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Veterinarian-Reviewed: Top 5 Oral Heartworm Preventives for Dogs in Canada (2025) — Compare Heartgard Plus, Interceptor Plus, Sentinel Spectrum, NexGard Spectra & Simparica Trio

Published on Thursday, August 21, 2025

Oral heartworm preventives are monthly and extended-release medications that stop heartworm disease by eliminating infective larvae before they mature into adults. In Canada in 2025, the category includes classic single-purpose chewables and a growing number of combination tablets that also address intestinal worms and provide flea and tick control. Consumers are increasingly choosing oral preventives for convenience, palatability, predictable dosing, and the ability to combine multiple protections into a single monthly tablet. Veterinary guidance, local heartworm risk, product safety profile for specific breeds, and ease of administration are key drivers in purchase decisions, while online availability and subscription services have made consistent monthly compliance simpler for Canadian pet owners.

Quick Menu

1. Best Simple Heartworm Preventive

2. Best for Broad Intestinal Parasite Coverage

3. Best Heartworm + Flea Egg Control

4. Best Flea/Tick + Heartworm Combo

5. Best Comprehensive Broad-Spectrum Preventive

1
BEST SIMPLE HEARTWORM PREVENTIVE

Heartgard Plus Chewables

Heartgard Plus Chewables

Heartgard Plus Chewables has long been a market staple for oral heartworm prevention, combining ivermectin with pyrantel to protect against heartworm, roundworms and hookworms. Its position rests on decades of clinical use and a typically lower per-dose cost compared with newer combination chewables, making it a budget-friendly baseline option versus broader-spectrum products like Simparica Trio and NexGard Spectra that also address fleas and ticks.

4.7
★★★★☆

  • Heart-focused protection

  • Dog-approved taste

  • Heart-focused protection

  • Dog-approved taste

Review Summary

88%

"A long-trusted monthly chewable praised for easy dosing and reliable heartworm prevention; most owners report good palatability with only rare side effects."

  • Monthly simplicity

  • Monthly chewable with ivermectin + pyrantel to prevent heartworm disease and treat common intestinal roundworms.

  • Monthly simplicity

  • Monthly chewable with ivermectin + pyrantel to prevent heartworm disease and treat common intestinal roundworms.

Increased Safety & Security

Time-Saving Convenience

Heartgard Plus Chewables has long been a market staple for oral heartworm prevention, combining ivermectin with pyrantel to protect against heartworm, roundworms and hookworms. Its position rests on decades of clinical use and a typically lower per-dose cost compared with newer combination chewables, making it a budget-friendly baseline option versus broader-spectrum products like Simparica Trio and NexGard Spectra that also address fleas and ticks.

  • Heart-focused protection

  • Dog-approved taste

  • Monthly simplicity

  • Monthly chewable with ivermectin + pyrantel to prevent heartworm disease and treat common intestinal roundworms.

  • Beef-flavored, easy-to-administer tablet many dogs accept readily.

  • Heart-focused protection

  • Dog-approved taste

  • Monthly simplicity

  • Monthly chewable with ivermectin + pyrantel to prevent heartworm disease and treat common intestinal roundworms.

  • Beef-flavored, easy-to-administer tablet many dogs accept readily.

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$150-240 CAD

2
BEST FOR BROAD INTESTINAL PARASITE COVERAGE

Interceptor Plus

Interceptor Plus

Interceptor Plus pairs milbemycin oxime with praziquantel to deliver reliable monthly heartworm prevention plus expanded tapeworm and intestinal parasite coverage. It holds a market-leader role for owners prioritizing stronger gastrointestinal parasite control than Heartgard, while generally being more affordable than multifunctional flea-and-tick combination chews such as NexGard Spectra or Simparica Trio.

4.5
★★★★☆

  • Broad parasite control

  • Tapeworm takedown

  • Broad parasite control

  • Tapeworm takedown

Review Summary

83%

"Well-regarded broad-spectrum preventive that covers heartworm and many intestinal parasites; users praise efficacy but some report picky dogs or occasional gastrointestinal upset."

  • Easy monthly chew

  • Combines milbemycin oxime and praziquantel to prevent heartworm and treat tapeworms plus other intestinal parasites.

  • Easy monthly chew

  • Combines milbemycin oxime and praziquantel to prevent heartworm and treat tapeworms plus other intestinal parasites.

Increased Safety & Security

Time-Saving Convenience

Interceptor Plus pairs milbemycin oxime with praziquantel to deliver reliable monthly heartworm prevention plus expanded tapeworm and intestinal parasite coverage. It holds a market-leader role for owners prioritizing stronger gastrointestinal parasite control than Heartgard, while generally being more affordable than multifunctional flea-and-tick combination chews such as NexGard Spectra or Simparica Trio.

  • Broad parasite control

  • Tapeworm takedown

  • Easy monthly chew

  • Combines milbemycin oxime and praziquantel to prevent heartworm and treat tapeworms plus other intestinal parasites.

  • Monthly chewable available in multiple dose sizes to suit different dog weights.

  • Broad parasite control

  • Tapeworm takedown

  • Easy monthly chew

  • Combines milbemycin oxime and praziquantel to prevent heartworm and treat tapeworms plus other intestinal parasites.

  • Monthly chewable available in multiple dose sizes to suit different dog weights.

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$180-260 CAD

3
BEST HEARTWORM + FLEA EGG CONTROL

Sentinel Spectrum

Sentinel Spectrum

Sentinel Spectrum combines milbemycin oxime, lufenuron and praziquantel to prevent heartworm, interrupt the flea life cycle by inhibiting egg development, and treat tapeworms—offering a unique technical advantage for households focused on reducing flea populations in the environment. It provides broader parasite coverage than Heartgard and better flea-egg control than Interceptor Plus, though it does not directly kill adult fleas or ticks like NexGard Spectra or Simparica Trio.

4.3
★★★★☆

  • Flea egg blocker

  • Wide-spectrum defense

  • Flea egg blocker

  • Wide-spectrum defense

Review Summary

78%

"Valued for broad parasite coverage including flea egg and tapeworm control; owners like the convenience but note higher cost, larger tablet size, and occasional palatability issues."

  • Tail-wag flavor

  • Includes milbemycin oxime for heartworm prevention and lufenuron to inhibit flea egg development.

  • Tail-wag flavor

  • Includes milbemycin oxime for heartworm prevention and lufenuron to inhibit flea egg development.

Increased Safety & Security

Time-Saving Convenience

Sentinel Spectrum combines milbemycin oxime, lufenuron and praziquantel to prevent heartworm, interrupt the flea life cycle by inhibiting egg development, and treat tapeworms—offering a unique technical advantage for households focused on reducing flea populations in the environment. It provides broader parasite coverage than Heartgard and better flea-egg control than Interceptor Plus, though it does not directly kill adult fleas or ticks like NexGard Spectra or Simparica Trio.

  • Flea egg blocker

  • Wide-spectrum defense

  • Tail-wag flavor

  • Includes milbemycin oxime for heartworm prevention and lufenuron to inhibit flea egg development.

  • Also contains praziquantel for tapeworm treatment, offering multi-parasite protection in one monthly chew.

  • Flea egg blocker

  • Wide-spectrum defense

  • Tail-wag flavor

  • Includes milbemycin oxime for heartworm prevention and lufenuron to inhibit flea egg development.

  • Also contains praziquantel for tapeworm treatment, offering multi-parasite protection in one monthly chew.

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$200-300 CAD

4
BEST FLEA/TICK + HEARTWORM COMBO

NexGard Spectra

NexGard Spectra

NexGard Spectra blends the afoxolaner ectoparasiticide with milbemycin oxime to deliver both monthly heartworm prevention and rapid flea and tick kill in a single oral chew, appealing to owners who want consolidated protection. Its technical edge is proven adulticidal activity against fleas and ticks, which can reduce the need for additional topical or collar-based products and offer cost savings compared with non-ectoparasitic heartworm-only options like Heartgard or Interceptor Plus.

4.6
★★★★☆

  • Flea & tick killer

  • Heartworm prevention

  • Flea & tick killer

  • Heartworm prevention

Review Summary

86%

"Combines flea/tick protection with heartworm and intestinal worm control in a single chewable and is widely praised for effectiveness and taste; a minority report vomiting or lethargy after dosing."

  • Treat-like beef

  • Monthly chewable combining afoxolaner to kill fleas and ticks with milbemycin oxime for heartworm prevention.

  • Treat-like beef

  • Monthly chewable combining afoxolaner to kill fleas and ticks with milbemycin oxime for heartworm prevention.

Increased Safety & Security

Time-Saving Convenience

NexGard Spectra blends the afoxolaner ectoparasiticide with milbemycin oxime to deliver both monthly heartworm prevention and rapid flea and tick kill in a single oral chew, appealing to owners who want consolidated protection. Its technical edge is proven adulticidal activity against fleas and ticks, which can reduce the need for additional topical or collar-based products and offer cost savings compared with non-ectoparasitic heartworm-only options like Heartgard or Interceptor Plus.

  • Flea & tick killer

  • Heartworm prevention

  • Treat-like beef

  • Monthly chewable combining afoxolaner to kill fleas and ticks with milbemycin oxime for heartworm prevention.

  • Provides rapid flea and tick control while also preventing heartworm and treating common intestinal worms (rounds, hooks, whips).

  • Flea & tick killer

  • Heartworm prevention

  • Treat-like beef

  • Monthly chewable combining afoxolaner to kill fleas and ticks with milbemycin oxime for heartworm prevention.

  • Provides rapid flea and tick control while also preventing heartworm and treating common intestinal worms (rounds, hooks, whips).

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$250-360 CAD

5
BEST COMPREHENSIVE BROAD-SPECTRUM PREVENTIVE

Simparica Trio

Simparica Trio

Simparica Trio combines sarolaner, moxidectin and pyrantel to provide broad-spectrum monthly protection against heartworm, multiple intestinal worms, and rapid flea and tick control, positioning it as a premium all-in-one oral preventive. Although typically priced higher than single-purpose heartworm pills such as Heartgard, its comprehensive coverage can reduce overall pet-care expenses by replacing separate dewormers and ectoparasite treatments, making it a direct competitor to NexGard Spectra with different active-ingredient advantages.

4.6
★★★★☆

  • Triple-action protection

  • Rapid flea control

  • Triple-action protection

  • Rapid flea control

Review Summary

87%

"Highly-rated once-monthly oral that covers fleas, ticks, heartworm, and intestinal parasites; owners report strong effectiveness and good palatability though a small percentage note adverse reactions in sensitive dogs."

  • Chicken-crave chew

  • Triple-action chewable (sarolaner, moxidectin, pyrantel) offering flea/tick control plus heartworm and intestinal parasite prevention.

  • Chicken-crave chew

  • Triple-action chewable (sarolaner, moxidectin, pyrantel) offering flea/tick control plus heartworm and intestinal parasite prevention.

Increased Safety & Security

Time-Saving Convenience

Simparica Trio combines sarolaner, moxidectin and pyrantel to provide broad-spectrum monthly protection against heartworm, multiple intestinal worms, and rapid flea and tick control, positioning it as a premium all-in-one oral preventive. Although typically priced higher than single-purpose heartworm pills such as Heartgard, its comprehensive coverage can reduce overall pet-care expenses by replacing separate dewormers and ectoparasite treatments, making it a direct competitor to NexGard Spectra with different active-ingredient advantages.

  • Triple-action protection

  • Rapid flea control

  • Chicken-crave chew

  • Triple-action chewable (sarolaner, moxidectin, pyrantel) offering flea/tick control plus heartworm and intestinal parasite prevention.

  • Covers a wide range of parasites in one monthly dose, including fleas, ticks, heartworm, roundworms and hookworms.

  • Triple-action protection

  • Rapid flea control

  • Chicken-crave chew

  • Triple-action chewable (sarolaner, moxidectin, pyrantel) offering flea/tick control plus heartworm and intestinal parasite prevention.

  • Covers a wide range of parasites in one monthly dose, including fleas, ticks, heartworm, roundworms and hookworms.

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$300-420 CAD

What the Research and Guidelines Say About Oral Heartworm Prevention

Scientific evidence and professional guidelines support monthly administration of macrocyclic lactone drugs to prevent the development of heartworm disease by killing early larval stages. Peer-reviewed clinical trials and regulatory reviews confirm that properly dosed oral preventives are effective and generally well tolerated. Combination products that pair heartworm prevention with intestinal parasite control or flea and tick agents reduce polypharmacy and can improve owner adherence. Safety considerations and rare breed sensitivities are described in the literature, so veterinarian assessment remains important before selecting a product.

Veterinary guidelines, including those from leading heartworm experts, recommend year-round prevention in areas of risk and seasonal prevention where appropriate.

Macrocyclic lactone compounds such as ivermectin, milbemycin oxime, and moxidectin target early larval stages and form the backbone of effective heartworm prophylaxis supported by clinical trials.

Combination formulations (for example those adding isoxazolines or praziquantel) have been evaluated in controlled studies and show broad parasite coverage with convenience advantages.

Clinical safety and pharmacovigilance reports emphasize correct dosing by weight and note breed-specific precautions, particularly for some herding breeds with known sensitivity to certain compounds.

Real-world adherence studies show that simplified regimens and palatable chewables increase on-time dosing, which directly improves protective effectiveness.

In Canada in 2025, oral heartworm preventives remain a practical and effective cornerstone of canine parasite control. The top options covered on this page — Heartgard Plus Chewables, Interceptor Plus, Sentinel Spectrum, NexGard Spectra, and Simparica Trio — each offer reliable heartworm protection with differing extras for intestinal parasites, fleas, and ticks. For many owners seeking an all-in-one monthly chew that combines heartworm, intestinal parasite, and flea and tick control, Simparica Trio is often the best single-tablet choice, although individual recommendations vary by dog and region. We hope you found what you were looking for; if you want to refine or expand your search, use the site search or product filters to compare dosages, age and weight limits, pricing, and veterinary guidance.

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  • Combination Broad Spectrum Parasite Preventives for Dogs
  • Environmental Flea Control Products for Dog Homes

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