Fleas can cause a great deal of distress to our canine companions. Their main effect is making dogs itchy; the flea saliva that’s injected into a dog’s skin during a bite causes inflammation, and an affected pet will bite and scratch themselves to try and get some relief. This results in hair loss and redness of their skin, and in some cases quite severe trauma and bleeding.
These pesky parasites have some other effects, too. Fleas are the intermediate host for the tapeworm Dipylidium Caninum. Dogs that frequently chew and bite their hair will eventually have worn teeth because hair is very abrasive. There have been cases of dogs being affected by plague, a bacterial infection that is spread by fleas. Lastly, because fleas drink blood to survive, they can cause blood loss anaemia and even death in young puppies.
It’s easy to see how fleas can make dogs miserable and unwell, and they may become lethargic and appear even depressed because of them. So we’ve put together all the information you need to be able to spot the signs and symptoms of them.
Are fleas the problem? Other causes of itching in dogs
Fleas are not the only cause of itchy skin in dogs however, and sometimes it’s tricky to work out why your pooch is scratching. However, there are some clues you can look for that can help you to identify the cause.
Spread your dog’s fur so you can look closely at their skin, particularly on their rump. Look for adult fleas running around, or even small black grains that look like sand. These grains are flea faeces and they consist mostly of digested blood. One trick is to comb your dog’s fur onto a damp piece of white paper. The small black grains will reconstitute into reddish coloured blood. The presence of adult fleas or flea faeces is a good indication that fleas could well be contributing to your dog’s scratching.
Take particular notice of where on their body your dog is scratching and biting because this can help to work out what’s making them so itchy. Those dogs with flea irritation chew at their tummy and inside their thighs. If they have an actual allergy to flea saliva, the most likely areas you’ll see inflammation and hair loss are on their lower back and tail. Atopic dermatitis and food allergies are also common causes of skin itching in dogs and they tend to affect a dog’s ears, feet, and face1. Even if a dog’s main issue is atopic dermatitis or food allergy, the presence of fleas can make the itching even worse2. Sarcoptes mites make dogs extremely itchy, but they prefer the hairless skin of the ear flaps, elbows, and tummy, which is not unlike the distribution of itching associated with atopic dermatitis or food allergy.
Another type of mange that can affect dogs is Demodex. These mites live in the hair follicles of all dogs but in some individuals, they proliferate and make the hair fall out. The mites themselves don’t cause dogs to scratch, but the secondary bacterial or fungal infection that follows is very itchy.
Bacterial and fungal skin infections are a source of irritation and itching but they tend not to be a primary problem. The Staphylococcus bacteria and Malassezia fungus are normally found on a dog’s skin and don’t cause any problems. However, when the skin environment changes, they multiply and cause an itchy and often smelly infection. Common underlying causes of skin changes that lead to these secondary infections are allergies, parasites, hormonal diseases, and conditions that reduce the effectiveness of a dog’s immune system.
Flea prevention methods to keep your dog healthy and happy
To protect your dog from the misery of a flea infestation, you need a two pronged approach. The first thing to do is to treat the adult fleas that are already living on their body. You can do this by using an effective flea control product either by mouth or applied to the skin. These need to be used according to their directions or they won’t be effective. It’s important to keep using these products regularly, to kill fleas that your dog may pick up from the ground as they’re out and about walking or playing at the park.
The second part of your flea control regime involves eliminating the intermediate stages of the flea lifecycle that can be found in your dog’s environment, which includes your carpet, furniture, and garden. Flea eggs and pupae are resistant and difficult to kill. The best way to keep them under control is with the use of environmental insecticides and physical removal by vacuuming your home and regularly washing your dog’s bedding in very hot water. There are also insecticidal products that can be used in your garden to keep fleas in check.
There are many reasons why your dog may be scratching. Fleas are by far the most common cause of itching in dogs, and you’ll need to be consistent in your treatment of your pet and their environment to prevent them adversely affecting your canine best friend’s health and wellbeing.
1Bruet, V, Roussel, A, Imparato, L, Desfontis, JC, 2012. Characterization of pruritus in canine atopic dermatitis, flea bite hypersensitivity and flea infestation and its role in diagnosis. Vet Dermatol., 23(6), 487-e93. 2Saridomichelakis, MN, Olivry, T, 2016. An update on the treatment of canine atopic dermatitis.. Vet J., 207(0), 29-37. 3Dawson, RD, 2004. Efficacy of diatomaceous earth at reducing populations of nest-dwelling ectoparasites in Tree Swallows . Journal of Field Ornithology , 75(3), 232-238.
Author info: Dr Audrey Harvey is a graduate of the University of Queensland, Australia, and has worked in small animal practices for 25 years. She is particularly interested in obesity management and the role of exercise in resolving behaviour problems in dogs.