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You’ve likely heard about heartworms – the sinister spaghetti noodles whose babies ride like Valkyries in the bellies of mosquitoes to invade our pets’ heart and lung vessels to potentially fatal effect. Dramatic intro, check! Well, I’m here to break down four heartworm misconceptions that I often encounter in my clinic which I believe benefit all pet owners no matter the country of residence.
Misconception 1. Indoor cats don’t need heartworm preventatives.
Well that’s a double negative, and your cats may now be positive…for heartworms. Far too often, heartworms are often only associated with canines (dogs, coyotes, foxes), and while our feline friends ARE less susceptible, that doesn’t exempt them from being able to contract and suffer greatly from the disease. Furthermore, no approved treatment for cats yet exists. While this may not necessarily be a death sentence, lifelong effects can still occur to their cardiac and respiratory systems or even other areas of the body if the worms migrate internally. All in all, no fun for your fur babies.
And unless by some miracle your home is an impenetrable fortress from the hellions that are mosquitoes, your indoor cat can still become infected. It only takes one bite for a mosquito to transmit the heartworm larva (microfilariae) from an infected animal to your precious kitty. With these factors in mind, we highly recommend using preventatives in all cats in susceptible areas (see next point).
Dirofilaria immitis, dog heartworm
Misconception 2. My area is too cold for heartworm carrying mosquitoes.
There is some truth to this depending on where you live, but it’s not quite so simple. In order for heartworm larva to mature into their infective stage in the mosquito, they require a sustained minimum environmental temperature for roughly two weeks. Some of you reading this, like those of you in the UK for example, can take a sigh of relief as your climate does not *currently* support heartworm transmission to your pets.
However, my American readers living along the border of Canada should swallow that sigh. Not to doomsay, but current research indicates that heartworm incidence is spreading, including in Europe and the United States. In fact heartworm is present in all 50 US states. And we don’t recommend skipping treatment in those cold winter months. For maximum risk mitigation, year-round prevention is best as it is impossible to predict the many fluctuating variables that infection depends on such as spikes in temperature, mosquito life spans, insect species, etc.
Lastly, and this includes you aforementioned UK residents, always check with a veterinarian if you intend to travel with your furpanion to areas where there is potential for infection (esp. my Australian readers who ma frequently travel between tropical and temperate climates) to see if heartworm prevention should be considered even if temporarily.
Misconception 3. A negative heartworm test result means no infection.
The heartworm test your veterinarian likely performs routinely is only able to detect adult female heartworms, and it takes about 6-7 months for transmitted larvae to develop to that stage. Put more simply, if your pet isn’t on preventative, a negative result only says that there are no symptom causing adults currently in your pet, not that there aren’t babies that couldn’t turn into adults at any time in the next 1-7 months depending on time of infection.
This is also what makes missed dosages scary, and why year-round prevention as said previously is so important. Heartworm preventatives only work retroactively, meaning if you give a dose on, let’s say, November 1st, you are only killing any larvae that have infected your pet in October. When you miss a dose, the untreated larvae may have progressed to a stage that is now not treatable with the next months dosage – AND like already said (I just want to really drill this in) they may not be detectable for at least 6 more months when they become nasty adults! Always consult with your veterinarian in instances of missed dosages to see if they think it is a good idea to schedule an additional heartworm test in 6 months.
Misconception 4. Natural remedies can replace heartworm preventatives.
There are MANY sources online touting the benefits of garlic and other herbs for natural pest prevention. However, you will be hard pressed to find any with clinical data supporting the claim that garlic kills adult heartworms. Moreover, garlic is a well-known toxin to dogs and similar to onion, it can cause anemia (low red blood cells). Now don’t freak out if you’ve been giving garlic and not realizing this. The toxic dosage for serious health effects to occur is quite high. However, why give a relatively untested, potentially toxic ingredient to your loved one? There are so many tried and true FDA approved alternatives on the market already!
And before you say it, I’ll beat you to it. Yes there are potential side effects of any medication you give to your animals, including monthly preventatives. However in most cases, side effects are often limited to temporary itching, diarrhea and vomiting, if any at all. If you have concerns though, or have a dog prone to seizures, always feel free to ask your veterinarian about their recommendations. We don’t mind – it’s our job!
Lastly, preventing heartworm is BY FAR easier than treating it. It’s easier on your pet, on your wallet, on your relationship, and on both of your mental health. Treatment is very involved, with months of strict cage rest, painful injections for your pet, risk of further serious disease and death due to potential anaphylaxis from larvae being killed, other potential complications, and a $2000 or higher bill to boot!
Final Thoughts
I can go on forever about heartworms, and perhaps I will in a future post. In the meantime, I hope you found these heartworm misconceptions useful and educational. If you have any questions reach out to us and we can discuss your concerns in more detail! Otherwise, I hope I was able to shed some light on why your own veterinarian begs you to purchase that 6 months pack of Simparica Trio at your yearly exam. (You’ll thank us later!)
TLDR:
1) Cats can get heartworms, although less susceptible, yes even if indoor
2) Always use heartworm preventatives if living in a susceptible area, or if traveling to one.
3) Negative heartworm tests do not mean infection is not potentially occurring.
4) Prevention is SO much cheaper and easier than treatment!!!