Why are some pets more susceptible to fleas?

Species and breed differences

Some animals are simply more attractive to fleas. Dogs and cats are the most common hosts, but even within these groups, susceptibility varies.

Certain dog breeds with thick coats, such as Golden Retrievers, Border Collies and German Shepherds, provide fleas with warmth, protection and easy hiding places. Long or dense fur can make it harder to spot fleas early, allowing infestations to grow before they’re noticed.

Cats, particularly those that groom less thoroughly or spend time outdoors, can also be prime targets. Small pets like rabbits and ferrets are not immune either, especially if they live in environments shared with cats or dogs.

Skin chemistry and body temperature

Fleas are highly sensitive to chemical cues. They are attracted to warmth, carbon dioxide and specific skin secretions. Pets with higher body temperatures or particular skin oils may be more appealing hosts. Just as mosquitoes prefer certain humans, fleas show preferences too. Some pets naturally produce skin chemicals that fleas find irresistible, while others produce scents or oils that are less attractive.

Immune system strength

A pet’s immune system plays a major role in flea susceptibility. Healthy animals can sometimes tolerate a few flea bites with minimal reaction, whereas pets with weaker immune systems may experience more severe itching, inflammation and discomfort.

Young animals, elderly pets and those with underlying health conditions are often more vulnerable. Stress can also suppress immune function, making pets easier targets for parasites.

Flea Allergy Dermatitis (FAD)

Some pets are not just susceptible to fleas… They are allergic to them. Flea Allergy Dermatitis is a common condition where a pet has an exaggerated immune response to flea saliva. In these cases, even a single bite can cause intense itching, hair loss, scabs and skin infections.

Pets with FAD often appear “more flea-prone” because their symptoms are more obvious, even if there are only a few fleas present. 

It’s crucial to keep pets with a flea allergy on a consistent flea preventative routine. This way they are unlikely to have fleas jump on them and have zero chance of fleas biting them, which causes a bad reaction. Itch monthly flea subscription is tailored to your pet and delivered every month to your door, for free. Try Itch Flea Treatment for Dogs or Itch Flea Treatment for Cats to prevent fleas and their eggs, all year round.

Grooming habits

Grooming makes a difference. Cats are generally meticulous groomers, which can help remove fleas before they become established. Dogs that groom less effectively or pets that struggle to groom due to obesity, arthritis or dental problems may harbour fleas more easily.

Regular brushing by owners also plays a role. Pets that are groomed frequently, e.g. with a flea comb are more likely to have fleas detected early, reducing the chance of a full infestation. Click here to find out which is the best flea comb to use on your pet.

Lifestyle and environment

A pet’s lifestyle has a huge impact on flea risk. Outdoor pets, or those that regularly interact with other animals, are far more likely to pick up fleas. Parks, gardens, kennels, catteries and even visits to friends’ homes can all be sources of exposure.

Indoor pets are not completely safe either. Fleas can hitch a ride into the home on clothing, shoes or other pets, then establish themselves in carpets, bedding and soft furnishings.

Warm, humid environments are especially flea-friendly, which is why infestations are more common in spring and summer — although modern central heating means fleas can thrive all year round.

Click here to find out where fleas hide in your house!

Preventative Care (or lack of it)

Perhaps the biggest factor in flea susceptibility is prevention. Pets that are not on a regular, effective flea control programme are far more likely to become infested. Inconsistent treatment, incorrect dosing or using products not suited to the pet’s species can all reduce effectiveness. It’s also important to treat all pets in the household, focusing on just one animal often allows fleas to survive and spread.

In multi-pet homes, fleas often appear to “prefer” one animal. This can happen because one pet goes outdoors more often, has a thicker coat or reacts more strongly to bites. Meanwhile, the other pets may still be carrying fleas without showing obvious symptoms.

This is why treating only the visibly affected pet rarely solves the problem.

Some pets are more susceptible to fleas because of who they are, how they live and how their bodies respond to parasites. Understanding these factors helps explain why flea problems can feel so persistent and why prevention is always better than cure. With the right knowledge and a consistent approach, even the most flea-prone pets can stay comfortable, healthy and itch-free.