Keeping Pets When You're Diagnosed With Cancer

Infection risks can run high during cancer therapy

Pets can be a great source of comfort and companionship during cancer treatment. In fact, research has shown that pet therapy can have often profound benefits during chemotherapy if appropriate precautions are taken. Having a pet by your side can decrease feelings of loneliness, promote a sense of well-being, and even reduce the need for pain medications.

In the end, safety and foresight are all you really need to protect yourself from any infection or illness your pet can inadvertently give you.

Cancer patient cuddles with dog
KatarzynaBialasiewicz / iStock / Getty Images

Understanding Zoonotic Infections

We don't often think of catching diseases from pets, but the simple fact is that as many as 60% of known infectious diseases can be passed from animals to humans. Called zoonotic infections, these are the types of diseases that are spread through bites, scratches, and contact with the saliva or feces from pets and other animals.

People undergoing chemotherapy are more prone to these infections due to the immune suppressive nature of the drugs, which lower the number of white blood cells needed to fight disease

There are around 30 to 40 infectious organisms that can be spread from animals to humans, the vast majority of which are rare. The more common types are around us every day and tend to only cause disease when our immune system is severely compromised.

Cat-Borne Infections

The most serious cat-related infection is toxoplasmosis caused by the protozoan Toxoplasma gondii. The disease is considered widespread with upwards of 30 percent of the population having evidence of a prior infection. While symptoms are most often mild to non-existent in healthy individuals, it can be serious in those with compromised immune systems, leading to seizures, blindness, and encephalitis (swelling of the brain).

Another common cat-related infection is bartonellosis (cat scratch fever) caused by the bacterium Bartonella henselae. After getting scratched by an infected cat, people can experience symptoms similar to that of mono, including a sore throat, fatigue, and swollen glands in the neck and/or armpits. Kittens are more likely to spread the disease than adult cats.

Dog-Borne Infections

As with cats, your dog can inadvertently spread infection when you are scratched, bitten, or come to contact with their feces. Exposure to eggs of the dog's tapeworm (echinococcosis) is known to cause serious liver disease. While rare in the U.S., it is believed that over a million people have been infected worldwide.

Other infections can be spread by flea bites from your pet, including bartonellosis, allergic dermatitis, Yersinia pestis (plague), and epidemic typhus is seen occasionally in rural parts of the U.S.

Bird-Borne Infections

The most common disease transmitted by birds is psittacosis, an infection caused by the bacteria Chlamydia psittaci. Symptoms in humans include fever, muscle pain, headache, diarrhea, fatigue, dry cough, and vomiting.

Birds with psittacosis often appear sickly with rash, eye discharge, diarrhea, and a general lackluster appearance. The bacteria is typically spread by contact with either a sick bird or its droppings.

Infections Caused by Reptiles, Amphibians, and Fish

While careful handling can prevent many pet-borne infections, reptiles and amphibians appear to be the exception. Some oncologists, in fact, recommend that pets such as iguanas, snakes, lizards, frogs, and salamanders be completely avoided during chemotherapy. Reptiles and amphibians are known to harbor bacteria such as salmonella and campylobacter, all of which can easily be transmitted by touch.

For their part, aquarium fish can sometimes carry Mycobacterium marinum, a bacterial disease commonly identified by nodules on the fish's skin. Contact with either the fish or the inside of the aquarium can pass the infection to those with compromised immune systems. Symptoms include the formation of skin lesions called granulomas. In rare cases, the bacteria can spread through the bloodstream to infect other organs.

Tip for Avoiding Pet-Borne Infections

There are a number of ways to avoid getting infections from your furry, scaled, or a feathered friend:

  • Have your pet checked by your veterinarian for any infections or illnesses prior to the start of chemo or radiation therapy.
  • Ensure your pet has gotten all of its shots.
  • Wear gloves when cleaning the litter box, birdcage, or aquarium (or have someone else do it).
  • Handle your pet more gently to avoid scratches or bites.
  • Trim and file your cat's nail (or have the pet parlor do it for you).
  • Keep your cat indoors.
  • Put a flea collar on your dog or cat and use flea powder or dip if the pet is scratching.
  • Wash your hand regularly if you have an outdoor pet (or after play dates with other pets).
  • Wash your hands after cleaning a litter box, birdcage, or aquarium even if you've used gloves.
  • Take your pet to the vet immediately if it has any sign of illness, including vomiting or diarrhea.
  • Consider having a friend keep your pet while it is ill or board it with your vet.
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12 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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  2. Centers for Disease Control and Prevention. Zoonotic diseases. Updated July 14, 2017.

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  4. Washington State Department of Health. Animal transmitted diseases.

  5. Centers for Disease Control and Prevention. Parasites - Toxoplasmosis (Toxoplasma infection). Updated September 28, 2018.

  6. Centers for Disease Control. Bartonella Infection (Cat Scratch Disease, Trench Fever, and Carrión’s Disease). Updated March 5, 2019.

  7. Centers for Disease Control and Prevention. Parasites - Echinococcosis. Updated July 16, 2019.

  8. World Health Organization. Echinococcosis fact sheet. Updated March 23, 2020.

  9. Traversa D. Fleas infesting pets in the era of emerging extra-intestinal nematodes. Parasit Vectors. 2013;6:59. doi:10.1186/1756-3305-6-59

  10. New York State Department of Health. Psittacosis (ornithosis, parrot fever, chlamydiosis). Updated August 2017.

  11. Washington State Department of Health. Salmonella from Reptiles and Amphibians.

  12. Centers for Disease Control and Prevention. Invasive Mycobacterium marinum infections. Updated November 2003.

Additional Reading
  • Hemsworth, S., and Pizer, B. "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; ISBN 9781617797460.