Can I Keep My Pets If I Have Cancer?

Pet Infections and Other Risks to Cancer Patients

Woman petting dog on bed
Woman petting dog on bed. CaiaImageCLOSED

Pets can be a great source of comfort and companionship during cancer treatment. In fact, pet therapy for cancer patients has been found to have significant benefits when appropriate precautions are taken. What safety measures will you need to take with your pets during treatment? Are there any pets you should not have if you have cancer? And what else do you need to know if you are a pet owner facing cancer?

Benefits of Pets for People with Cancer

Before considering all of the possible harmful effects of having a pet during cancer treatment, it's important to note the flip side; the positive influence of our furry and feathery friends upon the emotional health of people with cancer. Without going into much depth, studies have found a few of these benefits for cancer patients to be:

  • Decreased psychological distress
  • Decreased need for pain medications
  • Decreased fatigue

In addition, studies looking at the effect of pets on physical health have also found that having a pet improves mood, decreases feelings of loneliness, and may even enhance the will to live.

Zoonotic Infections - Why Pets Can Be a Risk During Cancer Treatment

We don't often think of catching infections from the non-human animals around us, but it's thought that around 60 percent of the microorganisms that infect man, may be exchanged between other animals and humans.

The term zoonotic infections is used to describe these infections which can jump between species.

Before getting too concerned, however, it's important to mention right away how most of these infections are spread. The risk of many of these infections is small when animals are handled carefully. Transmission most often occurs via bites and scratches or through contact with saliva or feces—exposures that are often preventable with careful handling of pets and conscientious clean up.

Risk of Infection During Cancer Treatment

You may think of a low white count during chemotherapy (chemotherapy-induced neutropenia) as the main reason for concern with regard to infections with cancer, but there are several ways in which you could be at risk. These include:

  • Decreased ability to fight infections after surgery
  • Low white blood cell count during chemotherapy
  • Decreased bone marrow function due to the presence tumor in the bone marrow
  • Side effects of radiation therapy such as open sores
  • Abnormal immune functioning due the cancer itself or cancer treatments

Even if you are not currently planning on having chemotherapy, it's helpful to think ahead. Some pet related infections can linger, and this could be a problem if you were to have chemotherapy or a bone marrow transplant later on.

Most Common Risk from Pets with Cancer

While at last count there were 30 to 40 infectious organisms that can be spread from non-humans to humans, the vast majority of these are very uncommon. Taking a look at these infections based on the type of pet may make it easier for you to plan accordingly.

Cats and People with Cancer

Curling up with a kitty can be just what the doctor ordered during cancer treatment, but a few words of caution deserve mentioning.

The most serious cat-related infection during cancer treatment is Toxoplasmosis, caused by the protozoan Toxoplasma gondii. The infection is common, with 25 to 30 percent of the population having evidence of a prior infection. While the infection is often mild or asymptomatic, it can be very serious in people who have a compromised immune system, leading to seizures, blindness, or even encephalitis. It can also be problematic, causing congenital disease when contracted during pregnancy, and is the reason that pregnant woman are often advised to avoid litter boxes. During cancer treatment it's important to wear gloves when cleaning the litter box, or better yet, have someone else take on this chore. Cats that go outside are much more likely to acquire and transmit the infection. Wearing gloves when gardening is also recommended, especially if outdoor cats visit your garden.

Another common "cat related infection" is cat scratch fever (bartonellosis.) This infection, caused by the bacterium Bartonella henselae, often resembles strep throat or mono. There are 25,000 cases reported each year in the U.S., but the true incidence is likely much higher. Following a scratch from a cat, people may develop a sore throat and red, tender, and swollen glands in their neck or armpits. It is very treatable with antibiotics, but as noted earlier, people who are immunosuppressed due to chemotherapy or other cancer factors may have a decreased ability to fight the infection and become much sicker. The infection occurs much more often with kittens than adult cats. Precautions such as gentle handling of cats, keeping cats indoors, and keeping nails clipped and filed, can decrease the risk. If you choose to adopt a cat during cancer treatment, some oncologists recommend finding an adult cat instead of a kitten for this reason.

Keeping cats indoors is very important for those living with cancer, and studies also tell us that this is healthier for our cats as well. Cats and kittens can pick up infections when they eat "wild game" such as rodents and birds, and are also more likely to become infected with bacteria if they use a "community litter box" such as an uncovered sand box. Trimming your cats nails can decrease the risk of scratches which could lead to infection—and will likely keep your furniture in better shape as well.

Cat bites and scratches can often be avoided with gentle handling. Studies tell us that most bites occur from a cat being stepped on, startled, or held against its will.

Dogs and People with Cancer

Man's best friend can be truly a friend if you take a few precautions. As with cats, the greatest problems arise from exposure to secretion such as feces, and from scratches and bites. And just as kittens can be more problematic than adults cats, puppies can pose more of a risk to people with cancer. If possible, this is probably not the best time to adopt a new puppy or kitten.

Human infection from exposure to eggs of the dog tapeworm, echinococcosis, can cause serious liver disease. While there are over a million people carrying this infection worldwide, it is rare in the United States.

As with cats, dogs may also become the reservoir for fleas and ticks which can carry disease. Keeping your dog free from fleas, and carefully checking for ticks, can lower the risk of these exposures.

Birds and People with Cancer

The most common infectious disease contracted from birds is Psittacosis, an infection with the bacteria Chlamydia psittaci. Birds with this disease which can cause pneumonia, rashes, and a headache, usually appear sick, so avoiding sick birds is the best way to avoid contact. Wearing gloves when cleaning the bird cage, or having someone else take over this duty for you, may also be wise when you are living with cancer.

Reptiles, Amphibians, and People with Cancer

While careful handling and safety measures can prevent many pet related infections, reptiles may be an exception. Some oncologists recommend that pets such as iguanas, snakes, and lizards be avoided completely during chemotherapy. Reptiles commonly harbor bacteria such as Salmonella and Campylobacter. Likewise, exposure to amphibians such as frogs, toads, and salamanders is best avoided during cancer treatment.

Fish

Aquarium fish may carry Mycobacteium marinum, an illness which can appear as nodules and spread through the body in people who are immunocompromised. That said, using gloves when cleaning the aquarium, or having someone else take over this duty, is a fairly easy way to avoid this concern.

Wild and Exotic Animals

In addition to the risk of infections, keeping wild or exotic animals as pets can be dangerous during cancer treatment. It's best to leave wild animals in the wild. There are several infections hunters are at risk for developing. If you are a hunter, make sure to take extra precautions during cancer treatment.

Coping with Fleas

Keeping your pets free from fleas is important for both of you during treatment. With cats, the best way to avoid fleas is to stay inside, but dogs may need to wear flea collars. Talk to your veterinarian about the best way to prevent fleas. In addition to bites which could itch and become infected, fleas can pass on disease. Yersinia pestis, also known as the plague, This bacterium can be carried on rodents and transmitted to your cat via fleas.

Other Pet Transmitted Infections

There are a number of other infections which can be transmitted from pets to owners, but thankfully many of these are quite rare. Some of these include Cryptosporidium, Giardia, Rhodococcus, and dermatophytes (which cause ringworm.) Just as we practice "universal precautions" in the hospital, it is a good idea to simply be careful and minimize exposure to animal secretions wherever they happen to occur.

Cleaning Up After Your Pets During Cancer Treatment

If you are unable to find someone else to change your cat's litter box, always wear latex or rubber gloves, and consider using a mask as well. Wash your hands with soap and water afterward. A disposable litter box is also an option—just toss the box into the trash every few days. If your white blood cell levels drop to a certain level after chemotherapy, your doctor may advise you to avoid cleaning your cat's litter box until your levels increase.

The same level of precaution should be practiced with cleaning up after your dog. Always wear a mask and rubber or latex gloves and wash hands afterward.

Make a Plan for Emergencies

Every pet owner should have an emergency plan in place, but cancer patients should be especially diligent. Enlist the help of a friend or family member who can care for your pet in your unexpected absence. If you do not have anyone who can care for your pets, explore the idea of temporary foster care in the event you need emergency care. Your veterinarian may be able to recommend a suitable foster home if needed.

Be wary of boarding your animals or allowing them to go on "playdates" at the dog park. Even if your animal is up to date on their vaccinations, these may not provide full protection against contracting illnesses that can compromise your health.

Ensure Your Animals Are Healthy Before, During, and After Treatment

To prevent infection, make your animals are in good health before you begin treatment. A simple exam with your veterinarian can help to identify any health problems that may affect your personal health while undergoing chemotherapy. While bacterial, viral, and disease that animals develop often do not affect humans, they can compromise the pet's immune system, making them susceptible to infections that may compromise your health, especially during chemotherapy. During the exam, you may want to ask several questions, such as:

  • What infections can my pet give me?
  • How can I prevent my dog or cat from being infected with infections that may affect my health?
  • What can I do to safely prevent tick and flea infestation? (Ticks and fleas can carry bacteria that may impact your health).
  • Do you know of a foster family that may care for my animals if I need help?

Pets and Human Safety

There are a few tips you should follow to ensure your pet stays healthy during your cancer treatment. First, do not allow your pets to drink from the toilet. This spreads many infections and may expose your animal to toxins from your chemotherapy medications.

If your dog begins vomiting or has diarrhea, see a vet promptly. It is important to help identify the cause of the symptoms. But be careful: cleaning up vomit from animals also potentially puts you at risk of being exposed to bacteria and viruses.

Make sure your pets are up to date on rabies shots and seek medical attention for any bite inflicted by a wild animal. Rabies is almost universally fatal, unless prevented shortly after exposure.

Sources:

Hemsworth, S., and B. Pizer. Pet Ownership in Immunocompromised Children – A Review of the Literature and Survey of Existing Guidelines. European Journal of Oncology Nursing. 2006. 10(2):117-27.

Safdar, A. "Principles and Practice of Cancer Infectious Diseases." (2011). Humana Press.

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