How Can You Tell If Your Dog Has Fleas?

The short answer

The quickest way to tell if your dog has fleas is the wet paper test. Comb your dog over white kitchen paper, add a few drops of water to any dark specks, and if they turn reddish brown, it's flea dirt. Scratching, nibbling at the back end and small bites on your own ankles are the other big clues.

• Live fleas are easy to miss. Flea dirt (tiny dark specks) is usually easier to find.
• Look first on the lower back and just above the base of the tail.
• Flea dirt turns reddish brown on wet paper because it's digested blood. Ordinary dirt doesn't.
• If your dog has fleas, your home almost certainly has them too.
• Fleas are seen all year round in UK homes, not only in summer, because central heating keeps them going.

"But I've never seen a single flea on him"

It's the first thing most owners say. They see the scratching, they part the fur, and there's nothing there.

That doesn't mean your dog is flea-free. Fleas are tiny, fast and good at hiding in thick fur. PDSA points out that live fleas are not always easy to see, and that most of them live in the environment rather than on your pet.

The RSPCA estimates that 95 per cent of flea eggs, larvae and pupae live in the home, not on the animal. So the few adult fleas on your dog are only a small part of the story.

The good news: you don't need to spot a flea to know they're there. You just need to know what else to look for.

The signs your dog might have fleas

PDSA and the RSPCA list the same core signs. You might notice:

• Scratching, licking or chewing more than usual
• Turning quickly or jumping up to nibble at their back end
• Enjoying a scratch or a tickle far more than normal, because they're itchy
• Tiny dark specks in the fur (flea dirt), often on the lower back
• Bites, spots, scabs or a rash
• Bald patches, sore areas or rough, spiky fur
• Redness and irritation, or thickened skin (for example around the ear edges)
• Small browny-black insects moving through the fur
• Unexplained itchy bites on you, often around your ankles or arms

The RSPCA's advice is simple: if you answer "yes" to any of these, it could mean fleas.

Not every dog scratches

Some dogs carry fleas and barely seem bothered. Others react badly to just a few bites. So a dog that isn't scratching still needs checking now and then.

How to do the wet paper test, step by step

This is the check the RSPCA recommends. It takes about five minutes.

1. Get a fine-toothed comb. A flea comb is ideal.
2. Lay down something white. Kitchen paper or a white towel works well.
3. Stand your dog over it. Comb through the fur, paying most attention to the lower back and the area just above the tail.
4. Tap the comb onto the paper. Any fleas or flea droppings will land on the white surface.
5. Add a few drops of water. Watch the dark specks.
6. Read the result. If the specks turn reddish brown, it's very likely your dog has fleas.

Why does it work? Flea droppings are made of digested blood. When they get wet, the blood colour shows. Ordinary garden dirt stays dark.

If you're still not sure, the RSPCA says to speak to your vet.

Where to look on your dog

Fleas can be anywhere, but some spots are worth checking first:

• The lower back and above the base of the tail. PDSA names these as the places to check for flea dirt.
• The back end and back legs. Watch for your dog nibbling here.
• The ear edges. The RSPCA mentions thickened skin around the ears as a possible sign.
• Your dog's bed. Specks of flea dirt often collect where your dog sleeps.

Short-haired dogs need checking too. The RSPCA says regular grooming, even for short coats, is one of the best ways to spot fleas and ticks early.

Why finding them early matters

Fleas aren't only an itch. Both charities explain that they can cause bigger problems if left alone.

Flea allergy

Some dogs are allergic to flea saliva. PDSA says these dogs suffer intense itching and irritation every time they're bitten.

Blood loss

Fleas feed on blood. PDSA warns that large numbers can cause anaemia, a dangerous level of blood loss, especially in young, old or ill dogs.

Tapeworm

Fleas can pass tapeworm to dogs if they swallow an infected flea. Both charities say to worm your dog too if they've had fleas.

A growing problem at home

A female flea can lay up to 50 eggs a day, according to the RSPCA. That's up to 1,500 in her lifetime. PDSA puts it another way: 50 fleas on your dog can mean up to 1,000 fleas or eggs in your home.

Why UK dogs get fleas in autumn and winter

Many people think fleas are a summer problem. The RSPCA says UK flea season usually runs from April to November, with fleas most active in summer.

But fleas can be a problem all year round. When we turn the heating on, our homes become warm, cosy places for fleas to keep breeding indoors. PDSA agrees that fleas are seen year round for this reason.

So a November flea check is just as worthwhile as one in July.

What UK vet charities advise

• RSPCA: comb your pet over white kitchen paper and add water; if the specks turn reddish brown, it's very likely fleas.
• RSPCA: treat both your pet and your home, because fleas can survive in the environment without a host for many months.
• RSPCA: vacuum furniture, floors and skirting boards, clean bedding regularly, and throw away the vacuum dust bag after each use.
• PDSA: if you think your dog has fleas, call your vet practice. They can tell you which flea product to use and how often.
• PDSA: treat all the dogs, cats and rabbits in your home at the same time, and wash bedding at 60°C or hotter.
• PDSA and RSPCA: some dog flea products and household flea sprays contain permethrin, which is highly toxic to cats. Never use a dog product on a cat.

Found flea dirt? What to do next

Don't panic. Lots of loving owners find fleas. Here's a simple plan:

1. Call your vet practice. Ask which flea treatment suits your dog. Have your dog's weight ready.
2. Treat every pet at once. If one pet has fleas, assume they all might. Use only products made for each species.
3. Treat your home. Vacuum floors, furniture and skirting boards. Empty or throw away the vacuum bag straight away.
4. Wash bedding hot. PDSA advises 60°C or hotter for your dog's bed, blankets and throws.
5. Worm your dog. Ask your vet about tapeworm treatment.
6. Keep checking. Repeat the wet paper test every week or two for a while.

Once the problem is cleared, the job becomes prevention. PDSA says it's easy to stop fleas coming back if you keep checking and protecting your pets and home regularly. The hard part for most families is the routine. Monthly treatments get forgotten, and gaps are exactly when fleas sneak back in. That's why long-term prevention, with no gaps, is worth thinking about.

Myth vs fact

Myth: If I can't see any fleas, my dog doesn't have them.
Fact: Live fleas are hard to spot, and most of the flea population lives in your home. Flea dirt is often the first clue.

Myth: Fleas are only a summer problem.
Fact: The RSPCA says fleas can be a problem all year, because heated homes let them keep breeding indoors.

Myth: Clean homes and clean dogs don't get fleas.
Fact: The RSPCA says fleas can turn up even in the most spotless home or on the cleanest pet.

Myth: A dog that isn't scratching can't have fleas.
Fact: Some dogs barely react, while allergic dogs react strongly. Regular checks are the only way to know.

Your flea check checklist

• ✔ Comb your dog over white kitchen paper once a week or so
• ✔ Add a few drops of water to any dark specks and look for reddish brown
• ✔ Focus on the lower back, above the tail and the back end
• ✔ Check your dog's bed and your own ankles for bites
• ✔ Keep protection going all year with long-lasting natural protection

Frequently asked questions

What does flea dirt look like on a dog?

Flea dirt looks like tiny black or dark brown specks, a bit like ground pepper, often on the lower back. On wet white paper it turns reddish brown.

Can a dog have fleas without scratching?

Yes. Some dogs show very few signs, so it's worth doing a comb check now and then even if your dog seems comfortable.

How do I know if fleas are in my house?

Unexplained itchy bites on your ankles or arms are a common clue. PDSA says that if your dog has fleas, your house will have them too.

Can I see fleas with the naked eye?

Adult fleas are small browny-black insects that you can see, but they move fast and hide in fur. Flea dirt is usually easier to find than the fleas themselves.

Should I take my dog to the vet for fleas?

PDSA says to call your vet practice if you think your dog has fleas. Book an appointment if your dog has sore, infected or very itchy skin, or seems unwell.

Final thoughts

You don't need to see a flea to find one. A comb, some kitchen paper and a few drops of water will tell you in minutes. Make it a regular habit, all year round, and pair it with steady prevention such as the BIO-COLLAR™ so there are no gaps for fleas to slip through.

Keep reading

• How Do Dogs Get Fleas?
• How Do You Get Rid of Fleas in Your House?
• Why Do Fleas Keep Coming Back After Treatment?

Sources: RSPCA, "How to get rid of fleas" (rspca.org.uk, read 3 November 2026); PDSA Pet Health Hub, "Fleas on dogs" (pdsa.org.uk, published April 2020, read 3 November 2026). This article is general information, not veterinary advice. If you're worried about your pet's health, contact your vet.