Why does my dog have fleas with a Seresto collar

The Seresto collar is designed to prevent fleas and ticks from latching onto your dog, but that doesn’t necessarily mean that it will always be 100% effective. It’s not uncommon for a pet to still have fleas even when wearing a Seresto collar. This may be caused by a few different factors.

It is possible that the fleas your dog are carrying are resistant to the active ingredients in the Seresto collar. This means that even though the active ingredients are present on your dog’s skin, they don’t have a sufficient effect against these particular fleas.

Additionally, you may need to apply more than one Seresto collar to effectively repel fleas and ticks. Most manufacturers recommend using two Seresto collars – one for the neck area and one for the middle of the back – in order to achieve complete coverage of all regions of your pet’s body where pests typically latch on. This ensures that there are no gaps or areas on your pet’s body which remain unprotected.

It is important to note that if using two collars, you should leave at least 2 inches between them as positioning them too close together can impede their effectiveness. If you feel like you may have placed the collars too close together, try readjusting them with some space between them so that each has an opportunity to fully disperse its active ingredient across your pet’s body surface.

Finally, it is important not to forget about environmental pest control as well, since this can help reduce infestations both inside and outside of your home which could attract parasites onto your pet as well as increase their likelihood of contracting diseases related to parasitic infections such as Lyme Disease or Rocky Mountain Spotted Fever.

Incorrect application of the Flea Collar

When it comes to getting rid of fleas, a Seresto collar is an effective tool. However, if it’s not applied correctly, it can be completely ineffective.

First and foremost, make sure the collar fits your dog correctly. If it’s too big or can you put a flea collar on a puppy too tight, then the active ingredients may not be able to reach the skin where they need to go. The collar should fit snugly against your dog’s neck but still allow two fingers to fit underneath. If necessary, cut the excess length off (but save the excess in case you end up needing it down the line).

Also, when applying a Seresto collar make sure all old collars are removed first and washed in hot soapy water because some flea treatments have residual active ingredients that could interfere with potency of the new one.

Fleas Reproducing Too Quickly For The Collar To Keep Up

Fleas reproduce incredibly quickly, sometimes more quickly than the Seresto collar can keep up with. The Seresto collar is designed to kill existing fleas and the eggs they have laid, but it can’t always prevent new fleas from jumping onto your pet and reproducing.

This is why proper pest control is so important when protecting your pet from fleas. Seresto collars can help preventfleas from reproducing if used in combination with other methods of pest control such as vacuuming, spraying or fogging your home, treating your pet bedding outdoors, and even getting your yard treated for pests by professional companies.

With a few simple steps you can help ensure that the flea problem will not return anytime soon and ensure that your beloved pet remains furigal free!

Insufficient Coverage Of The Collar

The Seresto collar is designed to provide long-lasting flea and tick protection, but in some cases the coverage may not be adequate enough to protect your dog completely. This could happen for a few reasons:

1. Inaccurate fitting – If the Seresto collar isn’t fitted tightly enough, there can be gaps where fleas can enter. Make sure the fit is secure and comfortable for your pup.

2. Insufficient treatment time – The Seresto collar needs time to work; it won’t have any effect on existing fleas until after 2 hours of wearing it. Also, the effects can wear off if the collar isn’t replaced every 8 months, so it’s important to keep track of when you replace it for optimal effectiveness.


One possible reason your dog has fleas with a Seresto collar may be allergies. Flea allergies in pets are caused by the proteins in the flea saliva, which irritate and inflame a pet’s skin. Thus, allergies can be one of the most common causes behind why your pet might have fleas even with wearing a Seresto collar.

An allergic reaction can cause intense itching or scratching, leading to sores on your pet’s skin. Fleas enjoy these wounds as they provide an ideal feast! If your pet is experiencing an allergic reaction from the bites, their skin will likely become more susceptible to flea infestation even when wearing the Seresto collar.

If you notice that your dog is reacting to fleabites by scratching excessively or having red and swollen spots on their skin, a visit to the vet for testing may be necessary. The vet will likely perform some type of sensitivity test to check for food and environmental allergens that may trigger skin reactions. After that, they can work on how best to help alleviate your pet’s symptoms and find relief from any pesky fleas.

Final Answer

No matter what type of flea treatment you use on your pet, it’s important that you follow up with regular inspection and a comprehensive prevention program. Additionally, consult your vet if you’re concerned about an existing flea problem so that they can suggest more effective products and dosages.