Fleas are easy to underestimate: the few you see on your dog are only the adults, while their eggs, larvae and cocoons are quietly developing in your carpets and the dog’s bed — which is why getting rid of them means treating every pet and the home, and why preventing them is so much easier than clearing an infestation.
The most important first
- Fleas peak from mid-summer into fall in many temperate regions, but they can turn up year-round indoors.
- Look for flea dirt: reddish-black specks that leave a red-brown stain on a damp paper towel.
- Treat every dog and cat in the home with a product your vet recommends for each animal, and follow the label exactly.
- Treat the home too: wash bedding and vacuum where pets rest. Control can take 6 weeks to 3 months.
- Young puppies are most vulnerable. Heavy infestations can cause anemia — call your vet.
Last updated: November 8, 2026
When fleas are most common
In Great Britain, Farrell and colleagues (2023) analysed records from 191 veterinary practices and found fleas noted in 0.25% of dog consultations and 1.17% of cat consultations. Cases were recorded in every year of the study, peaking between July and October, and were most common in animals under 12 months old.
In mainland Portugal, Pereira and colleagues (2025) examined 1,052 dogs and found fleas on 33.6% of them. Dogs were more likely to have fleas in spring, summer and fall than in winter, and dogs that received no insecticide treatment had about five times the odds of infestation. The cat flea, Ctenocephalides felis, made up 85.7% of the fleas found on dogs — so yes, the fleas on your dog are usually cat fleas.
Why the home matters as much as the dog
The Merck Veterinary Manual’s pet owner guide, written by flea researcher Michael Dryden, explains that a female flea can lay up to 50 eggs a day. The eggs drop off onto bedding, carpets and soil, hatch in 1 to 6 days, and the larvae hide deep in carpet fibers, cracks and shaded soil. The pupae can wait in their cocoons for weeks, or even up to a year, before hatching when a host comes near. The Companion Animal Parasite Council (CAPC) notes that adult fleas generally live 2 to 3 months.
That is why a single treatment rarely solves the problem: new fleas keep emerging from the home for weeks.
How to check your dog
- Part the coat over the lower back, base of the tail and thighs, and look for fleas or flea dirt.
- Use a flea comb and tip what you find onto a damp white paper towel. Flea dirt dissolves into a reddish-brown smear.
- Watch for signs: the Merck Veterinary Manual lists intense itching, scratching, licking or chewing — especially over the hips, base of the tail and thighs — hair loss and scabs.
- No fleas seen doesn’t rule them out. Dogs that groom a lot, especially allergic ones, may have very few fleas visible.
In practice
A new puppy owner notices her dog scratching at the base of his tail in late August. She finds a few black specks with a flea comb, and they turn red on a damp tissue. She calls the vet, treats both the puppy and the family cat with products the vet recommends for each, washes the dog beds and vacuums every day — and is told to expect fleas to keep appearing for several weeks while the home clears.
(Illustrative, composite scenario.)
Getting rid of fleas
Following the Merck Veterinary Manual and CAPC:
- Treat every pet in the household with a product your veterinarian recommends — not just the one that’s scratching. Never use a product on a species or weight it isn’t labelled for.
- Wash pet bedding, throw rugs and carriers.
- Vacuum where pets sleep, paying close attention to crevices in sofas and chairs and under sofas and beds.
- Treat the home where your vet advises, focusing on places where eggs and larvae collect. Merck notes that spraying the whole yard is not recommended; shaded spots where the dog lies are what matter.
- Be patient. Merck notes that control can take 6 weeks to 3 months, and you may still see some fleas during that time.
CAPC recommends treating all dogs and cats year-round, throughout their lives, to stop flea populations getting established in the home.
Why fleas matter beyond the itch
- Tapeworms. Dogs pick up the tapeworm Dipylidium caninum by swallowing infected fleas while grooming. CAPC notes that children can be infected the same way. Cociancic and colleagues (2026) describe a three-year-old whose tapeworm was misdiagnosed as pinworm; a relative’s dog was the likely source.
- Anemia. CAPC warns that heavy infestations can cause iron deficiency anemia and even death, especially in young animals.
- Other infections and allergies. Fleas can carry Bartonella (cat scratch disease) and rickettsial bacteria, and they are a common cause of allergic skin disease.
What about natural remedies? In a 2026 review, Bava and colleagues found that some essential oils show promising activity against fleas and ticks in the laboratory, but that reliable results in real animals are held back by volatility, unstable formulations and variable products. Natural does not automatically mean safe, so talk to your vet before using them.
When to call your veterinarian
- A young puppy with fleas, pale gums, weakness or poor appetite.
- Intense itching, hair loss, scabs or skin infection.
- Rice-like segments around your dog’s tail or in the feces (possible tapeworm).
- Fleas that keep coming back despite treatment.
- If in doubt, call — your vet would rather hear from you early.
Work on it
A few minutes here will teach you more than re-reading the article.
Ask yourself
- Are all the pets in my home on flea prevention, cats included?
- When did I last wash my dog’s bedding?
- Do I know which product is right for each of my animals?
Find out & check
- Ask your vet which flea prevention suits your dog’s age, weight and lifestyle.
Do one thing
- Run a flea comb through your dog’s coat this week and do the damp paper towel test.
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Sources & further reading
- Farrell S, McGarry J, Noble PM, Pinchbeck GJ, Cantwell S, Radford AD, Singleton DA (2023) — Seasonality and other risk factors for fleas infestations in domestic dogs and cats. Medical and Veterinary Entomology 37:359–370. doi.org
- Pereira A, Cruz A, Novo T, FleaPT group, Maia C (2025) — Epidemiological and molecular characterisation of flea infestations in dogs and cats in mainland Portugal. Parasites & Vectors 18:263. doi.org
- Dryden MW, Merck Veterinary Manual (2024) — Fleas of Dogs (pet owner version). merckvetmanual.com
- Companion Animal Parasite Council (2017) — Fleas (guidelines for dogs and cats). capcvet.org
- Cociancic P, Prieto V, Comas J, Esteban JG (2026) — Pediatric Anal Pruritus and Misdiagnosis: Dipylidium caninum in a Spanish Child with a Review of Reported Human Cases. American Journal of Tropical Medicine and Hygiene 115:333–339. doi.org
- Bava R, Bulotta RM, Castagna F, et al. (2026) — Essential Oils for Flea and Tick Control in Companion Animals: A Critical Review of Efficacy, Safety, Resistance Mitigation and Integrated Pest Management. Antibiotics 15:312. doi.org
Where evidence is limited, recommendations rest on established practice and expert judgment, and may be updated as knowledge develops. This is general information and does not replace advice from your veterinarian.
Next steps
- Read next: Ticks and tick-borne disease in dogs.
- Related: Seasonal allergies in dogs: itching, paws and ears.
- Return to the guide: For your puppy buyers.