Rockland Animal Hospital

355 Old County Road
Rockland, ME 04841


It has come to my attention that at certain times of the summer, fleas on dogs and cats can become plentiful. Sometimes, despite your best efforts to control them, the flea-control products you use do not always appear to be working as well as in previous months or even years. The painful reality is that regardless of the product chosen for your dog or cat, there are times when flea populations in the surrounding environment sky-rocket and jump onto your pet with daily frequency and in high numbers. No product works like a Teflon shield to deflect new fleas from getting on your furry friend. Actually, on a well-protected pet, the fleas you see today are not likely the ones you will see tomorrow.   In fact, fleas that have jumped on a Frontline Plus treated pet have long begun the process of dying by the time you visualize them on your pet’s belly or forehead. Even so, the mere sight of them can be disturbing. To make matters worse, new fleas will hop on whenever the pet visits a flea-riddled area in its environment – be it outside or in. To the untrained eye, this leads to the perception of catastrophic product failure because you begin to see fleas every day. I would like to offer some perspective that might prove useful to understanding flea control and which I hope can help reduce the frustrations that arise when flea populations grow.

While there are many different fleas in the world, we are mainly concerned with just one type on our dogs and cats, and ironically, it is called the ‘cat flea’, Ctenocephalides felis. The flea is an insect and it can complete its lifecycle (adult, egg, larvae, pupa) in a matter of a few weeks to more than a half a year, depending on conditions of temperature and humidity and if there are suitable hosts around. A single female flea can lay up to 1200 eggs in her brief lifetime. Due to this amazing ability to reproduce, flea numbers can build up rapidly, either within your home or somewhere outside on your property, or both. Many hundreds of egg-laying female fleas contribute to “breeding ground hotspots” in cool, dark (shady), protected micro-climates within homes (beneath sofa cushions, pet hiding places, garages, basements, etc.) as well as in cool, shady areas around the outside of the house (beneath sheds, crawl spaces, stairways, garages, and landscaping vegetation. In addition to dogs and cats, opossums and raccoons ALSO carry and deposit the same species of flea and these also lay thousands of eggs around the home environment. (Skunks, squirrels, rabbits and mice typically do not carry the ‘cat flea’, although coyotes and fox likely do.) Now -- add a neighbor or relative’s dog or cat, a feral cat, or a homeless dog that receives no flea control to your household or outside environment -- and you have the perfect recipe for creating an extremely large burden of fleas both on your pets, and worse, in/around your home.

As each of these flea-infested animals enters your property and beds-down, rests or takes up residence, flea eggs fall off their hair coats (envision a salt-shaker) into those dark, humid, and out-of-the-way areas. The eggs mature into larvae (maggot stage) and then into the cocoon stage (pupae) where they then hatch and jump onto the next passer-by. When your dog or cat visits those areas, fleas will immediately jump on them – REGARDLESS of the product you have purchased from your veterinarian. To add to all of this, if YOU or another human family member goes beneath a raised deck to get your gas-grill and walk where any of these yard critters have deposited flea-eggs, you too might eventually acquire fleas and might be the unsuspecting contributor to an indoor flea infestation. While this type of infestation could take a matter of weeks to develop before you realize what is happening (actually seeing fleas on your pets and possibly you!), the fact is that untreated pets (and humans) are the source of flea contamination in the home environment. In turn, this leads to frustrating infestations and the belief that your current flea product ‘just doesn’t work any longer’.

What is the good news? When you use a product like FRONTLINE Plus (fipornil / (S)-methoprene), you are using a product that does three things: 1) kills adult, egg-laying fleas, 2) kills flea eggs (S-methoprene), and 3) kills ticks. When using a topical flea preventative that is put on top of the skin, it is ideal to use a product that contains an insect growth regulator (IGR) like (S)-methoprene and this is where the ‘PLUS’ comes in when we speak of FRONTLINE Plus.  Other products use IGRs called pyriproxifen or an inhibitor of insect exoskeleton growth called lufenuron. Regardless, if using a topical product always choose one that contains one of these IGRs or IGR-like compounds coupled to the compound that kills adult fleas. When EVERY dog and cat in a household receives FRONTLINE Plus on monthly basis, these pets will NOT be the ones contributing new eggs to the environment that will later hatch out into new fleas. Simply stated, the flea lifecycle is cut short when dogs and cats are properly treated because the tide of new eggs will have receded. Why? Because adult fleas are killed as well as any flea egg that she may have laid prior to dying. But – and here’s the ‘but’ -- even if ONE cat or dog in the household is left untreated -- the untreated pet will be the source of new fleas and worse, new flea eggs.  Lastly – it is very important to remember that all FRONTLINE-treated pets will continue to acquire new fleas when they step outside and visit the hidden areas described above. This is the same for all products, including K9 Advantix® II, Vectra® 3D, Revolution® or any of the oral preventatives -- no product on the market will stop fleas from getting on the pet with any consistency.

So once again, while you may see fleas on FRONTLINE Plus treated pets, they are in the process of dying and should be dead within 24 hours. Better, any eggs laid will not hatch (remember the IGR!). But the next day, it all starts over again – the dog or cat goes out, new fleas jump on – and if you didn’t know better, these look like the same fleas from yesterday. THIS IS WHY some people – including veterinarians from time to time – mistakenly get the impression that products are failing. Flea experts agree that LONG before thinking that a product is ‘failing’ or had failed, it is essential to think about the complex and time-consuming issues of untreated and poorly treated pets and visitor-animals that likely contributed – or continue to contribute -- to the underlying problem.

So what flea and tick products should you buy? I recommend FRONTLINE Plus because I understand what it can and cannot do and because it is a very well-studied product. It is approved for dogs and cats, puppies and kittens and even pregnant and lactating dogs and cats. It is the world’s most popular flea and tick product. In the USA, it is designed to be sold only through veterinary hospitals because Merial believes that only through education and discussion will the product be used optimally and compliantly. When purchased through your veterinarian, FRONTLINE Plus carries with it the Satisfaction Plus Guarantee whereby your pet and environmental flea problems will be remedied by Merial should you have an issue with product purchased at your veterinarian. When used correctly, consistently and on all dogs and cats in the household for the duration of when conditions are ripe for flea reproduction, FRONTLINE Plus treated pets do not begin a flea infestation. You might still see fleas for up to a day -- but rest easy -- they are not reproducing. But when you see an untreated neighbor pet, a homeless dog or cat, and or an opossum and raccoon -- you are looking at the ‘Typhoid Mary’ of someone’s future flea problem.


®FRONTLINE is a registered trademark of Merial

®K9 ADVANTIX is a registered trademark of Bayer Animal Health

®VECTRA 3D is a registered trademark of Ceva Animal Health

®REVOLUTION is a registered trademark of Pfizer Animal Health

™Satisfaction Plus Guarantee is a registered trademark of Merial. Please read the full description of the program. Available only from your veterinarian.