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Ask the Vet: Hair Follicle Infection in Dogs

Hair Follicle Infection in Dogs

Hair follicle infections in dogs can create troublesome symptoms which warrant a veterinary visit. To better understand this condition, it's firstly important knowing exactly what hair follicles are, what's their main functions and how infections happen. Veterinarian Dr. Ivana Crnec discusses hair follicle infections in dogs and what happens at the vet's office as far as diagnosis and treatment.

 Superficial folliculitis in a Staffordshire bull terrier with atopic dermatitis.

Superficial folliculitis in a Staffordshire bull terrier with atopic dermatitis.

Hair Follicle Infections in Dogs 

The hair follicle is a part of the skin that grows hair. The infection of hair follicles is medically known as folliculitis. In the majority of cases it is caused by bacterial infections. However, on occasions, folliculitis can be caused by fungal infections, parasitic infestations and hormonal imbalances.

Generally speaking, folliculitis can be caused by systemic diseases and skin diseases. The most common folliculitis-causing systemic diseases are: Cushing’s disease (also known as hyperadrenocorticism), hypothyroidism and immune-mediated disorders.

Almost all skin diseases can eventually cause folliculitis. However, the most common folliculitis-causing skin diseases are: fungal infections, presence of external parasites (particularly fleas), callus dermatitis, acral lick granuloma, canine acne, allergies, interdigital cysts, skin fold pyoderma and idiopathic furunculosis (in German Shepherds).

When the hair follicles become inflamed, pustules form within the affected follicles. As the inflammatory products accumulate, the follicles develop into sinuses (widened cavities) that drain onto the surface of the skin. If the infection goes deeper into the skin, it is called furunculosis.

As previously stated, bacteria are by far the most common cause of folliculitis in dogs. In most instances, they multiply because other conditions allow this process to happen.

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In a nutshell, every condition that leads to impaired immune response can eventually cause folliculitis. This is because due to the impaired immune response, the organism is not capable of defending itself efficiently. In such cases the normally found skin bacteria can overgrow and over time invade the hair follicles thus causing pain and inflammation.

Hormonal disorders, particularly hypothyroidism works in a similar manner – it reduces the function of the immune system thus disabling a proper immune response and leaving the organism unprotected.

Some dog breeds are at higher risk of developing folliculitis which in such cases is known as breed-specific folliculitis. The Miniature Schnauzer is particularly prone to developing a type of breed specific folliculitis known as Schnauzer comedo syndrome.

Generally speaking, dog breeds with excessive skin folds or wrinkles are more likely to develop folliculitis. The risk of developing folliculitis is also higher in dogs with allergies.

Signs of Hair Follicle Infections in Dogs

Annoying itchiness and intense swelling are the most indicative signs of folliculitis. It goes without saying that the exact clinical presentation depends on the underlying cause. However, generally speaking, dogs with folliculitis will show the following signs and symptoms:

  • Superficial skin erosions
  • Skin ulcerations
  • Pimples, pustules and bumps
  • Skin scaling
  • Redness
  • Skin darkening
  • Excessive shedding
  • Hair loss.

Usually the skin changes are located in certain areas of the body. The most commonly affected areas include the armpits, groins and abdomen. The signs and symptoms also tend to vary based on the patient’s coat type. For example, short-haired breeds form hair clumps on the coat’s surface. Long-haired breeds are more difficult when t comes to spotting the skin changes. The most obvious changes in long-haired breeds include excessive shedding, scaly skin and dull coat.

If left untreated, the infection spreads and goes into the deeper layers of the skin which results in a more serious form of infection known as furunculosis. This complication can occur in any breed of dog and anywhere on hair-covered parts of the body. However, the complication is most frequently seen in German Shepherds, Collies, Irish Setters, Jack Russell Terriers, Labrador Retrievers, Leonbergers and Old English Sheepdogs.

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At the Vet's Office 

As with any other conditions, the process of setting a diagnosis starts with a thorough physical examination. The vet will take the dog’s full history, and the received info, combined with the results of the physical examination, are the basis for setting a differential diagnosis.

To make the right diagnosis, and later on, determine the best treatment strategy, the vet will suggest performing bacterial culture. For this purpose, a sterile swab of the affected area of skin will be taken. This enables the vet to identify the infectious agent and find out which antibiotic is best suited.

If a parasitic infestation is suspected, the vet will suggest a skin scraping test. To do the test, the vet will gently scrape the surface of the skin and look at the scraping under a microscope.

In most cases the folliculitis is caused by bacterial infections. Therefore, the treatment of choice includes antimicrobials which can be used in the form of topical creams, ointments and shampoos, oral tablets or injection solutions.

It should be noted that bacterial folliculitis in dogs can be challenging when it comes to treatment. This is because most antimicrobial drugs cannot reach the skin. To make them capable of reaching the skin, they need to be administered in high-doses and over a prolonged period of time (usually between 3 and 12 weeks).

It is advisable to choose the ideal antibiotic based on the results of bacterial cultures. When dealing with bacterial folliculitis certain antibiotics are more efficient than others. The most commonly used antibiotics are erythromycin, clindamycin, tetracycline and penicillin. These antimicrobials are particularly useful because of their anti-inflammatory properties as well as for their antibacterial action.

Antiseptics and antiseborrheic shampoos, such as those containing benzoyl peroxide, help to flush out the follicles. However, it should be well-understood that these aids are only beneficial if combined with other treatments.

In other cases, the treatment should also include resolving the underlying issue. If the underlying cause is hormonal imbalance the treatment includes returning the hormonal values within the normal values. If the underlying cause is flea allergy dermatitis the treatment includes proper and effective flea control.

Cost of Treating Hair Follicle Infection in Dogs

The exact cost of diagnosis and treatment depend on the underlying problem. Non-complicated cases are relatively affordable to treat, usually costing $100 to 200. More complicated cases, involving a systemic problem as an underlying issue, are more expensive – usually $500 to 1000 or even more.

Some cases of folliculitis can be easily prevented. For example, keeping the skin folds clean and dry (in Pugs and Shar-Peis) minimizes the risk of developing bacterial foliculitis in the folds. Using efficient flea prevention eliminates the risk of developing folliculitis due to flea allergies.

Photo Credits:

Research gate, Suggested guidelines for using systemic antimicrobials in bacterial skin infections: Part I - Diagnosis based on clinical presentation, cytology and culture Creative Commons Attribution-NonCommercial 3.0 Unported

About the Author

Dr. Ivana Crnec is a graduate of the University Sv. Kliment Ohridski’s Faculty of Veterinary Medicine in Bitola, Republic of Macedonia.

ivana crnec

She currently practices as a veterinarian in Bitola and is completing her postgraduate studies in the Pathology of Domestic Carnivores at the Faculty of Veterinary Medicine in Zagreb, Croatia.

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