Skin Infections in Dogs: Fungal & Yeast Infections
While bacterial skin infections make up the majority of the skin infection cases in canines, fungal and yeast infections are also commonly encountered. Yeast and fungal infections can occur as a primary condition but often happen secondary to an underlying cause. Yeast and fungal infections cause varying degrees of symptoms depending on how severe the condition is. Proper identification and diagnosis are necessary for effective treatment. Keep reading to learn about these types of skin infections and how you can help your pup!
Fungal vs. Yeast Infection
Fungal and yeast infections are commonly and mistakenly interchanged because of the similarities in how the conditions develop and the close relationship between the two types of organisms, but it’s important to note that these are two different infections and respond to certain medications differently.
Though both are technically fungal microorganisms, yeast has different biological, physical, and physiological properties than most fungal species, especially those that cause common fungal skin infections in dogs. These differences can be of importance when treating both types of infections, as certain antifungals, like Griseofulvin, that work well against common fungal skin infections are ineffective in treating yeast skin infections in dogs.
Differentiation between the two organisms can be done using various diagnostic tests. Getting samples or smears from the affected skin and examining it under the microscopic is usually helpful in diagnosing yeast infections in dogs. Yeast has a distinct appearance under the microscope, making identification relatively simple. Culture and isolation may be needed in some cases of fungal infection to arrive at a more specific diagnosis.
Types of Fungal Skin Infections in Dogs
Fungal skin infections are very common in dogs and can happen in any breed of any age. There are several types of fungal infections, but they can be generally grouped into two main categories: systemic and cutaneous.
Systemic fungal infections are generally more severe compared to cutaneous ones. This type of fungal infection involves the invasion and infection of a dog’s internal system by the fungal microorganism. As these infections target internal organs, the resulting symptoms are systemic in nature and generally more serious.
Aspergillosis infections in dogs are caused by different Aspergillus sp., which are commonly found in the soil. These organisms can cause respiratory or systemic infections in canine patients. The mode of transmission is mainly inhalation and happens when a dog sniffs and smells contaminated soil.
The most common manifestation of aspergillosis in dogs is a nasal infection affecting the nasal passages and sinuses, occasionally affecting the areas around the eyes. This results in excessive sneezing, localized pain, and epistaxis (nose bleeds.
In rare cases, after the fungal organism infects the nasal passages, it enters the dog’s bloodstream and causes a widespread infection called disseminated aspergillosis. Commonly seen in German Shepherds, disseminated aspergillosis causes systemic signs like vomiting, lethargy, and inappetence in infected dogs.
This is another systemic fungal infection in dogs caused by Blastomyces sp. The fungal organism is commonly found in moist soil and decaying vegetation found in North America. Infection happens when a dog inhales the fungal microorganism. Blastomycosis infects the lungs and causes pneumonia. Infected dogs present with respiratory symptoms such as coughing, fever, inappetence, lethargy, and weight loss. Early treatment with oral antifungal medications can eliminate the infection and the prognosis of infected canines are mostly good.
Ringworm in dogs is a cutaneous form of fungal infection caused by a group of fungal microorganisms called dermatophytes. In dogs, the species commonly responsible for dermatophytosis infections are Microsporum sp. and Trichophyton sp. species. Clinical signs that are commonly seen in cases of canine dermatophytosis include alopecia (hair loss), skin redness, circular rash, and pruritus (itchiness).
Dermatophytosis is considered contagious and zoonotic, meaning an infected dog can transfer the infection to other dogs or even humans. Most cases of canine dermatophytosis respond well to topical antifungal medications such as creams and ointment, but severe cases may need oral antifungal treatment.
Yeast Infections in Dogs
Yeast infections in dogs are commonly caused by different species from the genus Malassezia sp. These are unicellular, fungal microorganisms that appear as “footprint”-shaped under the microscope. Often considered as a commensal skin microflora, yeast skin infection only happens when the dog’s innate defenses are compromised due to several skin conditions. Malassezia dermatitis in dogs is often secondary to an underlying disease, usually allergic dermatitis.
Canine yeast infections are commonly seen in skin folds, axillary (armpit) and inguinal regions, and ears of infected dogs. Infection results in redness of the skin with hyperkeratosis or thickening, and hyperpigmentation. Generalized skin yeast infections tend to be itchy and infected dogs will scratch excessively.
Most cases of skin yeast infection can be treated with topical antifungal medications like shampoos, topical sprays, or creams. Severe cases of skin yeast infection will require systemic antifungal therapy, but it’s important to note that not all antifungal medicines are effective against yeast cells. Proper identification and diagnosis are needed for the treatment to be effective.
As mentioned, the majority of canine Malassezia dermatitis cases are secondary to an underlying condition, and addressing the primary disease is essential in completely controlling the yeast infection. A proper diagnostic approach is necessary for dealing with skin yeast infections in dogs.
It’s best to visit your vet if you suspect that your dog may have signs of fungal or yeast infection.
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