Hookworms, the Disgusting Parasites That Suck Our Dogs' Blood, Are Now Resisting Drug Treatments
Hookworms, the nasty-as-hell parasites that suck our dogs' blood, have become even more of a threat to our dogs' health.
New research from the University of Georgia confirmed what the university's veterinary school first reported in 2019: Hookworms are now seemingly resistant to the three primary drugs U.S. veterinarians use to eliminate them. It's definitely not good news, perhaps enough to keep some pups from visiting communal areas like the local dog park. However, there are preventative measures dog parents can take, and there is treatment hope on the horizon.
The first step in keeping your pet safe from these nasty little critters? "You want to reduce the possibility of exposure," says Randy Wheeler, DVM and executive director of the Iowa Veterinary Medical Association.
What Are Hookworms?
First, let's get reacquainted with hookworms, which are disgusting. You can read more in the Daily Paws guide to understanding hookworms, but here are the basics: The small, hook-shaped parasites attach themselves to the walls of our dogs' intestines to suck the canines' blood, sometimes causing anemia (which can be life threatening), extreme weight loss, diarrhea, and weakness.
Once inside the dogs, hookworms mate and deposit their eggs in the canine stool. When the dog poops, the baby hookworms descend into the soil. Other dogs become infected when they ingest the worms or when the worms burrow into their skin. Now prepare yourself, it gets even more gross: hookworms can also infect us humans. They're repulsive—and to make things worse, now hookworms are fighting off medication.
New Research About Hookworms
The University of Georgia study focused on current and former racing greyhounds, who've occupied sandy racetracks that are ideal for breeding hookworms. Because of that, the dogs are dewormed monthly, UGA explains in a news release. Just under 80 percent of the dogs evaluated tested positive for hookworms.
More importantly, the dogs treated with U.S.-approved deworming drugs—fenbendazole, pyrantel pamoate, and milbemycin oxime—still registered hookworm infections after they'd been treated. The study reports that fenbendazole registered an efficacy rate of 26 percent, while pyrantel pamoate and milbemycin oxime reached 23 percent and 9 percent, respectively. The study found that the drug-resistant worms live on after the drug passes through the dogs' systems, and soon, they're the only kind left.
Compounding the problem, the resistant worms are spreading beyond greyhounds to the general dog population, according to both UGA researchers and the American Veterinary Medical Association. With greyhound racing a nearly extinct sport, the dogs are now mostly family pets.
"There's a very committed greyhound adoption industry because they are lovely dogs," Ray Kaplan, professor of veterinary parasitology, said in the UGA news release. "I used to own one. But as those dogs are adopted, the drug-resistant hookworms are going to show up in other pet dogs."
How You Can Prevent Drug-Resistant Hookworm Infections
The drug-resistant hookworms are now out there among the general population of pets, so the best way to keep your pet safe is to avoid exposure in the first place. How can you keep your dog from being infected? Kaplan suggests one, perhaps drastic, idea.
"Personally, I would not take my dog to a dog park. If your dog picks up these resistant hookworms, it's not as easy as just treating them with medication anymore," he says.
Now, that might not be an option if your dog absolutely loves the dog park and needs that fenced neighborhood space to get much-needed off-leash exercise. Any high-trafficked areas where dog poop might be scattered in addition to the dog park might be worth avoiding, if you can. But if not, it's a smart idea to can clean your dogs' feet after each trip, Wheeler says. You can also avoid areas where there might be feces from stray animals, and you'll want to be a stickler about keeping your yard poop-free, whether it's your own dogs' or not. Pick it up and dispose of it safely to help keep eggs from infested poop from making a home in your yard.
"Those are just pretty good ideas to keep in the back of your mind at home," Wheeler says.
Plus, you can always talk with your veterinarian, he adds. They'll be able to tell you whether they've seen drug-resistant hookworms in your area and whether you should take extra precautions to keep your pooch safe.
Help on the Way?
This is a familiar situation to Wheeler, who's worked as a mixed-animal veterinarian. In the past, he's had to move livestock to different pastures and make sure animals are cleaned up to avoid certain infections. Then, there's waiting for a new kind of treatment.
"There'll be new things that come out that can help control this," he says.
One of those new things might already exist. The UGA researchers, Kaplan and Pablo Jimenez Castro, noted that emodepside, a dewormer only approved for use on cats in the United States, shows promise eradicating the drug-resistant dog worms.
The American Association of Veterinary Parasitologists has also formed a task force to help track and limit the spread of the drug-resistant worms. It's encouraged vets to follow up with patients they do treat for hookworms to see if the drugs did their jobs.