Fleas: getting to know your dog’s worst enemy

By Gemma Hopkins on 04 January 2017

Wet noses, waggy tails and lots and lots of love. It’s easy to see why dogs make so many friends. Unfortunately, they also have lots of unwanted friends – and they don’t come much more unwanted than the flea. With a nod of the head to the old saying that knowledge is power, here’s the nitty-gritty on nobody’s favourite insect.

A flea lifecycle

A flea is a wingless insect. And like any insect, its life has several stages: eggs, larvae, pupae and finally adults. From egg to expired, the entire lifecycle typically lasts around three-four weeks but can be as short as 12 days in warm conditions. When it’s much cooler, for instance in the garage or spare room, developing fleas – known as pupae – can survive as long as six months to a year. This is their normal evolutionary behaviour – it’s how they survive the winter and why you won’t get rid of fleas overnight with a single bath.

Typically in a flea infestation only around 5% are adults lodging in your pup’s fur. The rest of the burden will be hidden around your home and even the garden, as minute eggs, larva and pupae, all waiting to grow into a fully formed flea. It’s why focusing on treating your pooch only when you see a flea could result in them re-appearing. A lot. To win the flea fight, you have to take measures in your home too – a house and hound approach.

Fleas are ludicrously good at jumping

Fleas are flightless, but incredibly good at jumping. If it was the Olympic high jump, it would be the same as a particularly limber-limbed athlete clearing the bar at over 150 feet. These jumping skills come in handy. Once fleas emerge from pupae, they leap onto unsuspecting dogs and begin feasting on their blood within seconds. Oh yes, those jumping skills are matched only by a flea’s drinking ability. A female can take in fifteen times her bodyweight per day.  

Watch out – Fleas are everywhere

Ever wondered why fleas are so prevalent? Consider this: an adult female will begin laying eggs within 24 hours of its first meal – and will lay around 2,000 eggs in its lifetime. She is also very clever and lays more eggs when your pooch is having a snooze– so wherever your pet lies, there will be a build-up of eggs.

How do you know if your dog has fleas?

Surprisingly not all dogs will scratch if they have fleas. Part their coat quickly, especially on the back, and you may just see one wriggle away – but no guarantees, fleas are very fast.  Your best bet is to look for flea dirt: little brown specks on the surface of your dog’s skin. These small bits of debris are actually flea faeces, consisting mainly of digested blood. Brush them onto wet kitchen paper and they will dissolve into a reddish brown blood.  

What happens if you don’t tackle fleas?

Some dogs seem to ignore them, but as the flea numbers increase they will soon get irritated.  In fact, fleas are one of the most common causes of serious skin disease in dogs – dogs that are allergic to fleas can get nasty skin rashes.  

Visit your vet

The trick to keeping your dog happy and flea-free is to break the flea lifecycle. So as well as vigilant carpet vacuuming and regular fur grooming, you should keep treating your dog for fleas even when you don’t suspect an outbreak. Ask your vet for medication that kills fleas fast throughout the course to ensure you truly break the lifecycle and prevent infestations.

And remember: if you have other dogs or cats – if one has fleas, then they will all have them.



Gemma holds an RCVS Certificate in Veterinary Cardiology and continues to work part time in practice to remain up to date and continue her interest in cardiology.

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