Skin Problems in Dogs and Cats

By Dr Joanna De Klerk

Skin diseases in dogs and cats are a common and difficult area of animal companionship.

There are a number of types of skin problems we’ll cover in this article.

Parasitic problems, a bacterial disease, fungal disease, allergies, contact irritations, autoimmune disease and many others. Many textbooks have been written on this subject, so we won’t write another, but we’ll cover the more important topics for dog and cat owners.

Parasitic Problems


An obvious and common cause of skin problems. You can read more about diagnosing and treating them here. Read Article: Fleas

You can also read more about the best Dog and Cat Flea Treatments


These are caused by mites, and there are a number of them.

Demodectic Mange or ‘Demodex’ is a condition of young puppies or occasionally of old dogs. It is generally thought to involve some kind of immune deficiency of the individual, which predisposes to the Demodex infestation, as this mange does not seem to be infectious.

It usually starts on the face, especially around the eyes, with simple baldness, which extends & worsens. It’s not itchy at this stage. Some cases self-limit, progress no further and heal. But in others, pustules start to develop involving bacterial infection, and the problem escalates. Hill’s have done a great article on how to tell if your dog has mange.

Treatment of the infection with antibiotics is necessary, but the eradication of the mites is essential and difficult. Many treatments have been tried, but Amitraz is the current favourite in our practice. Demodex does have a nasty habit of recurring, however. Most common in short-haired breeds.

Sarcops / Scabies

This is a very itchy condition. There are 2 forms – doggy/foxy or human. They’re both infectious to dogs and humans. Often we see dogs with the human form, which they have caught whilst visiting a multi-person institution.

And of course, it can spread in the opposite direction. The skin becomes thickened and inflamed, especially behind the ears, in the armpits and groins of the dog. Treatment is a bit easier than with Demodex. Amitraz can be used, as can organo-phosphate products. Or ivermectins, where they are licensed.

In the UK Selamectin can be used for this and other uses. Read Veterinary Practice’s guide on treating canine scabies.


Also known as ‘walking dandruff’. This causes itchiness & much scurf and is very common in Boxers (and Rabbits!). Simple repeated insecticidal shampoos will usually resolve this, though it can also affect humans.

Harvest Mites

These collect in small orange clumps between the toes, or on the belly of dogs and cats. They can be quite an irritant. Again, bathing or spraying directly with an insecticidal treatment and repeating at weekly intervals will usually be effective.

Read YuMove’s guide to Harvest Mites.

Harvest Mites
Credit: Animal Magic Dog Club

Ear Mites

Also known as ‘Canker’. This is not so much a skin problem, but close. Ear mites cause lots of wax to form in the ears and are very irritating. They are also very infectious indeed. All dogs and cats in the house must be treated, cleaning out the ears, and then applying insecticidal ear drops repeatedly.

This should be done twice weekly for a month. It’s essential to treat ALL the pets. Otherwise, if just 1 or 2 mites survive in an untreated pet, then the whole problem will start over, a few weeks later!


In the UK, ticks are mainly an annoyance. But abroad, well there they may carry some very nasty diseases. If you are thinking of taking your dog to the continent, please read the advice on the government website first or speak to your vet.

In the UK, ticks (which always have a second species of animal in their life cycle) are usually sheep ticks or hedgehog ticks. They are small insects, which jump onto a passing dog or cat and bury their legs into the skin of the pet. They feed off the pet and then grow up to several millimetres in length.

Then they usually fall off, if left to their own devices. However, their removal is not quite so easy. Many things are suggested & none are perfect. The problem comes if most of the tick is removed, but tiny fragments of its legs remain embedded in the skin. This is why you need a proper Tick Removal Tool.

This can turn into a nasty, septic, sore reaction lump and will need veterinary attention. Prevention is always better than cure – Frontline Spray or Frontline Spot On are reasonably effective preventions against ticks, though their period of action is shorter for this purpose than against fleas.

Occasionally, ticks can be responsible for spreading “Lyme Disease” in the UK – this causes lameness and high-temperature conditions which can be quite difficult to both diagnose and to treat.

How To Remove A Tick From A Dog

Bacterial Diseases

There are a whole group of bacterial diseases affecting the skin. In simple terms, such diseases vary with the type of organism involved, and how deep the infection penetrates within the skin.

The commonest skin pathogen is Staph aureus, but there are many others including E.coli in various forms and Pseudomonas. If a bacterial skin problem becomes difficult, then it is very important to:

  1. Identify the organism and then
  2. Carry out an antibiotic sensitivity test on the organism itself

This will detect the most useful antibiotics to use. It will also detect those to which the bug is resistant, and which would be useless. This can save a lot of money! Antibiotic treatment is very important.

It also may well need a long course to deal with a skin problem, far longer than the 5-day course that we may be accustomed to, so do be patient. If your vet prescribes a one or two-month course, it is likely to be for a very good reason.

Wet Eczema

This is a particular form of bacterial skin disease. It looks the worst, but is usually easier to treat than dry bacterial eczema! Wet eczema tends to occur in warm/hot weather, and it starts off with minor scratching and in no time erupts into a wet, septic area of discharge.

It’s important to clip & clean the area with mild antiseptics. Stop the pet scratching the affected area, and use antibiotics, either topically, or by mouth, for several days, according to your vet’s advice.

Anal Furunculosis

This is a disease of GSDs. It involves the massive breakdown of tissue next to the anus, with secondary infection. But antibiotics alone will not sort this one out. It is now thought to be caused by an auto-immune condition, where antibodies attack normal tissue.

Until recently, radical surgery was the usual treatment, but now, the anti-rejection drug Cyclosporin is being used, with some success.

Fungal Diseases


Ringworm is NOT caused by worms, but by one of a group of fungi. It is a highly infectious disease, not particularly itchy, and needs very specific treatment. Usually, a dog or cat will catch ringworm from either another animal or from an infected place – such as a kennel, cattery, calf shed, stable, fence post etc.

Wooden buildings will carry ringworm spores indefinitely. Wooden buildings are not a good idea when ringworm gets into them. They CANNOT be properly disinfected.

Diagnosis of ringworm requires a plucking of the fur from the edge of the affected area to be cultured. The fungal culture can take 1-4 weeks to grow, so you have to be patient. If positive, then specific anti-fungal treatment is necessary.

Either an antibiotic called griseofulvin can be used – but NOT in pregnancy – or various baths/washes can be administered regularly. It’s a long job.


This is another fungal infection, involved in longstanding, greasy/seborrhoeic type skin conditions. Once diagnosed, it is best treated using an anti-bacterial & anti-fungal shampoo such as “Malaseb”. Malassezia can be part of a long term problem.


There are so many, and varied allergies so we’ll need to keep it simple. Allergens (the things triggering allergies) can be inhaled, ingested, or touched by the skin. So that opens up vast numbers of possibilities.

The commonest allergens are flea saliva, and house dust mites. Then there are also pollens, certain dietary proteins (eg dairy products & gluten), grass, household chemicals, and many, many others. Generally, allergies are suspected in itchy skin problems, where other, mainly infectious causes, have been ruled out.

Tests can be done to attempt to identify the allergen involved. There are recently developed blood tests, of varying accuracy. Some dermatologists will carry out intra-dermal patch testing.

IF you identify the allergen, then treatment is simple. Avoid the allergen! That’s not usually so simple at all, but you have to try!

Sometimes, a dermatologist may suggest a desensitisation programme.

But as fleas are the most common allergen, thorough flea control is usually the most important basis for allergy management.

The condition can also be managed with diet. These specialist hypoallergenic foods are to be used on an exclusive basis.

Contact Irritations

These are often considered to be allergies, but they aren’t really. These problems are caused by the irritant effect of a substance which the dog is lying on, on the dog’s skin. So the problem will usually be confined to the belly area & the underside of the paws.

Substances involved include cement dust from building work, dry carpet shampoos, caustic type irritants, new carpets, and freshly cut grass. There are doubtless many, many more. The simple proof of a direct contact irritant is to put the dog into a bland environment – such as a wooden based kennel – and see if the problem disappears.

Autoimmune Diseases

These are diseases where the body reacts against itself – in this case against its own skin tissue. Conditions such as Anal furunculosis – mentioned above under Bacterial Diseases – would be included.

But the biggest group of conditions here are the “Pemphigus” group, which have various manifestations. These are really specialist diseases, of a complex basis. Steroids are often necessary to control them.

Take-Home Message

Never ignore fleas. They are the single most common cause of skin diseases and can often go undetected. Prevention is better than cure!

If your pet licks themselves excessively, stop them doing it!

If you’re in any doubt, consult your vet.

Lastly, make sure you have pet insurance as skin disease can be expensive to treat and manage.