Best Online Pet Pharmacy 2026: Canada Pet Care vs US Alternatives

The Seresto Flea & Tick Collar is the only OTC (no prescription) product in this comparison — available without a veterinary prescription, making it accessible for pet owners who want flea and tick protection without a vet visit. The collar releases imidacloprid (kills fleas) and flumethrin (repels and kills ticks) continuously for up to 8 months. At $60 for 8 months, it's the lowest cost-per-month protection here. Limitation: the Seresto collar does not address heartworm, intestinal parasites, or flea eggs — for comprehensive parasite prevention, a prescription product covering heartworm is still needed. The collar was subject to a temporary EPA review for adverse event reports; the EPA concluded it can remain on the market with enhanced warning labels. Common complaint: some dogs remove collars or react to the collar material (skin irritation at contact point); monitor the neck area for the first 2 weeks.

Heartgard Plus is the prescription standard for heartworm prevention in the US — monthly chewables containing ivermectin (kills heartworm larvae) and pyrantel (treats roundworm and hookworm infections). At $110 for 12 months, it's the most comprehensive heartworm coverage per dollar here. Prescription requirement means an up-to-date heartworm test is typically required before a veterinarian will prescribe — annual testing is standard of care even for year-round prevention. Important: Heartgard Plus does NOT provide flea or tick protection — it addresses heartworm and intestinal worms only. For complete protection, pair with a separate flea/tick product (Seresto collar, Bravecto, or NexGard). Common note: ivermectin is contraindicated in some herding breeds (Collies, Australian Shepherds, others) with MDR1/ABCB1 gene mutations at standard doses — confirm with your veterinarian before use in these breeds. The most established, longest-market-history heartworm prevention product available.

Bravecto Chews are the 12-week oral flea and tick treatment — one chew provides 12 weeks of protection versus monthly dosing for NexGard or other monthly treatments. At $100 for a 2-pack (6 months of protection), the convenience of quarterly dosing versus monthly reduces the risk of missed doses. Fluralaner provides effective coverage against fleas and four tick species (Ixodes scapularis, Dermacentor variabilis, Amblyomma americanum, Rhipicephalus sanguineus). Prescription required. Like all oral flea/tick products, Bravecto does not provide heartworm protection — pair with Heartgard or another heartworm preventive. Common complaint: some dogs experience vomiting or diarrhea in the first 24 hours after the first dose; administer with food to reduce GI upset. Bravecto's 12-week duration is the primary differentiator over NexGard — if reducing monthly administration is a priority, Bravecto is the practical choice.

NexGard Chewables are the monthly oral flea and tick treatment — the most widely prescribed oral flea and tick product in the US since its launch. Afoxolaner provides coverage against fleas and four tick species. At $123 for 6 months, it's $23 more than the Bravecto 2-pack for equivalent duration of protection. The monthly dosing frequency allows easier monitoring of medication compliance compared to the 12-week Bravecto interval. Prescription required. NexGard does not prevent heartworm — pair with Heartgard Plus or another heartworm preventive for complete parasite coverage. The NexGard PLUS formulation (separate product) combines afoxolaner with milbemycin for heartworm, roundworm, and hookworm coverage in one monthly chew — a practical choice for reducing pill count. Common complaint: some dogs experience lethargy or vomiting after the first dose; administer with food. Longest track record of any isoxazoline flea/tick oral product.

Sentinel Spectrum is the most comprehensive single-product parasite prevention here — monthly chewable combining milbemycin oxime (heartworm prevention + roundworm/hookworm treatment), lufenuron (prevents flea eggs from hatching, breaking the flea life cycle), and praziquantel (tapeworm treatment). At $140 for 12 months, it costs $30 more than Heartgard Plus for the added flea reproduction control and tapeworm coverage. Critical note: Sentinel Spectrum prevents flea REPRODUCTION but does not kill adult fleas — in environments with existing flea populations, Sentinel must be paired with a flea-killing product (Seresto collar, or a separate flea-kill treatment) until the existing adult flea population dies off. This is the most common source of owner confusion: dogs on Sentinel still have adult fleas because Sentinel kills eggs, not adults. Once the adult population cycles out (6-8 weeks), flea-free maintenance works well. Best for environments with low flea pressure where prevention rather than active flea killing is the goal.