Seasonal nutrition for pets: heat, cold and body weight

Cats given free access to food eat noticeably less in summer than in winter. In a four-year study of 38 colony cats in southern France, average food intake in summer was about 15% lower than in the winter months, with the peaks and troughs tracking outdoor temperature and day length. The cats' body weight did not change with the seasons, which suggests they were adjusting intake to need. Dogs are less well studied, but cold clearly raises energy use, and the practical rule for both species is the same: feed to body condition, and expect the right portion to shift a little through the year.

Summer heat, appetite and water

Smaller appetites

A dog or cat that eats a little less on hot days, but is bright, drinking and passing normal urine and stools, is usually just adjusting. There is no need to push a normal portion. Feeding in the cooler early morning and evening helps, and a slightly smaller portion is reasonable if the animal is less active. A pet that stops eating altogether, or is lethargic as well, should be seen by a vet.

Heat-related illness

Food is a small part of summer safety. The bigger risk is heat. In UK primary-care records, most cases of heat-related illness in dogs were triggered by exercise, severe illness was more likely when a dog could not escape the heat, as in a parked car, and death was more likely in older and flat-faced dogs, which cool themselves less well. Heat illness also happened on days that did not feel very hot: the median temperature on the days of these events was 16.9°C (62°F).

Walk dogs in the cooler parts of the day, shorten or skip exercise in hot weather, never leave a pet in a car, and provide shade and fresh water at all times. Heavy panting, drooling, weakness, vomiting or collapse in the heat is an emergency. Cool the dog with water and get it to a vet straight away.

Getting more water in

• Keep several water bowls around the home and carry water on walks.
• Wet food adds water to the diet, which helps cats in particular, as many drink little.
• Water can be added to dry food. Any broth must be free of onion and garlic, which are toxic to dogs and cats.
• Frozen treats such as ice cubes made from water or a little plain wet food add fluid and something to do.

Food spoils faster

Wet food left in a warm room spoils quickly and attracts flies, so pick up what is not eaten promptly. Raw food carries more risk. When FDA laboratories tested pet foods, a notable share of raw pet food samples carried Salmonella or Listeria. The FDA's raw pet food guidance advises covering and refrigerating leftovers immediately or throwing them away. Dry food keeps better, but its fats can turn rancid in a hot garage or in direct sun, so store bags sealed in a cool, dry place.

Autumn coat growth and appetite

In the cat study, intake climbed through autumn and was highest from about October to February. Many double-coated dogs also grow a thicker coat as days shorten. A complete and balanced food supplies the protein and fatty acids needed for coat growth, so autumn is not a reason to add supplements to a healthy animal's diet.

If appetite rises, let body condition decide whether to feed more. Increase the portion only if the dog or cat is losing condition or is spending more time outdoors in the cold. A dull, thin or patchy coat is worth mentioning to the vet, since it can reflect illness as well as diet.

Winter cold, activity and joints

Energy needs outdoors and indoors

Staying warm costs energy. In a laboratory study, adult dogs acclimated to 3°C (37°F) for four weeks increased their energy expenditure by 38%. Dogs that live or work outdoors in winter may therefore need noticeably more food, and their weight and body condition should be checked often.

Most pets live in heated homes, and many are less active in winter. Cold weather outside is not by itself a reason to feed them more. Appetite may still rise, as it did in the cat study, so let body condition rather than the weather decide the portion.

Joint comfort

Many owners notice that older dogs with arthritis are stiffer in cold, damp weather. Keeping the dog lean matters most, since extra weight adds load to painful joints. A warm, padded bed away from drafts and shorter, more frequent walks also help. For supplements, a 2022 meta-analysis found clear pain relief from omega-3-enriched diets and supplements in osteoarthritis, and no meaningful effect from glucosamine and chondroitin. Stiffness that is getting worse should be assessed by the vet, as effective pain relief is available.

Winter hazards

• Antifreeze: ethylene glycol tastes sweet, and very little is lethal. The minimum lethal dose of undiluted ethylene glycol is 1.4 mL/kg in cats and 4.4 to 6.6 mL/kg in dogs, and in colder climates most poisonings happen in autumn, winter and early spring, according to the Merck Veterinary Manual. For a 4 kg cat that is less than 6 mL, roughly a teaspoon. Clean up spills, store containers closed and out of reach, and treat any suspected exposure as an emergency.
• De-icers and grit: salt and ice-melt products can irritate paws and upset the stomach if licked off. Wipe or rinse paws after winter walks.
• Frozen water: check outdoor water bowls several times a day in freezing weather.

Spring weight checks and allergies

Spring is a good time to check whether winter added weight. Run a hand along the ribs: they should be easy to feel under a thin layer of fat without pressing hard, with a visible waist from above. If they are hard to find, reduce the portion gradually and recheck in a few weeks.

Spring also brings pollen, grass and mold, and environmental allergies can look very like a food allergy. If itching flares in spring, have the vet work out the likely cause before changing the diet. An elimination diet trial is the way to test for food allergy, and it only works if the diet change is planned and strict.

Sources

1. Seasonal variation in the voluntary food intake of domesticated cats (Felis catus). PLoS One, 2014.
2. Risk factors for severe and fatal heat-related illness in UK dogs: a VetCompass study. Veterinary Sciences, 2022.
3. Get the facts: raw pet food diets can be dangerous to you and your pet. U.S. Food and Drug Administration.
4. Evidence for cold-induced but not for diet-induced thermogenesis in adult dogs. Journal of Nutrition, 1987.
5. A 2022 systematic review and meta-analysis of enriched therapeutic diets and nutraceuticals in canine and feline osteoarthritis. International Journal of Molecular Sciences, 2022.
6. Ethylene glycol toxicosis in animals. Merck Veterinary Manual.