Expert advice from a Vet: Pet skin and microbiomes

Cat Henstridge, also known as @cat_the_vet, is a small animal vet.

Given her interest in all types of animal health – including the skin – we decided to collaborate and explore the pet skin microbiome.

Research around the skin microbiome of animals such as dogs and cats is still in its infancy, but here Cat takes us on a whirlwind tour of dog skin health and allergies and answers questions from our readers around pet skin issues and management.

Pet skin: dog skin health, microbiome and allergies

Your pet’s skin is amazing!

It’s their largest organ, their protective barrier from the outside world and it has an amazing microbial ecosystem completely unique to them [1].

We’re just starting to learn about the skin microbiome in pets and its importance, but what we do know is fascinating!

For example, dogs with atopy, allergic skin disease, have a less diverse skin microbiome than dogs without the condition [2].

It seems that healthy skin promotes the growth of a varied microbial population, and those organisms in turn help to keep the skin in good condition. So, when the skin is poor, so is the microbiome.

We do not know which comes first, bad skin or unbalanced bacteria, but it is likely they influence each other in a vicious cycle.

Atopic dogs also have a weak skin barrier. The joins between their skin cells are leaky, allowing moisture to escape, so their skin is dehydrated and vulnerable. This also lets allergens in, triggering the immune system and causing irritated skin – this means our dogs scratch, causing further damage.

Think of their skin as an old brick wall. The cells are the bricks and the joins between them are cracked and flaking cement.

And when atopic dogs are having a flare-up, they have higher levels of ‘bad’ bacteria on the skin [3], likely further triggering the immune system, and making the skin even more itchy.

What can we do to help?

The mainstay of treatment is always anti-inflammatory medications. Once the immune system has been triggered and the skin inflamed, it is more sensitive and more vulnerable. Calming this down allows the balance to start being restored.

Topical treatment with anti-bacterial and anti-yeast formulations decreases the ‘bad’ bacteria and yeast, and encourages the re-growth of the good ones. It also removes allergens, preventing further triggering of allergic sensitivities. Many formulations also contain topical moisturisers to strengthen the skin barrier and reduce dehydration [4].

Using skin supplements with omega-3 fatty acids (EPA & DHA) is also beneficial. They improve the health and efficiency of the skin barrier and aid in calming the immune response.


Why does my dog have fatty lumps on her skin?

Most fatty lumps on pets aren’t actually on the skin but underneath the skin, and the quality of the skin doesn’t have anything to do with the fact that these lumps are there, but the golden rule with any lump or bump that appears on your pet is to always get it checked out just to make sure it’s nothing nasty.

Why does my pup gnaw at his paws? Is he allergic to something?

Chewing at paws can be a sign of allergy in dogs but allergies are rare in puppies. So, if your puppy is chewing at its feet quite a lot, I would definitely get them checked out just to make sure that they’re not developing any infections or have any other issues such as broken nails.

Why has the fur on my white dog’s paw turned dark red?

The fur on your white dog’s paw turning a reddy brown colour is due to saliva staining and generally a sign that they are licking their paws too much.

If this is happening, it could be a sign of allergies and I would definitely get them checked out by your vet.

Is dandruff normal for dogs?

No is the short answer, and if there is an excessive amount of dandruff or if your dog also seems to be itching a lot, I would definitely get them checked out by a vet. It can be a sign of dry skin and skin allergies, but there are some mites that can cause dandruff and even look like dandruff themselves, so I’d definitely go for a check-up.

Is it normal for my dog’s eyelids to be a bit dry and crusty every day?

This is a bit of a difficult one. If you mean, is it normal for dogs to have a little crusting of sleep on the inside of their eye when they wake up in the morning, then yes it can be.  If the eye isn’t sore or weeping or excessively red, then you can just get in there with some cotton wool and water and wipe it away. But if it becomes very excessive and it’s happening all day or after every nap, then I would definitely get them checked out by your vet just to make sure we haven’t got any eye infections or any problems with tear production.

What should you do for dogs with dry skin?

There are two ways that we can tackle dry skin in our dogs, from the inside, and from the outside. From the inside is the use of skin supplements enriched with all the great quality oils that they need to keep the skin as supple and healthy as possible, and for a strong and healthy skin barrier.

On the outside, it’s things like foam, showers, shampoos and make-up pads that are enriched with moisturizers to keep our dogs’ skin in great health. For recommendations on these kinds of products, I would always ask your vet.

My cat is scratching is constantly scratching but doesn’t have flees, how do I tell if its eczema? 

Here is the interesting thing about scratching and cats – cats will very rarely scratch at themselves if they are itchy, they are in fact far more likely to groom, especially if it’s something like flees, and they can groom so much that they can groom themselves bald.

If your cat is scratching excessively, especially on their head or face, I would be worried about issues like ear infections. Food allergies in cats can also cause them to have really itchy faces. So, it’s a bit of a strange one, but it does occur, so I would definitely go and get them checked out by a vet.

How do you manage yeast infections on dogs’ skin in humid /tropical climates?

When it comes to yeast infections on a dog’s skin, it’s a chicken and egg situation. The yeast can make the skin a itchy, inflamed and sore, but itchy, inflamed and sore skin is a great place for yeast to live, and certainly, if you live in a hot, sweaty and humid environment, this is not very helpful.

I would tackle this in two ways. First, I would get some anti-yeast treatment onto the skin, which can come in the form of shampoos and foams. We’ve even got some great pads we can wipe over the skin now. But second, I would also focus on getting that skin health as perfect as it possibly can be. For that, I would get those skin supplements that will really strengthen that skin barrier and make that skin really strong, so it’s a less nice place for the yeast to live.

I have a French bulldog, is there anything I can do to prevent future skin issues?

Frenchies are very genetically prone to allergic skin disease but unfortunately, there’s nothing you can really do to influence those genes. However, there are a couple of things you can do to increase the skin health and improve the skin barrier, hopefully reducing any symptoms should they develop them.

The first thing I would consider is feeding them a diet specifically for skin support and skin health – there are plenty of dietary options now on the market – and also maybe include a supplement to get that skin as supple and strong as it possibly can be.

You should also make sure your parasite prevention control is absolutely tip-top, especially against fleas, as even a single flea bite can cause sensitive skin to really flare up. So, something as simple as wiping down their belly and paws after every walk gets rid of the allergens that are sitting on the skin, which can irritate the skin so much, and this can really help to reduce the symptoms of itching and soreness.


1. Cusco, A. et al. Individual signatures define canine skin microbiota composition and variability. Front. Vet. Sci. (2017).
2. Rodrigues Hoffmann, A. et al. The skin microbiome in healthy and allergic dogs. PLoS ONE (2014).
3. Charles, B. W. et al. Longitudinal evaluation of the skin microbiome and association with microenvironment and treatment in canine atopic dermatitis. J. Invest. Dermatol. (2016).
4. Nutall, T. Topical therapy in canine atopic dermatitis: new products. Comp. Animal (2020).
5. Magalhães, T. R. et al. Therapeutic effect of EPA/DHA supplementation in neoplastic and non-neoplastic companion animal diseases: a systematic review. In Vivo (2021).
6. Logas, D. et al. Double-blinded crossover study with marine oil supplementation containing high-dose icosapentaenoic acid for the treatment of canine pruritic skin disease. Vet. Dermatol. (1994).

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