Home-provided comfort care may not be for everyone. Caring for a terminally ill animal is an emotionally difficult and time-consuming responsibility. In most cases, the animal will lose some body functions, which will require you to provide an increased level of care. Owners who decide to provide comfort care at home should consult with a veterinarian who is knowledgeable about home comfort care and can provide information and support. In particular, a comfort care plan should be developed, followed, and adjusted as the condition of the pet changes.

One primary goal of comfort care is the control of pain. Once that issue has been covered, other issues may also need to be addressed. For example, it may be necessary to relocate the pet’s bed and change water and food containers to make sleeping, eating, and drinking easier and less painful. Family members may also re-arrange their schedules to spend more time with the pet and provide more attention, well-loved treats, and affection. Because visits to the veterinarian are often stressful for a pet, you might elect to reduce the number of such visits. If so, you may need to learn how to perform medical tasks such as giving injections. These are all issues you will need to discuss with your veterinarian when you make the decision to provide home comfort care.

quiz link

Test your knowledge

Take a Quiz!