Fleas on dogs


Fleas are tiny insects that live on dogs, cats and in your home.

They cause itchy skin, spread disease and can bite humans too. Fleas feed on blood and can cause young, small, old or poorly pets to become very unwell with blood loss (anaemia).

Think your dog has fleas? You will need to treat all your pets and also your home. Your vet will be able to advise which products to use. It’s easy to prevent fleas by using a veterinary flea product regularly.


Never use a dog flea treatment on a cat.

How to tell if your dog has fleas

If your dog has fleas you may notice:

  • Scratching
  • Flea dirt (commonly in the fur around the lower back)
  • Bites or a rash (on them or yourself)
  • Bald patches (alopecia) or spikey fur
  • Smelly, infected skin
  • Enjoying scratches and tickles more than usual because they are so itchy
  • Turning quickly or jumping to nibble their back end
  • Live fleas – it’s unusual to see live fleas, most fleas live in the environment
  • Your dog may become unwell - fleas feed on blood so if your pet is very young, small, old or poorly they can become dangerously unwell with anaemia (blood loss).
Photograph of little black flea dirts in a white dog's fur

Flea dirt in a dog's fur

When to contact your vet

Contact your vet practice for advice if you think your dog may have fleas. Your vet will recommend an appropriate flea product that you should use as regularly.

You know your dog best. If they don’t have the symptoms listed above but you are still concerned it’s always best to contact your vet.

Can I have flea treatment without seeing my vet?

Pop in or give them a call - if your dog is healthy and visits the vet regularly, your surgery may be happy to give you advice and flea treatment without an appointment. If your dog hasn't been seen by a vet for a while or you have tried flea treatments which haven’t worked it is best to book an appointment.

Your vet surgery will need to know how much your dog weighs so they can provide the right medication. For this reason you may need to weigh your dog at home.

How do dogs catch fleas?

Your dog is most likely to pick up fleas in the summer months because this is when fleas are the most active. Common ways to come into contact with fleas include:

  • Other animals, cats and dogs share fleas
  • Outside in the garden or elsewhere
  • The house they live in
  • People bringing them into the home e.g. on shoes.
Illustration showing fleas in the home

Most of a flea problem is in the home, 50 fleas living on your dog = 1000 fleas in the home

How to get rid of fleas

Contact your vet for accurate advice and treatment if you think your dog might have fleas. There are a lot of myths and ‘old wives tales’ that give false information about how to treat fleas.

You'll need to:

Treat all of your pets

  • Treat all of your pets (dogs, cats and rabbits) regularly.
  • Always use a prescription flea product (from a vet or pharmacy, or from a locked cabinet in a pet shop). They are trialled and tested very rigorously and always have an active ingredient that will kill fleas and/or stop them from breeding.
  • Products you can buy without a prescription (e.g. from a supermarket or pet shop) often contain a weak repellent or a less effective ingredient. They may not work or you may have to apply them very regularly for them to continue to work. This often works out to be very expensive.
  • Your vet will be able to tell you which flea product is most suitable for you and your dog.
  • Your dog might need other veterinary treatment if they have developed bald patches, infections or wounds caused by flea bites.

Treat your house

  • Most of a flea problem is in the house. 50 fleas living on your dog means 1000 fleas in the home. Fleas and their eggs can survive in the house for up to a year. Your vet will be able to recommend a suitable product and when to use it.

Treat for worms

  • Fleas can pass worms to dogs. De-worm your dog regularly with a product that covers them against tapeworms, especially if they have had fleas. Your vet will be able to recommend a suitable product.


Never use a dog flea treatment or a household flea spray on a cat. They often contain permethrin which is extremely poisonous to cats.

Contact your vet immediately if your cat has come into contact with a dog flea treatment or household flea spray.

Will fleas keep coming back?

It can take time to sort a flea problem but once they’re gone it’s easy stop them coming back. Continue to regularly treat your pets and follow our tips below.

Preventing fleas

Treat all cats, dogs and rabbits regularly

Treat all of your cats, dogs and rabbits as regularly as your vet recommends. Regularly check for flea dirt (as shown above) in your dog's coat, particularly around their back end and above the base of their tail.

Vacuum regularly

Vacuum regularly especially around your pets' bedding and under furniture. Keep your house as clean as possible.

Wash your pets' bedding regularly

Wash bedding at 60°C or hotter to kill fleas and their eggs.

Ensure visiting pets are treated for fleas

Only allow flea-free cats, dogs and rabbits into your home.

Do flea collars or flea shampoos work?

Flea collars bought without a prescription are not usually very effective. They often only kill the fleas close to them, and by the time the flea has been killed it may have already bitten your pet and laid eggs in your home. There are some effective flea collars available – speak to your vet for more information.

Flea shampoos are also often ineffective.

If you are unsure – speak to your vet practice about which product would be best for your pet.

Can humans catch fleas?

Fleas can bite humans but don't live on us. You may notice itchy little bite marks especially around your ankles or on your arms if your dog has fleas.

See the NHS website for more information on human insect bites.

Photograph showing little red raised bumps on a human's leg due to flea bites

Flea bites on a human leg

Published: June 2018

PetWise Pet Health Hub – brought to you thanks to support from players of People’s Postcode Lottery 

Illustrations by Samantha Elmhurst