It was nearly 90 degrees Fahrenheit in Brooklyn one day last summer when I came upon two women assisting a clearly injured, stray cat. The feline, which had apparently passed out, now panted in pain and heat as it awaited a ride to the vet.
As global temperatures continue to smash records, those who can afford it may switch their air conditioners on a bit earlier each summer. But most other species don’t have that luxury. That includes our feline neighbors living in urban, manmade heat islands.
There are an estimated 60 to 100 million feral cats in the United States, according to People For The Ethical Treatment of Animals. Encroaching populations of stray cats have been well-documented from Hawaii and Los Angeles to Connecticut, New York City, and Florida. There’s a theory, laid out by Grist, that rising temperatures could cause the feral cat population to swell. Warmer winters might extend the “kitten season,” which typically occurs in the warmer months between spring and fall (though little research has been done in this area).
Then, there’s a worry that cats may fall ill in extreme heat. In 2023, a Humane Society worker from Phoenix told Time that they witnessed seven stray pet deaths in a two-and-a-half-month period from May to July. Last year, veterinarians in India reported seeing several heatstroke cases per day as a historic heat wave blanketed South and Southeast Asia; local stray animal charities said that “scores of dogs and cats have died.” In Thailand, where temperatures soared above 104 degrees during that same heat wave, rescue shelter operators said that pets were eating less and refusing to move. It’s left veterinarians and caretakers searching for the best practices for preventing their heat-induced suffering.
“If cats are not being actively fed and managed by a caretaker, they could potentially have a much harder time in the heat from lack of water.”
Kathleen O’Malley
director of community cat education, Bideawee’s Feral Cat Initiative
The science of extreme heat stress on cats is still in its infancy. Dr. Emily Hall, a veterinarian at the Royal Veterinary College in London who previously researched heat impacts on dogs, has a student researcher studying heat illness in cats. An Australian study found an increase in heat-related illness in dogs from New South Wales between 1997 and 2017. Hall’s team is working on a similar study in the United Kingdom. That hasn’t been published yet, but preliminary work hints at a similar trend.
Still, cats generally tolerate heat better than dogs. Our feline friends descend from the African wildcat. ”That’s a desert animal,” said Kathleen O’Malley, director of community cat education at Bideawee’s Feral Cat Initiative. Bideawee is a no-kill shelter and rescue organization in New York City. “There is a bit of African wildcat in all of our cats,” O’Malley said.
That’s why domestic cats don’t drink as much water as dogs. “They evolved in the desert and are used to getting most of their water from their prey,” O’Malley explained. Nonetheless, cats do require a steady supply of fluids to survive. “If cats are not being actively fed and managed by a caretaker, they could potentially have a much harder time in the heat from lack of water,” O’Malley said.
O’Malley also noted that many well-intentioned feral cat caretakers put out only dry food. That means some community cats aren’t getting the much-needed hydration they would get from wet food or a clean, inviting bowl of water.
Cats also intuitively seek shaded areas when the sun starts blazing. While it might look like the cats in your neighborhood have suddenly disappeared, they’re just taking measures to protect themselves. “I care for some of the neighborhood cats myself, and this happens every year,” said Peter Wolf, a data analyst at Best Friends Animal Society, an animal welfare organization. “It still catches me a bit off guard and is a little unnerving.”
But although cats are better protected from heat-related illness than their canine counterparts, they’re not fully immune. At some point, cats can no longer cool their body temperatures without intervention, Hall said.
“If I were thinking about a feral cat colony, I’d want to make sure they had access to shade, fresh water, and someone keeping an eye on them.”
Dr. Emily Hall
veterinarian, Royal Veterinary College
Heatstroke—which occurs when a cat’s body temperature exceeds 104 degrees—can be fatal in cats. Hall noted that she’s seeing more cats with underlying health problems who struggle with hot temperatures due to the lack of air conditioning in the U.K. Flat-faced cats, like Persians and Himalayans, are more susceptible to breathing issues, putting them at an increased risk of heatstroke.
Early signs of heatstroke look similar in cats and dogs, though they’re usually more subtle in felines. These include panting, restlessness, pacing (which may be to seek shade or water), drooling, red gums or tongue, an increased heart rate, and vomiting or diarrhea. Advanced stages can manifest as lethargy, confusion, seizures, weakness, or collapse.
Hall recalled an older cat she knows that’s become a repeat offender of wandering into greenhouses. “It goes into the conservatory looking for it to be warm in the morning,” Hall said. The cat then gets confused and hot. “[The owners] had to barricade the conservatory so that their cat can’t get in there anymore because it’s been in the hospital being treated for heatstroke at least once, if not twice.”
These sorts of misadventures are usually what get cats in trouble. “Someone doesn’t see them, shuts the door, and all of a sudden they are trapped in an incredibly hot environment,” Hall said. “If they go into sheds and things looking for shade and then get shut in, they’ve got no water.”
If you do encounter a cat experiencing heat-related illness, Hall said the most critical thing to remember is: “Wet, then vet.” The aphorism reflects best practices for treating heat exhaustion issued by the American College of Veterinary Emergency and Critical Care’s Veterinary Committee on Trauma. Bring the animal to a cool location and offer them small sips of water or an ice cube, but don’t force it. Place a cool towel on your cat’s back or their belly if they allow it. Putting water on their paw pads or ears also helps. Then, immediately call a vet for emergency care.
And, like humans dealing with extreme heat, prevention is always better than treatment. That might be easier for an indoor pet rather than an alley cat, but caretakers can take precautions nonetheless. “If I were thinking about a feral cat colony,” Hall said, “I’d want to make sure they had access to shade, fresh water, and someone keeping an eye on them.”
Biome
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