It’s not just the Key deer being ravaged by a flesh-eating worm in the Florida Keys. Pets are also starting to turn up with gruesome infections.
While wildlife managers have focused largely on the endangered herd and the 107 deer killed since August, vets say they have treated at least nine suspected cases in dogs, cats, rabbits, pigs and a tortoise. Two feral cats had to be euthanized, said Marathon Veterinary Hospital’s Doug Mader. Those numbers are higher than the three reported by the Florida Department of Agriculture, which only counts cases confirmed in lab tests, largely because of the confirmation process.
“That’s the tough part about this whole thing. You look at them and it walks like a duck, but you have to have confirmation that it’s a duck,” said Keys Animal Hospital veterinarian Kyle Maddox, who treated an infected dog earlier this month.
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The discrepancy in numbers, and expanded war on the screwworm that now covers eight islands and this week drew a new team of volunteers fanning out with medicated bread to feed deer, has only increased anxiety among pet owners. Vets, however, stress the risk to pets remains far lower than the peril posed to the wild deer.
Residents in the Middle Keys and staff at the National Key Deer Refuge first reported seeing deer with gory injuries in August as the herd’s rutting season kicked off. Males typically turn up with head and neck wounds, but when the injuries appeared to fester and deer began dying, staff started collecting samples. On Sept. 30, they confirmed the herd, the last remaining on the planet, was infected with the first U.S. screwworm outbreak in 30 years. By then, residents were already finding deer cowering in garages and under porches.
It was just so scary until we found out what it really was and that was even more frightening.
Big Pine resident Susan Rich
“We put out the fly trap bags and were just catching oodles of flies,” said Susan Rich, a real estate agent in Big Pine who fled with her two dogs, a yorkie and fox terrier, to her Key West house after finding a wounded deer in her garage. “I thought it had eaten rat poison. It was just so scary until we found out what it really was, and that was even more frightening.”
Meanwhile, pets started appearing with wounds. Beginning in late August, Mader treated a rabbit that likely had a screwworm infection, followed by two pigs, two cats and three dogs. He also treated a tortoise likely infected.
In past years, it’s not been uncommon for pet wounds to get infected with other kinds of maggots, he said. “We see that a few times a year. But we saw it a lot this summer and that’s when the deer started showing up positive. That’s when we put two and two together that something more was going on.”
In the weeks since, the rising number of ghastly deer deaths have left people shaken. On Friday, Maddox said he had four appointments with pet owners wanting information about the flies.
It’s almost like walking zombie deer, like something out of a bad movie.
Marathon Veterinary Hospital vet Doug Mader
“It’s almost like walking zombie deer, like something out of a bad movie,” Mader said.
While refuge staff have begun treating deer with a prophylactic medicine that can protect them against screwworm infections, no such drug exists for pets. But vets and wildlife biologists say the risk among pets monitored by owners is much lower than wild animals, as long as pets are checked at least twice daily for wounds. If they do find sores, owners need to cover the wounds or keep animals indoors. An infected soar will contain white rice-like pieces. The eggs generally hatch in about 21 hours, which is why it’s important to check twice daily.
“The single best thing people can do is monitor their pets and monitor them for wounds,” Maddox said.
Screwworms, which look like house flies with large orange eyes, will only lay their eggs in warm, living tissue. (Reptiles are excluded from the federal lists of affected animals, but Mader said fellow vets in South America where screwworms remain a problem routinely find iguanas and other cold-blooded reptiles infected because temperatures remain so warm.) When the eggs hatch, the larvae feed on the tissue, causing severe pain as the maggots burrow deeper. When they are ready to pupate after about six days, the maggots drop to the ground, allowing them to easily spread to other animals.
Thousands of larvae can infect animals. Maddox said the dog he treated earlier this month had hundreds of maggots that had eaten away a good bit of the dog’s foot. And despite some anecdotal evidence that doubling up on heartworm and other medicines could fend off the flies, no scientific studies have confirmed the effectiveness, he said.
If [pet owners] can just be vigilant, their pet is not really at high risk.
Keys Animal Hospital vet Kyle Maddox
“If [pet owners] can just be vigilant, their pet is not really at high risk,” he said. “It’s these animals that develop wounds and are not being monitored.”
That includes a large feral cat population in the islands, which live outside and go unchecked. The Keys Society for the Prevention of Cruelty to Animals delivered a sick cat that was unmarked to Mader on Thursday, but could not determine whether it belonged to one of the feral colonies.
“It was the worst case we’ve seen,” he said. “Someone found it dying in a backyard, full of screwworms.”
SPCA officials say they’ve been trying to contact colony managers — an unofficial group of advocates who try to track the cats — to provide help, urging them to check cats at least twice a day.
“More times is better. As many times as you can check and have your hands on them. And if you see an open wound consult your vet immediately,” said executive director Tammy Fox. The same goes to anyone who spots a wounded stray animal. “Contact the Marathon campus or the Key West campus [of the SPCA] so we can try to help.”
The outbreak initially overwhelmed the small staff at the refuge. Residents say calls for help sometimes took too long and not enough was being done to treat the imperiled deer, whose numbers dropped to about 25 before they were added to the endangered species list in 1957. An early plan to control the outbreak with sterile male flies — a method that helped wipe out the flies in the U.S. in the 1950s and 60s — was expanded this week to include treating deer with doramectin and administering antibiotics to sick deer, even though refuge staff say the fragile deer rarely do well under their care.
A team of 20 refuge volunteers has also begun feeding deer bread laced with the doramectin and marking them with paint. By Thursday afternoon, about 50 deer had been treated and will be retreated weekly, said ranger Kristie Killam.
People are going to see [volunteers] doing things we’ve spent 50 years telling them not to do: feeding the deer.
Florida Keys National Wildlife Refuges ranger Kristia Killam
“People are going to see [volunteers] doing things we’ve spent 50 years telling them not to do: feeding the deer,” she said.
The teams are focusing on Big Pine and No Name keys, but will likely expand as more volunteers are trained, she said.
A quarantine is in effect for much of the island, from the south border of Key Largo to Key West, with a highway checkpoint at mile marker 106 requiring an inspection of any animal being moved. Since the first week of October, more than 1,200 pets have been checked — including 1,176 dogs, 35 cats, four horses, six birds and one rabbit. No infections have been found. The U.S. Fish and Wildlife Service has also expanded the release of clinically modified flies to mate with wild female flies and whose offsprings will become sterile and contain the outbreak to eight islands from No Name Key west to Summerland.
With the snowbird season around the corner, Mader and Rich both say they are getting lots of questions from seasonal residents who frequently bring pets.
“We’ve had people calling and saying ‘I’m not coming,’” Mader said. “We want people to be educated, but not afraid. I have two dogs that live outside and I don’t worry about them. But I do check them twice a day.”
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