What does a bacterial skin infection look like on a dog

Skin Infections in Dogs

What Are Skin Infections in Dogs?

Skin infections are conditions that are caused by infectious organisms such as bacteria, fungi, or parasites. All areas of skin can be affected, including inside the ears and nose, as well as the hair and nails.

The severity of the disease depends on the type of infection and can vary from very mild to painful and itchy. Some organisms that cause skin infections are transmissible (or contagious), which means the infection can be passed to another mammal through direct contact or the environment. There are also infections that are caused by organisms that normally live on the skin and are not considered contagious.

Types of Skin Infections in Dogs

• Bacterial

• Fungal

• Parasitic

• Viral

Symptoms of Skin Infections in Dogs

• Redness

• Bumps or raised areas of the skin

• Itchiness (you may see your dog scratching, licking, and/or chewing the skin)

• Scales or flakes

• Crusts or scabs

• Hair loss (alopecia)

• Oozing or discharge (blood, pus, clear)

• Skin color changes (darker or lighter)

Causes of Skin Infections in Dogs

There are many causes of skin infections in dogs. Some infections are primary infectionsan infection directly caused by an infectious organism. Other infections are secondary infections and occur because of an underlying disease process that triggers an infection.

Primary Infection

Scabies is an example of a primary parasitic skin infection. Dogs acquire scabies by direct contact with an infected animal. The scabies mite then causes the clinical signs associated with the disease. Ringworm is an example of a primary fungal infection and is acquired due to contact with infected individuals or an infected environment, including soil.

Secondary Infection

A common example of a secondary skin infection is one due to skin allergies. The allergies cause inflammation of the skin, which then provides an environment favorable to organism growth. Bacteria or fungi that normally live on the skin are then able to multiply, leading to a bacterial or fungal skin infection.

How Veterinarians Diagnose Skin Infections in Dogs

There are several basic skin tests that are useful in diagnosing a majority of skin infections. The most common ones are:

• Skin scrapes: A dull scalpel blade is used to scrape the top layer of the skin; effective for finding skin parasites like demodex.

• Skin cytology: A sample is collected by pressing a microscope slide directly to the skin lesion or via a needle and syringe and then looked at under the microscope for bacteria, fungi, or abnormal skin cells.

• Tape preps: Clear tape is used to collect a sample of hair or skin to find bacteria, fungi, or parasites when viewed under the microscope.

• Cotton swabs: A cotton swab is used to collect a sample, most often from inside the ear, to diagnose bacterial, fungal, or parasitic infections.

• Cultures: A sample of skin, hair, or discharge is collected onto a growth plate to look for bacterial or fungal growth over time. This test can also be used to learn which antimicrobial medication is best to treat the infection.

Treatment of Skin Infections in Dogs

The treatment of a skin infection depends on the type of infection, the location of the infection, and the condition of the dog. Bacterial skin infections are treated with oral (by mouth) antibiotics, and/or topical products such as medicated shampoos, conditioners, sprays, and ointments. Common products include:

Fungal infections are treated similarly, with antifungal medications, and parasites are treated with antiparasitic medications.

To help the skin heal and to prevent future infections, other treatments are used to support healthy skin. For example, when treating an ear infection, special ear cleaners are used in addition to the antimicrobial medication. Omega-3 fatty acid supplementation is another treatment used to help resolve and prevent infections. Prevention is often the best medicine and regular bathing and grooming can be helpful for not only treating skin infections but also preventing them from occurring in the first place.

For secondary skin infections, it is important to treat the primary cause of the secondary infection. Skin allergies, for example, frequently require medications to reduce inflammation and allergic reactions. Treating a skin infection without treating the allergy will likely lead to another infection. Food allergies require special diets to reduce skin inflammation. If a food allergy is suspected, your vet will work with you to determine an appropriate food trial,to slowly remove certain ingredients and introduce possible allergies to determine the culprit.

Recovery and Management of Skin Infections in Dogs

The time it takes to treat a skin infection depends on the type of infection, the ability to treat primary causes of the infection, and the severity of disease. Sometimes the most difficult part of the treatment is sticking with treatments for as long as needed.

Some skin infections can be difficult to treat because of antimicrobial resistance. Antimicrobial resistance occurs over time, when microbes develop defenses against our medications, making those medications ineffective. In those cases, treatment can take longer and may require further testing.

Infections can resurface, especially if the primary cause of the infection has not been treated or resolved. Dogs with chronic conditions such as allergies or other diseases are more likely to have repeat infections.

Managing skin infections successfully can be complicated, time consuming, and expensive. Following your veterinarians recommendations closely and being patient during the treatment period is important for resolving the infection and preventing recurrence in your pup.

Featured Image: iStock.com/Sergeeva

WRITTEN BY

Dr. Rania Gollakner

Veterinarian

Rania Gollakner received her Doctor of Veterinary Medicine degree in 2010 and a Master of Public Health in 2017. She practiced companion...

Skin Infections in Dogs: Bacterial Infections

Symptoms of Skin Infection in Dogs

Clinical signs associated with a skin infection in dogs can vary depending on the specific cause, but early manifestations of the skin condition can be similar regardless of the cause. Commonly seen symptoms are itchiness, hair loss, and generalized discomfort. Skin flaking and crusting can also be seen in some cases of skin infection.

Generalized redness, erythema, and skin inflammation can also be observed in dogs with skin infections. Untreated and severe cases will eventually emit a pungent or foul odor, and can even be fatal to highly susceptible and immunocompromised animals.

Types of Skin Infection in Dogs

Skin infection in dogs can be generally classified into 2 types: bacterial and fungal. Several bacterial and fungal species can invade and penetrate the skin barrier and cause infection in canines. Inflammation and breaks on the skin barrier can increase the risk of these microorganisms taking over, leading to an infection.

Its important to determine what type of skin infection an affected animal has because the treatment for both types is different. Medications that can control and eliminate bacterial organisms will have no effect against fungal infections, and likewise, anti-fungal medications are ineffective against bacterial skin infections.

Proper identification and diagnosis are important to have a specific and targeted treatment for your dogs skin infection.

Common Bacterial Skin Infection Causes in Dogs

Pyoderma is the most common bacterial skin infection in dogs. This bacterial skin infection is characterized by the presence of purulent (pus-like) discharge from the skin and is commonly caused by several species of bacteria.

Pyoderma in dogs is differentiated based on the tissues of the skin involved in the disease. Infections that only affect the topmost layers are called superficial pyoderma, and pyoderma that infiltrates and infects the deeper layers of the skin are called deep pyodermas. Superficial pyoderma accounts for the majority of pyoderma cases in dogs.

Most superficial pyoderma cases occur spontaneously and often present with a localized skin lesion. Loss of hair, or alopecia, is typically seen in superficial pyoderma cases, along with erythema (redness) and purulent discharge. Superficial pyoderma lesions tend to cause severe discomfort and will result in affected dogs trying to scratch or bite on the lesions, making the condition worse. The most common bacteria that causes this type of pyoderma is Staphylococcus pseudointermedius.

Deep pyodermas, on the other hand, usually have a triggering cause. Oftentimes, deep pyodermas result from untreated superficial pyodermas. Some cases of deep pyoderma are caused by the same bacterial species, but other organisms like E. coli, Proteus sp., and Pseudomonas sp. can also cause infection. Deep pyoderma cases affect the deeper portions of the hair follicle which results in erythema, hyperpigmentation, swelling, and skin ruptures. Affected areas of the skin are often painful and swollen.

Diagnosing & Treating Bacterial Skin Infections in Dogs

As mentioned, treatment for skin infections in dogs will ultimately depend on proper identification and diagnosis. The best way to diagnose skin infection in canines is through skin cytology, bacterial and/or fungal culture, and identification. Several methods like skin scraping, smear biopsy, and acetate cytology have proven effective in determining whether a skin infection is bacterial or fungal in nature. Identification of specific bacterial or fungal causes will involve culturing and isolating the bacteria taken from skin samples.

Most bacterial skin infections respond well to antibacterial medications. Localized and solitary bacterial infections can easily be treated with topical medications such as antibacterial creams and ointments. A more generalized infection will often need systemic antibacterial therapy for treatment.

Similarly, fungal infections are mostly treated with topical medications such as ointments or medicated shampoos, depending on how widespread the lesions are. Systemic antifungal medications are usually only prescribed in severe cases of fungal skin infections because of their potential liver and kidney side effects.

Read more:

Skin Infections in Dogs: Fungal & Yeast Infections

Common Skin Parasites in Dogs

My Dog Wont Stop Licking His Paws - Help!

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Dog Bacterial Skin Infections [With Pictures & Vet Advice]

Canine skin disease is a common problem that can affect any breed. Most dog lovers have had some experience caring for dogs with red, itchy skin.While all dogs are vulnerable to canine skin disease, some breeds are more susceptible.

For example, Shar Peis and French Bulldogs are prone to infections in their skin folds. Labradors and Golden Retrievers attract hot spots, while Basset hounds are prime real estate for yeast and bacterial growth.Dermatological problems can be very frustrating.Not only is your pooch uncomfortable, but the necessary treatments can often be prolonged.

Working as a veterinary technician in a busy veterinary hospital, Ive treated many dogs suffering from itchy, painful skin. From what I have seen, the surest path to resolving the problem is to obtain an accurate diagnosis right from the start.

Symptoms of bacterial skin disease

The majority of canine skin infections are bacterial.They are usually secondary to another disease process.Here are some of the main symptoms to watch out for that many indicate bacterial skin infection (also known as pyodermas):

1. Redness, pustules, or papules
2. Crusty lesions or flaky skin
3. Swelling, oozing or draining of a blood-tinged fluid or pus
4. Small red bumps

The picture below shows a red, circular lesion that is quite inflamed (staphylococcus bacterial infection). This is sometimes called a bullseye lesion:

With bacterial infections, there is usually inflammation of the hair follicle called folliculitis. This can lead to the build-up of crusts (scabs form). There may be small bumps (papules), raised hairs (tufted papules) and hair loss. Learn more about Folliculitis.

The picture below shows several pustules and inflamed red skin from a bacterial skin infection.

Skin infections can lead to skin irritation that may result in hyperpigmentation and black spots on a dogs skin. As hyperpigmentation results from chronic irritation, these spots will lie flat as part of the skin and will not have a mass-like appearance.

Bacterial skin infections (usually Staphylococcus sp.) cause black spots on the skin in the same manner as injuries, as the infection damages the skins barrier. This damage is a result of the inflammation present secondary to the infection.

When the infection clears in response to treatment, the spots should fade as well. It is normal to see black spots remain much longer after the infection is resolved. The circular sores associated with bacterial infections are referred to as epidermal collarettes. As these sores resolve, the skin becomes hyperpigmented.

Some of these signs are shared by other diseases, like certain immune disorders and neoplasias.Your veterinarian will be able to determine the true cause of the symptoms using their experience and diagnostic tools.

Four Common causes of bacterial skin infections in dogs

Any illness that weakens your dogs immune system increases the chance of a bacterial skin infection. The following interfere with the skins health in a more direct way:

1. Cushings Disease

Cushings Disease decreases the amount of normal collagen found in the skin, causing the skin to become weak and thin with extra folds. The skin may develop dark lesions as well as small raised bumps.Unfortunately, this makes the dog a prime candidate for a secondary bacterial infection.View pictures of dogs with Cushings disease.

2. Hypothyroidism

Hypothyroidism decreases the activity of certain enzymes resulting in changes to the natural skin barriers.The skin develops a darker pigment, there are areas of hair loss and the skin becomes more susceptible to bacterial infection.

3. Flea bite dermatitis

Flea bite dermatitis is an allergic reaction to flea saliva.Your dog will develop itchy skin with hair loss starting on the back and extending to the base of the tail. If left untreated it can progress forward up to the neck and head.Your dogs licking and chewing the itchy skin causes scabs and red bumps, leaving the skin vulnerable to secondary bacterial infection.

4. Sarcoptic scabies and demodex

Sarcoptic scabies and demodex are two parasitic mites that can infect a dogs skin.Demodex is a natural inhabitant of dog skin and only becomes an issue when a dogs immune system is compromised.On the other hand, scabies is spread from dog to dog.

Both of these infections cause great damage to the skin and increase the chance of a bacterial infection setting in.An infection of scabies or demodex is commonly called mange. You will see hair loss and red, scaly skin.

Note: Sarcoptic mange or scabies is contagious to people.

More types and causes of bacterial skin infections

Pyodermas can be classified by the depth of tissue affected. Allergies, immune disorders, and some cancers often underly a bacterial infection.

Surface pyoderma

Only the outermost layer of skin, the epidermis is affected. Hot spots or acute moist dermatitis and skin fold pyoderma are examples of a surface pyoderma.

Hot spots

Canine hot spots are self-induced.When a dog scratches and chews at an itch they may cause small breaks in the skin.As they continue to chew the nerves become inflamed and cause more itching which leads to more chewing.

A hot spot can start as a tiny red spot and very quickly become a large red lesion infected with bacteria. Often they ooze blood-tinged fluid.

The initial itch can be due to fleas, insect bites, allergies, anal sac impaction, or matted fur that pulls at the skin and causes an itch. Additionally, boredom or anxiety can make a dog chew or lick incessantly causing a hot spot.

Skin fold pyoderma (intertrigo)

The friction caused by skin rubbing against skin causes inflammation.The area becomes moist and therefore an ideal place for bacteria to grow.Yeast also likes this environment and is often an additional pathogen (disease-causing organism).

Skin fold pyoderma appears as reddened skin with discharge. There may be a foul odor. The skin folds may need to be spread open to see the inflammation.

Superficial pyoderma

The outer layer of the skin, the epidermis is affected along with the hair follicles.Hair loss, redness, crusty lesions and bumps may be seen.Puppy pyoderma and folliculitis are examples of superficial pyodermas.

Puppy pyoderma

This is one bacterial skin infection that doesnt typically have an underlying disease involved.Puppies skin is sensitive and when it becomes irritated from things in the environment the bacteria that normally live on the surface of a dogs skin cause an infection.

It usually occurs on sparsely haired areas such as the belly, armpits and groin.Puppy pyoderma appears as red bumps or lesions that are sometimes scaly and itchy.

Folliculitis

A common ailment of dogs, folliculitis causes a moth eaten appearance to the hair coat along with redness and itching.Raised red bumps or pustules and flaking, crusty skin may be seen.Sometimes a foul odor may be noticed.Folliculitis is often seen secondary to allergies. View more pictures of folliculitis in dogs.

Deep pyoderma

In deep pyoderma, the deeper levels of the skin, the dermis and the subcutis are affected.This may start as superficial pyoderma and progress to a deep infection. In some cases, a deep pyoderma may arise on its own.Its often secondary to ademodex infection.

Redness, swelling, nodules, or fistulous tracts draining bloody fluid or pus may seen.There may be a foul odor.This is a painful condition, so prompt veterinarian care is necessary.

There are different types of deep pyodermas, including furunculosis and lick granulomas. Furunculosis is when the deep layers of the skin closest to the hair follicles become infected or red and painful nodules are seen. These usually occur in between the toes, around the anus, and on the face.

Also known as acral lick dermatitis, lick granulomas cause a localized lesion that is red, bumpy, and raised.It starts with excessive licking of the same spot.The licking may come from an allergic itch or it could be behavioral.These granulomas usually occur on the wrist, ankles, hocks, or feet.They can become fairly large and unsightly, looking like a tumor.

Diagnosing bacterial skin infections in dogs

Like any disease, obtaining a diagnosis starts with the clinical signs or symptoms. Your veterinarian is familiar with the different types of lesions affecting various areas of the body and this information aids in diagnoses.

But because most skin infections have similar clinical signs, tissue sampling is important.Tissue samples can be obtained via impression smear, skin scraping, or fine needle aspirates.

The samples are examined microscopically and may be submitted for culture and sensitivity testing.Any bacteria cultured is then tested for its sensitivity to various antibiotics.This lets the doctors know which antibiotic will be the most effective for your dog.

Red, itchy skin!Do I need to take my dog to the vet?

Besides the most minor cases, its a good idea to have skin irritations checked by a vet.Skin disease can progress quickly, so its smart to check for any serious diseases that may be the underlying cause.

Here are some reasons your dog needs to be seen by a veterinarian immediately:

1. The skin disease is extensive, covering a large portion of your dogs body
2. Your dog is showing other signs of illness such as trembling, vomiting, or not eating
3. If your dogs skin is bleeding or oozing

Let your vet know the severity of the symptoms so that they will get you in to have your dog seen right away. Untreated skin infections can lead to systemic disease causing serious illness. Moreover, if your dog seems uncomfortable or in pain from constant itching and scratching, you may want to see a vet on an emergency basis to relieve the discomfort.

If the affected area is small and the symptoms are mild, you can try treating your dog on your own with commercial products.There are many shampoos, ointments and all natural remedies for your dogs itchy, inflamed skin. However, its a good idea to consult your veterinarian before using any at home treatment options so that they can recommend ones that are safe and effective.

When attempting a home remedy monitor your dog closely. If the symptoms worsen or there is no improvement after a few days, you need to see a veterinarian.Its imperative to get your dog on the right course of medications quickly to ensure a good outcome.

Treatment options

Surface pyodermas and some superficial pyodermas may resolve with daily bathing using a medicated shampoo prescribed by your veterinarian.

Oral antibiotics are often necessary to cure bacterial skin infections. In addition, medicated shampoos, sprays, or ointments are normally prescribed.It may take three to four weeks to be rid of the infection. Resistant cases may take eight to twelve weeks to cure. As the dog parent you must be diligent, bathing your dog as often as the vet prescribes.

Its necessary for your vet to treat the underlying disease to fully rid your dog of the infection. The cost to treat your dogs pyoderma varies depending on the severity of the infection and how quickly your dog responds to treatment.A mild infection may cost from $200 to $400 to treat.A serious infection could go much higher, costing from $500 to $1000.

These estimates include the exam fee, bloodwork, tissue sampling, cytology (microscopic evaluation of cells), culture and sensitivity, antibiotics, medicated shampoos and sprays.The underlying disease will also need to be addressed and that will involve further diagnostics and medications.

Zoonosis: can I catch my dogs nasty skin infection?

The majority of canine bacterial skin infections are caused by Staphylococcus species, some of which are contagious to people.People with compromised immune systems should use care to not come into contact with the infected dog and the dogs bedding.Healthy individuals should wash hands after handling the dog and perhaps temporarily forgo sharing the bed.

What can I do to prevent a bacterial skin infection in my dog?

Prevention of any disease starts with good nutrition and good hygiene. Regular bathing, keeping their ears clean and wiping skin folds daily goes a long way for skin health. Good grooming, trimming excess hairs of the feet and regular brushing to avoid mats is also important.Keeping up with flea and tick preventative is helpful as well.

Regular exercise helps keep your dog mentally healthy and may keep them from the excessive licking and self mutilation that bored, anxious dogs engage in.

• Elana Benasutti is a Certified Veterinary Technician in the state of Pennsylvania. She earned her degree from Harcum College located in Bryn Mawr, Pa. Elana spent her first ten years as a certified technician working as the ultrasound technician in the Radiology Department at the University of Pennsylvanias veterinary teaching hospital, MJR VHUP. Elana spent the next seventeen years as a critical care nurse in the Intensive Care Unit of MJR VHUP.

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