Dermatitis

Dermatitis – that sounds dryly medical at first, but it hits many dog owners right in the middle of everyday life. It refers to a skin inflammation that manifests itself through itching, redness and visible changes to the skin. It can be triggered by allergies, infections, parasitic infestation or quite mundane irritants from the dog’s environment.

What forms of dermatitis are there in dogs?

Atopic dermatitis is the best-known form – and unfortunately also the most stubborn. Here, the immune system reacts hypersensitively to environmental allergens such as pollen or house dust mites. Certain breeds are clearly at a disadvantage here: Golden Retrievers and French Bulldogs carry a hereditary predisposition that often shows itself already in the first year of life.

Hot spots can develop frighteningly quickly. When a dog licks or scratches itself raw, these weeping, circular wounds can literally develop within hours. Long-haired dogs that like to swim are particularly at risk afterwards – the damp fur under the dense topcoat is an ideal breeding ground.

Contact dermatitis appears exactly where the skin had direct contact with an irritant. This could be the new rubber collar, a different cleaning agent on the floor or the ivy growing in the garden – visible skin redness develops within a few hours.

Flea allergy dermatitis doesn’t even need a full flea infestation. A single bite is enough. The saliva of the flea triggers a chain reaction in sensitive dogs that can lead to weeks of itching – and this, even though you may not find a single flea anymore.

What triggers dermatitis in dogs?

Parasites such as Demodex mites actually live on every dog’s skin without ever being noticed. Only when the immune system is weakened do they multiply uncontrollably and leave behind bald, inflamed spots.

In food allergies, it is particularly tricky that they develop against proteins that the dog has tolerated without problems for years. Beef is at the very top of the list of triggers – followed by wheat and dairy products.

Hormonal disorders such as hypothyroidism weaken the skin from the inside. Sebum production gets out of balance, the coat becomes dull and the natural protective barrier of the skin collapses – an entry point for infections of all kinds.

How do I recognise dermatitis in dogs?

Permanent scratching and licking are the first warning signs that should be taken seriously. A dog that cannot sleep at night due to excessive itching is already suffering considerably.

Redness appears first in the most sensitive areas: belly, armpits, between the toes. The affected skin feels warm and can develop a sweetly unpleasant odour – this is no coincidence, but often an indication of secondary bacterial colonisation.

Hair loss occurs where there is the most mechanical scratching. Circular bald spots point more towards fungal infections, while diffuse hair loss over larger areas is more frequently due to hormonal causes.

How does the vet diagnose dermatitis?

A skin scraping brings parasites to light that remain invisible to the naked eye – a quick and uncomplicated first step.

Cytological examinations can detect bacterial infections or fungi. For this, the vet sticks a slide onto the affected skin area and can often read the results within minutes.

Allergy tests work differently in dogs than in humans. Intradermal tests are considered more reliable than blood tests, but they require brief sedation of the animal.

What treatment options are available?

Antihistamines have a significantly weaker effect in dogs than in humans. Only a proportion of treated animals respond at all – on the other hand, the side effects are comparatively low.

Cortisone injections provide rapid relief during acute flare-ups. However, in the long term, they weaken the immune system and can trigger diabetes in individual cases. They should only be used when there is severe distress and after careful consideration by a vet.

Special shampoos containing chlorhexidine or benzoyl peroxide noticeably reduce the bacterial load on the skin. The following regimen has proven effective: every three days for two weeks, then weekly for maintenance.

In Switzerland, immunotherapy – i.e. desensitisation – is the only treatment for atopic dermatitis that addresses the underlying cause rather than merely suppressing symptoms. In the largest review on this topic, symptoms improved by at least half in around 60 per cent of dogs; in just under a third, immunotherapy alone was sufficient to control the discomfort (664 dogs, Fennis et al., Veterinary Dermatology 2022). Treatment lasts at least one year and costs several hundred Swiss francs, but for many dogs it is the only path to genuine long-term improvement.

What can I do at home?

Cool compresses help surprisingly well with acute itching. A damp towel from the fridge, applied for ten minutes – simple, but effective.

Omega-3 fatty acids from fish oil strengthen the skin barrier from within. If you start this, patience is required: the effect only sets in after six to eight weeks.

The air in your home should not be too dry. Dry heating air in winter worsens any dermatitis – this is a factor that many underestimate.