Marlow, a Shih Tzu, came to see us after struggling on and off for some time with a recurring skin condition.

His skin problems had previously improved with antibiotics and anti-itch medication, and for a little while his signs would remain under control. Unfortunately, the improvement was only temporary, and before long his skin would flare up again.

When I met Marlow, he was feeling suitably sorry for himself. He had areas of missing fur, thickened skin, scabs and scale. His owners were understandably keen to get to the bottom of what was going on.

Because Marlow’s skin disease was recurring, we wanted to investigate the underlying cause rather than simply treating another flare-up. We performed several dermatological investigations, including skin scrapes, hair plucks and skin biopsies. The skin scrapes and hair plucks were assessed in clinic and were reassuringly normal. The skin biopsies were sent to an external laboratory for histopathology, so we had to wait a little longer for those results.

In the meantime, Marlow still needed to be comfortable. He started on his usual combination of steroids and antibiotics, alongside a vigorous course of topical treatment to help manage the inflammation and support his skin.

Thankfully, Marlow’s biopsy sites healed extremely well. Coincidentally, by the time he was ready to have his stitches removed, his biopsy results were back too.

Marlow’s histopathology showed chronic hyperplastic dermatitis. This is a non-specific finding, but in Marlow’s case it was suggestive of chronic self-trauma – in other words, ongoing itching and scratching. The biopsy helped confirm that Marlow’s skin had been caught in a cycle of chronic irritation and self-trauma, but it didn’t tell us what was actually making him itchy in the first place.

What was Marlow allergic to?

The three main categories of allergy

When investigating allergic skin disease in dogs, we broadly consider three major categories.

1. Ectoparasites

The first possibility was ectoparasites, such as fleas and mites.

Marlow was already receiving routine parasite prevention through his health plan, and his skin scrapes and hair plucks were clear. These findings were reassuring and made a parasitic cause less likely.

However, flea allergy can be particularly tricky. An allergic dog does not necessarily need to have a large number of fleas present to develop significant skin disease. Even limited exposure can potentially trigger a substantial reaction in a susceptible dog.

2. Food allergens

Dogs can develop an allergic response to particular ingredients within their diet, with dietary proteins being common triggers. Food allergy can cause persistent or recurrent itching and can sometimes be difficult to distinguish from other forms of allergic skin disease.

One of the most useful ways of investigating suspected food allergy is through a carefully controlled elimination diet trial. This involves feeding a suitable diet for a specific period while avoiding other foods and treats, followed by a controlled reintroduction where appropriate.

This meant that what Marlow ate – including his treats – became an important part of his management.

3. Environmental allergens

Dogs can react to allergens in their everyday surroundings, including things such as house dust mites, storage mites, grass and tree pollens, weeds and other plant allergens.

Environmental allergies can be particularly challenging because these allergens can be difficult to avoid. Some dogs may experience seasonal flare-ups, while others can have problems throughout the year.

For Marlow, we therefore needed to consider all three categories and look at the whole picture rather than relying on a single test.

Changing Marlow’s management

In light of the investigation results, we discussed ways of reducing Marlow’s potential exposure to allergens in the future.

Marlow started on a hypoallergenic diet, and his owners became very careful about their choice of treats.

This is an important point for owners. There are many foods and treats available that use the term “hypoallergenic”, but not every product making this claim will necessarily be suitable for a strict dietary trial. If you are unsure whether a particular food or treat is genuinely appropriate for a hypoallergenic diet, I would strongly recommend speaking to your veterinary professional. Feeding additional foods that contain potential allergens can make a dietary trial difficult to interpret and may ultimately make it much harder to determine whether food is contributing to your pet’s skin disease.

Marlow continued his course of steroids for another month while his skin settled. He also had regular shampooing and foot bathing as part of his topical management. The foot baths, incidentally, were not something Marlow was particularly keen on!

Marlow today

I saw Marlow again just last week, and he looked absolutely incredible.

His skin was looking comfortable, and his hair was growing back – ginger!

It was wonderful to see such a transformation. It was also very clear how much hard work Marlow’s family had put into his care. Managing chronic skin disease can require a great deal of patience, consistency and commitment at home, and their efforts were clearly paying off.

Marlow is continuing on a tapering dose of steroids while we work towards finding the best long-term strategy to minimise future flare-ups and keep his skin comfortable. But he is still very much in a state of monitoring.

But perhaps the best news of all came from his owners: Marlow is much happier too.

The truth is that skin disease can be challenging and frustrating. It can take time to reach a diagnosis, and successful management often involves a combination of medication, lifestyle changes, and plenty of commitment from owners at home.