Flea and Tick Prevention for Dogs With Seizures: Vet Guide

Dogs with seizures still need flea and tick prevention; which product is safest depends on their seizure history, so let a vet who knows it choose.

If a seizure lasts more than five minutes, or your dog has more than one seizure in a short span, go to an in-person emergency vet now.

Seizing right now? Keep your dog from falling or hitting anything, keep your hands away from the mouth and time it; full steps are below.

Why do dogs with seizures still need flea and tick prevention?

Because the parasites do not care about the diagnosis. The Merck Veterinary Manual notes that fleas cause flea allergy dermatitis, transmit the tapeworm Dipylidium caninum and can cause iron-deficiency anemia in heavily infested animals, especially young ones. Flea eggs, larvae and pupae develop off the dog, in carpets and upholstery, which is why Merck states that lifelong flea control is required to prevent reinfestation.

Cornell's Riney Canine Health Center calls year-round prevention best practice because ticks can be active at 40 degrees Fahrenheit and fleas thrive indoors. In Florida that means fleas and ticks all year; in New York and Virginia the tick season is long. The RexVet flea and tick prevention page covers how a video visit works.

What does the FDA isoxazoline alert actually say?

In September 2018 the FDA issued an Animal Drug Safety Communication alerting pet owners and veterinarians to the potential for neurologic adverse events (muscle tremors, ataxia and seizures) in dogs and cats treated with isoxazoline-class products. The products named were Bravecto, Nexgard, Simparica, Credelio and the topical Revolution Plus.

The FDA did not ban, recall or warn against these products; it states that they "continue to be safe and effective for the majority of animals". And because the neurologic events were seen consistently across the class, the FDA asked manufacturers to add label information highlighting them. The FDA says veterinarians should review each patient's medical history and decide, with the owner, whether an isoxazoline product is appropriate, and that adverse events should be reported to the manufacturer or the FDA.

What do the product labels say about seizure history?

The NexGard (afoxolaner) label on DailyMed states that the isoxazoline class "has been associated with neurologic adverse reactions including tremors, ataxia, and seizures" and advises to "use with caution in dogs with a history of seizures or neurologic disorders". It adds that seizures have been reported even in dogs without a seizure history.

The label also describes the US field study: dogs with a pre-existing history of seizures experienced seizures after dosing, one on the same day as the first and second doses, and another 19 days after the third dose. Whether the product played a part in any one dog is a judgment for the veterinarian who knows that dog.

These are prescription-only products: the label states that federal law restricts the drug to use by or on the order of a licensed veterinarian. RexVet has pages on Nexgard for dogs, Bravecto for dogs and Simparica for dogs.

Who decides: the veterinarian who knows your dog's seizure history

A caution on a label is not a ban; it tells the prescriber to look at the individual dog first. Cornell adds that isoxazoline chewables "have been associated with a rare occurrence of seizures", and if your dog has a history of seizures you should consult your veterinarian before using them.

What the vet weighs:

How often the seizures happen and how well they are controlled
Which anti-seizure medications your dog takes
Age and breed
Flea and tick pressure where you live in Florida, New York or Virginia
Whether your dog has ever reacted to a dose of any flea or tick product

VCA notes that idiopathic epilepsy is the most common form and is considered inherited; other causes include liver disease, kidney failure, brain tumors, brain trauma and toxins. This article recommends no product as the right flea and tick prevention for dogs with seizures; the prescribing veterinarian makes that call.

If the next dose is due and you are unsure, a RexVet veterinarian licensed in Florida, New York or Virginia can look at your dog by video ($64.99), go through the seizure history and current medications, and talk through the isoxazoline question and the alternatives. If the veterinarian decides medication is appropriate, they can prescribe where state rules allow.

What are the alternatives to isoxazoline chewables, and what are their cautions?

Merck lists the main flea-control drug classes as isoxazolines, fipronil, imidacloprid/dinotefuran, selamectin, flumethrin collar combinations and spinosad. None is a blanket recommendation for a dog with seizures.

Topicals. Cornell notes that permethrin-based topicals repel ticks while fipronil products, such as the one on RexVet's fipronil topical for dogs page, do not. Permethrin products are for dogs only, and Cornell adds that many dog products are not appropriate for cats, so mention any cat in the house before a switch. Most topicals should dry for two days before bathing or swimming. A topical is not automatically isoxazoline-free; some topical combinations contain one, so ask the vet which class a product belongs to.
Collars. Flumethrin/imidacloprid collars must fit properly with skin contact, and Cornell notes that regular submersion in water may shorten their efficacy.

Oral spinosad and plain topical selamectin exist too, with their own limits. None is the obvious choice, so every alternative here comes with the same instruction: ask the vet who knows your dog's seizure history for a switch plan before the next dose is due.

Why should you never stop prevention without a plan?

A gap in Florida, New York or Virginia is not neutral. Fleas return from the eggs and pupae already in the house, and ticks do not wait; the RexVet tick-bite guide covers Lyme and the other tick-borne diseases in each state.

If the alert has made you doubt the product, the fix is a vet-made switch plan timed before the next dose is due, not a skipped dose. The plan may mean staying on the current product or changing class; the veterinarian weighs that against the parasite risk where you live.

Do not stop or change seizure medication on your own

Two separate instructions. First, the anti-seizure medication: VCA states that anticonvulsant medication that is started and then discontinued may raise the risk of more severe seizures, so never stop, skip, reduce or change it without the vet. Second, the flea and tick product: do not stop or switch that on your own either.

Tell the vet every anti-seizure drug your dog takes and how the seizures have been lately. See the RexVet dog seizures and epilepsy guide and the post on what dog seizures look like and what owners should do.

What should you do if your dog has a seizure after a flea or tick dose?

Keep your dog from falling or knocking objects onto itself (VCA's first instruction): move them away from stairs and water.
Keep your hands away from the mouth. A seizing dog can bite without meaning to.
Time the seizure.
Note the product and the date of the last dose.

Go to an in-person emergency clinic now, not a video visit, if the seizure lasts more than five minutes (status epilepticus), if there is more than one in a short span (cluster seizures), if it is your dog's first-ever seizure, or if your dog is not recovering normally afterward. VCA says status epilepticus and cluster seizures require immediate veterinary treatment.

Afterward, report the reaction to the manufacturer or the FDA, and tell your veterinarian what happened before any next dose is due.

When does an online vet visit help, and when should you go in person?

Go in person, to an emergency clinic, for an active seizure, cluster seizures, status epilepticus, a first-ever seizure, or a dog not recovering normally. Telehealth is for triage and non-emergency planning; a video visit cannot stop a seizure or examine a collapsed dog.

A video visit fits the other situation: the chewable is due, the alert is worrying, and you want a plan built on the seizure history and current medications so prevention does not lapse. RexVet veterinarians are licensed in Florida, New York and Virginia only.

If your dog is stable and the next dose is coming up, a RexVet veterinarian licensed in Florida, New York or Virginia can look at your dog by video ($64.99) and help you plan before it is due.

Frequently asked questions

Can a dog with seizures take Nexgard, Bravecto, Simparica or Credelio?

Only if the veterinarian who knows your dog's seizure history decides it is appropriate. The Nexgard label, for example, says to use the product with caution in dogs with a history of seizures or neurologic disorders, and the FDA says these products continue to be safe and effective for the majority of animals while asking vets to review each patient's history first.

Did the FDA ban or recall isoxazoline flea and tick products?

No. In its September 2018 alert the FDA stated that the products "continue to be safe and effective for the majority of animals" and asked manufacturers to add label information about the neurologic events.

Should I stop my dog's flea and tick prevention if he has epilepsy?

Not on your own. Merck notes that lifelong flea control is required to prevent reinfestation, and a gap in Florida, New York or Virginia lets fleas and ticks back in. Ask the vet who knows your dog's seizure history for a plan before the next dose is due; that plan may or may not involve a change.

What are the alternatives to isoxazoline chewables for a dog with seizures?

Other classes exist, including fipronil or permethrin topicals, flumethrin/imidacloprid collars, oral spinosad and topical selamectin, and none is a blanket recommendation. Each has cautions of its own (Cornell: cat households, two days of drying before bathing or swimming, collar fit and water). The vet chooses with your dog's seizure history in mind.

What should I do if my dog has a seizure after a flea and tick dose?

Keep your dog from falling or hitting objects, keep your hands away from the mouth, time the seizure and note the product and dose date. A seizure over five minutes, more than one in a short span, a first-ever seizure or a dog not recovering normally means an in-person emergency clinic now. Afterward, report the reaction to the manufacturer or the FDA and tell your vet before the next dose is due.