An animal rescue group is warning dog owners about the possible dangers of playing with tennis balls.
The Humane Animal Project in Hempstead, Texas, says four dogs in its care have had serious reactions, including what resembles chemical burns, after licking or chewing Penn tennis balls purchased from a Costco store in Katy, Texas.
Symptoms include “swollen tongue, white ulcerations, heavy drooling, difficulty in drinking, eating or breathing,” according to the group. “Several of the dogs required IVs because of the pain caused while drinking and eating. Several vets have described the ulcers as ‘chemical burns.’”
The company behind the balls says it’s looking into the situation but has not heard of any similar reports.
The business “stands behind the quality of Penn tennis balls,” Allison Barnett, a brand manager for Head Penn Racquet Sports, tells PEOPLE. “Tennis balls are made for tennis; they are not marketed or sold as pet toys, but we want to assure our customers that no toxic materials are added to our tennis balls, and we would never knowingly market a product that harms animals or humans.”
Barnett says Penn isn’t aware of anything new in the production of its tennis balls. “We have checked with our VP of manufacturing and he doesn’t believe that anything in the manufacturing process has changed in years, however we are investigating further to confirm this,” she says.
Costco declined a request for comment.
Alfred Restivo says dogs at the Texas shelter he opened in 2014 have been playing with tennis balls without incident for years. But about four months ago, a 6-year-old border collie named Sydney got sick after licking a Penn Championship extra-duty tennis ball, brand new out of the can, he says.
“The dog was in horrible pain,” Restivo tells PEOPLE, saying she was drooling and howling. “Her tongue was so swollen it was bigger than her mouth.”
Sydney recovered after treatment, but after three more of the rescue’s dogs started exhibiting comparable problems, “we figured it out,” he says. “It’s from the balls just being in their mouth and them licking them. It doesn’t even have to be chewing.”
Dr. Tim Gaffrey, a veterinarian in Waller, Texas, who treated Sydney, confirmed the dog came in with swelling, mouth ulcers, and her tongue “was so swollen it was pushing out of her mouth,” he says. “That combination of symptoms, it looks like a dog that had oral contact with an irritating substance. Another way of saying that is chemical burns.”
Owners should contact their vet or an animal control poison hotline “if they’re concerned after their pet plays with a toy,” says Gaffrey, noting he cannot say with certainty what caused the medical issues experienced by Sydney, who has since left the Hempstead shelter after being adopted.
Restivo says the other dogs who suffered reactions are also now healthy and doing well.
Dr. John de Jong, president-elect of the American Veterinary Medical Association, says he has never heard of dogs having the same kind of complications after coming in contact with a tennis ball, and it is difficult to pinpoint what caused the problems.
“Tennis balls are a great toy for dogs, especially those who like to chew,” he says, but cautioned, “whatever toys you’re giving your dogs, watch them.”
Both veterinary doctors say the only concern they have had with tennis balls is that animals might chew them up and swallow the pieces, which could cause a stomach or intestinal obstruction.
“Typically tennis balls are very, very safe,” de Jong says. “And very loved by dogs.”