Climate change doesn't just affect habitats for wildlife. It's also affecting cats and dogs.
Fleas and ticks are getting smaller, but there are more of them, they eat more often, and they're causing problems in what used to be the colder months.
Heartworm is spread by mosquitoes, but those mosquitoes — which used to be found only in certain regions — are now carrying the disease all over the United States.
Increased temperatures have turned kitten season into a year-long event instead of a spring ritual. The weather is even disrupting hibernation for a California woman's pet tortoises.
NASA recently declared that 2015 was the hottest year on Earth in 136 years of record-keeping with an average temperature of 58.62 degrees.
For pet-owners, those changes may mean rethinking preventive care like giving dogs flea and tick repellent and heartworm pills.
For example, now that heartworm has been found in every state, "I don't know why a person wouldn't give his dog heartworm pills once a month. That seems like a no-brainer," said Gregory D. Ebel, professor and specialist in infectious diseases at Colorado State University's veterinary school in Fort Collins.
Ticks cause Lyme disease in dogs as well as in humans. The bugs are most active in warm months, but with cities in the Northeast and Midwest setting record highs this past December, calendars no longer offer guidance on when pet-owners should worry and when they can relax. Dogs should be checked for ticks, just like people, and veterinarians can offer guidance on a variety of pest repellent products.
Margery Cooper, a dog owner in Brooklyn, New York, lost her beloved dog Scout to complications from Lyme disease a few years ago. She's now the owner of Penny, a mixed-breed rescue, and she's vigilant about checking Penny for ticks, especially after they go on hikes together.
Madeline Bernstein, president of the Society for the Prevention of Cruelty to Animals Los Angeles, has even noticed changes in her 18-year-old tortoises, George and Mulan. They normally hibernate from October or November to April or May. But they were late going down this season and in mid-January, one of them was up walking around in 70-degree weather, Bernstein said.
She made sure it didn't eat. "Going back to sleep with undigested food could kill it," she said.
At work, Bernstein is surrounded by more evidence of climate change: twice as many kittens. "Flea season used to be seasonal too, but now we treat for fleas all year long," Bernstein added.
John Trumble, a distinguished professor of entomology at the University of California, Riverside, said environmental conditions are creating larger populations of smaller fleas and ticks that will eat more frequently, develop more rapidly and spread more pathogens.
Drought in Texas and California has dried up small water sources that once served horses, sheep and other animals. Now, he said, wet weather brought by the El Nino phenomenon will create all kinds of pools and puddles that will draw the pests, "setting the animals up for an increase in insect-borne diseases like West Nile virus," a mosquito-borne disease that affects horses and people.