NexGard for Dogs: Uses, Dosage and Side Effects

Veterinarians prescribe NexGard® to:

• Kill adult fleas
• Prevent flea infestations
• Kill ticks that transmit diseases
• Help manage flea allergy dermatitis as part of a comprehensive control plan

NexGard® works systemically, meaning parasites must bite the dog to be exposed to the medication. Because of this:

• It does not repel fleas or ticks
• Parasites must attach briefly before dying

NexGard® does not:

• Treat internal parasites (worms)
• Replace environmental flea control in heavy infestations
• Prevent mosquito-borne diseases

Mechanism of action:

• Afoxolaner interferes with the regulation of nerve signals in fleas and ticks.
• This causes overstimulation of the parasite’s nervous system, leading to uncontrolled nerve activity.
• Fleas may become more active just before they die, making them more noticeable on the dog.
• The result is the paralysis and death of the parasite.

Activity persists for approximately 30 days. Here is what pet parents may notice:

• A brief increase in scratching or itching may occur shortly after the first dose
• This is usually temporary and related to flea activity, not a reaction to the medication

Isoxazoline-class drugs, including NexGard®, have been associated with rare neurological adverse events such as tremors. These events can occur even in dogs without a prior history of neurological problems, though they are uncommon.

• Have a history of seizures, tremors, or neurological disorders
• Are under 8 weeks of age
• Weigh less than 2 kg
• Are severely ill or debilitated

NexGard®:

• Should not be combined with other isoxazoline products unless directed
• Does not eliminate the need for regular parasite risk assessment

General principles:

• Tablets should be given whole (do not split unless directed)
• Can be given with or without food
• Observe your dog for a few minutes after dosing to confirm that the tablet has not been dropped, spit out, or partially chewed and lost.
• If vomiting occurs within two hours of administration, or if it is suspected that the full dose was not consumed, contact your veterinarian. Re-dosing with a whole tablet may be recommended.
• If vomiting occurs more than 2 hours after dosing, re-dosing is generally not required, as the medication is typically absorbed by then.

Small dogs receive the lowest strength tablet appropriate for their weight range. For most small dogs, this means chewables designed for dogs weighing 1.81-10.89 kg. This contains 11.3-28.3 mg of afoxolaner, depending on the exact weight range. Important points:

• Small dogs are more vulnerable to dosing errors
• Never approximate doses by cutting tablets
• Reweigh dogs regularly, especially during growth or illness

Medium-sized dogs typically tolerate NexGard® well when dosed correctly. Dogs in this category usually weigh 10.91-27.21 lbs. They can receive a NexGard® chewable containing 68 mg of afoxolaner, matched to their exact body weight. Veterinary guidance may include:

• Monitoring for gastrointestinal or neurological signs during the first few doses
• Reinforcing strict monthly scheduling

Commonly reported side effects:

• Mild vomiting
• Diarrhoea
• Reduced appetite
• Lethargy
• Flaky/dry skin
• Dandruffy coat

These effects are usually mild and self-limiting. Less common but more serious side effects:

• Tremors
• Muscle twitching
• Seizures
• Loss of coordination
• Restlessness or hyperactivity
• Dermatitis (including papules, rashes)
• Allergic reactions (including swelling, hives)

If a dose of NexGard® is missed:

• Give the missed dose as soon as you remember
• Resume monthly dosing from the new date
• Do not double the dose

Contact your veterinarian promptly if your dog experiences these signs of emergency:

• Persistent vomiting or diarrhoea
• Tremors, seizures, or unusual coordination problems
• Severe lethargy or weakness
• Signs of an allergic reaction (facial swelling, hives, difficulty breathing)
• Accidental ingestion of multiple tablets

Accidental overdose may occur if multiple tablets are ingested or if the incorrect tablet strength is given. Possible signs of overdose include:

• Severe gastrointestinal upset
• Neurological signs such as tremors or seizures
• Excessive drooling or agitation

To maintain safety and effectiveness:

• Store at room temperature
• Keep tablets in the original blister packaging
• Protect from moisture and heat
• Keep out of reach of pets and children
• Do not use expired tablets