Pets are a key part of families. Giving them a long, happy life is important. One way to do this is by taking preventive measures when approaching your pets overall health.
For certain diseases, prevention is the key to keeping pets healthy. For heartworm disease, this stands true. But, what is heartworm disease? And, what is the safest heartworm prevention for dogs?
When it comes to our furry friends, nothing matters more than keeping them healthy and safe. As a dog owner myself, I know the anxiety that comes with choosing the right medications – especially something as important as heartworm prevention. With so many options out there, figuring out the safest heartworm medication for dogs can feel overwhelming.
Why Heartworm Prevention Matters
Before diving into specific medications, let’s understand why this is so crucial. Heartworm disease is no joke – it’s a potentially fatal condition caused by foot-long worms that live in your dog’s heart, lungs, and blood vessels. All it takes is one bite from an infected mosquito to put your pup at risk.
The reality is stark approximately one million dogs across the United States are currently affected by this devastating disease. The treatment for established heartworm infection is difficult, risky and expensive – often costing $1,000-$1500 or more. Compare that to just $70-$200 annually for prevention, and the choice becomes clear.
What Makes a Heartworm Medication “Safe”?
When we talk about “safety” in heartworm medications we’re looking at several factors
- Effectiveness – Does it reliably prevent heartworm disease?
- Side effect profile – How likely is it to cause adverse reactions?
- Breed considerations – Is it safe for all dog breeds including those with genetic sensitivities?
- Ease of administration – Will your dog actually take it consistently?
- Additional benefits – Does it address other parasites too?
Top 5 Safest Heartworm Preventatives
After reviewing veterinary recommendations and product profiles here are the safest options currently available
1. Heartgard Plus (Ivermectin + Pyrantel)
Heartgard Plus remains one of the most trusted names in heartworm prevention, and for good reason.
How it works: Ivermectin targets heartworm larvae before they can develop into adults, while pyrantel tackles intestinal parasites.
Safety profile:
- Generally very safe for most dogs
- Used at low doses that are safe even for many sensitive breeds
- Comes as a beef-flavored chewable that most dogs happily accept
Considerations: Some herding breeds with the MDR1 gene mutation may be sensitive to ivermectin. However, at the low doses used in Heartgard, it’s typically considered safe. Your vet might recommend alternative options if your dog is one of these breeds.
Cost: $35-$70 for a six-month supply, depending on your dog’s weight.
2. Sentinel (Milbemycin Oxime)
Sentinel offers broader protection by combining heartworm prevention with flea population control.
How it works: Milbemycin oxime prevents heartworm disease while lufenuron disrupts the flea life cycle.
Safety profile:
- Safe for dogs with the MDR1 gene mutation
- Can be used in puppies as young as 4 weeks (weighing at least 2 pounds)
- Controls four types of intestinal parasites
Considerations: While it prevents flea reproduction, it doesn’t kill adult fleas, so supplemental flea control might be necessary.
Cost: $45-$90 for a six-month supply, varying by dog size.
3. Revolution (Selamectin)
Revolution provides comprehensive parasite protection in a topical form.
How it works: Selamectin enters the bloodstream through the skin to prevent heartworm disease while also treating various external and internal parasites.
Safety profile:
- Good option for dogs who refuse pills
- Broad-spectrum protection against multiple parasites
- Generally well-tolerated
Considerations: Some dogs experience temporary hair loss at the application site. The dog should stay dry for 24 hours after application.
Cost: $85-$120 for a six-month supply, depending on your dog’s size.
4. ProHeart (Moxidectin)
ProHeart stands out by offering extended protection from a single injection.
How it works: Moxidectin is slowly released into your dog’s system over 6 or 12 months.
Safety profile:
- Eliminates concerns about forgotten monthly doses
- Can’t be spit out or vomited like oral medications
- Also treats existing hookworm infections
Considerations: Requires a veterinary visit for administration. While generally safe, rare but serious side effects have been reported, particularly in dogs with pre-existing conditions.
Cost: $50-$100 for the 6-month injection or $90-$180 for the 12-month injection.
5. Advantage Multi (Imidacloprid + Moxidectin)
Advantage Multi combines heartworm prevention with powerful flea control in a monthly topical solution.
How it works: Moxidectin prevents heartworm disease while imidacloprid kills adult fleas.
Safety profile:
- Good alternative for dogs who refuse oral medications
- Treats and controls several intestinal parasites plus ear mites
- Well-established safety record
Considerations: Your dog should stay dry for 24 hours after application. Some pet owners note a strong odor.
Cost: $90-$130 for a six-month supply, depending on dog size.
Special Considerations for Certain Dogs
MDR1 Gene Mutation
Some herding breeds have a genetic mutation (MDR1) that affects how they process certain medications. Breeds commonly affected include:
- Australian Shepherds
- Border Collies
- Collies
- German Shepherds
- Old English Sheepdogs
- Shetland Sheepdogs
- Miniature American Shepherds
If your dog belongs to one of these breeds, medicines containing milbemycin oxime (like Sentinel) are often considered safer than those with ivermectin.
Puppies
Not all heartworm preventatives are suitable for very young puppies. Sentinel can be used in puppies as young as 4 weeks, making it one of the safest options for young dogs.
Dogs with Existing Health Conditions
Dogs with certain health issues might need specific heartworm preventatives. Always discuss your dog’s full medical history with your vet before starting any medication.
How to Give Heartworm Prevention Safely
No matter which product you choose, follow these tips to ensure maximum safety:
- Always test first – Your dog needs a heartworm test before starting prevention
- Stay consistent – Give the medication on the same day each month
- Follow weight guidelines – Use the correct dosage for your dog’s weight
- Watch for reactions – Monitor your dog after giving a new medication
- Year-round protection – The American Heartworm Society recommends prevention 12 months a year
Common Questions About Heartworm Prevention Safety
Can my dog get heartworms even while on prevention?
While heartworm preventatives are highly effective, no medication is 100% guaranteed. Annual heartworm testing is still recommended even for dogs on consistent prevention.
Is heartworm prevention necessary in winter months?
Yes! The American Heartworm Society recommends year-round prevention. Temperature fluctuations can extend mosquito activity, and missing doses leaves your dog vulnerable.
Can I skip a month and double up the next month if I forget?
Absolutely not! Never double up on doses if you miss a month. Contact your veterinarian immediately if you miss a dose, as the medication only kills heartworm larvae retroactively.
Do indoor dogs need heartworm prevention?
Yes, they do. Mosquitoes easily enter homes through doors and windows, and it takes only one bite from an infected mosquito to transmit heartworm larvae.
Are there natural alternatives to prescription heartworm medications?
No natural products have been scientifically proven to effectively prevent heartworm disease. The risks of using unproven methods far outweigh any perceived benefits.
Making Your Final Decision
The “safest” heartworm medication ultimately depends on your individual dog’s needs, health status, and lifestyle. What works perfectly for one dog might not be ideal for another.
Consider these factors when making your decision:
- Your dog’s breed (especially if they’re prone to the MDR1 mutation)
- Your dog’s age and weight
- Other parasites in your area
- Your dog’s preferences (will they take a pill? hate topicals?)
- Your lifestyle (can you remember monthly applications?)
- Budget considerations
My Personal Experience
I’ve tried several heartworm preventatives with my own dogs over the years. My Border Collie mix couldn’t tolerate ivermectin products due to suspected MDR1 sensitivity, so we switched to Sentinel with great results. My Lab, on the other hand, does fine with Heartgard Plus and actually gets excited when he sees the package come out each month!
When my senior dog developed kidney issues, our vet recommended switching preventatives to reduce strain on his system. The point is, what’s “safest” might change throughout your dog’s life.
The Bottom Line
The safest heartworm medication is one that:
- Is appropriate for your dog’s specific health needs
- Has been prescribed by your veterinarian
- You will administer consistently as directed
Remember, all heartworm preventatives require a prescription from your veterinarian, which typically means an annual heartworm test. This testing is crucial, as giving preventatives to an already-infected dog can cause serious complications.
At the end of the day, the “safest” option is working closely with your vet and being consistent with whichever medication you choose. After all, the real danger isn’t in the minor differences between these well-tested medications—it’s in not providing any protection at all.
Your furry friend is counting on you to make the right choice for their long-term health and wellbeing. Don’t they deserve the best protection you can give them?
Delivered every month.
Most heartworm preventatives come in packs of three or six. That means pet parents have to remember to give their dogs their treatment every month.
Look for a product that does the work for you by delivering your pet’s dose every month right when they need it.
Is heartworm treatment the same as prevention?
No. Heartworm treatment is for dogs infected with heartworm disease. Heartworm prevention medication is for healthy dogs who are not heartworm-positive.