Hot weather directly affects both food safety and an animal's appetite. Proper storage and feeding management reduces microbial risk while also helping to manage the drop in appetite that occurs in the heat. This article addresses the storage of wet, dry and raw food, the increased pathogen and spoilage risks in hot weather, bowl hygiene, appetite management and hydration in light of institutional guidelines and current scientific literature.
Source Transparency
This topic rests mainly on institutional/regulatory guidance (FDA, AAFCO, AVMA, WSAVA); the storage times and the "danger zone" (4-60 °C) logic come from there. The sections on mycotoxins, fat oxidation, pathogens and appetite are backed by peer-reviewed research. The source type for each claim is indicated in the text.
1. Wet Food: Leaving It Out and Storage
Opened or bowled wet food should stay at room temperature for about 2 hours at most; in hot weather this window is even shorter. Leftover wet food should be sealed tightly and kept in the refrigerator (4 °C and below), and an opened can should be used up within a few days (FDA, 2024; AAFCO, n.d.). This is an institutional guideline based on the "danger zone" (4-60 °C) logic of general food safety.
2. Dry Food: Storage, Moisture, Oxidation and Mycotoxins
Dry food should be stored in its original packaging, in a cool, dry place (preferably below 27 °C) (FDA, 2024; AAFCO, n.d.). A peer-reviewed nuance: in a study where opened dry food was stored at 25 °C and 35 °C for up to 120 days, no meaningful bacterial or yeast-mold growth was detected as long as water activity remained low (Park et al., 2025) — meaning the real risk is moisture uptake, and keeping the packaging from taking on moisture is critical. When humidity and temperature rise, two risks increase: (1) mycotoxin/aflatoxin contamination can develop in the food under poor storage and is toxic (Yang et al., 2023); (2) oxidation/rancidity in fat-rich foods accelerates in the heat and degrades the fatty acid profile and antioxidant capacity (Kępińska-Pacelik et al., 2025).
3. Storage in Hot Weather — Summary Table
| Food type | Left out (room) | Storage |
|---|---|---|
| Wet / canned (opened) | Under 2 hours; shorter in heat | Sealed, refrigerator below 4 °C, a few days |
| Dry (opened) | Remove after the meal | Original packaging, cool-dry below 27 °C, protect from moisture |
| Raw | As short a time as possible | Frozen; once thawed, refrigerate, use quickly, strict hygiene |
| Treats / dry treats | — | Cool-dry, sealed container |
4. Pathogen Risk (Increases in Heat)
The risk of Salmonella and Listeria in pet foods is marked especially in raw foods: in a surveillance study, pathogens were very rare in dry/semi-moist samples, whereas Listeria and Salmonella were detected in a substantial portion of raw/jerky samples (Nemser et al., 2014). In a European study examining raw meat-based diets, high levels of Enterobacteriaceae and pathogens were found in the majority of samples (Nüesch-Inderbinen et al., 2019). A recent review summarizes the presence of Salmonella and mitigation strategies (Dhakal et al., 2024). The AVMA adopts a cautious policy on raw/undercooked animal-protein diets because of the risk of transmission to animals and humans (AVMA, 2023). Because heat accelerates the growth of these pathogens, hygiene and the cold chain become more critical in the summer months.
5. Bowl Hygiene and Biofilm
Food and water bowls should be washed with hot, soapy water after every meal (AAFCO, n.d.). Bowls are an important source of microbial contamination; the feeding type and cleaning method affect the bacterial load on the bowl (Raspa et al., 2023). Since biofilm and bacterial growth accelerate in the heat, regular and effective cleaning becomes even more important in the summer months.
6. Appetite, Feeding Time and Food Temperature in the Heat
- Feeding behavior decreases in hot weather: in a survey study, a drop in appetite was reported in 58.7% of dogs and 71.8% of cats (Palestrini et al., 2022). For this reason, feeding can be shifted to the cooler hours of the day.
- Food temperature affects aroma and appetite; aging cats prefer warm food (37 °C) (Eyre et al., 2022). In hot weather, however, food should be served fresh and warmed food should not be left standing (Freeman, 2022).
- Small, frequent portions reduce the amount of food left out in the heat.
7. Hydration and Signs of Dehydration
Moist food contributes to hydration during hot periods by increasing water intake (Buckley et al., 2011). Signs of dehydration include reduced skin elasticity (skin turgor / "skin-tent" test), dry gums and mucous membranes, lethargy and loss of appetite; when in doubt, veterinary evaluation is needed (Cornell Feline Health Center).
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Calculate your animal's daily water requirement based on its weight; adequate water intake is the first line of defense during hot periods.
Calculate Water Requirement8. Signs of Spoiled Food and a Summer Routine
- If you notice a sharpening or souring of the smell, a change in color, mold, or insects/larvae, discard the food.
- Open wet food per meal; put the leftover in the refrigerator and follow the 2-hour rule.
- Keep dry food in its original packaging, sealed and in a cool-dry place; do not leave the large sack standing in a humid garage or an open area.
- Wash the bowl and water daily; refresh the water during the day.
- Move feeding times to the cooler hours; use small, frequent portions.
9. References
- AAFCO. (n.d.). Product handling safety. Association of American Feed Control Officials.
- AVMA. (2023). Raw or undercooked animal-source protein in cat and dog diets (policy). American Veterinary Medical Association.
- Buckley, C. M. F., et al. (2011). Effect of dietary water intake on urinary output, specific gravity and relative supersaturation for calcium oxalate and struvite in the cat. British Journal of Nutrition, 106(S1), S128-S130.
- Cornell Feline Health Center. (n.d.). Hydration. Cornell University College of Veterinary Medicine.
- Dhakal, J., Cancio, L. P. M., Deliephan, A., Chaves, B. D., & Tubene, S. (2024). Salmonella presence and risk mitigation in pet foods: A growing challenge (review).
- Eyre, R., et al. (2022). Aging cats prefer warm food. Journal of Veterinary Behavior, 47, 86-92.
- Freeman, L. M. (2022). Keeping your pet's food temperature just right. Petfoodology, Tufts University Cummings School of Veterinary Medicine.
- Kępińska-Pacelik, J., et al. (2025). Changes in the fatty acid composition and antioxidant properties in mono-protein dry dog foods.
- Nemser, S. M., et al. (2014). Investigation of Listeria, Salmonella, and toxigenic E. coli in various pet foods. Foodborne Pathogens and Disease.
- Nüesch-Inderbinen, M., Treier, A., Zurfluh, K., & Stephan, R. (2019). Raw meat-based diets for companion animals: A potential source of transmission of pathogenic and antimicrobial-resistant bacteria. Royal Society Open Science, 6(10), 191170.
- Palestrini, C., et al. (2022). Do intense weather events influence dogs' and cats' behavior? Analysis of owner reported data (survey).
- Park, D., et al. (2025). Effects of temperature on the microbial growth and quality of unsealed dry pet food.
- Raspa, F., et al. (2023). Pet feeding habits and the microbiological contamination of dog food bowls: Effect of feed type and cleaning method.
- U.S. Food and Drug Administration. (2024). Proper storage of pet food & treats.
- U.S. Food and Drug Administration. (2024). Tips for safe handling of pet food and treats.
- WSAVA Global Nutrition Committee. (2021). Global nutrition guidelines & toolkit. World Small Animal Veterinary Association.
- Yang, L., et al. (2023). Natural mycotoxin contamination in dog food: A review on toxicity and detoxification methods. Ecotoxicology and Environmental Safety.