A label-based guide to NexGard Plus for dogs, including parasite coverage, safety cautions, heartworm testing, and how it differs from regular NexGard.

Parasite prevention should be selected with your dog's current weight, age, heartworm test status, neurologic history, exposure risk, and other medications in mind.

NexGard Plus is a prescription monthly chewable for dogs that combines afoxolaner, moxidectin, and pyrantel. The easiest way to understand it is this: regular NexGard is a flea and tick product, while NexGard Plus adds heartworm prevention and treatment/control of certain adult roundworms and hookworms.

That added coverage can simplify prevention for many dogs, but it also adds decision points. A dog should be tested for existing heartworm infection before use, and dogs with seizure or neurologic history need a label-aware risk conversation because afoxolaner is an isoxazoline.

What NexGard Plus covers

The U.S. label says NexGard Plus is for oral use in dogs only and is restricted to use by or on the order of a licensed veterinarian. It is labeled for dogs and puppies 8 weeks of age and older that weigh at least 4 lb.

Parasite or risk	Label-based coverage	Practical note
Heartworm disease	Prevention of heartworm disease caused by Dirofilaria immitis	Dogs should be tested for existing heartworm infection before administration. It is not effective against adult heartworms.
Fleas	Kills adult fleas and treats and prevents flea infestations	Flea control is often household-wide, especially when cats or untreated dogs are present.
Ticks	One-month treatment and control of black-legged, brown dog, American dog, lone star, Gulf Coast, and longhorned tick infestations	Tick risk is regional. Your clinic may tailor product choice to local tick species.
Lyme-related claim	Prevention of Borrelia burgdorferi infections as a direct result of killing Ixodes scapularis vector ticks	This is not a Lyme disease treatment and does not replace tick checks or vaccination discussions where relevant.
Adult hookworms	Treatment and control of adult Ancylostoma caninum, Ancylostoma braziliense, and Uncinaria stenocephala	Persistent hookworm problems may need fecal testing, environmental control, and additional treatment.
Roundworms	Treatment and control of Toxocara canis and Toxascaris leonina	Puppies and high-exposure dogs may still need fecal monitoring.

What it does not cover

NexGard Plus is not a universal parasite medication. It does not replace all deworming, diagnostic testing, or environmental control. It is not labeled for cats, not effective against adult heartworms, and not a treatment for heartworm-positive dogs.

It also should not be treated as interchangeable with products sold in other countries under similar brand names. Labels and ingredient combinations can differ by market. Use the product prescribed by your veterinarian.

NexGard Plus versus regular NexGard

Feature	NexGard Plus	Regular NexGard
Active ingredients	Afoxolaner, moxidectin, pyrantel	Afoxolaner
Fleas and ticks	Yes, monthly	Yes, monthly
Heartworm prevention	Yes	No
Roundworm/hookworm treatment and control	Yes, for labeled species/stages	No
Heartworm test before use	Yes, per label	Heartworm testing still matters for the dog's separate heartworm plan
Best fit	Owner wants one monthly chew for broad parasite prevention	Dog already has a separate heartworm/deworming plan or needs flea/tick-only coverage

If you are comparing NexGard Plus with Simparica Trio, see NexGard Plus vs Simparica Trio. If you are comparing regular NexGard with Bravecto for flea and tick control, see Bravecto vs NexGard.

Safety and monitoring

Afoxolaner is an isoxazoline. FDA's isoxazoline fact sheet says the class has been associated with neurologic adverse reactions including tremors, ataxia, and seizures in some dogs and cats, while also noting that these products are considered safe and effective for many animals. The NexGard Plus label states that afoxolaner has been associated with adverse neurologic reactions and should be used with caution in dogs with a history of seizures or neurologic disorders.

The NexGard Plus label says safe use has not been evaluated in breeding, pregnant, or lactating dogs. That does not mean every such dog will have a problem; it means the evidence on the label is limited and the veterinarian should make an individualized decision.

In a field safety and effectiveness study, the label lists diarrhea, vomiting, lethargy, itching, dermatitis, anorexia, and muscle tremor among observed reactions. Contact your veterinarian if your dog has repeated vomiting, severe diarrhea, marked lethargy, intense itching, swelling, hives, tremors, wobbliness, seizure activity, or any sign that feels abnormal after dosing. Seizures, collapse, trouble breathing, or pale gums are emergency signs.

Heartworm testing is not optional context

Because NexGard Plus includes heartworm prevention, the heartworm part of the label matters. The label says dogs should be tested for existing heartworm infection before administration and that infected dogs should be treated with an adulticide at the discretion of the veterinarian. NexGard Plus is not effective against adult D. immitis.

FDA consumer guidance and CAPC guidelines both support year-round heartworm prevention and routine testing. This is why clinics may require a heartworm test before approving refills, especially if doses were missed, records are unclear, or the dog is new to the practice.

Practical questions for your vet

Is my dog's heartworm test current enough to start or continue NexGard Plus?
Does my dog's neurologic history make an isoxazoline product a poor fit?
Is the 4 lb minimum and current weight band still appropriate for my dog?
Which ticks are most relevant in our area?
Should I still run fecal testing if this product covers some roundworms and hookworms?
What is the plan if my dog vomits after the chew, refuses part of it, or misses a month?