Veterinarians are advising pet owners not to exercise their animals while the Washington area's heat advisory is in effect.
"A mild amount of exercise in these extreme temperatures could be deadly," said Lee Morgan, a veterinarian with the Georgetown Vet Hospital.
Morgan, who has been practicing veterinary medicine for 14 years, said he was shocked to see dog owners running their pets along the C&O Canal Tuesday afternoon.
"It just takes an instant for them to go into thermic overload," he said, adding that older Labradors and golden retrievers are especially susceptible to heat-related illnesses.
Morgan said he has seen an influx of four-legged heat stroke patients the past few days.
"Usually when they come in they are salivating uncontrollably, extremely weak and panting heavily," he said.
He suggested cats stay indoors and pet owners leave air conditioning on all day.
He also said owners should leave out plenty of water and walk animals on cool grass rather than hot pavement that can burn their paws.
Dogs and cats have higher average body temperatures than humans do and can't sustain high levels of heat, he said. The animals also lack the lack the ability to acclimate to the heat -- meaning Tuesday's extreme heat following last week's break of cooler weather will increase their risk of hyperventilation.
"If you run three miles a day every day with your dog, that doesn't mean he won't have a problem doing even a lighter exercise in this heat," he said.