Worms in the Heart? You’ve got to be kidding! If you think they are gross to think about, you should see them. They clog up the lung’s arteries that leave the heart and can get way out into the circulation. They are spread from dog to dog by the mosquito. When a mosquito takes a blood meal from an infected dog they can take in the microscopic babies (larvae) that are circulating in the blood stream. The larvae must go through a change in the salivary glands of the bug, then when the mosquito bites another dog (or even the same dog) these larvae continue to mature. The process after the larvae are “injected” into the dog until they are adults in the Heart takes about 6 months. It only takes one mosquito. I live inside and I still get bitten.
When the adults are in the heart they start to cause lots of signs. We see inflammation, increased heart size, fluid accumulation in the abdomen, lethargy, exercise intolerance, coughing, as well as death. Once the adults set up in the heart the damage to the heart valves, heart muscles and lungs begins. You’ve heard the old adage, that an Ounce of Prevention is Worth a Pound of Cure.” This is definitely the case with Heartworms (Dirofilaria Immitis). Our prevention first came out as a once daily pill that improved into a once daily chewable tablet. (Does anybody out there remember Filaribits?) It was wonderful when the first monthly pill came out and even better when it became chewable. Most all of the products now control more parasites than just heartworms.
Most of the preventions control the maturation of the heartworm by preventing the progression from the 4th larval stage to the 5th. It is important to remember that the medication does not stop the Heartworms when the mosquito bites the dog, but probably 2-3 months later. When someone tells us that we had a hard freeze and don’t have any mosquitoes around, they don’t realize that it’s the bite they got 3 months ago that is the problem. This is also the reason why we give the Heartworm Prevention all year long, especially in our area.
Is there actually resistance going on? Yes, the experts finally agreed. Some of the drug manufacturers initially tried to convince us that it was because our clients weren’t giving the medication properly. My argument was, why did my clients do it well for a decade then all of a sudden stop being able? Another problem I had with their hypothesis was that it was only happening from Dyersburg down through the Delta and into Louisiana. Sort of hurt my feelings that they blamed us dumb southerners for the problem. When the resistance started, my Associate Stephanie Wardlaw was taking care of all of the dogs' Heartworm Prevention in her husband's Training Kennel. She was in charge of giving the medication every month, so when some of the dogs came down with Heartworms and the company said that it was probably due to insufficient dosing, Dr. Wardlaw was NONE TOO HAPPY with the blame placed on her by the manufacturer. Plus, she isn't a dumb Southerner, she went to Vet School up north in Minnesota. She practices in Paris now................ Paris, TN.
It was very frustrating for us, as veterinarians, to go into an exam room with someone, who had depended on us and purchased medication from us, to tell them their dog was Heartworm Positive because the medicine failed to work. All of the monthly oral products have had failures. Some of the Drug Companies backed up their guarantee, but some were hard to deal with. We no longer carry their product. The percentages of product failures weren’t high, but percentages don’t matter when it’s your dog……. Or MY patient!
What do we do now? We still carry a monthly oral product that is backed up by its manufacturer, but we actually recommend 2 other products that have not had problems. Advantage Multi is a monthly topical medication that controls intestinal worms and fleas in addition to Heartworms. We have had great success with this product in a lot of different ways. ProHeart is an injectable that is given every 6 months that also controls Hookworms. I have been pleased with how well this works and clients love the convenience of just coming in every 6 months to get a quick injection. These 2 products have a different active ingredient than the other oral products, but more importantly the drug stays in the system a lot longer than the others.
I had a client that had several dogs that she had acquired a prevention from the internet. She gave it religiously, but over half of her dogs ended up being positive. She decided to have them tested since one of her dogs actually died from Heartworm Disease that had been on continual treatment every month.
The treatment of dogs with adult heartworms is variable. I tell my staff that every patient is different from many standpoints, and treatment decisions are based on many different variables. Some are treated with a series of injections while some are treated with a specific Prevention. There is a relatively new addition to the treatment regimen that the experts feel helps out. The patients are put on a particular antibiotic that attacks a bacteria (Wolbachia) that lives in the adult heartworm. Since that bacteria is beneficial to the heartworm, when it is killed the adult heartworm is weakened. This is given during the treatment and studies show, that improves efficacy and reduces reactions.
Take Home message:
Start your puppies early, use a prevention that you can remember to administer, make sure that your dog is tested to catch the infection early and give all year long.
When the adults are in the heart they start to cause lots of signs. We see inflammation, increased heart size, fluid accumulation in the abdomen, lethargy, exercise intolerance, coughing, as well as death. Once the adults set up in the heart the damage to the heart valves, heart muscles and lungs begins. You’ve heard the old adage, that an Ounce of Prevention is Worth a Pound of Cure.” This is definitely the case with Heartworms (Dirofilaria Immitis). Our prevention first came out as a once daily pill that improved into a once daily chewable tablet. (Does anybody out there remember Filaribits?) It was wonderful when the first monthly pill came out and even better when it became chewable. Most all of the products now control more parasites than just heartworms.
Most of the preventions control the maturation of the heartworm by preventing the progression from the 4th larval stage to the 5th. It is important to remember that the medication does not stop the Heartworms when the mosquito bites the dog, but probably 2-3 months later. When someone tells us that we had a hard freeze and don’t have any mosquitoes around, they don’t realize that it’s the bite they got 3 months ago that is the problem. This is also the reason why we give the Heartworm Prevention all year long, especially in our area.
Is there actually resistance going on? Yes, the experts finally agreed. Some of the drug manufacturers initially tried to convince us that it was because our clients weren’t giving the medication properly. My argument was, why did my clients do it well for a decade then all of a sudden stop being able? Another problem I had with their hypothesis was that it was only happening from Dyersburg down through the Delta and into Louisiana. Sort of hurt my feelings that they blamed us dumb southerners for the problem. When the resistance started, my Associate Stephanie Wardlaw was taking care of all of the dogs' Heartworm Prevention in her husband's Training Kennel. She was in charge of giving the medication every month, so when some of the dogs came down with Heartworms and the company said that it was probably due to insufficient dosing, Dr. Wardlaw was NONE TOO HAPPY with the blame placed on her by the manufacturer. Plus, she isn't a dumb Southerner, she went to Vet School up north in Minnesota. She practices in Paris now................ Paris, TN.
It was very frustrating for us, as veterinarians, to go into an exam room with someone, who had depended on us and purchased medication from us, to tell them their dog was Heartworm Positive because the medicine failed to work. All of the monthly oral products have had failures. Some of the Drug Companies backed up their guarantee, but some were hard to deal with. We no longer carry their product. The percentages of product failures weren’t high, but percentages don’t matter when it’s your dog……. Or MY patient!
What do we do now? We still carry a monthly oral product that is backed up by its manufacturer, but we actually recommend 2 other products that have not had problems. Advantage Multi is a monthly topical medication that controls intestinal worms and fleas in addition to Heartworms. We have had great success with this product in a lot of different ways. ProHeart is an injectable that is given every 6 months that also controls Hookworms. I have been pleased with how well this works and clients love the convenience of just coming in every 6 months to get a quick injection. These 2 products have a different active ingredient than the other oral products, but more importantly the drug stays in the system a lot longer than the others.
I had a client that had several dogs that she had acquired a prevention from the internet. She gave it religiously, but over half of her dogs ended up being positive. She decided to have them tested since one of her dogs actually died from Heartworm Disease that had been on continual treatment every month.
The treatment of dogs with adult heartworms is variable. I tell my staff that every patient is different from many standpoints, and treatment decisions are based on many different variables. Some are treated with a series of injections while some are treated with a specific Prevention. There is a relatively new addition to the treatment regimen that the experts feel helps out. The patients are put on a particular antibiotic that attacks a bacteria (Wolbachia) that lives in the adult heartworm. Since that bacteria is beneficial to the heartworm, when it is killed the adult heartworm is weakened. This is given during the treatment and studies show, that improves efficacy and reduces reactions.
Take Home message:
Start your puppies early, use a prevention that you can remember to administer, make sure that your dog is tested to catch the infection early and give all year long.
A dog's heart that is FULL of adult Heartworms.
This dog is NOT pregnant. The abdomen is full of fluid because the heart isn't functioning properly. This is all secondary to Heartworm Disease.
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