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Dog Flea & Tick Preventive Size Picker — NexGard, Bravecto, Frontline, K9 Advantix

Which NexGard, Bravecto, Frontline, or K9 Advantix size fits your pup’s weight? This picker maps your dog’s lbs to the manufacturer-matched chew or topical tier. Never split a chew or apply half a tube — the active ingredient is calibrated for the entire weight band. Year-round flea and tick prevention is the Companion Animal Parasite Council standard, even in cold climates.

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Correct product size
NexGard — 24.1–60 lb
For a dog weighing 25 lb

All NexGard sizes

  • 4–10 lborange
  • 10.1–24 lbblue
  • 24.1–60 lbpurple
  • 60.1–121 lbred
Never split tablets or apply half a tube. Under-dosing fails to protect; over-dosing can cause toxicity. If weight is between sizes, use the larger.

Oral chew vs topical spot-on: which flea/tick preventive should you pick?

AspectOral chew (NexGard, Bravecto)Topical spot-on (Frontline, K9 Advantix)
Duration1 month (NexGard) — 3 months (Bravecto)1 month
Works throughBloodstream (kills on bite)Skin oils (kills on contact)
Swim / bath proofYes — fully systemicWait 48h after application
Tick protectionYes — also prevents Lyme transmission windowYes — repels before bite
Best forActive swimming dogs, multi-pet homesMosquito-heavy zones (K9 Advantix)

Flea / tick preventive terminology

Isoxazoline
Drug class behind NexGard, Bravecto, Simparica — kills fleas and ticks by binding insect GABA receptors.
Spot-on
Topical preventive applied between the shoulder blades; spreads via skin oils across the body.
Weight tier
Manufacturer-defined dose bracket — splitting between tiers underdoses and creates resistance pressure.

Frequently Asked Questions

Which flea preventive is best for my dog?

Depends on lifestyle. NexGard and Bravecto are oral chews (monthly/12-weekly); Frontline Plus is topical monthly; K9 Advantix also repels mosquitoes and ticks. Consult your vet for region-specific recommendations (Lyme areas: tick-specific products).

What if my dog is between sizes?

Use the LARGER size. Under-dosing fails to kill fleas/ticks; slight over-dosing within product ranges is safe. Never split doses or mix products.

Can I give half a NexGard chew?

No. NexGard chews are dosed to provide the correct mg/kg. Splitting one chew gives an unknown dose. Always use the correct-size chew for your dog's weight.

How often should I apply flea preventive?

Monthly for most topicals (Frontline, Advantage, K9 Advantix) and oral chews (NexGard, Credelio). Bravecto chews last 12 weeks; Bravecto topical 12 weeks. Year-round application is CAPC-recommended even in cold climates.

Sources & References

  1. [1]
    CAPC Guidelines — Flea & Tick Prevention — Companion Animal Parasite Council
  2. [2]
  3. [3]

Common mistakes to avoid

  • Stopping preventive in winter in warm climates (south of Mason-Dixon) — fleas thrive year-round.
  • Applying topical after a bath too soon — most topicals need 48h of natural skin oils to distribute.
  • Using old or expired product — active ingredients degrade after 2-3 years.

When to call the vet immediately

  • Tick found attached >24 hours — increased Lyme, Rocky Mountain spotted fever risk. Save the tick in a bag and call your vet.
  • Severe reaction at application site — switch to oral preventive (Bravecto, NexGard, Simparica).

Pro tips

  • Oral preventives (Bravecto) can be 2-hour kill for ticks vs 8-12 hours topical — important in Lyme-heavy regions.
  • Year-round heartworm + flea/tick combo is cheapest via Chewy or PetRx ($15-30/month depending on size).
  • Treat the house if there’s a flea outbreak — the pet is 10% of the problem, eggs in carpet are 90%.