A guide for owners with itchy dogs

As a pet owner, it’s certainly frustrating to see your dog scratching all the time. At times, you may even feel hopeless as he starts scratching again once the medication finishes. Well, here are some things you need to know about your itchy dog (and yes, he can be a normal dog again!).

Why is my dog scratching?

You give your dog medication from the vet and his itchiness stops but the moment the medication finishes, he starts itching again! Sounds familiar? Well, it’s most likely because the main/underlying cause has not been identified or kept under control. This is one of the reasons why properly treating an itchy dog takes time (often 3-4 months minimum) and why regular follow ups with your vet is important.

There are many reasons why a dog would itch, ranging from common causes, like allergies, to rarer ones like autoimmune diseases. In this guide, however, we will only focus on the common causes of itch.

1. Parasites

Certain parasites, like the Sarcoptes mites, can cause intense itching for a dog. Other parasites, like Demodex sp., may not cause itching but they can result in secondary bacterial infection that can result in itch. Fortunately, with newer over-the-counter medications like Nexgard, Simparica and Bravecto, these mites can be easily treated or prevented.

Microscope images of an adult mite and eggs of Sarcoptes scabiei isolated from raccoon dogs. Bar=100 µm. [1]

2. Allergy

This is probably the most common cause for itch in a dog, especially in adult dogs. There are 4 common allergies – flea bite allergy, contact allergy, food allergy and atopy/environmental (eg. pollens). There is no cure for allergies, but they can be managed well. Therefore, it’s important that these allergies are identified and ruled out one by one systematically as it will affect both you and your dog’s wellbeing in the long run. For example, if your dog has food allergy, all you need to do to manage the itch is to ensure he eats food that he’s not allergic to. He may not need any long-term medications. On the other hand, if he is atopic (eg allergic to pollens), he will need to take medication to control the itch, potentially for life! In some cases, some dogs may be both allergic to certain food and environmental allergens, which may mean the dog will need both dietary management as well as long term medication. This systematic ruling in/out process is also the reason why it often takes months before we can “properly” treat an itchy dog.

Dog with atopic dermatitis[2]

3. Infection?

Fungal infections like ringworm can definitely result in itch. However, more commonly in adult dogs, a dog may only have bacterial or yeast infection. Now, these can definitely cause a lot of discomfort to the dog and may even slow down healing, especially if the dog has a hypersensitivity towards yeast. But they are often not the main reason. These organisms can be found even on normal animals (and humans!) but they don’t usually cause an infection unless there’s an underlying cause which weakens the skin barrier, such as allergies. If these underlying causes are not managed well, the bacterial or yeast infection will only recur after the medication stops.

Bacterial infection[3]

 Greasy skin due to yeast infection (bottom)[4]

4. Hormonal?

One common hormonal reason for itch in dogs is hypothyroidism, which is disease resulting in low thyroid hormones. The disease itself does not cause the itch, but like allergies, it increases the likelihood of a parasitic, bacterial or yeast infection. Unfortunately, in Malaysia, we do not have a single test to confirm whether a dog has hypothyroidism. Your vet may rely on a combination of clinical signs and a total thyroid test (TT4) to suspect hypothyroidism. However, the TT4 test is not conclusive as they may be falsely decreased depending on the time of the day and even in allergic dogs with severe skin infection. For a more accurate, albeit more expensive diagnostic test, we can send a blood sample overseas to test for thyroid-stimulating hormones (TSH). This can help us better diagnose hypothyroidism, especially when used in combination with the total thyroid test.

What can I do?

Firstly, it’s highly recommended that you take your dog to a vet as they will need to examine your dog to give it the appropriate treatment. It may be tempting to purchase the medication over the counter to avoid the hassle of bringing your pet to the vet or to save on consultation fees. But without allowing your vet to check your dog and discuss the treatment plan with you, you may end up misdiagnosing the disease. At best, you will end up spending more money than you really need to. But at worst, you may make things more severe with inappropriate treatment. For example, inappropriate use of antibiotics can lead to antibiotic resistance where eventually, we’ll run out of options to treat a simple skin infection. In severe resistant cases, you may even need to wash your dog in bleach, which will not be a pleasant experience for both you and your dog!

Your vet may recommend a particular treatment plan which may include starting your dog on a special diet. It is crucial that you follow the treatment plan strictly. For example, if your vet recommends giving a particular food for a food trial, it is vital that you do not give any other food during the trial period. This is because it will confound the results, making the trial invalid (and therefore, wasting your time, money and energy).

Your vet may prescribe antibiotics and anti-itch medications for your dog. It is important that you give according to the vet’s prescription. Certain drugs that require twice daily dosing, like antibiotic, should be given every 12 hours whenever possible. It is best that you do not stop prematurely before consulting your vet as it may make matters worse.

Some of you may be wondering if supplements/”natural products” are helpful. Supplements can definitely help with your dog’s recovery but it’s often insufficient to control active inflammation as a sole therapy. In fact, some may take up to 2 months to see their benefits. In most cases, you will still need at least anti-itch medication from your vet to control the itch in the initial stage.

Which anti-itch therapy can I go with?

The most common anti-itch medications in Malaysia are antihistamines, prednisolone/steroids, cyclosporine (ie Atopica), Apoquel and Cytopoint. Without going into too much detail, here’s a quick summary of each of them[5]:

    • Antihistamine (eg. cetirizine) may be potentially helpful in combination with other drugs, especially if given long term, but their effects are often variable and may not be entirely helpful in the initial stages.

    • Steroid (eg. prednisolone) is a cheap and effective drug in controlling itch but there are many potential side effects, such as diabetes and urinary tract infections, especially if given long term. It’s not recommended to give this long term unless there’s no other option.

    • Cyclosporine (ie Atopica) is a good option for long term management of itch in dogs with atopy. However, it is not suitable for use during trials (eg food trial) because trials are often short-term and cyclosporine may take a while before it reaches a steady level in the body to control the itch (potentially up to 4-6 weeks).

    • Apoquel is a non-steroidal fast-acting drug that is as effective in controlling itch as steroids, if not even better. It has been shown to have a lot less side effects compared to steroids and is relatively safe to be given once daily long term. However, this drug is not cheap, especially in the first two weeks, where your dog will need to take it twice daily.

    • Cytopoint is an antibody injection that specifically targets a protein called interleukin-31 (IL-31) which causes itch in dogs. Because it is targeted, it has a lot less side effects compared to steroids and other therapies. In fact, because it is an antibody, it is a good option for dogs with kidney or liver disease as it is not processed through those organs. One injection can potentially last 4-8 weeks, so it is a convenient option for owners who do not want to or are unable to give daily medications to their dog. The downside to this amazing drug, however, is that it is also not cheap.


Besides these medications, owners with atopic dogs may also want to consider allergen-specific immunotherapy (ASIT). To put it simply, we send a blood sample to an overseas laboratory to test for allergens your dog is allergic to. They then put the allergens in a vial and this is injected into your dog over several weeks in increasing doses so the body “gets used to” the allergens. This is the only therapy that works with the body’s immune system and may potentially prevent itching in the long term. The downside to this therapy is that it takes time (about 6-12 months) and is costly (a couple of thousands Ringgit). However, it has been shown to be effective in about 50-60% of cases and it’s worth a try, especially for the more severe cases.

Conclusion

Itchiness in dogs is not a hopeless situation. There is no cure, but as mentioned before, your dog can live a normal itch-free life. Yes, it is time-consuming to get down to the root cause, but once identified, there are medications and therapies which we can use to help manage the itch. So don’t dally – bring your dog in to your nearest vet now to put him on the road to an itch-free life! He’ll thank you for it!

 

Dr James Tan Jin Liang

Taipan Veterinary Clinic & Surgery

 

[1] Credit to: Epizootic of sarcoptic mange in raccoon dogs (Nyctereutes procyonoides) in relation to population density – Scientific Figure on ResearchGate. Available from: https://www.researchgate.net/figure/Microscope-images-of-an-adult-mite-and-eggs-of-Sarcoptes-scabiei-isolated-from-raccoon_fig2_322589928 [accessed 13 Jun, 2023]

[2] Credits to Dr Peter Hill. Taken from the Australasian Veterinary Dermatology Advisory Panel (AVDAP) Guidelines for the Diagnosis and Management of Pruritus in Dogs, 2nd Ed.

[3] Credits to Dr Mandy Burrows. Taken from the Australasian Veterinary Dermatology Advisory Panel (AVDAP) Guidelines for the Diagnosis and Management of Pruritus in Dogs, 2nd Ed.

[4] Credits to Dr Mike Shipstone. Taken from the Australasian Veterinary Dermatology Advisory Panel (AVDAP) Guidelines for the Diagnosis and Management of Pruritus in Dogs, 2nd Ed.

[5] Adapted from the Australasian Veterinary Dermatology Advisory Panel (AVDAP) Guidelines for the Diagnosis and Management of Pruritus in Dogs, 2nd Ed.