Fleas on pets
Fleas. Not something any pet owner welcomes! Unfortunately though, most pets will come into contact with fleas at some point in their lives, even if they are strictly indoors cats.
To best protect your pet against fleas, or treat them if you do find fleas, it helps to understand why fleas are a problem - and why they can be such resilient parasites.
Why are fleas a problem?
Fleas are a problem for many reasons! They are abundant and widespread, spreading fast particularly in warm and humid conditions, and happily feeding on the blood of many hosts - be they pets, wildlife or even human. They are hardy little insects, usually living for 2-3 weeks before being groomed out by their host, but the maximum recorded life of a flea is 160 days! Fleas are expert hitchhikers and can easily be carried into the home on humans, animals (such as other pets including dogs and outdoor cats, or rodents), clothing and bags.
Fleas themselves aren't just the problem - as well as being painful and itchy, flea bites can actually cause a number of additional problems in both pets and humans including anaemia (especially in young kittens or puppies, or in elderly pets with a heavy infestation), Flea Allergic Dermatitis (FAD), tapeworms and Bartonella (cat scratch disease). Find out more about the issues fleas can cause in both pets and humans and about the symptoms of fleas on dogs or cats.
When exactly is flea season in the UK?
Fleas thrive in warm conditions and historically fleas tended to be active when our British weather warmed up in the spring and summer seasons. However, nowadays, with centrally-heated houses, fleas are a year-round threat.
In fact, flea pupae – the cocoon stage – can lay dormant for long periods of time, waiting for the right conditions so adult fleas can emerge. Fleas can also find warmth and shelter during the winter months by living on not just our pets, but wildlife too, such as foxes and rats, or in animal dens.
That’s why it’s important pet owners help protect their dogs and cats from fleas all year round, even during the winter months, to preserve their health and prevent a dreaded home flea infestation.
Break the flea lifecycle to get rid of fleas
When we think of fleas, we conjure up the image of the adult flea, when in fact fleas take many forms when they’re developing. When we know the different growth stages of a flea, it can help to quickly tackle an invasion:
Stage 1: Flea eggs
Once an adult female flea has found a host and eaten a blood meal, she can then reproduce and begin to lay eggs. The eggs are tiny white objects, usually around 0.5mm in size, which is smaller than a grain of sand! It makes it almost impossible to see them, particularly if they’re scattered around your house in the carpet and on the sofa.
Female fleas usually lay up to 50 eggs a day1. Flea eggs represent around 50% of the entire flea population in the home.
Your dog or cat will then unwittingly distribute the eggs on the flea’s behalf, as they fall off your pet when they move around the home and in the surrounding environment.
When the temperature and humidity is right, the eggs will hatch and larvae emerge.
Stage 2: Flea larvae
Flea larvae instinctively avoid direct sunlight because they’re negatively phototactic (they move away from light) and so bury themselves deep into materials and fabrics.
Because they can’t yet feed on a host, they survive by eating flea dirt from the environment, the name given to adult flea faeces. Essentially, flea dirt is dried blood and looks like a trail of black specks. It can sometimes be visible on your pet's fur, skin, bedding or furniture.
Flea larvae are a white, almost see-through colour and have no legs. They develop over one to two weeks and are larger than flea eggs, growing up to 5mm long.
In a household flea infestation, larvae make up 35% of the total population. They will be found hiding in dark parts of your home, including carpets, under furniture, under skirting boards, and in pet bedding.
Stage 3: Flea pupae
Flea pupae refers to the cocoon stage of the flea life cycle and they make up 10% of the home flea population. This is the final stage before it turns into an adult flea, which can take several days or weeks. If conditions aren’t right, the pupae can survive for months and sometimes more than a year.
The cocoon protects the pupae while it develops. The sticky outer layer of the cocoon keeps pupae hidden deep in fabrics and carpets. This helps to keep it out of reach of vacuums and helps to protect pupae from chemicals in some household flea removers.
Once developed, the adult flea won’t emerge until they sense a potential host nearby. They are clever and will pick up on vibrations, rising levels of carbon dioxide and body heat, indicating that your dog or cat is nearby.
Stage 4: Flea adults
When an adult flea emerges from the cocoon, they will seek a host to feed on, usually within a few hours. If fleas can’t find a pet (and in some cases, a person) to feed on, they won’t survive.
Female fleas can only reproduce once they’ve fed and they’ll begin laying eggs within a few days.
Adult fleas change in appearance once they’ve eaten too. A newly emerged adult flea is very small, about 2-6mm long, has a flat-bodied appearance and they’re dark in colour. When the bloodsucking creatures have had their fill, they grow into a recognisable flea shape and take on a lighter shade.
They account for 5% of a home flea infestation and are usually found on your pet where they can continue the cycle of feeding and laying eggs for a number of weeks.
Only by breaking the flea life cycle can you stop fleas.
How to break the life cycle of a flea
Now you know the development stages of a flea, it can help you to understand why it’s so important to take action as soon as you spot one on your pet.
Step 1: Kill and prevent fleas on your pet
There is a vast array of flea control products available to suit your pet and your lifestyle, including:
Flea collars can vary in how they work; Seresto Flea and Tick Control collar kills fleas (and repels and kills ticks) through contact without the need for them to bite your pet2. Just put it on your pet like a normal collar and with Seresto they’re protected for 7-8 months.
Spot-on flea treatments, such as Advantage Spot-on, contain a small amount of liquid that is applied to the skin at the base of the pet's head (for cats) or between the shoulder blades (for dogs) once a month. Many pet owners find them convenient as they are easy to apply. Advantage Spot-on kills fleas within 24 hours and prevents further infestations for 4 weeks. Fleas are killed through contact with the treated pet and do not have to bite to die2.
Tablets are another commonly used method to protect pets from fleas and can be given either by putting the tablet in with your pet's food or treats, or by gently giving it directly into their mouth. An example of a tablet available for preventative flea control in dogs is Advantage Chewable Tablet. This a tasty, meat-flavoured chewable tablet that provides fast-acting, reliable protection, killing fleas in just 4 hours and ticks in 8 hours3. For preventative flea control in cats, speak with your vet. If your pet already has an infestation of fleas, one Capstar tablet starts killing adult fleas in just 15-30 minutes and lasts 24 hours; to prevent a re-infestation of fleas, you'll need to use a longer-acting preventative product afterwards too.
Remember, your pet will only be fully protected from fleas when regularly using a preventative flea product. It can help to make a note of the date that you first gave the product, so you know when to re-treat. When applying flea treatments, you will need to choose the right product for your pet’s age and weight; always make sure you read the label and consult your vet or local pet retail store if you’re unsure.
Responsible use of medicines in pets
When we use pet health treatments, be they for parasites or for other health issues, it's essential that they are used responsibly. Find out more about the principles of responsible use of medicines in pets.
Flea treatment options
Don’t forget about worms
Fleas can carry the tapeworm parasite, a nasty intestinal worm which can be transmitted to your pet if a flea is ingested, so it's important to worm alongside flea control for full coverage. Speak to your vet about treatment options and frequency.
Step 2: Eradicate all flea stages in the environment
Once you have treated your pet, you need to turn your attention to ridding your home of fleas.
You’ll need to clean your whole house, not just the areas your pet frequents because people move eggs, larvae and pupae around the house too. When cleaning you’ll want to pay particular attention to fabrics, carpets and soft furnishings where adult fleas and the younger flea life-stages can bury themselves.
- Wash your pet’s bedding and toys - remove any fur from the bedding before washing and dispose of it in general waste, then always wash the bedding on a hot wash, ideally at 50˚C or above, as the high temperature will kill the fleas and their eggs which may be hiding there. Try drying it using heat, such as in a tumble dryer, rather than air drying.
- Wash your own bedding too, especially if your pet sleeps on your bed!
- Vacuum thoroughly – Vacuum all floors, carpets, rugs and sofas, including areas under furniture where larvae like to live. Remember to empty your machine to stop flea eggs hatching inside.
- De-flea your car too. If your pet spends time in your car, they may have spread flea eggs there. If this is the case and the eggs are not dealt with swiftly, they can easily lead to re-infestation of your home.
- Other treatments – Speak to your vet about other treatments that can be used if you have a home infestation. Don't forget to treat other pets in the house or garden at the same time.
A flea infestation can be incredibly frustrating to get under control and may take many months to resolve despite doing all the right things, but the sooner you act, the easier you can remove them. It is quite normal to continue to see adult fleas emerging from the resilient pupae for some time after first treating your pet and the house, but with the right treatment these fleas will quickly die breaking the flea life cycle. Taking consistent and thorough action that targets every stage of the flea’s life will get them out of the house, and treating your pets regularly will go a long way to stopping them from returning.
Want to know more?
What is flea allergy dermatitis?
Find out more about flea allergic dermatitis in dogs and cats
- ESCCAP
- Mehlhorn et al. Parasitol Res (2001) 87:198-207, information is regarding mode of action and is not intended to relate to speed of kill or to imply parasites can be completely stopped from biting.
- Advantage Chewable Summary of Product Characteristics.
