Unfortunately, certain strains of heartworms are able to resist current heartworm medications.
This appears to be true mostly — but not exclusively — in the south.
So, if you happen to live in the southern part of the United States, be sure to talk with your veterinarian about the best options for you and your dog.
If you’re like me, even if you don’t live in the south, you will keep your dog on a heartworm prevention year round for the following reasons…
Facts About Heartworms
Heartworm disease is a serious and potentially fatal condition caused by parasitic worms living in the arteries of the lungs and occasionally in the right side of the heart of dogs. —American Heartworm Society
- Heartworms come from infected mosquitoes.
- When an infected mosquito bites your dog, your dog becomes infected with heartworms.
- A mosquito gets the heartworm from another infected dog first — which is why veterinarians tend to see increased rates of heartworm disease in dogs within small geographical regions. Mosquitoes typically stay within one geographical area, and they just keep biting more and more dogs within that area passing heartworms on to more and more dogs. This vicious cycle continues until there is a hard freeze which ultimately kills the mosquitoes for that season. However, in places like the south, there is no hard freeze, so you have mosquitoes year round. As a result, the number of heartworm cases continue to increase year round.
- The earlier your dog gets treatment for heartworms, the better the prognosis. But, if you wait, the odds of your dog surviving heartworms are not good.
- Contrary to popular belief, there are no months in the year when your dog is naturally protected. Your dog can get infected with heartworm disease just as easily in December as in June. If that’s not enough reason to keep your dog on a heartworm preventative, keep in mind those times when your dog travels with you to other states as well.
What Canine Heartworms Look Like
A friend of mine is a veterinarian. These are photos of Nicole P. and her colleagues surgically removing heartworms from a dog:
Now see what heartworms look like on a slide under a microscope:
Symptoms & Treatment For Heartworm Disease
Often, dogs will show few, if any symptoms during the early stages of heartworm disease.
This alone, is the best reason to keep your dog on a heartworm preventative (year round). Otherwise, you might not even find out that your dog has heartworms — until it’s too late.
Think about it this way:
- Heartworm prevention costs about between $40 and $150 a year, depending on the weight of your dog and the medication you choose.
- The cost to treat heartworm disease is between $500 and $800, depending on the age & health of your dog, how quickly your dog was diagnosed, and how many worms are inside.
In addition to keeping your dog on a year-round heartworm preventative (which, as a bonus, also kills intestinal parasites year round), having your dog tested annually for heartworms is your best defense against the deadly, infected mosquitoes. It’s a simple blood test done in your veterinarian’s office. Puppies should get their very first heartworm test at 7 months of age.
The time from infection to microfilaria [finding baby worms in the blood] is about 7 months, so when your pet is tested this spring (and the AmericanHeartworm Society recommends testing all dogs yearly even if they are on preventatives) we are really looking for last year’s infections. —Keith Niesenbaum, DVM
If your dog shows any of the following signs, take your dog to the vet right away:
- Shortness of breath
- Nose bleeds
- Unwillingness to play
- Difficulty breathing
If your dog does have heartworms, the following things are going on without you even realizing it:
- The lungs aren’t functioning normally.
- The heart isn’t functioning normally.
- The kidneys aren’t functioning normally.
Veterinary tests and x-rays are the only way to confirm that your dog has heartworms.
The treatment for heartworm disease is expensive (for you) and grueling (for your dog). Basically, a form of arsenic is used to kill the heartworms inside your dog. It’s a long process, and your dog must be in otherwise good health just to be able to withstand the treatment.
More About Dog Heartworms
- Heartworms In Dogs: Facts vs Myths
- Why Your Dog Needs Heartworm Prevention
- Advantage vs Advantix: An Important Difference
- Can Heartworm Preventatives Be Given Late?
- FAQ About Heartworms From The American Heartworm Society
- Are Heartworms Getting Worse? (See also, parts 2, 3, 4, 5, 6 this veterinarian’s seminar)