Supporting Strength During Illness: Managing Weight and Muscle Loss in Dogs

Cancer along with kidney and heart disease reduces appetite, lowers energy, and effects how your dog’s or cat’s body uses nutrients. This causes weight loss. 

If nausea is a side effect of medication or the illness itself, your pet’s weight loss can be even worse. This type of weight loss happens in animals who eat normally and leads to the loss of muscle and fat.

The loss of muscle leads to strength loss and weakness which makes it harder for your animal to stay active. The type of muscle loss can have affects internally, and be associated with a weaker immune system, and slower healing and recovery.

Dogs and cats that stay strong during illness have a better chance of longer survival and better quality of life.

Your veterinarian would like to share tools on how to support your dog or cat during this time of illness. By focusing on good nutrition, muscle support, and gentle activity you can help your dog stay strong and full of life.

Nutrition: Fueling Muscle

Nutrition is one of the best ways to help your dog maintain strength.

Pick Diets That Provide:

• Moderate to high levels of highly digestible animal-source protein. Aim for 75 grams per 1,000 kcal (calories) per day. Exception: animals with kidney disease that may require lower levels of phosphorus or if advised by your veterinarian.
• Healthy fats like omega-3 fatty acids from cold-water fish
• Some evidence suggests feeding lower simple carbs is helpful for cancer patients

Dogs with cancer, heart, and kidney disease are complex, and these are general suggestions. Always follow your veterinarian’s specific recommendations on prescription diets and any changes to your dog’s food, as they know your pet’s individual needs best.

Feed Strategies to Keep Them Eating

Your dog or cat may want to eat but feel nauseous from the illness and medication. These strategies help prevent food aversion and keep them eating.

• Break your dog’s daily meal into 4–6 smaller meals spread throughout the day instead of the usual breakfast, lunch, and dinner. Feeding smaller, more frequent meals can make eating less overwhelming
• Warm food to increase aroma and appeal • Add warm bone broth to increase hydration
• Feed in a low-stress environment away from other pets in the home • Hand feed or other food from a plate to make mealtimes more engaging
• Try different types of food – change from kibble to canned wet food or fresh frozen
• Try different protein types – change from chicken to duck or turkey
• Look for signs of nausea – excessive drooling, smelling food then licking lips instead of eating

If your dog or cat stops eating their normal food or you notice those signs of nausea, don’t wait to tell your vet. To prevent dangerous weight loss and make your dog’s illness worse, your vet has options for medications that can help.

Strong Muscles Are the Difference

Muscle loss makes walking slower, going upstairs harder, and a struggle to get up from a seat. Weaker cats had trouble using the litter box and jumping up onto cat beds. Weaknesses reduce the quality of life in all animals.

Exercises to build strength and endurance are good for healthy dogs, but your dog's exercise may be a challenge. If advised by your veterinarian, take shorter, more frequent walks. Other low-impact strength and cardio-building options are swimming or an underwater treadmill. A canine rehabilitation or sports medicine veterinarian can create a safe, customized exercise plan.

Muscle Supplements 

In addition to exercise, supplements can make a real difference. Fortetropin®, which powers MYOS’s exclusive veterinary muscle formulas, has been shown to help maintain and build lean muscle, improve mobility, and support recovery. 

In senior dogs with reduced mobility, daily use led to noticeable improvements in strength and activity scores starting around 6–12 weeks. Because muscle support is ongoing, continued daily use is recommended as part of your dog’s long-term plan.

Other Ways to Heal 

Therapies like acupuncture can help with the side effects of cancer, heart, or kidney medication. Massage and class III or IV LASER, myofascial work, can make a dog or cat with arthritis more comfortable. This is important if they can’t take regular pain medication, and overall comfort.

A healthy digestive system is helpful in keeping your dog or cat eating. Any vomiting or diarrhea should be discussed with your vet and managed right away to reduce digestive inflammation and discomfort.

References / Further Reading

1. Repac, J. A., Alvarez, L. X., & Amstutz, K. L. (Eds.). (2026). Handbook of canine exercise therapy. Wiley-Blackwell.
2. Hetrick, Katie, et al. "Evaluation of Fortetropin in Geriatric and Senior Dogs with Reduced Mobility." The Canadian Veterinary Journal, vol. 63, no. 10, Oct. 2022, pp. 1057- 60. PubMed, https://pubmed.ncbi.nlm.nih.gov/36185794/ 
3. Freeman, L. M. "Cachexia and Sarcopenia: Emerging Syndromes of Importance in Dogs and Cats." Journal of Veterinary Internal Medicine, vol. 26, no. 1, 2012, pp. 3-17. Wiley Online Library, https://doi.org/10.1111/j.1939-1676.2011.00838.x. 
4. Ogilvie, Gregory K. "Interventional Nutrition for the Cancer Patient." Clinical Techniques in Small Animal Practice, vol. 13, no. 4, Nov. 1998, pp. 224-31. ScienceDirect, https://doi.org/10.1016/S1096-2867(98)80007-8.