Ask a vet online – my dog has skin allergies, how do I help?

Question from Leona Poppleton:

my dog has skin allergies and so gets very dry skin and sometimes scabs that look quite painful is there anything that I can get or do to help this?

Answer: Scabby Skin

Hi Leona, thanks for your question about your dog’s skin. Allergies with skin symptoms are pretty common in dogs, so I’ll briefly discuss allergic disease, then go on to some of the many different treatment options.

What are skin allergies?

The phrase “skin allergies” refers to the itching, scratching and sore skin that allergic dogs get. However, it doesn’t have to be caused by something on the skin – e.g. food allergies (although quite rare in dogs) can lead to skin symptoms – so “allergic skin disease” is a better term.

Essentially what is happening is that the dog’s immune system misidentifies a harmless substance as a dangerous threat, and tries to attack it, causing soreness and itching. Allergic reactions may be triggered by a wide range of substances such as pollen, certain foods, fleas, mites, plants or even some washing powders. In a large number of cases, there’s no specific “allergy” involved, but the dog has a disease called Atopy (or Atopic Dermatitis), where the immune system reacts abnormally to a wide range of different stimuli. Atopy is partially genetic, and is more common in some breeds (e.g. West Highland White Terriers).

How is it diagnosed?

It is important to get allergic skin disease properly diagnosed by your vet because there are many contributing factors and different underlying problems. As a result, diagnosis can be long and exasperating! In addition, diagnosing Atopy requires ruling out all other possible causes.

1) Initially, its vital to make sure that there aren’t any parasites (especially fleas!) on the dog – this is a LOT harder than most people think, and usually requires treatment of the affected dog, all other pets in the house, and the house itself. (A side note here – there are a lot of over-the-counter products available for treating fleas: some work, some don’t work, and some are very dangerous if not used correctly. I would strongly advise talking to your vet for advice, particularly as the most effective treatments are prescription-only medicines, some of which will also act over time to treat the environment as well as killing adult fleas).

2) The next step is to make sure there aren’t any skin infections that could be contributing to the symptoms, or mites burrowing into the skin. This may require skin scrapes to remove a layer of skin (it really doesn’t hurt!) and tape-strip tests to check for yeasts or bacteria.

3) There are a number of allergy tests available – these mostly use blood samples; intradermal tests (injection of test substances into the skin) may be more reliable, but they are expensive and difficult to perform.

4) To rule in or out food allergies, a controlled food trial is essential. This can be done with truly novel food sources, but in general it is more effective and practical to use a hypoallergenic diet from your vet. These diets are formulated so that the proteins are broken down so small that the immune system can’t recognise it. In a food trial, the dog is fed ONLY the controlled diet (no treats or snacks!) for a number of weeks. If the symptoms resolve, you reintroduce the original diet one item at a time, to determine what’s causing the allergy.

But why does it make my dog itch so much?

Itching is what’s called a “summative, threshold” experience. This means that there is a threshold level, below which itching won’t be felt. Anything that stimulates an itch (“pruritic”) response such as a flea bite, an allergy, or a skin infection, raises the level of “itch” until it breaks this threshold and the dog feels itchy. In most allergic dogs, several different factors combine to make the itching overpowering. Unfortunately, actually scratching makes things worse – this is called the “itch/scratch cycle”.

What are the scabs I can sometimes see?

Scabs generally mean one of three things:

1) Flea bites

2) Skin infection

3) MOST COMMONLY – self-inflicted skin damage caused by scratching. The skin is sore because it’s been scratched, and it’s been scratched because its sore etc etc… Scratching also damages the skin and allows infection to become established, which makes the itching worse.

What can I do about it?

The bad news is that most allergies cannot be cured, only managed. However, with good management, most cases of allergic skin disease can be fully controlled the vast majority of the time. There are a number of classes of treatment, which I’ll deal with in turn; however, many cases will require multiple overlapping treatments, so it is essential that you work with your vet to put together a management programme.

1) Disease modifying treatments

These attempt to reduce the underlying allergic response. The most effective are licensed immune-modifying drugs such as ciclosporin*, which when used long term reduces the allergic response. There is great hope for immunotherapy, where the immune system is gradually taught to tolerate certain allergic substances; this must be made up by a lab specifically for your dog’s allergies. Sometimes an allergy can be “cured” by this route, but it is more usually used to reduce the dog’s sensitivity.

2) Relieving symptoms

These act specifically to reduce the sensation of “itch”. There are three main drugs used for this. Firstly, antihistamines; these are not licensed for use in dogs and may have noticeable side effects, but a vet can legally prescribe them under the cascade if necessary. My experience is that they aren’t very reliable in dogs, but may be useful in some cases. There is also a new drug called oclacitinib which works purely to suppress a dog’s itch sensation. Finally, there are steroids. These reduce inflammation, mildly suppress the immune system and are very, very effective at reducing itching. They’re also inexpensive; however, if used long term, they have a wide range of side effects. They’re often best used as a “rescue” treatment, although steroid creams and sprays that can be applied directly to the sore spots on the skin have fewer side effects.

3) Reducing other sources of itching

This category would include products such as antibiotics for skin infections and antifungals for yeast infections (many of which are available as medicated shampoos), and parasite treatments for fleas and mites.

4) Reinforcing the skin barrier

This is a relatively new area, but seems to be a really useful in some cases or in addition to other treatments. There are soothing and hydrating shampoos which work to remove allergic substances from the coat and soothe the skin; as well as oatmeal shampoos which seem to have an anti-itching effect. Finally, there are the ω-3 fatty acids which appear to help many itchy patients; they may be in the diet (particularly in “skin” or “dermatology” diets), added to food as a supplement, or used as a topical spray or spot-on.

Overall, you and your vet need to find the combination of treatments that suit your dog. Managing the allergic pet is a big task, but I hope this has helped, and that you can keep your dog comfortable!

David Harris BVSc MRCVS

* PS – you may notice I’m using generic drug names not brand names in this article. This is because, for legal reasons, I’m not permitted to name specific brands in a blog like this. If you want to know more, check out the government’s Veterinary Medicines Directorate website.

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14 thoughts on “Ask a vet online – my dog has skin allergies, how do I help?

  1. Hi I have a 12 year old female choc point Siamese cat who has been dedicating dahirroia round the house for months we have taken her to the vet and they say she is dehydrated and have given her laxative and tabs and an enema we have still got the prob she doesn’t use her box at all but is still eating and social able she has lost a lot of weight and we are unable to let her into the bedroom she only does this where there is soft furnishings like throws or rugs can u suggest what to do as the cleaning is constant she doesn’t wash her self very well either and smells

    1. Hi Carol, as your vet has been dealing with her, it’s best you revisit and speak to them. They should be able to help by giving you advice that is appropriate for her case.

  2. Hi I have a 12 year old female choc point Siamese cat who has been dedicating dahirroia round the house for months we have taken her to the vet and they say she is dehydrated and have given her laxative and tabs and an enema we have still got the prob she doesn’t use her box at all but is still eating and social able she has lost a lot of weight and we are unable to let her into the bedroom she only does this where there is soft furnishings like throws or rugs can u suggest what to do as the cleaning is constant she doesn’t wash her self very well either and smells

    1. Hi Carol, as your vet has been dealing with her, it’s best you revisit and speak to them. They should be able to help by giving you advice that is appropriate for her case.

  3. Hi Carol, I agree with Dave – you really need to go back to your vet about this; diarrhoea with weight loss suggests a fairly serious mecical problem that needs proper investigation.

  4. Hi Carol, I agree with Dave – you really need to go back to your vet about this; diarrhoea with weight loss suggests a fairly serious mecical problem that needs proper investigation.

  5. My shar pei has had skin problems about a month after I had her. She has had skin scrapings for mange come back negative. She also had blood tests for the same come back negative it comes an goes she’s on a special diet prescribed by my vet I think she has an allergy to something but have tried ruling out everything is there anything I can give her to keep her allergies undercontrol as I don’t want her on steroids for the rest of her life could anyone help 🙁

  6. My shar pei has had skin problems about a month after I had her. She has had skin scrapings for mange come back negative. She also had blood tests for the same come back negative it comes an goes she’s on a special diet prescribed by my vet I think she has an allergy to something but have tried ruling out everything is there anything I can give her to keep her allergies undercontrol as I don’t want her on steroids for the rest of her life could anyone help 🙁

  7. My 1 year old male lab has recently broken out into acne/sores on face. My cousin is a vet and thought allergies, however he doesn’t itch or notice them, no red eyes, no hair loss, or sores anywhere else except chin and cheeks. They seemed to start post neutering. I’ve been treating as canine acne, washing with dog shampoo to keep clean and putting antibiotic medicated cream but now I’m wondering if Its something else and need to see a vet?

    1. Hi Jordyn, these things can arise for many reasons. I think it’s sensible to see a vet who can better make a diagnosis from looking at the sores and by talking through your lab’s history at length. It’s great that they aren’t bothering him at the moment however secondary problems might arise in time and it’s good to be sure that you’re treating the issue in an effective way. It could be something simple and relatively easy to treat (in which case it’d be great to ‘nip it in the bud’) otherwise your vet is best placed to devise a diagnostic and treatment plan. Best of luck.

  8. My 1 year old male lab has recently broken out into acne/sores on face. My cousin is a vet and thought allergies, however he doesn’t itch or notice them, no red eyes, no hair loss, or sores anywhere else except chin and cheeks. They seemed to start post neutering. I’ve been treating as canine acne, washing with dog shampoo to keep clean and putting antibiotic medicated cream but now I’m wondering if Its something else and need to see a vet?

    1. Hi Jordyn, these things can arise for many reasons. I think it’s sensible to see a vet who can better make a diagnosis from looking at the sores and by talking through your lab’s history at length. It’s great that they aren’t bothering him at the moment however secondary problems might arise in time and it’s good to be sure that you’re treating the issue in an effective way. It could be something simple and relatively easy to treat (in which case it’d be great to ‘nip it in the bud’) otherwise your vet is best placed to devise a diagnostic and treatment plan. Best of luck.

  9. Hello, I have a shih tzu girl,sage, she has yellow scabs on the bridge of her nose and the area between her eyes and just alittle on the top of her head. They protrude just alittle and they are hard. She also has a small open wound that look like a scratch. I was wondering what it could be and how I could treat it?

    1. Hi Elijah. It’s possible that she’s popped her head into something like a bush and scratched her face, but as there can be many causes of skin problems, I’d recommend popping Sage along to your vet for a check-up. This way, you can get a full diagnosis and make sure she’s on the right treatment for her skin

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