Dogs don’t get spots… or do they? 

It is definitely possible for dogs to develop spots, otherwise known as pustules. But, unlike humans, they don’t get them as a matter of course and there’s usually an underlying reason why they are having a skin breakout. Let’s explore the importance of a healthy skin barrier and what happens when things go wrong.

Normal dog skin

Your dog’s skin acts as a barrier to the outside world. This layer of protection is essential for keeping harmful invaders such as bacteria and yeast out. The skin is a major organ in the body, responsible for many functions, and makes up at least 10-15 % of your dog’s total body weight.

The skin is made of three main layers:

The epidermis (outermost layer)

This is the part we can see. It is covered in keratinocytes which form a protective layer that is constantly shed and renewed. As well as helping to keep harmful things out of the body, it also acts to keep moisture and bodily salts in. Other cells in this area determine pigmentation (melanocytes), sensory input from touch, temperature etc (Merkel cells) and immune functions (Langerhans cells)

The dermis (middle layer) 

The dermis houses important structures like hair root follicles and sebaceous (oil) glands, which then exit up through the epidermis to the skin surface. The sebaceous glands are responsible for secreting an oily substance known as sebum. This helps to keep your dog’s skin soft and flexible, as well as further protecting the skin surface. It is also what gives your dog’s coat its shine. Sweat glands can also be present, but in dogs, these are only found in the feet and are not your pet’s main way of cooling themselves. The dermis also contains blood vessels, which are important for regulating body temperature, and nerves. 

The subcutis or hypodermis (innermost layer) 

This layer contains fat and muscle. This subcutaneous fat acts as insulation and shock absorption, as well as being an important energy reserve. 

When the skin becomes damaged in some way, this can affect its ability to do its job effectively and harmful pathogens can start to invade. Damage can occur due to external factors, like a bite wound, or because of issues within the body itself. Autoimmune problems and allergies are an example of this, leading to skin inflammation and secondary infections.

Good skin and coat condition is important, not only because it helps your dog look their best, but also because of the important role it plays in your dog’s health.  

What happens if the skin is diseased?

If your dog’s normal skin barrier is damaged, then disease can occur. Skin disease can present itself in several different ways, but symptoms could include a combination of the following –

  • Pruritus – increased itchiness, which may be seen as excessive licking, scratching or rubbing.
  • Pustules – otherwise known as spots, more on this below.
  • Alopecia – hair loss, which can occur due to the underlying condition, or may be secondary to the animal overgrooming and self-traumatising.
  • Erythema – redness and inflammation of the skin surface.
  • Increased odour – your dog may smell more than usual due to secondary skin infections
  • Dry, flaky skin – the skin may appear dull, scaley or scurfy. 
  • Hyperpigmentation – the skin may become darker, or grey due to ongoing irritation and self-trauma.
  • Skin thickening – the skin becomes more thickened, appearing wrinkly or cobblestone-like, due to ongoing issues.
  • Sores, scabs or wounds – your pet may have sores, either due to the primary disease process or because they have been self-traumatising because of extreme itchiness.

That’s all very interesting… but why does my dog have spots?

Let’s now hone in on the original question and explore pustules in more detail.

Pustules (or spots) are small, red, inflamed bumps in the skin that are filled with pus. This pus is usually white, yellow or clear in colour. Pus is a fluid made up of dead white blood cells, which are present because they have been fighting a localised infection in the skin. On some pustules, this fluid will be visible, whereas others may have already burst, and some may have pus trapped deeper beneath the skin.

Your dog may just have one or two pustules, or they could have multiple. There is usually associated inflammation, with the surrounding skin often looking pinker than normal. Pustules are often much more obvious in the non-haired bits of your dog’s body, such as their abdomen and groin. 

What causes pustules?

Pustules are just a symptom of disease; they are not in themselves a diagnosis. Infection of the skin can be referred to as pyoderma, which can actually occur for a few different underlying reasons. Sometimes this cause is obvious, but other times it can occur in seemingly healthy animals. 

Depending on the findings of your pet’s examination, your vet may need to suggest a few tests to properly understand the cause and best treatment options. 

Here are a few different conditions that could lead to pustules developing on your dog – 

Allergic skin disease

Dogs with skin allergies are much more prone to secondary infections. With allergies, the dog’s protective skin barrier becomes less effective. Reactions to allergens can lead to inflammation and itchiness, and the skin will become further diseased through self-trauma (licking and scratching). This means that low levels of bacteria and yeasts found normally on the skin of most dogs can start to get a foothold and multiply. This can present as spots, but you may also notice moist patches and an increased odour. 

Dogs can be allergic to an array of things, with atopic dermatitis (environmental allergies (e.g. grass pollens and house dust mites), food allergies and allergies to flea bites all possible.

Skin trauma

Skin trauma can provide an opportunity for bacteria or yeasts to penetrate the skin barrier, causing a secondary pyoderma. This could be from a simple bite or scratch injury. It could also arise from other issues such as urine scalding or coming into contact with something that has damaged the skin surface such as a concentrated chemical irritant.

Parasites

An underlying parasite issue could lead to skin irritation and secondary infections. Flea-allergic dermatitis can cause problems in affected dogs. These animals are allergic to proteins in flea saliva, creating a reaction as well as the general irritation that the bites cause. Microscopic mites burrowing in your pet’s skin can also create issues. Sarcoptic mange is caused by a mite that can be spread between dogs, wildlife or people. Demodectic mange is caused by a different mite that normally lives at low levels in healthy dogs, but their numbers can multiply in some individuals.

Autoimmune disease

Autoimmune disease is where the body attacks itself. In dogs, Pemphigus Foliaceus is perhaps the most well-known of these conditions. In this disease the body’s immune system is attacking the attachment between skin cells, leading to scabs, sores and pustules. Autoimmune disorders are rare in dogs and your vet will usually need to diagnose them through taking skin samples (including biopsies).

Skin fold dermatitis

Some breeds inherit wrinkled, folded skin through poor selective breeding. The areas of skin within these folds are very warm and moist, which can be a breeding ground for bacteria and yeast. The skin then becomes further inflamed, moist and irritated. The area often develops an odour and can be painful for affected animals. Commonly affected breeds include Shar Pei, Bulldogs and Pugs. 

Sometimes the exact cause isn’t clear

For example, young dogs (below 12 months old) are, like human teenagers, more prone to pustular skin disease. In these adolescent dogs, the exact cause isn’t always clear, but it is common enough to be termed Canine Acne.

What are the treatment options for pustules?

Treatment is aimed at resolving the underlying issue as well as clearing up the spots themselves. By managing any underlying factors that are affecting your dog’s skin and coat health, it is possible to reduce the chances of pustules occurring again in the future. 

Treatment will depend on the individual animal and the causes, but could include –  

  • Topical treatments of shampoos – A prescription shampoo may be required to treat your pet’s skin infection or medicated wipes. These will also help to soothe inflammation
  • Antibiotics – Oral antibiotics may be necessary in some dogs with bacterial skin infections. It is important to complete the course as instructed.
  • Anti-parasite treatment – Ruling out parasites as an underlying cause of disease is important but using preventative treatments will also help to stop future problems as well. This is especially important for dogs that suffer from flea-allergic dermatitis (FAD). 
  • Medication to reduce itchiness – Some dogs with pustules may be itchy, so this should be controlled. This will make them feel more comfortable and also stop them from traumatising the skin. There are many different options and types available including steroids (prednisolone), oclacitinib, cyclosporin, monoclonal antibodies and antihistamines. 
  • Immunotherapy – If your pet has had allergy testing then immunotherapy can be explored. A liquid medication is formulated containing the allergens that your dog is reactive to, in small quantities. This medication can be administered to your dog via regular injections, to gradually desensitise them to their allergens. 
  • Surgery – Surgery may be suggested for some animals, usually those that are suffering from skin fold dermatitis. Removing excess skin folds may be essential in these patients.
  • Regular washing and drying of skin folds – Some dogs can be managed through regular cleaning of their skin folds.
  • Change of diet – A long-term change of diet is required in animals with food allergies. This is a strict diet that must be rigorously followed to avoid your pet encountering a trigger. Your vet will talk you through conducting a dietary trial if food allergies are suspected. 
  • Supplementation with essential fatty acids (EFAs) – EFAs can help improve the skin barrier and coat condition. These can be given as a supplement or may be found in some skincare/allergy diets. 
  • Avoiding contact with known irritants – If your dog reacts to a certain carpet cleaner or fabric softener, then avoiding the use of these products should stop future skin flare-ups.

Summary

The skin is an incredible organ, but pustules can be a sign that something is going wrong. These spots can occur on your dog for several reasons, so it is important to ask your vet for advice. Some cases of pyoderma can be easily treated through a course of medicated shampoo or anti-parasite treatment, whereas others will require more investigation and long-term management. 

It is important not to put things off, as delaying treatment may only make problems harder to resolve. Contact your vet if you have any concerns at all about your dog’s skin health.