For the majority of pets in North America, April marks the start of the heartworm season. Dogs and heartworms can be a deadly combination, but protecting your pooch from this dangerous parasite is simple—treat them for fleas and ticks. In fact, many flea and tick topical treatments now also include mosquito repellent, which is the carrier of heartworms.
It takes about a year for the evidence of heartworm to appear. So, while April is typically the month for prevention, it’s also when veterinarians begin to include heartworm tests in annual checkups.
How to Detect Heartworms in Dogs
Heartworms can be detected through blood tests, and in severe cases, they may show up on X-rays. Heartworms look like thin strands of spaghetti—initially shorter, but with much more serious effects than just weight gain. They are free-floating parasites that live in the right ventricle of the heart and the blood vessels near it. The right ventricle is the lower-right side of the heart, which receives de-oxygenated blood. A parasite floating around in the heart can cause sudden death, sometimes even from just one heartworm. Heart failure is the most common symptom in dogs with heartworm, making prevention far preferable to treatment.
If a dog has never been treated for heartworm prevention, or if they are more than eight weeks old or have missed a few treatments, they need to be tested before starting heartworm prevention. Without testing, there’s a significant risk of a severe, potentially fatal reaction if the dog already has heartworms. This is counterproductive to the desired result, which is to prevent heart problems in the dog. Despite the extra cost, heartworm testing is not just an unnecessary vet bill; it’s a crucial step in safeguarding your dog’s health.
Online medications have become quite popular, especially for flea, tick, and heartworm prevention. However, there’s a caveat in the fine print: these companies typically state they don’t guarantee the medication will work, only that it’s the “exact same” medication you would purchase from your vet. This disconcerting disclaimer can be difficult to interpret, and if it doesn’t make sense, it’s best to avoid it.
In the past, you had to bring your dog to the vet’s office for flea and tick treatment prescriptions. Now, most vets will sell them over the counter as long as your dog is a patient of the practice. The same is true for heartworm prevention. Provided the dog hasn’t missed any scheduled doses and has had the appropriate testing, you can now purchase heartworm prevention without taking your dog to the office.
While some pet owners provide heartworm protection for their dogs from April to November, it’s actually recommended that they receive treatment year-round to ensure complete prevention. Weather is unpredictable, and despite our best efforts to control it, December can still bring warm days before the mosquitoes have died off. It’s unfortunate when a dog is treated for only half the year, only to be accidentally exposed during the off-season. Prevention doesn’t add much to your annual vet bill, and the peace of mind is well worth it.
Dogs and heartworms are no joke. Heartworm begins with a mosquito bite. The mosquito picks up the heartworm larvae from an infected dog, and after about two to three weeks, the larvae mature to an infective stage within the mosquito. When the mosquito bites another dog, it injects the infective larvae into the healthy dog. Over the next several months, the larvae grow into little worms, eventually migrating to the heart, where they continue to grow and become full-grown heartworms, feeding on the dog’s heart tissue and blood. If left untreated, heartworms can grow up to 14 inches long and will eventually cause death by restricting blood flow and heart function.
Dogs with heartworm may begin to show symptoms such as trouble breathing, lethargy, difficulty climbing stairs, shortness of breath, blue-tinted gums, and other signs of heart disease. Unfortunately, heartworm is a problem that can’t be solved without preventative measures. Treatment can cause anemia, shock, listlessness, and even heart failure. Dogs treated for heartworm endure pain, illness, and face a long recovery period.
