Understanding fleas and their impact on companion animals

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Understanding fleas and their impact on companion animals

Preventing and controlling flea infestations are essential parts of responsible pet ownership, and requires a multi-pronged approach involving both the animal and their environment. Fleas are small, parasitic insects that live on the blood of their hosts. Fleas can infest a variety of animals, including dogs, rabbits, guinea pigs, mice, and even humans. Fleas are a persistent problem, especially in warm, humid environments and, as climate change increases such conditions, infestations may also become more common and widespread.

RSPCA Australia
Tuesday, 1 July 2025

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Preventing and controlling flea infestations are essential parts of responsible pet ownership, and requires a multi-pronged approach involving both the animal and their environment.

Fleas are small, parasitic insects that live on the blood of their hosts. Fleas can infest a variety of animals, including dogs, rabbits, guinea pigs, mice, and even humans. Fleas are a persistent problem, especially in warm, humid environments and, as climate change increases such conditions, infestations may also become more common and widespread.

Flea infestations often cause irritation and itching and may result in painful skin damage, allergic reactions, and infections. In severe cases, especially in very young or old animals, heavy flea infestations can cause anaemia due to significant blood loss. Fleas can also transmit disease-causing micro-organisms (e.g., internal parasites, viruses).

How do fleas spread?

Fleas are highly mobile and opportunistic. They jump from one host to another and can also be picked up from the environment. Adult fleas feed on the blood of animals and lay eggs on the animal’s fur, which then fall off into the surrounding area. Flea eggs can be found in carpets, furniture, bedding, and even the soil outside your home, where they wait for the right conditions—mainly warmth and humidity—to mature into larvae, pupae and then adult fleas, continuing the cycle.

Grooming your animal regularly can help you spot fleas early. You might see adult fleas in the hair or on the skin (they are 1-2mm long and dark brown) or you might see “flea dirt” (the faeces of fleas, which are small black specks that turn red when placed on a wet tissue). A fine-toothed flea comb can be a useful tool to check your companion animal for flea dirt. In some cases, you may not see fleas or flea dirt but will notice signs like excessive scratching (although not all animals will be itchy if they have fleas), red or irritated skin, and hair loss, which could suggest a flea allergy or infestation. These signs need prompt veterinary attention.

Preventing and treating flea infestations

Using an effective flea preventative product year-round can keep your companion animal flea-free. It’s essential to consult with your veterinarian to determine the best product for your pet. Different animals may require different treatments, and it’s important to ensure that the product you use is both safe and effective for the species and individual. For instance, flea treatments designed for dogs can be toxic, and even fatal, to cats, so always follow veterinary advice.

If your companion animal has fleas, in addition to treating them you need to treat the environment to remove flea eggs, larvae, and pupae (which can survive for weeks to months). Vacuum your home frequently and regularly, especially carpets, furniture, and crevices where flea eggs and larvae may be hiding. Wash your pet's bedding and any fabric that they frequently use in hot water to kill any eggs or larvae. Consult your veterinarian about insecticides and other treatments that are safe to use around your home. Outdoor areas like kennels, runs, or enclosures should also be treated.

Prevention is far easier than dealing with a flea infestation. By staying proactive with effective flea prevention treatments and maintaining a clean environment, you will help keep your companion animal flea-free and comfortable.

For more information visit the RSPCA Knowledgebase

This piece was originally published in Australian Community Media newspapers.

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