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Reducing the Risk of Cancer in Animals

Reviewed ByLaurie Hess, DVM, DABVP, The MSD Veterinary Manual
Reviewed/Revised Modified Jul 2025
v102055401

Pet owners can take steps to lower the risk of certain cancers. One of the most effective methods is spaying (removing the reproductive organs of female pets) or neutering (removing the testicles of male pets). These procedures can greatly decrease the risk of breast cancer in females and testicular cancer in males, especially if performed at the right time.

For female cats, spaying before their first reproductive (heat) cycle, which can happen as early as 4 months, greatly decreases the risk of breast cancer. In dogs, the timing of spaying or neutering can depend on breed and other health factors. Your veterinarian can advise you on the ideal time to spay or neuter your pet based on its individual needs.

Will Good Nutrition Keep My Pet From Getting Cancer?

Although no specific diet can prevent cancer, good nutrition and care help pets stay healthy and fight diseases. Like overweight people, overweight pets face many health issues, including a higher risk of cancer. Veterinarians can help owners assess their pet's weight and adjust their diet accordingly.

How Can I Reduce My Pet's Risk of Cancer?

Pet owners can decrease their pet's cancer risks by limiting their animals' exposure to sunlight and UV rays. Animals with light skin or fur are particularly susceptible to developing cancer. Pets that are exposed to secondhand smoke are also at higher risk of developing cancer, so creating a smoke-free environment eliminates the risk of smoke contributing to cancer in pets.

Possible Signs of Cancer

Changes in a pet’s behavior or appearance can indicate it may have cancer. Although these signs don’t always mean cancer, noticing them and consulting a veterinarian early can improve treatment outcomes. Signs to watch for include:

  • A growing or changing lump

  • Swollen lymph nodes

  • Sudden abdominal swelling

  • Unexplained bleeding (from the anus, reproductive tract, mouth, nose, or other organs)

  • Difficulty breathing, chewing, or swallowing

  • Persistent sores or swellings

  • Bad breath or unusual odors

  • Dry cough

  • Recurrent vomiting or diarrhea

  • Weight loss or decreased appetite

  • Lack of interest in activities

  • Signs of pain, like limping or stiffness

How Do Veterinarians Monitor Pets for Cancer?

If you suspect your pet has cancer, it’s important to see a veterinarian quickly. Regular check-ups to screen for cancer are crucial as pets age. Veterinarians may use x-rays, ultrasound, CT scans, and other methods (including sampling potentially cancerous masses with a needle and looking at the sample under a microscope) to check for cancer, along with blood and urine tests. Early detection is key to better treatment outcomes.

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