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Symptoms such as itching, redness, pustules, hair loss and odour can be very troublesome for pets and owners alike. But, when you’re not an expert, it can be difficult to know what the cause of the problem is, and if you need to be concerned. In this article, we discuss skin infections in pets, including how to spot the signs, diagnosis, and treatment. 

So, how do I know if my pet has a skin infection? The signs of a skin infection in pets include dry, crusty skin, redness, a sour odour, pustules, hair loss, and itchiness. However, these symptoms can also be attributed to other skin conditions, therefore it is vital to consult your vet for diagnosis.

Read on to learn more about skin infections in pets, and how to spot the signs.  If you have a concern please book an appointment online or call us.

brown puppy scratching itself

How Do I Know if My Pet Has a Skin Infection?

Whilst the signs of skin infections in pets are similar for cats and dogs, and are usually reasonably easy to spot, they can vary somewhat between species and breeds. They will also present differently depending on a number of factors, including age, health status, the cause of infection, and how long they have had the infection.

External skin infections such as cuts, burns, and allergies will often be easy to spot, presenting with redness, spots, pustules, discharge and an unpleasant odour. They may also be warm to the touch. Deeper skin infections, such as abscesses, will typically swell up into a hot, painful lump. You may find that your pet tried to chew or lick at the area for relief. 

Symptoms of skin infections in pets include:

  • Flaky, crusty, or scaly skin
  • Redness
  • Itchiness
  • Pimple-like pustules
  • Seeping of blood or pus
  • Hair loss or hair standing on its ends
  • Swelling or ulcerated skin
  • Change in odour
  • Brown nails
  • Thickening of the skin

What Do Skin Infections Look Like in Pets?

Skin infections are typically fairly easy to spot in pets, especially if you know what to look for. Below, you’ll find some of the most common characteristics of skin infections in cats and dogs. 

Flaky, Crusty, or Scaly Skin

Infected skin may present as flaky, crust or scaly as a result of the skin drying out excessively. This can be uncomfortable, itchy, and sometimes painful for pets.


Many skin infections will present with redness of the affected area, and may be accompanied by flaky, crusty skin, pustules, spots, and ulcers.


Itchiness is a common sign of skin infections, and will often also present alongside redness, and crusty skin. Don’t allow your pet to scratch at it too much, though, as it could make the problem worse, and may spread it to other areas of the body.

Pimple-Like Pustules

Just like in human infections, your pet may develop pimple-like pustules as a result of infection. Be careful to avoid touching these. What’s more, these pustules may seep blood or pus if disturbed. 

Hair Loss or Hair Standing on its Ends

In short-haired breeds, your pet’s coat may seem to protrude or stand on its ends, and mimic hives. In long-haired breeds, you may notice patchy hair loss.

Swelling or Ulcerated Skin

Deep infections may make the skin appear swollen, and can develop ulcers, abscesses, and other lumps which may be red and hot to the touch.

Change in Odour

If your pet has dry, crusty skin, or has developed pustules or abscesses, your pet’s odour may change if they begin to seep or discharge.

Brown Nails

Brown nails may be a sign of yeast infection of the nail beds. This is usually a result of allergies due to foot chewing.

Thickening of the skin

If infections and inflammation are not caught early, the skin may thicken over time as a way of protecting itself. You may also notice hyperpigmentation. If you notice any of the above symptoms in your pet, ensure to contact your vet for assessment. Left untreated, infections can have severe consequences further down the road. 

What are the Most Common Skin Infections in Pets?

Whilst skin infections can be easy to spot, they can be difficult to diagnose and determine the cause of the infection. That said, some of the most common skin infections include:

Bacterial Skin Infections (Pyoderma)

Bacteria naturally lives on your pet’s skin and is usually harmless. However, if your pet’s skin barrier is damaged, infection can take hold. Typically, bacterial infections present with red, circular patches on the skin that can sometimes have a odour. 

Hot Spots (Acute Moist Dermatitis)

Hot spots (also known as acute  moist dermatitis), are patches of infected skin that appear red, look wet, and often weep. They tend to develop very quickly, and are caused by an infection within the skin. 

Yeast Dermatitis

Yeast infections may cause your pet to develop a greasy coat and a sour odour. It is caused by the fungus malassezia pachydermatis, which when abnormal growth occurs, can cause dermatitis. 


Ringworm is a fungal skin infection that can cause hair loss and crusty, red skin. It is very contagious and can be easily spread to other pets (different species), and humans. Symptoms of ringworm include patches of red, raised, crusty skin, alopecia, dandruff, and mildly itchy skin. Don’t be fooled by the name, though, ringworm doesn’t always present in rings and circles.

What Can Skin Infections Be Mistaken For?

The symptoms of skin infections can easily be mistaken for other skin conditions, and vice versa. It’s always a good idea to consult your vet when you notice such symptoms, however, below we have outlined a number of conditions which skin infections can be mistaken for. 

  • Allergies

    Second to fleas, allergies are one of the most common skin problems in pets. Often, allergies will present with similar symptoms to infections, including itching and redness. In more severe cases, you may also notice hives, swelling, and rashes.

  • Fleas & Parasites

    Fleas are a very common skin problem, causing itchy skin. Other parasites such as mites and lice can also cause itchy skin, alongside red, irritated skin. It would be very easy to mistake fleas and parasites for a skin infection, or vice versa.

  • Dermatitis

    Atopic dermatitis, or chronic dermatitis, is a skin disease in cats and dogs that is the result of allergies to, for example, airborne or ingested substances. This allergy causes your pet to lick, rub, bite, or scratch the skin, just like with an infection. They may also occasionally cough or sneeze.

  • Hormone Problems

    Most hormone problems will have an effect on your pet’s skin and fur. This is less likely to be mistaken for a skin infection, but similar symptoms relate to hair loss; Hyperthyroidism can cause thinning of the hair, whilst Cushing’s Disease may cause bald patches and lumps in the skin.

sad Orange cat laying on ground

What Causes Skin Infections in Pets?

It can be difficult to determine the exact cause of skin infections in pets. They can be caused by a number of different factors, and can easily be mistaken for another skin problem. However, some of the most common causes of skin infections in pets include:

Fleas and other parasites


Chronic dermatitis

Poor grooming

Wounds & broken skin from scratching or accidents

Hereditary & genetic conditions

What Causes Recurrent Skin Infections in Pets?

Whilst some skin infections are bacterial, often a result of wounds, some infections can be recurrent due to underlying conditions. Because of this, it is incredibly important that your vet gets to the bottom of the cause of your pet’s skin infection, so that any underlying causes can also be treated. Thus, minimising the chance of recurrence.

A common cause of recurrence is skin allergies. If the allergy is not determined and managed, then the skin infection may keep coming back each time your pet comes into contact with the allergy. Hormonal conditions, as well as hereditary and genetic factors, may also cause skin infections to recur if the condition is not diagnosed and effectively managed.

How are Skin Infections Diagnosed in Pets?

The exact diagnosis of skin infections in pets can often require a detailed medical history, followed by various diagnostic tests. Many skin infections have similar symptoms, and can also be mistaken for other skin conditions. As such, it can take time for your vet to make an exact diagnosis, if at all. 

During the medical history, your vet will ask a number of questions, such as:

  • The primary complaints – what’s bothering your pet
  • The length of time that the problem has been present, and the season that you first noticed the problem
  • The age of your pet
  • Breed
  • Any notable behaviours, such as licking, rubbing, scratching or chewing the skin
  • The area of the body in which the problem was first noticed
  • Any other health conditions
  • How often you bathe your pet
  • Flea and parasite prevention
  • Any changes in environment
  • Any other abnormal changes to your pet’s health and behaviours

Your vet will also conduct a physical examination of the fur and the skin underneath. They will be looking for skin lesions such as pustules, discolouration, scars, ulcers, alopecia, scales/crust, blackheads, and others. 

From here, if a diagnosis has not yet been made, your vet may choose to conduct laboratory tests. For this, they may collect samples such as:

Skin Scrapings

One of the most common diagnostic tests for skin infections. This test can be superficial, collecting information from the surface of the skin, or deep, collecting information from within skin follicles. 


This test collects a large amount of skin debris and can trap parasites, enabling vets to determine if the cause is parasitic.

Hair Trichogram

Another common diagnostic test and is increasingly being used in place of skin scrapings. Hair is plucked from the follicle and examined for mite infestations, dermatophyte infections, dysplastic hairs, and sometimes, genetic diseases.


Cytology is useful for identifying bacterial, fungal, and, possibly, neoplastic skin diseases. Several skin smears are taken and sent to a laboratory for examination.

Fungal Cultures

Samples are taken from affected lesions and incubated for 14 days. 

Bacterial Cultures

Intact pustules are ruptured with a needle and swabbed before being sent to a laboratory for examination.


Biopsies are used in more severe or unusual cases of infection. Several samples may be taken for examination.

Blood & Urine Samples

If systemic signs of illness are present, your vet may request a CBC, chemistry panel, and urinalysis to help identify the cause.

How are Skin Infections Treated in Pets?

Treatment for skin infections in pets will depend on the type of infection, the cause of the infection, severity, other relevant conditions, age, species, and other contributing factors. 

Bacterial infections (pyoderma) will typically be treated with oral antibiotics, topical sprays, and shampoos. There is a wide range of antibiotics, but your vet will choose the most appropriate for the condition. Such treatments usually take between 2-6 weeks, and should continue until at least 1 week after symptoms have disappeared. Similarly, fungal infections may be treated with antibiotics, alongside anti-fungal topical treatments, such as shampoos and ointments. 

If there is an underlying cause of the skin condition, that condition will also  be treated to help resolve the problem. 

Can I Treat My Pet’s Skin Infection Myself?

If you notice the signs of a skin infection, it is vitally important to consult your vet. Your vet has the knowledge and equipment to be able to diagnose your pet’s skin infection, and determine a suitable treatment that will help to resolve, or manage the condition. It’s highly unlikely that a store-bought, at-home treatment will sufficiently treat the infection, and you may end up making the problem worse. 

Dermatology Services at Knutsford Vets

Knutsford Vets offers a wide range of dermatology services to help get to the bottom of your pet’s skin problems. Led by Dr Rachael Canines, the dermatology team at Knutsford Vets are on hand to diagnose the cause and offer you the treatment or advice required to help you successfully manage the issue. Find out more about pet dermatology or book your appointment today.

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