How many fleas can live on a cat or dog?


Flea-infested cats and dogs typically have less than 20 fleas living on them. It’s believed that pets can support a maximum of 200 to 300 fleas. However, one study showed that fleas won’t abandon their host, even when the corporeal population exceeds 300.


Average Number of Fleas on Pets

When infested with fleas, the average dog or cat will have less than 20 fleas living on them. The flea population on an animal is referred the as the “flea burden”.

Maximum Number of Fleas on Pets

It’s theorized that dogs and cats are capable of supporting a maximum of 200 to 300 fleas. And, once this population baseline is reached, the fleas begin jumping off the animal. One study refuted this claim by showing that fleas won’t abandon their host, even when populations exceeds 300 fleas. Regardless, a burden of over 200 fleas on a dog or cat is rare. 150 fleas on an animal is considered high.

Younger Animals Have more Fleas

There’s a direct relationship between a host’s age and the number of fleas living on the animal. More fleas are found on young animals. Juvenile cats, for example, aren’t as seasoned at grooming compared to older cats. Additionally, mature cats may have better immune systems, thicker skin, and changes in their blood capillaries.

Animal Surveys

Flea Burden on Cats

One study surveyed 200 stray cats for fleas, and found 164 had fleas. An average of 20 fleas were found on the infested cats. The most heavily infested cat had 161 fleas living on it.

In southern California, domestic cats were surveyed for fleas. Of 701 cats, 323 were infested. A total of 6729 fleas were recovered, and 85% of them were female. There were two main distributions, cats with less than 7 fleas and cats with more than 50 fleas (Fig 1). At a maximum, one kitten had 440 fleas.

Fig 1 Number of cats (y-axis) with varying populations of fleas (x-axis).

1578 fleas were recovered from 81 stray cats in New Zealand. The average flea burden of 19.48 fleas. At a maximum, one cat had 108 fleas.

A survey done in Spain counted the fleas on cats which were bought into veterinary clients. From 217 tested cats, 1938 fleas were recovered. On average, an individual cat had 9 fleas living on it. However, in one extreme case, a cat had a flea burden of 245 fleas.

A survey was done on cats in southern California. 70% of the infested cats had less than 7 fleas.

In Georgia, an average of 28.2 fleas were found per feral cat.

In Australia, the average flea burden on cats was 7.7 fleas.

In 1915, a survey on cats found that at most a cat had 30 fleas. On average cats had 4.24 fleas. 139 homeless or stray cats were surveyed, and 114 had fleas.

In Albania, the number of fleas found on cats was between one and nine.

In Wisconsin, of 16 infested cats, the average flea burden was 8.15 fleas. At a maximum one cat had 164 fleas.

A survey in Hungary studied 1000 cats brought into veterinary clients. 229 cats were infested with fleas. An average of less than 5 fleas were found on the cats. The largest flea burden was seen on a cat with 118 fleas.

Flea Burden on Dogs

A survey done in veterinary clinics in Italy found fleas on 246 of 1376 tested dogs. A total of 960 fleas were discovered. 79 dogs (32.1%) had 1 to 5 fleas living on them, 89 dogs (36.2%) had 6 to 20 fleas, and 78 dogs (31.7%) had over 20 fleas.

In New Zealand, a survey was done on stray dogs and cats captured by authorities. 357 fleas were recovered from 48 dogs. The mean flea burden for an individual dog was 7.44 fleas. There was a max of 54 fleas found on one dog.

In Australia, the average number of fleas per dog is 10.2.

In one extreme case, a single dog in Spain had 967 fleas living on it.

In Albania, the flea burden on dogs ranged from 1 to 80.

In Wisconsin, 9 infested dogs had an average of 4.5 fleas per dog.

A Hungarian survey tested 2267 dogs in veterinary clients. 319 dogs were flea-infested. On average, less than 5 fleas were found per infested dog. At a maximum, an individual dog had 95 fleas.


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  • Terralyn November 2, 2016, 3:39 pm

    My dog is only 20 lbs but he has a lot of fleas! How long do we have to get them off of him before it starts to do damage to his body???

    • Adam Retzer November 2, 2016, 4:26 pm

      It’s best to get them off as soon as possible, as they are continually biting. The bites cause irritation. If your dog is allergic (flea allergy dermatitis), the irritation can be severe. This can lead to excessive grooming, resulting in hair loss and skin infections. There are also multiple diseases that fleas can spread to dogs.

      Each female flea lays around 25 eggs a day. They fall into the environment (carpets) and develop there. The longer the dog goes untreated, the more eggs will accumulate in the environment. If the problem is neglected too long, the infestation can get severe and will be much harder to control.