Common dog parasite is mutating to resist the drugs that destroy it

One of the most common parasites that infest dogs — hookworms — is developing a resistance to all of the drugs approved by the FDA to treat the infection, according to a new study from the University of Georgia. This parasite infects a dog's intestines, leading to anemia, weight loss, and other issues that threaten the dog's health and life.

According to research from the university's College of Veterinary Medicine, hookworms are mutating in a way that makes them multi-drug resistant. This is a big problem, particularly in cases where dogs are exposed to environments where hookworm infections are common: dog parks, race tracks, and kennels, for example.

The study focused on fecal samples taken from an active racing kennel, greyhound adoption kennels, and vets that work with adoption groups. The vast majority of greyhounds were found to have hookworm infections, the researchers reveal, noting that dogs that didn't test positive still likely had infections from the parasite.

The infections were present despite treatments designed to kill off hookworms, presenting a scenario of widespread resistance to multiple drugs. What is driving the resistance? Among other things, environments where dewormers are used frequently allow drug-resistant hookworms to survive and spread to other dogs.

The multi-drug resistant worms will eventually become the predominant variety found in these environments as the other hookworms will be killed off by the drugs. As well, the researchers explain that dogs aren't often tested to see whether the infection is truly gone after receiving a dewormer, meaning infections may remain and grow into a full-blown disease.

What can be done about this problem? The researchers say that these hookworms seem to be vulnerable to a dewormer that only has FDA approval for use in cats (in the US, at least). Veterinarians are only able to administer this drug to dogs, the experts caution, but it does provide an avenue for treatment.