FDA Approves NexGard Chewables for prevention of infections that cause Lyme disease in dogs
The U.S. Food and Drug Administration has approved NexGard for the prevention of Borrelia burgdorferi infections by this medication killing Ixodes scapularis, a type of Black-legged tick that carries the bacteria. The Borrelia bacteria is an infectious bacteria that causes Lyme disease in dogs. The black-legged tick is also known as the deer tick. Lyme disease can cause serious illness in both animals and people. Fever, loss of appetite, lameness, joint swelling, and lethargy are common warning signs in dogs. In severe cases, Lyme disease can affect the kidneys, nervous system, or heart. Learn more about Lyme disease on our blog.
NexGard is a prescription flea and tick preventative for dogs contains afoxolaner. This medication works by absorbing into the dog’s bloodstream to treat and prevent flea infestations and kill ticks. Effective against Black-legged tick, American Dog tick, Lone Star tick, and Brown dog tick.
NexGard is formulated to give protection for 30 days and is a soft, beef-flavored chew. Dogs can also be bathed or go swimming at any time because it is given orally and does not create a residue on the skin or hair coat. It is also designed for safe administration alongside heartworm and other medications. NexGard chewables can be given to dogs 8 weeks of age and older and weighing 4 pounds or greater. It is available in four sizes: 4-10 lbs, 10-24 lbs, 24-60 lbs, and 60-121 lbs and three, six, or 12-month quantities.
NexGard Chewables Approved by Dog Owners
Check out what other dog owners are saying about it. We’ve included some reviews straight from our website.
Convenient Marianne Verified Buyer
My golden had Lyme disease a few years ago and this product, Nexgard, has kept her protected. We have a large deer population in our neighborhood and I feel confident using Nexgard
Works great! Jack Verified Buyer
My German shepherd is 2 years old and he has yet to get a tick because l have given him nexgard since he was a puppy.
Awesome, fast results Kim Verified Buyer
We have been having such a difficult time with ticks this year even though we’ve been using both a topical treatment along with a Seresto Flea collar. Our golden retriever has been on NexGard since the beginning of the month and we are thoroughly pleased with the results, not 1 flea since we started and no itching either. We’ll definitely continue to use both VETRX Direct and NexGard, I highly recommend it.
Lyme disease, also called Borreliosis, is an infectious disease caused by Borrelia bacteria. The disease is transmitted to humans and animals through the bite of an affected tick. A tick first picks up the bacteria by attaching to infected animals like deer, mice, or birds. The deer tick and black-legged tick are the ticks that commonly carry and spread the Borrelia bacteria, which is responsible for Lyme disease. Learn how ticks spread disease from the CDC. Ticks are found in forests or grassy, wooded areas near marshes, rivers, lakes or oceans. Deer ticks live in moist, shady areas near ground level, and cling to tall grass and brush.
Symptoms and Treatment
Photo courtesy CDC
The warning signs and symptoms of Lyme disease in dogs and cats can vary. Symptoms can appear months after a tick bite, may be vague, and often mimic other diseases leading to difficult or a potential misdiagnosis. If left untreated, Lyme infections can affect the kidneys, nervous system, and heart. Veterinarians can take an antibody blood test, which can show whether an animal has been exposed to the Borrelia bacteria and help determine an appropriate treatment. Common signs include:
Painful or swollen joints
Loss of appetite
Swollen lymph nodes
Antibiotics are commonly prescribed to treat Lyme infections in dogs and cats. Some animals may require more than one round of treatment to lessen signs of infection. Antibiotics may not eliminate the infection completely, which can lead to symptom flare-ups or permanent conditions.
Who Is at Risk?
Animals that spend time outdoors, especially in tick-infested areas, have a higher risk of exposure. Both people and animals may be bitten by ticks during outdoor activities or even while spending time in their own back yards. View forecasts for Lyme Disease in your area.
The best way to protect your pet from disease is avoidance from ticks and taking precautionary steps. Start by using a reliable tick-preventative product for your pet. Fortunately, there are highly effective preventative products for both cats and dogs. Preventatives must be used consistently in order to provide effective longterm tick control. It is best to talk with your veterinarian about which one is right for your pet and your area of the country. It is important that the product you use repels the types of ticks in your area. If you live in a climate with freezing temperatures, don’t be fooled, ticks can hibernate over the winter.
If spending time outdoors, it’s important to find and remove any ticks on you or your pet as soon as possible. The longer a tick stays attached, the more likely it will transmit disease. Pets can bring Lyme infected ticks into the house, which can then attach to other animals and people, spreading the disease.
How To Check Your Pet For Ticks:
Run your hands slowly over your dog or cat’s entire body feeling for bumps or lumps. Ticks can be very small and like to hide out inside ears, between toes, under the tail and collar, and in the armpit and groin areas. Don’t forget to check yourself too!
Additional Tips to Avoid Ticks
Vaccination. Preventative vaccines are available for dogs. Ask your veterinarian whether a Lyme disease vaccination is appropriate for your dog.
Keep lawns, shrubs, brush, and trees trimmed to help reduce tick populations.
Keep woodpiles neatly stacked and remove leaf piles.
Place a 3 ft barrier of wood chips or gravel between yards and wooded areas to prevent tick migration.
Consider a pesticide application to control an infestation. Use caution with pets.
Lyme Disease Risk to Humans
Dogs and cats cannot directly transmit this disease to humans. Because people and their pets are often together outdoors as well as indoors, a Lyme disease diagnosis for your pet could be a warning for you to consult a physician. Additionally, dogs and cats may bring infected ticks into the household, which can attach to another animal or person, and transmit disease. Learn more about Lyme disease in humans at CDC or Lyme Disease.org
VetRxDirect carries a large selection of tick preventatives for dogs and cats including topicals, oral medications, collars, shampoos, sprays, and products for the home. Visit our website for more information and check out a few we’ve listed below!
Effipro Plus is a topical treatment for cats that kills all stages of fleas and ticks including deer ticks, brown dog ticks, American dog ticks, and lone star ticks. It also kills chewing lice and repels mosquitoes that can carry heartworms. Apply Effipro Plus once a month for long-lasting, waterproof protection.
Bravecto is a prescription strength topical just for cats. Bravecto gives your cat protection against fleas and black-legged ticks (deer ticks) for 12 weeks,and dog ticks for 8 weeks. It contains fluralaner as a long-acting insecticide to not only kill but also help break the life cycle. Bravecto is also designed to eliminate fleas in as little as 8 hours.
NexGard is a prescription, chewable flea and tick preventative for dogs contains afoxolaner It kills adult fleas, black-legged tick, American dog tick, Lone Star tick, and brown dog tick. NexGard is formulated to give protection for 30 days and is FDA Approved to Prevent Lyme Disease
Effitix Plus is a broad spectrum topical for dogs. It kills and repels all life stages of fleas and ticks including brown dog ticks, deer ticks, lone star ticks, and American dog ticks. Effitix Plus also repels and kills mosquitoes that may carry heartworm, repels biting flies, kills lice, and helps control sarcoptic mange.
We know that keeping fleas and ticks away from your pets and out of your home is your priority. There are many different options available to help keep these pests away, and it may be tricky to determine which product does what. Your veterinarian can also help you determine exactly which product will best suit your dog or cat. We’ve put together a list of the different types of flea and tick preventatives and how they work.
These liquid medications come in a tube applicator and are applied to your dog or cat’s skin. Topicals or “Spot Ons” are usually placed by parting the hair at the base of the neck or between the shoulder blades. Depending on the product, the topical medications work 2 ways. Some absorb through the skin into the bloodstream and kill the pest once they bite. Others spread across the body with the natural skin oils and kill or repel the pest on contact. For dogs or cats that are difficult to give oral medications, topical pest treatments are preferred by owners.
These medications come in a soft chew or chewable tablet that your dog or cat can eat like a treat. Once given, the medication circulates in the bloodstream, and when a flea or tick bites your dog, it’s exposed to the pesticide and dies. Oral medications may be preferred over topicals for animals who easily take pills. Owners may come in contact with the liquid while applying it or touching their animal.
Shampoos and Dips
Flea and tick shampoos obviously help clean your dog and cat but more importantly help wash away and kill the nasty pests quickly on contact. Shampoos need to sit for a short period of time before rinsing to allow them to work. Some shampoos stay effective for days after a bath but are ideal for short-term treatment only. Dips are used similarly but are left to dry without rinsing, and are very concentrated.
Flea and tick collars are worn around your dog or cat’s neck and come in adjustable sizes. The collars work against pests by releasing their ingredients over the animal’s skin. Depending on the brand, collars can provide 5-12 months of protection before needing to be replaced. Owners may prefer collars as a “hands-off” approach over administering topical or oral medications.
Fleas and ticks are the most common external parasites on dogs and cats, and the most common nuisance for pet owners. They flourish during the warm weather months but easily hitch rides inside, and can be a year-round problem.
Fleas Are Biting Machines
Can you believe that just one flea can bite up to 400 times a day? So you can imagine just how uncomfortable a flea infestation can be for a dog or cat. Even a few fleas can cause skin problems for your pet and may not be readily observable. Fleas can cause allergic skin reactions in both cats and dogs which may be difficult to tell apart from seasonal allergies. They also carry tapeworm larvae, which can lead to intestinal tapeworm infections. Control of fleas has always been a challenge because only adult fleas live on the pet. Flea eggs, larvae, and pupa live off the pet, outside and in the household.
Ticks: Hardy Disease Carriers
Tick prevention is important because as we know, they carry various diseases that pose serious health risks. Lyme Disease, Rocky Mountain Spotted Fever, and ehrlichiosis are the most common. These diseases can be difficult and expensive to treat and sometimes impossible to cure. The goal is to prevent ticks from getting onto your dog or cat. If you live in a climate that experiences yearly freezing temperatures, you may notice ticks become less active or disappear but don’t be fooled, they can hibernate over the winter.
Fortunately, there are lots of effective preventative medications to help control fleas and ticks. It is best to talk with your veterinarian about which one is right for your dog or cat and your area of the country. We stock a full range of flea and tick treatments to keep your dog and cat safe and healthy.
NexGard for Dogs
NexGard is a prescription, chewable flea and tick preventative. It kills adult fleas and ticks NexGard is formulated to give protection for 30 days and is easy to give with a soft, beef-flavored chew that dogs enjoy.
Provecta For Dogs
Provecta Advanced is a 5-way parasite treatment for dogs. It kills and repels ticks, all life stages of fleas, and mosquitoes on contact before they bite. It also repels biting flies and kills chewing lice.
Bravecto For Cats
Bravecto is a prescription strength topical just for cats. Bravecto gives your cat protection against fleas and black-legged ticks (deer ticks) for 12 weeks, and dog ticks for 8 weeks. Bravecto is also designed to help eliminate fleas in as little as 8 hours.
Revolution For Cats
You won’t find a more hard-working medicine for your cat than prescription Revolution. It combats a host of parasites including fleas, heartworm, hookworm, roundworm, and ear mites with an easy-to-apply topical treatment.
Knowing how to protect you and your dog against ticks is the best defense in the fight against ticks. Tick prevention is important because as we know, they carry a variety diseases that pose serious health risks. Lyme Disease, Rocky Mountain Spotted Fever, and ehrlichiosis are the most common. These diseases can be difficult and expensive to treat and sometimes impossible to cure. The Brown Dog Tick, American Dog Tick, Black-Legged Tick or Deer Tick, and the Lone Star Tick are the most commonly found in the United States. Get to know the kind that live in your area so you know the risks.
It’s a good idea to check your dog daily for ticks, especially if you spend a lot of time outside. Run your hands slowly over your dog’s entire body feeling for bumps or lumps. Ticks can be very small and like to hide out inside ears, between toes, under the tail and collar, and in the armpit and groin areas. Don’t forget to check yourself too!
When You Find A Tick
If you find a tick on your dog, don’t panic. Use a pair of tweezers or the Tick Twister to grab the tick as close to your pet’s skin as possible, then pull back slowly until the tick is extracted from the body. Don’t grab the tick by the body, twist it, or pull too quickly. Disinfect the wound and apply an antibiotic cream approved by your veterinarian. Keep it clean and disinfected until it has healed.
Watch for signs of tick borne illnesses in your pet. Symptoms may not appear for up to three weeks. If you think a tick has bitten your pet and she’s behaving differently – loss of appetite, lethargy – talk your veterinarian right away.
Don’t Wait Until Tick Season
The goal is to prevent ticks from getting onto your dog or cat. If you live in a climate that experiences yearly freezing temperatures, you may notice ticks become less active or disappear but don’t be fooled, they can hibernate over the winter. Fortunately, there are lots of effective preventative medications on the market. It is best to talk with your veterinarian about which one is right for your dog and your area of the country. Be sure that the medicine you use repels the types of ticks in your area.
Around the Yard Keep your bushes, trees, and lawn trimmed to reduce ticks to help keep the tick population at bay. If you have a tick infestation in your yard, consider using environmental products or hiring an exterminator to address the problem. Use caution when treating your yard, many products can be harmful to people and animals.
We stock a full range of tick preventatives and treatments to keep your dog safe and healthy. Check out NexGard, Simparica, and Bravecto, chewable tick preventatives available at VetRxDirect.
Fleas. Just the word makes your skin crawl. And while I know it’s uncomfortable, it’s time to talk about fleas because the warm weather brings these nuisance bugs out in force. Read this quick Q&A for the topline on protecting your pet.
Q. Is there just one kind of flea?
A. No. There are more than 2000 types of fleas. The most common type of flea in North America is the “cat flea” – it loves dogs and cats. Fleas are hearty too, they can reproduce rapidly and some can live as long as 12 months.
Q. Are fleas dangerous?
A. Some pets just suffer itching and discomfort when they have fleas. Others are actually allergic to flea bites and can have a severe skin reaction called Flea Allergy Dermatitis. Fleas also can transmit tapeworm. Anemia is another issue for some pets with large infestations because one flea can consume up to 15 times its body weight in blood.
Courtesy of Cuyahoga Falls Veterinary Clinic / Flickr
A. If you see these signs, check your pet for fleas carefully.
Excessive itching, scratching and biting skin
Small, quickly moving brown bugs on the pet’s body
“Flea dirt” or flea droppings on the skin
Scabs and hot spots
Note: some pets can have fleas but not itch or scratch. If you see flea dirt or strange residue on your pet’s skin or coat, check for fleas.
Q. How can I protect my pet from fleas?
A. The market is full of effective flea preventatives. There are specific flea prevention and treatment products for dogs and for cats. You should not use canine flea control products on cats and vice versa. Some canine flea control products are lethal to cats.
Start by talking with your pet’s veterinarian who will recommend the best flea control program for your pet and your environment. Some preventatives are available over-the-counter, others require a prescription. There are oral, topical, and collar options – many are applied to your pet just monthly. Once you have a plan, stick with it to give your pet the best protection.
Q. How do you get rid of fleas on your pet?
A. Shampoos, sprays, and dips are available to treat pets that already have fleas. Again, talk to your veterinarian who can suggest the best remedy based on the severity of the situation and your pet’s condition.
Q. What do you do if you have fleas in your house?
A. Unfortunately, if your pet has fleas, there’s a good chance your house does too. Fleas can easily jump from one host to another and their eggs drop off your pet’s body on to your carpeting, couch, and bedding. If you have fleas in your home, clean your home thoroughly including all bedding, rugs, carpets, and upholstery. If you have a severe infestation, talk to your local pest control professional about a fogger or spray.
What’s your flea prevention plan for your pet? Do you like a particular product? Share your views by leaving a reply below. Alternatively, please leave ratings and reviews on any flea products available at VetRxDirect. Thank you.
We’re about to enter high tick season which runs from April through November in most parts of the country. So it’s time to arm yourself with the facts to protect your pets from these parasites.
Courtesy of B D / Flickr
Why is tick prevention so important? Ticks carry a variety of diseases that are dangerous to pets — in particular to dogs — including Lyme Disease, Rocky Mountain Spotted Fever, and ehrlichiosis.
Know Your Enemy
Do ticks live in your area? If so, what kind? It helps to know what you’re up against. Check the tick maps provided by the CDC to learn what ticks live in your area and how to identify them.
Courtesy of the CDC
It’s a good idea to conduct regular tick checks of your pets, especially if your pet spends a lot of time outdoors. Every day, run your hands slowly over your pet’s body including her head, armpits, and inside her ears. Don’t forgot to check yourself too!
What to do if you find a tick on your dog or cat:
Use a pair of tweezers or the Tick Twister to grab the tick by head where the mouth enters your pet’s body, then pull backwards steadily until the tick is extracted from the body. Don’t grab the tick by the body, twist it, or pull too quickly. Disinfect the wound and apply an antibiotic cream approved by your veterinarian. Keep it clean and disinfected until it has healed.
If your pet has several ticks or is infested with them, you can try a medicated shampoo or dip to kill the ticks on contact.
Watch for signs of tick borne illnesses in your pet. Symptoms may not be evident for up to three weeks. If you think a tick has bitten your pet and she’s behaving differently – loss of appetite, lethargy – talk your veterinarian right away.
Don’t Wait Until Tick Season: Prevention is the Best Medicine
Your goal should be to prevent ticks from ever latching on to your dog or cat. Fortunately, there are lots of effective preventative medications on the market. Your best bet is to talk with your veterinarian about which one is right for your pet and your area of the country. Be sure that the medicine you use repels the types of ticks in your area.
Here’s a quick overview of your options to fight ticks:
Oral Tick Preventatives – The market is full of preventative oral medications you give to your pet monthly to kill adult ticks and prevent eggs from hatching.
Topical Tick Preventatives – If you’d rather not give your pet a pill each month, ask your veterinarian about topical tick treatments that you apply to the skin each month.
Environmental Products to Kill Ticks – Keeping your bushes, trees, and lawn trimmed reduces the area ticks have to breed and helps keep the tick population at bay. If you have a tick infestation in your yard, consider using environmental products or hiring an exterminator to address the problem. Be sure to read the directions and understand how the products affect pets and people before you use them.
Seresto – One of the newest ways to protect your pet from ticks is the Seresto collar. It has a unique combination of ingredients and an innovative delivery system that protects your pet from ticks for up to eight months. It’s available for cats, too.
We stock a full range of tick preventatives and treatments to keep your pet safe and healthy. Which tick products do you use? And how are they working? We welcome your feedback and so do our other pet parents. Share your experiences with ticks by leaving a reply below. Alternatively, please leave product reviews on any of the tick products available at VetRxDirect. Thank you.
Ticks, those pesky little pests that are carriers for dreaded Lyme disease, are a dog owner’s worst nightmare. Every owner knows how much of a nuisance they can be and how susceptible our pets are to being bitten by them. Thankfully, there are many precautionary measures and preventative products available that can help you and your family in the battle against ticks.
Preventative Steps to Take
There are several things you can do to reduce the likelihood of your pet contracting a disease from these pests:
• Routinely check your pets for ticks, especially after they have been outdoors. In the instance you find a tick, remove it immediately.
• Use a tick prevention spray on your backyard to reduce the habitat in which ticks can live and thrive.
Flea infestation. Makes your skin crawl doesn’t it? Despite advancements in flea prevention treatment, flea infestations are still a fairly common in homes with dogs or cats. Part of the problem is misconceptions about flea prevention leave some pet owners vulnerable to these pesky, proliferous pests.
Here’s the truth about three common misconceptions:
“I’m treating my pet for fleas, so my home is protected.”
Many people think treating their pets with flea preventatives like Frontline Plus or Advantix will protect their homes from every flea — or even resolve an existing environmental infestation. They don’t. Topical flea preventatives and collars are designed to project just your pet and only kill the fleas on your pet. Of course, if your pet doesn’t bring home the bugs, preventatives help to reduce the chances of flea infestations in your home and yard.
“All flea preventatives are the same.”
Wrong. There are many different flea preventatives on the market, and knowing the difference makes a difference. The flea has four stages in its life cycle: egg, larvae, pupae, and adult. Some preventative treatments only kill adult fleas. If you use these alone, the flea life cycle can continue on your pet. Other preventatives contain an insect growth regulator (IGR) that breaks the flea life cycle and stops eggs and larvae from developing. For broad-spectrum protection for your dog or cat, be sure to choose a preventative treatment that contains an IGR. Ask your pet’s veterinarian about the best flea and tick preventative for your area, then check out VetRxDirect’s wide selection flea preventatives.
“I’ve treated my home so the fleas are all gone.”
If you have a flea infestation, you may want to consult the professionals about the best way to eliminate it completely. There are also plenty of effective “DIY” approaches that you can learn about online. Either way, stopping a flea infestation takes time and diligence; one treatment and thorough house cleaning may not be enough. Flea pupae that are in the cocoon stage are resistant to insecticides so you may continue to see fleas in your home for several weeks after treatment. Continue vacuuming and cleaning, especially in the areas where your pet spends the most time, to control any adult fleas that developed after the treatment. If fleas are still present after about a month, another treatment may be required.
As they say, “prevention is the best medicine.” To avoid flea problems, talk to your veterinarian about the best flea prevention treatment for your dog or cat and use it diligently to keep your pet — and your home – happy and healthy.
External parasites like fleas and ticks do not need to feed on a daily basis. Ticks, for example, can survive for well over one year without blood. Because they live outdoors, wild animals such as raccoons and opossums are the most common hosts. And when they walk through your yard in search of food or a safe route, some of the parasites they’re carrying jump ship and establish communities on your property. This is how most dogs become infested with fleas or ticks.
These pesky parasites are always in search of a new host and they breed very quickly. Fleas can lay eggs every twelve days and these eggs reach adulthood in a matter of weeks. Both species can jump several hundreds of times the lengths of their own bodies, which lets them easily ambush our canine friends in the backyard or at the park. Soon after, the females will begin to lay eggs and in a couple of weeks your pouch will be suffering from a full-fledged infestation.
Can fleas make my dog sick?
Yes, they can. When fleas feed on your pet, they inject saliva into his skin. A large number of dogs are actually allergic to flea’s salivary proteins, which results in a common skin condition called flea allergy dermatitis. Animals infested with fleas or ticks will bite and scratch at their skin in a vain attempt to relieve the itching or pruritus. After extended scratching sessions, the affected skin may become red and irritated. In extreme cases, inflammation, infections and other complications may occur.
Your dog can also get tapeworms from fleas.
Can ticks make my dog sick?
There are at least a dozen tick-transmitted diseases your canine friend can get from these parasites, including a few fatal ones like Rocky Mountain spotted fever, Lyme disease, ehrlichiosis, tularemia, and more. While it is true that most of these diseases are quite rare, it really does depend on where you live. It is a good idea to talk to your veterinarian about the local diseases that may affect your pet.
What are the best ways to prevent flea and tick infestations?
Fleas and ticks flourish in warm, humid environments. If possible, keep your home as dry as you can, and try not to give them a lot of places to hide. As we mentioned, fleas and ticks spend a lot of time away from their hosts. Most of that time is spent laying eggs and looking for other hosts. To do so, they have to have a place to hide and to build a nest. Carpets and rugs are a flea’s best friends, since they give them a place to reproduce and hunt for a host without anyone bothering them. We’re not saying you should throw out all your rugs and carpets, but it might be a good idea to remove them from common areas where your dog spends most of his time.
What are the treatment and prevention options for flea and tick infestations on dogs?
There are dozens of different products, from collars to spray, topical solutions and shampoos that provide flea and tick control for dogs. Most are inexpensive and can be purchased at nearly any pet shop or veterinary office. What are they?
Adams Plus Flea & Tick Shampoo with Precor – The easiest and most effective way to kill a slew of pesky parasites in one shot is to give your dog a bath. Adams Plus Flea & Tick Shampoo with Precor not only kills fleas, ticks, and lice, it also wipes out flea eggs, thereby eradicating the next generation of bloodsuckers. Safe for dogs, cats, puppies, and kittens, it is one of the most popular medicinal shampoos on the market today. Adams shampoos also contain soothing aloe, oatmeal, and lanolin, which mean they are safe for regular bathing. However, your canine friend should not require more than one flea and tick bath every few weeks, otherwise the infestation may require additional medications.
Frontline Plus for Dogs – One of the most trusted names in flea and tick prevention, Frontline Plus kills parasites at all stages and even puts an end to lice infestations. This topical monthly solution is easy to apply and is safe for dogs 8 weeks and older, including pregnant and nursing females. It is waterproof, so your canine friend will be protected even if he gets wet. Always consult your veterinarians before administering any new medication and follow the dosing directions on the product’s label.
K9 Advantix II for Dogs – Give your dog powerful five-way protection from dangerous and annoying pests including ticks, fleas, biting flies, mosquitoes, and lice with K9 Advantix II for dogs. Veterinarians recommend this broad-spectrum treatment because it’s effective, easy to use, and only requires monthly application. K9 Advantix II must NOT be used on cats.
Preventic Tick Collar –Preventic kills and detaches ticks for up to 3 months. This collar protects dogs over 12 weeks of age from Lyme disease and many other tick-borne diseases. Amitraz (the active ingredient) activity starts within 24 hours and continues for 90 days and is not affected by rainfall. Preventic is available in 2 sizes to fit most dogs.