The Most Common Causes of Itchy Skin in Dogs

Have you been wondering: why is my dog scratching so much? Do they seem to be itchy all the time? Maybe you’re starting to wonder – or worry – about what could be behind this behaviour? And you’re just getting concerned that it might be causing them discomfort…

The truth is there are many possible causes of itchy skin in dogs. Constant scratching could turn that sore spot into a wound, which could then become infected. Even if that doesn’t happen, it’s distressing for them and for us when they can’t seem to find relief.

Let’s see what common conditions could be causing your dog to itch and scratch all the time - and how you can help them.

1. Fleas

Fleas are the most important external parasite of dogs¹, and are a major source of itching. Flea treatment and prevention is a big benefit for any dog - and you, as many fleas will happily jump species and bite us².

To find out whether your pet does have a flea problem, try checking their fur with a little back combing or use a flea comb, and brush any debris onto white paper. Though the fleas themselves (brown, oval, jumping insects) may be hard to locate, their faeces (black dots that turn red when dampened) will be easily spotted. If you find any, your vet can help you select an appropriate treatment, as there are so many options. And while you are out shopping for your dog, consider getting the Vet-recommended solution or another environmental treatment for your house as well, as fleas on the dog usually indicate that 95% of the population is present in the environment³.

However, it is important to note that it is not always easy or even possible to find fleas on your dog, so even if you do not find any, it might still be possible that your dog has them – or other parasites. Mites and lice, while less common than fleas, are also important causes of itching, and are much harder to spot. In fact, one mite – Sarcoptes – is one of the itchiest parasites known, but is too small to see with the naked eye.

2. Allergies

Just as some of us have allergic reactions to factors in our environment, so can our pets. Certain substances (allergens) can lead to itching and scratching in dogs too. Frustratingly, identifying an allergy is challenging, but your vet will guide and support you through the whole process.

3. Infections

Again, skin infections are something that can affect dogs and humans alike. More often than not, the infection will either be due to bacteria or yeast, or a combination of both. It’s important to remember, though, that most skin infections are secondary. In other words, the skin has been damaged (often by scratching) and gets infected, but while the infection makes the itching worse, it’s not the primary cause.

However, there can be other causes for infection. Fungal infections, which your vet can refer to as ringworm (or sometimes dermatophytosis), often cause baldness, and sometimes itchiness too.

So, if your dog has a skin infection, it’s really important to take them to the vets not only to treat the infection, but also to pursue further investigations.

Parasites, allergies and infection are the three most common causes of itching in dogs⁵; however, there are other, less common, causes too.

5. Shampooing

Your dog’s skin is very protective against a number of threats, but it is also a delicate organ. It’s important to be mindful of the products you are choosing to use to care for your pet’s skin and coat. If your pet’s grooming products promise flowing fur but are delivering itchiness instead, then there’s a chance your favourite brand may not be the best for them. The ingredients in some shampoos may dry and irritate your dog’s skin; in other cases, they can even become allergic to them. Pick a skin-sensitive, dog-safe brand that will moisturise and nurture their skin, and that works well on your pet. Your vet will be happy to help you choose a product with an appropriate formulation.

Also, have you considered how frequently you are washing them? Expert opinions vary, but unless your dog is rolling in cowpats or other undesirable materials daily, you can leave weeks between washes rather than days.

6. The itch-scratch cycle

Yes, really: whatever triggered the itching, the act of scratching it can irritate the skin more. This leads to more scratching, which cases more skin damage, so more itching, so more scratching, so more itching.... and on and on, in a negative spiral! This is the key cause of a “lick granuloma”, which can be triggered by an insect bite or sting, a minor wound, an infection, or even something more subtle like mild arthritis or a behavioural problem. But, over time, repeated scratching and/or licking causes it to get worse and worse unless addressed.

While itching and scratching are common in dogs, there are a very wide range of causes – and while some itching is normal, too much is definitely an indication that there’s an underlying problem that needs looking at. But how much is too much?

Well, if they’re leaving scratches in their skin more than once in a blue moon, then that’s abnormal. So do seek veterinary attention sooner rather than later for them.

But if you’re not sure if it’s a problem, or just normal for them, try the itchy skin checklist [link: https://www.zoetispets.com/ca-en/dog/skin-conditions/assessment] – that can help you to decide if it’s abnormal or not. You can even print out the findings and take them to your vet, who is always best placed to help you get to the bottom of any issues.

^{1: Abdullah, S., Helps, C., Tasker, S. et al. Pathogens in fleas collected from cats and dogs: distribution and prevalence in the UK. Parasites Vectors 12, 71 (2019). https://doi.org/10.1186/s13071-019-3326-x
2: https://www.esccapuk.org.uk/page/Fleas/37/
3: Halos, L., Beugnet, F., Cardoso, L., Farkas, R., Franc, M., Guillot, J., Pfister, K., Wall, R. Flea control failure? Myths and realities, Trends in Parasitology, Volume 30, Issue 5, pp.228-233 (2014)
4: Gedon, N.K.Y., Mueller, R.S. Atopic dermatitis in cats and dogs: a difficult disease for animals and owners. Clin Transl Allergy 8, 41 (2018). https://doi.org/10.1186/s13601-018-0228-5
5: Paterson, S My Dog is Itchy, BSAVA Congress Proceedings 2020 p33 http://dx.doi.org/10.22233/9781910443774.2.7}