Scratching dog.

The Canine Skin Allergy Journey

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This blog is designed to take you through the various steps involved in managing allergy in your dog. The reason we refer to it as a journey is because when it comes to allergy there is no ‘quick fix’ and we must make decisions as we go, based on the information we have at that point in time. It requires flexibility and adaptability and is a journey that should be made alongside your vet to reach the best solution for you and your dog.


Where are you starting your journey from?

Allergy Map

Before starting any journey, it’s important to do some planning, and in this case that includes understanding all about allergy.

An allergy is when your dog’s immune system has an overreaction to what would normally be considered a harmless substance – this substance is known as an allergen. Instead of ignoring the allergen, their immune system gets it a bit wrong and views it as a threat. Exposure to the allergen therefore results in an increased production of something called IgE antibodies. Antibodies are made by white blood cells as part of the body’s defence against illness and disease. The IgE antibodies then trigger various reactions from other cells in the body and ultimately lead to the occurrence of the symptoms you see. The next time your dog meets the same allergen their immune system is ‘primed’ ready and so the reaction is much quicker.


Common Allergens

Common allergens in people and dogs include pollens, dust mites and insects (for us think mosquitoes, for dogs think fleas). If you’d like to know more about why allergy affects some dogs more than others please take a look at our separate blog on the allergy threshold, click here.


Travel companions

– you, your dog and your vet are on this journey together


Allergic skin disease is common, affecting around 10-30% of dogs and is often complex. If your dog has been suffering with symptoms for some time, you may feel frustrated that the problem has not been resolved more quickly. You may even feel that so much has already been tried that there is little point in doing more, other than accept the inevitable outcome that your dog won’t further improve. If allergy is the root of your dog’s issue then it is a life-long condition and will never be ‘cured’, but there are many different solutions available to help address it. Persevering to find the right ones for your dog can make all the difference to successfully managing their condition and quality of life long-term.


Go road sign.In order to be successful, the solutions must be sustainable. With this in mind, it is essential you are honest with yourself and your vet from the start about the amount of time and money you are able to commit, so that the solutions found will work for everyone in the long run. There is no magic bullet to solve the problem but the more involved and motivated you are, the better the outcome will be for your dog.

Wherever you are on your allergy journey right now, as part of the journey planning process your vet may ask you lots of questions about your dog’s previous symptoms and treatments (perhaps by completing a questionnaire); the more details you can provide at this point the better because gathering and reviewing this information is a critical step in setting off in the right direction.


Why are you making this journey?


We mentioned earlier that successful management is key to the welfare of your dog but we mustn’t forget that your dog’s symptoms can also impact the rest of the family too. Watching your dog in discomfort is upsetting to witness, with itching being the most common complaint. However, different dogs will respond to the ‘itch’ in different ways; do you identify your dog as a nibbler, an ear scratcher or a foot chewer? Perhaps they do all of the above or maybe their symptoms are something else entirely?


Is your dog a nibbler, scratcher or a chewer?



Sometimes itching isn’t the first symptom you notice; perhaps your dog has brown patches of hair coat (caused by saliva staining) or pink sore areas of skin that they have been repeatedly licking? Maybe they have musty or unpleasant smelling skin or ears (which can be caused by infections) or perhaps they have a visible rash or spots?


Common Symptoms of Canine Allergy


Canine symptoms infographic.


Seasonality and Severity

The symptoms of allergy do vary from dog to dog and at different times of the year; some dogs will have very mild signs that only bother them for one particular season, allowing them to be medication-free much of the time – these are known as seasonal allergies. In contrast to this, other dogs will suffer from severe and consistent symptoms, which may be much more difficult to control. Sadly, often seasonal cases will go on to have year-round problems later on.

The itch severity scale


This scale is sometimes used to grade how severe the itch is, which can be helpful as a baseline, to predict flare-ups, to monitor progress or to check the response to treatment:

Allergy Scale

Wherever your dog currently sits on the scale, once their skin is back under control you can play a key role in keeping them there by being the eyes, ears (and nose!) on the ground 24/7. By learning how to spot the first tell-tale signs that indicate your dog’s skin is starting to flare up again, you can help bring it back under control more quickly.


Skin damage


So why does your dog’s skin deteriorate so quickly? If your dog has even been over enthusiastic jumping up to greet you, or has accidentally caught you snatching a toy while playing, you will know what damage their teeth and nails can cause to the skin. From an evolutionary perspective these ‘weapons’ are assets, used by their ancestors to take down prey and fight off threats. However, when the teeth or nails are deployed to constantly try and relieve a compulsive itch (the kind we may feel after we’re bitten by a mosquito), it’s easy to see how the skin can very quickly get damaged.

Your dog’s skin has a protective barrier on the outside, designed to keep all the good stuff (like water) in and all the bad stuff (like allergens, bacteria and viruses) out. When this barrier is damaged it becomes ‘leaky’ and stops functioning as it should – moisture leaks out causing the skin to get dry and even cracked, and more allergens and bacteria can get into the skin, causing inflammation and infection.


The skin barrier

Skin Barrier Diagram

Scratching and biting the skin will cause direct damage to the barrier and can also introduce infections from the nails or mouth. To make matters even worse, some dogs with allergies are thought to be born with defects to this skin barrier, setting it up further to fail.


Skin barrier support


There are some important ways you can help to support the skin barrier, which will in turn help reduce the number of flare-ups. These may be topical products that can be applied to the skin, special foods or oral supplements; they all contain ingredients that aid the health of the skin, for example, essential fatty acids. Although these products alone are unlikely to be enough to solve the problem, they can play a key part in the successful long-term management when used in combination with other treatments. This is because firstly, they can help reduce the number of flare-ups and secondly, may allow a lower dose of other medicines with a higher risk of side-effects to be used.


How to know you’re on the right path – diagnosing allergic skin disease


Your dog has all the right symptoms so they must be allergic, right? Not necessarily! Confusingly, many other common conditions also cause these exact same signs and therefore need to be ruled-out before committing your dog to a life-time of allergy therapy. So how about running an ‘allergy test’ then? Again, it’s not that simple. Despite their name, ‘allergy tests’ are not designed, and should not be used, to diagnose allergies; instead they are used to help identify allergens to which the dog is sensitive after the diagnosis has been made. This information can be incredibly useful (as you will see later) but the fact remains that the only way to diagnose an allergy is through a process of ruling out the other common causes first.

Be warned, this is often the part of the journey when frustration kicks in! There is improvement, your dog responds to treatment but then as soon as it stops you are right back to the beginning again. It can be tempting to just leave them on the medication that helped and go no further, but is that the best option long-term? To help navigate a route past this often-bumpy stage of the trip, it can help to take a little time understanding why certain steps are necessary and what your vet can learn from them. It also helps to remember that this process is about things being struck off the list and not just trial and error.

Allergy is a life-long problem so you want the best life-long solution rather than a short-term fix, accepting that this may take a little time and effort to find is key.




One of the first things to rule-out are parasites that can live on the coat, and by that we mean fleas, mites and lice.

Flea, Louse and Mite

Whilst this is often a touchy subject, let’s get any awkwardness out of the way first by stating dogs get fleas! It is totally normal and does not in any shape, fashion or form suggest that your house (or dog for that matter) is unclean! The reality is that if you are not regularly treating your pets and home for fleas at the recommended intervals for the product you use, then they may well get fleas.

Fleas cause issues in two ways: firstly, if there are lots of them present, they can cause itching; and secondly, some dogs are allergic to the saliva in the flea bite, in which case even if they are only bitten once or twice, they will react to it and start itching.. Finding fleas is not always as straightforward as you think- your vet may spot a live flea while examining your dog (tricky as they are fast) or find flea dirt in their coat, either using the ‘wet paper’ test or when looking at skin samples under a microscope.


The Wet Paper Test 

Fleas feed on blood so when they poo it is basically changed blood known as ‘flea dirt’. If you brush the flea dirt onto a white piece of wet paper towel or damp cotton wool, the blood will leak out creating a little red halo around it. This is a common way to identify the presence of fleas.


Even if no flea dirt is spotted, fleas need to be ruled-out as a cause of itching. The good news is that whilst fleas are a relatively easy problem to fix it does still require some hard work and diligence on your part to ensure that they are eradicated from not only your dog but other pets and the home environment too. You may be shocked to learn that the fleas you find on your pet represent just 5% of the problem and that the other 95% is actually within your home!


Flea Diagram Pyramid

The diagram below shows the flea lifecycle and how so much of the population ends up being in the home environment rather than just on the pet.

Flea Life Cycle

Lice and mites are also on the rule-out list, though the good news is that many of the modern flea treatments will also kill lice and certain mites too. Mites may be spotted after taking skin samples from your dog, details of which are listed in the table below. Knowing which parasites are present is really helpful to your vet for successful long-term management.


REMEMBER: When we are talking about parasites (especially fleas), eradicating them once wins the battle but not the war! It is really important to maintain continuous, year-round flea prevention (plus cover for mites, lice and ticks if required), particularly in dogs suffering from allergies in order to help prevent flare-ups.


Skin sample tests


As already mentioned, skin sampling can be used to help us spot mites but is also needed to rule bacterial and yeast infections in or out. These infections can make your pet itchy, in which case if they are the sole problem, treating them with the appropriate medication will resolve the itch. We need to bear in mind however, that repeated skin infections are often a sign of an underlying issue such as allergy. Infections are more likely if skin barrier issues are present or the skin is being traumatised by itching, as mentioned earlier.

Some dogs will also have an allergy-type reaction to the bacteria or yeast itself (a bit like some reacting more to flea bites than others), in which case additional tests may be necessary to check for this and different therapies may be used to help.


Commonly used skin sampling tests and how they help


Test How it helps
Microscopy Samples are taken from the skin by doing coat brushings, scrapes, adhesive tape, or by swabbing the skin or ear. These samples are examined under a microscope to look for bacteria or yeast and for evidence of skin parasites or fungi. They may be sent to a laboratory for further testing.
Swab taken for bacterial culture A swab is taken to identify what bacteria are present on the skin/in the ear. The swab is sent to a laboratory and they will also work out which antibiotics will be effective against the bacteria.
Hair plucks The hairs are examined under the microscope to look for mites, fungi and to check hair growth. They can be helpful in working out if hair is falling out or if it is being pulled out due to scratching. The sample may be sent to a laboratory for further testing.
Fungal culture A sample is taken (often using a tooth brush to gather material) and sent to the laboratory to identify if any fungi are present and if so, what type they are (the hair pluck sample may also be sent off/used for this purpose).


Treating skin infections


Depending on the results, medicated topical antiseptic products (shampoos, wipes, sprays etc.) might be prescribed or oral/injectable antibiotics. As in human medicine, antibiotic resistance is becoming an ever more serious problem in animals and so topical therapy should be used whenever possible and appropriate.


TOP TIP:  You can play a big part here too, by continuing with any medication (oral or topical) as prescribed for the full duration (completing the course). This will not only help treat the infection properly now but will also reduce the chance of your dog getting resistant bacteria in the future. Attending all scheduled check-ups and keeping your vet informed of any concerns is also really important.


For many allergic dogs, good skin hygiene through the routine use of medicated topical antiseptic products is another key part of achieving long-term control.


Ruling out food allergies



We now hit a junction in the journey; for the majority of dogs ruling out a food allergy is the right way forwards at this point, to prevent having to retrace the route later. Food allergies can cause just the exact same symptoms as environmental allergies (with or without digestive symptoms in addition) and it is therefore impossible to tell just from their symptoms which of these an itchy dog may have. The one possible exception to this is dogs who genuinely only have seasonal symptoms and no digestive signs. To complicate matters further, it is not uncommon for dogs to have both food and environmental allergies together! If your dog does have any digestive symptoms, additional blood tests and/or a stool sample may also need to be sent for analysis first.

The only way to diagnose a food allergy is by conducting a food trial and this in itself should be seen as a diagnostic test. A blood test can be used to help decide which food to use for the trial. Like any diagnostic test, if a food trial is not run properly the results will be meaningless, so it is very important to follow the instructions completely.

So, what does ‘food trial’ actually mean? In a nutshell you will feed your dog a very strict diet (including all snacks and treats) for a period of at least 8 weeks. If the symptoms do improve, it is possible that ingredients in the original food may be the problem. In order to confirm this, you would then give the original food again to see if the symptoms return (this is known as ‘re-challenging’). This is an important part of the process because only then do we know it was the strict diet that caused the improvement rather than something else, or it just being a coincidence. Ideally, you would then investigate further to identify which individual ingredients of the food are causing the reaction so that these can be permanently removed from your dog’s diet. Ask your vet for a copy of the Avacta Animal Health ‘Food Trial Instructions for Dogs’, which explains common mistakes and also includes handy owner tips and an 8-week diary.

For some dogs with food allergies, removal of these problem foods will mean that their symptoms will completely resolve, preventing the need for life-long medication. Other dogs, which have a combination of both food and environmental allergies, are likely to only see a partial improvement as the other allergies remain. This partial improvement is still very beneficial though as the dietary changes often reduce the amount of medication needed long-term. Food allergies are common, especially in dogs with skin or ear problems, so while it’s important to recognise many dogs will not improve during the dietary trial, the potential benefit for those that do makes it an essential part of the diagnostic work-up and well worth doing.


Where next?


Stop sign.Finally, after many rule-outs, we have the diagnosis of an environmental allergy, otherwise known as atopic dermatitis. So, this is the end of the journey, right? Wrong!

While at this stage a huge pat on the back is deserved, and a rest stop may be required, this should only be seen as a view-point; we now have better clarity to make strategic choices on how to get to where we want to: optimal long-term management.

It’s also important to understand that much of the ‘rule-out process’ will need to be repeated over the years to keep on top of infections and other secondary issues which are common in allergic dogs.



Allergy testing


The next step in the journey is allergy testing, which can provide you with both additional management and treatment options for your dog to proactively help prevent flare-ups occurring, rather than just dampening down the symptoms afterwards.

The most commonly used and simplest method of allergy testing is for your vet to take a blood sample from your dog and send it to a veterinary laboratory, who will test it and send the results back. Your vet will then interpret the results alongside all the information from your dog’s history and work out which allergens are likely to be causing the problem. Once this is known, the allergens can then be avoided or at least exposure to them can often be reduced (for example, wiping their face after eating dry food to remove storage mites if these are found to be an issue).


Allergen specific immunotherapy (ASIT)

The main reason allergy testing is done is because it allows a special type of therapy, known as allergen-specific immunotherapy (ASIT), to be created specifically for your dog. Each therapy is tailor made and uses very small amounts of the relevant allergens to ‘re-educate’ the immune system. The allergens stimulate the immune system in a controlled way and because such a small amount is given, the symptoms are not usually triggered. Over time, the allergen specific immunotherapy is administered in gradually increasing amounts until a tolerance/maintenance level is reached. This exposure helps desensitise your pet to the allergens so that when it comes in contact with them for real, they cause less of a problem.

Many vets will opt to take the blood for allergy testing early on during the rule-out stages and ask the laboratory to store it until you are ready to test. This offers the benefit of getting the sample when your dog’s symptoms are at their worst (this helps the test work best) and before any medications are used that could affect the results (these are often needed to control the skin before you reach the diagnosis).


Looking at the whole journey


Hopefully by now you can understand why dealing with allergies is not simple and why a combination of options will create the best long-term management approach. Broadly speaking, the ‘allergy journey’ can be split into three parts:

  1. Settling the skin initially
  2. Long-term control
  3. Treating flare-ups

The benefits of long-term control are clear; the better this is, the less flare-ups there will be. The less flare ups there are, the happier and healthier the dog is, and the less negative impact it has on the family – in time, in money and in emotion.  In addition to this, it is often more cost effective to invest in proactively controlling the condition long-term, rather than treating each flare-up as it occurs, because flare ups can be very costly to treat.


Staying in Remission



When we are looking at medications to treat allergy symptoms, there are a variety of different ones available. They are often used in combination and it’s important to understand why you are using each one. One of the benefits of using a combination of solutions is that it can help to reduce the dependence on certain medications that have a higher risk of side-effects.


In addition to using immunotherapy and allergen avoidance (which change the dog’s response to allergens), treatments that stop the itch and reduce inflammation are often also required, at least in the initial stages. These treatments may also be used to treat flare-ups when they occur or might be part of the permanent solution to gain longer-term continued control. The use of products to support the skin barrier, offer antiseptic control and prevent skin parasite problems are also essential components of the solution for many dogs. The separate Avacta ‘Therapy Guide for Dogs and Cats with Allergies’ discusses and compares different treatment options and you can ask your vet for a copy.


Final Allergy Roadmap

So now we have the complete roadmap laid out it is time for you, with the guidance of your vet, to decide which route to take. Think about what you want to achieve short-term and where you want the long-term destination to be – these are often different answers. There are no right or wrong answers to this but by making the decisions with your vet and with your dog’s individual requirements at the heart of the plan, you increase the chance of success. You can help the process by being clear about what you can manage and asking for help if you are struggling. For example, many owners find it hard to bathe their dog, administer oral medication or spot the early signs of a flare-up and by giving your vet this information in advance, it will allow them to best support you and your dog along the way.

Atopic dermatitis (an allergy to things in the environment) is a life-long condition and what’s right now may not be right next year. However, throughout their life-time you will remain the single biggest factor in keeping your dog’s skin happy, healthy and controlled.

For further information on canine allergy click here.

Canine allergy management

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