HOUSTON — Some pets may be getting heartworms despite receiving preventative measures. Houston-area vets said it could be because of the medication or an increase in the mosquito population.
A single bite from an infected mosquito can send hundreds of parasites into an animal’s bloodstream. Once inside, the parasites travel to the heart and transform into worms. The prevention treatments work by killing the parasites before they reach the heart.
“It is just so simple and a lot cheaper to prevent,” said Dr. Brittany King with Banfield Pet Hospitals. “Once infected, there can be as many as 250 worms in one heart.”
Veterinarians have been preaching prevention for years. The makers of the most common heartworm preventatives have claims of 100 percent effectiveness printed on the box. So when a pet turned up with heartworms, emergency veterinarian Dr. Laurie Noaker told Local 2 that the blame has historically landed on the owner.
“As vets, when animals come up with a disease, it is fairly common, sometimes, to look at compliance,” said Dr. Laurie Noaker, with the Katy Freeway Emergency Animal Hospital.
Noaker said that a challenge to that thought came from a group of veterinarians in the Mississippi River Valley.
“They started to notice a lot of dogs were coming up positive on heartworms that were on the prevention,” Noaker said. “The vets were very clear about saying these clients were compliant and when enough vets report something, people take notice.”
In the last two years, lawsuits have been filed against the makers of heartworm preventatives challenging those claims of 100 percent effectiveness. Noaker said the attention from that has encouraged not only the companies in the business of making preventatives, but independent researchers, to test the current reliability of the treatments.
“In this situation, we have to be very careful about this and maybe look at the product that we are giving and begin to ask the questions, ‘Is there resistance developing? Are there problems with the medication? Do we need to increase the medication or tweak it a bit?’ So, I think they are beginning to study the issue,” Noaker said.
Scientists have already found some genetic mutations in the mosquitoes found in the Southern states and are doing research to see if those changes have affected the parasitic worms or the ability of the preventative treatments.
One theory blames the culprit. More aggressive mosquitoes may be leading to more bites and in turn, flooding a pet’s bloodstream with more parasites than the preventatives can handle.
“We know that roaches develop mutations to chemicals, and we have to tweak those chemicals,” Noaker said. “So it’s not odd to think mosquitoes are doing the same thing.”
Whatever the case, Noaker and King both said the only real option for pet owners is to make sure cats, dogs and even pet ferrets receive their heartworm treatments on a regular basis.
The American Heartworm Society found 56 percent of dogs seen by vets in Southern states have never received any heartworm prevention.
Bi-Yearly Shot Could Replace Heartworm Pills
A heartworm product returning to the market may make things easier for pet owners.
Veterinarian Dr. Brittany King with Banfield Pet Hospital said she has become a fan of ProHeart for one reason — the heartworm preventative is a single shot given every six months.
Most prevention methods are pills given to dogs, cats and ferrets once a month.
And you cannot be late on giving that monthly treatment, according to Dr. Laurie Noaker with the VERGI 24/7 Emergency Animal Hospital.
“Make sure you are giving your preventative every 30 days like clockwork,” Noaker said.
ProHeart left the market after some animals began having bad reactions to the medication. After reformulating the mixture, the shot is back in vets’ offices.
It uses a different active ingredient than many other preventatives to keep the parasites, carried through mosquito bites, from becoming worms in the heart.
“There is a study with that drug that gives really good results,” Noaker said. “One study had a 100 percent efficacy rate.”
And as for those forgetful cat and dog lovers, the fact that it can be given every six months doesn’t hurt when it comes to making sure the animals are protected.
“It can be a deadly disease,” said King. “It is just so simple and a lot cheaper to prevent it. ProHeart is more effective and we decrease the owner compliance problem.”
King said the shot is about $35 with a veterinary visit at Banfield Pet Hospital.
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