Cats are desert-origin, heat-tolerant animals; thanks to efficient water conservation and cooling behaviours they withstand heat better than dogs. But this tolerance is not unlimited. In cats, open-mouth breathing (panting) is not a normal cooling method as it is in dogs, but a serious alarm sign (Ljungvall et al., 2014). This article examines how a cat cools itself, the signs of heat stress, which cats are more at risk, the first aid an owner can apply, and prevention, in the light of current scientific literature.
Source Transparency
There is still no large case series directly on heatstroke specific to cats; the field is largely limited to canine data and case reports. This article rests on three tiers of sources and states the tier explicitly: cat-specific peer-reviewed studies, comparative physiology from the dog (with the species difference emphasised), and institutional guidelines (Cornell, International Cat Care, ASPCA, Merck).
1. How Do Cats Cool Down? The Physiology of Thermoregulation
Unlike humans, cats do not have widespread sweat glands over the body surface; prominent eccrine sweat glands are found only in the paw pads and this is a limited cooling route (Adams, 1966). The cat's principal cooling mechanism is licking its fur (grooming): the hollow, hook-like papillae on the tongue carry saliva to the base of the coat, and evaporation of the saliva lowers body temperature. Thermal imaging has shown that this mechanism produces a marked temperature drop at the coat surface and constitutes an important part of body temperature regulation (Noel & Hu, 2018). The cat also seeks cool surfaces, reduces its activity and retreats to shade.
The critical difference: in cats, open-mouth breathing (panting) is not a normal cooling method as it is in dogs. In healthy cats, resting and sleeping respiratory rates are consistently below 30 per minute (Ljungvall et al., 2014); a respiratory rate markedly above this, or open-mouth breathing, may signal heat stress, respiratory distress, heart disease or pain and is an alarm sign.
| Cooling route | Dog | Cat |
|---|---|---|
| Panting | Primary, normal | Rare — alarm sign |
| Saliva licking (grooming) | Limited | Primary cooling (Noel & Hu, 2018) |
| Sweat glands | Minimal (paws) | Minimal (paws only) (Adams, 1966) |
| Overall heat tolerance | Lower | Higher (desert origin) |
2. How Common Is It Clinically?
In a retrospective study of 1,440 cats presenting to the emergency department, the proportion of cats that were hyperthermic (elevated temperature) at admission was only 5.6%; in cats the real poor-prognosis indicator is low body temperature (hypothermia) (Pontiero et al., 2025). This supports why environmental heatstroke is seen less often in the cat than in the dog. Even so, hot, enclosed environments such as an overheated vehicle, a sun-facing closed balcony/veranda, a stuffy room and a carrier are a genuine risk for the cat.
3. Which Cats Are More at Risk?
Brachycephalic (flat-faced) breeds — Persian and Exotic Shorthair. As facial flattening increases, respiratory abnormality increases (Farnworth et al., 2016). Moderate-to-severe nostril stenosis was found in 86% of show-line Persian/Exotic cats (Anagrius et al., 2021), and plethysmography has demonstrated objective ventilatory restriction in these cats (Chen et al., 2026). A narrowed upper airway further limits an already rare panting capacity. The overall disease and mortality profile of Persian cats has also been documented in UK first-opinion data (O'Neill et al., 2019).
Obesity. In overweight cats, subcutaneous fat acts as insulation, and obesity is known to impair pulmonary function and lead to restrictive breathing (Saavedra et al., 2024). Together, these two effects physiologically reduce an overweight cat's capacity to shed heat. (Note: this source does not directly measure "heat tolerance"; the link is a physiological inference drawn from the documented insulation and respiratory restriction.)
Others. Elderly cats, very young cats, and cats with heart or respiratory disease tolerate the heat load less well.
4. Symptoms and an Important Distinction
Warning signs: open-mouth breathing or rapid breathing (abnormal in a cat), excessive drooling, lethargy, vomiting, incoordination, bright red gums and collapse. An important conceptual distinction is not to confuse hyperthermia (overheating) with fever: hyperthermia is a breakdown of temperature regulation due to an environmental/physical cause, whereas fever is an immune-driven, regulated elevation (Merck Veterinary Manual; Niedfeldt & Robertson, 2006). In cats the upper limit of normal body temperature is approximately 39.2 °C (Merck Veterinary Manual). Because this distinction changes treatment, veterinary assessment is essential.
5. High-Risk Scenarios
- Vehicle: A parked vehicle reaches lethal temperatures within a few minutes; a cat should never be left in a vehicle.
- Closed balcony/veranda and window edge: Sun-facing glazed areas heat up through the greenhouse effect; the cat should not be confined here, and shade and an escape route should be provided.
- Carrier: On a hot day, a stuffy carrier is a heat trap; ventilation and shortening of travel time are needed.
- Stuffy rooms: Rooms closed and unventilated throughout the day pose a risk; access to a cool room and water should be ensured.
First Aid — Cool Down and Get to a Vet Urgently
Move the cat immediately to a cool, shaded, ventilated place; dampen its fur with lukewarm (NOT ice-cold) water and provide air flow (a fan); offer cool water if it wants to drink, and reach a veterinarian without delay (International Cat Care; ASPCA; Cornell Feline Health Center). Ice-cold water can constrict the superficial vessels and paradoxically slow heat dissipation. Decisions on medication, fluid therapy and dosing belong to the veterinarian.
6. Hydration and Urinary Tract Health
Increased water loss in the heat concentrates the urine and can affect lower urinary tract health. An effective way to increase cats' water intake is moist (wet) food: a high-moisture diet increases total fluid intake and dilutes the urine compared with a low-moisture diet (Buckley et al., 2011). A recent review summarises that the diet's moisture format and viscosity determine water intake, that urine concentration rises on a dry-only diet, and that this is associated with the risk of feline lower urinary tract disease (FLUTD) (Kosmal et al., 2025). Epidemiologically, dry food only and the water source have been found to be risk factors for FLUTD (Piyarungsri et al., 2020). During hot periods, moist food together with a constant supply of fresh water provides a two-way benefit for both hydration and the urinary tract.
VetKriter Daily Water Requirement Calculator
Calculate your cat's daily water requirement based on its weight; during hot periods, adequate water intake is the first line of defence against heat stress and urinary tract problems.
Calculate Water Requirement7. Prevention Checklist
- Constant fresh, cool water (in several bowls); consider moist food.
- Provide shade and a well-ventilated cool area; never leave the cat in a closed vehicle or a stuffy environment.
- Extra monitoring during hot hours for brachycephalic, elderly, obese and heart/respiratory-disease cats.
- Recognise the respiratory rate: if it is above 30 per minute at rest or there is open-mouth breathing, consult a veterinarian.
- Offer cool surfaces (tiles) and cooling mats, and shift play to the cooler hours of the day.
Species-difference note: When the pathophysiology of canine heatstroke (core temperature above 41 °C, multi-organ damage and disseminated intravascular coagulation — Bruchim et al., 2017) is cited for mechanism, it must be stated clearly that the cat is more tolerant and that panting is an alarm sign in the cat.
8. References
- Adams, T. (1966). Characteristics of eccrine sweat gland activity in the footpad of the cat. Journal of Applied Physiology, 21(3), 1004-1012.
- Anagrius, K. L., et al. (2021). Facial conformation characteristics in Persian and Exotic Shorthair cats. Journal of Feline Medicine and Surgery, 23(12), 1089-1097.
- ASPCA. (n.d.). Hot weather safety tips.
- 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.
- Bruchim, Y., Horowitz, M., & Aroch, I. (2017). Pathophysiology of heatstroke in dogs – revisited. Temperature, 4(4), 356-370.
- Chen, C.-R., et al. (2026). Characterization of brachycephalic obstructive airway syndrome in cats using barometric whole-body plethysmography. Animals, 16(6), 959.
- Cornell Feline Health Center. (n.d.). Hydration. Cornell University College of Veterinary Medicine.
- Farnworth, M. J., et al. (2016). Flat feline faces: Is brachycephaly associated with respiratory abnormalities in the domestic cat (Felis catus)? PLoS ONE, 11(8), e0161777.
- International Cat Care. (n.d.). Hazardous weather and your cat.
- Kosmal, P. A. L., et al. (2025). Diet format, protein, amino acids, salt, and osmolytes, as well as water viscosity, affect water consumption in cats. Journal of Animal Science.
- Ljungvall, I., et al. (2014). Sleeping and resting respiratory rates in healthy adult cats and cats with subclinical heart disease. Journal of Feline Medicine and Surgery, 16(4), 281-290.
- Merck Veterinary Manual. (2024). Fever of unknown origin in animals.
- Niedfeldt, R. L., & Robertson, S. A. (2006). Postanesthetic hyperthermia in cats. Veterinary Anaesthesia and Analgesia, 33(6), 381-389.
- Noel, A. C., & Hu, D. L. (2018). Cats use hollow papillae to wick saliva into fur. PNAS, 115(49), 12377-12382.
- O'Neill, D. G., et al. (2019). Persian cats under first opinion veterinary care in the UK: Demography, mortality and disorders. Scientific Reports, 9, 12952.
- Piyarungsri, K., et al. (2020). Prevalence and risk factors of feline lower urinary tract disease in Chiang Mai, Thailand. Scientific Reports, 10, 196.
- Pontiero, A., et al. (2025). Triage body temperature predicts outcome in cats at emergency department admission: A retrospective study of 1440 cases. Journal of Feline Medicine and Surgery, 27(1).
- Saavedra, C., et al. (2024). Overweight and obesity in domestic cats: Epidemiological risk factors and associated pathologies. Journal of Feline Medicine and Surgery, 26(11).