What to feed your pet with cancer?

Diet & Supplementation in Pets with Cancer: What Dog and Cat Guardians Should Know

Cancer is among the most common health challenges faced by dogs and cats in small-animal veterinary practice. As in humans, the causes and treatments are complex — and many guardians seek to support their pets with diet and supplements. However, the best outcomes depend on tailoring the nutritional plan to the individual patient.

1. Why Diet Matters in Pets with Cancer

• As cancer advances, an animal’s metabolism often changes dramatically — appetite may drop, muscle mass may be lost (cachexia), and the body may struggle to get enough energy from normal foods. Kali’s Wish+1

• Research supports a nutrition approach that emphasizes higher-quality protein and unsaturated fats, while minimizing simple sugars and refined carbohydrates. Kali’s Wish

• Because cats are obligate carnivores and dogs are carnivore-biased omnivores, some human cancer-diet strategies (e.g., primarily vegetarian) may not be applicable for them. Kali’s Wish

• For pets already undernourished or food-averse, diets higher in energy (fat is more calorie-dense) may help maintain body condition. Kali’s Wish

2. Practical Nutritional Strategies

Here are some of the key considerations when supporting a pet with cancer through diet:

• High-Quality Protein & Fats: Choose animal-based proteins with good digestibility and fats rich in unsaturated fatty acids.

• Reduced Refined Carbs & Sugars: Lowering intake of refined carbohydrates may reduce the fuel available to rapidly growing tumour cells. Kali’s Wish

• Whole-food/raw or cooked home-formulated diets: Some practitioners favour raw whole-food diets or carefully cooked meals for pets with cancer — emphasising human-grade ingredients, a variety of coloured vegetables/fruit, and being mindful of bones or high-bone content in fragile patients. Kali’s Wish

• Hydration & Palatability: Ensuring food is palatable, served warm, and meets the energy needs of a weakened pet is critical. Some pets may only eat small amounts, so denser caloric foods help. Kali’s Wish

• Transition & Monitoring: For pets used to commercial diets, a careful transition is required — especially if they are in poor condition or already cachexic. Home-formulated diets must be carefully balanced for nutrients. Kali’s Wish

3. Supplements: What to Know

While many supplements are marketed for “cancer support,” the evidence in pets is limited — and some may interfere with conventional treatments like chemotherapy or radiotherapy. Kali’s Wish
Here are a few supplements discussed and key cautions:

• Antioxidants (Vitamins A, C, E, beta-carotene, lutein): These may play a prevention role, but in pets undergoing active cancer treatment, high doses might interfere because some treatments rely on oxidative stress to kill tumour cells. Kali’s Wish

• Mushroom extracts (e.g., Coriolus versicolor / Yun-Zhi): These have shown immune-modulating and anti-cancer properties in cell studies, but evidence in dogs and cats is scarce. Kali’s Wish

• Curcumin (from turmeric): Has shown anti-proliferative, anti-angiogenic and pro-apoptotic effects in cell studies; in animals, it’s generally well tolerated though blood-thinning properties and absorption issues apply. It must be used cautiously, especially in pets with haemorrhagic tumour types or immediately after surgery. Kali’s Wish

• Artemisinin (from Artemisia annua / Sweet wormwood): Shows selective cytotoxicity in tumour lines because tumour cells tend to have higher iron content; should not be used concurrently with large antioxidant doses or soon after radiotherapy. Kali’s Wish

Key takeaway: When it comes to supplements, the guiding principle from the original paper is:

“It is safer to give none than everything under the sun… start with a corrected and appropriate diet and do nothing else.” Kali’s Wish

4. Tailoring to Your Pet

Because each pet with cancer is unique, an individualized plan is essential. Consider:

• The type and stage of cancer

• Whether the pet is undergoing chemotherapy, radiotherapy or palliative care

• The pet’s current nutritional status (e.g., weight loss, appetite, vomiting)

• Tolerance to certain foods (e.g., raw vs cooked)

• The guardian’s time, budget, and willingness to prepare custom diets

Working with a veterinarian and/or veterinary nutritionist helps ensure nutritional adequacy and safety.

5. Monitoring & Adjusting

• Track body condition, appetite, weight changes, energy level and any side-effects of treatments.

• Adjust the food form (e.g., more “comfort” type foods when appetite is low), texture (soft, warm meals for inappetent pets), and energy density accordingly.

• Evaluate any supplement for interactions with medications or therapies before starting.

• Regularly revisit the diet and supplement plan as the pet’s condition evolves.

Conclusion

Nutrition and supplementation can play supportive roles in a dog or cat diagnosed with cancer, but they are not stand-alone cures. The most important steps are:

• Choosing a nutrient-dense and appropriate diet, tailored to your pet’s condition

• Being cautious and evidence-informed about supplements

• Working in collaboration with veterinary professionals

If your pet is fighting cancer, focus first on restoring/maintaining quality of life, appetite and body condition — and use diet & supplements as thoughtful supports, not panaceas.

Disclaimer: This blog is for informational purposes only and does not replace veterinary advice. If your pet has been diagnosed with cancer, please consult with your veterinarian or a veterinary nutritionist before making changes to their diet or supplements.