Fungal Infections in Dogs: Causes, Symptoms & Treatments

Fungal infections in dogs can range from mild skin irritations to serious systemic diseases affecting internal organs. The most well-known fungal infection is ringworm, which, despite its name, is caused by a fungus rather than a worm. These infections differ from bacterial ones and often require specialised treatment as many standard antibiotics are ineffective.

The Most Common Fungal Infection: Ringworm

Ringworm (dermatophytosis) is very contagious and appears as round, hairless, itchy lesions on a dog's skin. If left untreated, these spots can become sore and inflamed. Humans and other animals can catch ringworm through direct contact with these lesions, so careful hygiene and treatment with effective topical antifungal preparations are essential. If your dog shows signs of ringworm, consult your vet promptly for diagnosis and appropriate treatment.

Understanding Systemic Fungal Infections in Dogs

Systemic fungal infections affect the whole body, potentially involving the lungs, eyes, bones, and other organs. Blastomycosis is one such infection, more common in breeds like retrievers that frequent aquatic environments. Approximately 40% of affected dogs develop painful eye lesions, while 85% experience lung involvement. Skin abscess-like lesions may also appear anywhere on the body.

Blastomycosis: Key Facts

• Common in dogs living near water
• Symptoms include coughing, eye lesions, skin lumps, and weight loss
• Requires early veterinary diagnosis and antifungal therapy

Coccidiomycetes Infection

Coccidiomycetes can pose a serious health risk and is often mistaken for cancer on x-rays. Prompt and thorough veterinary testing is crucial to distinguish this fungal disease and initiate the right treatment to improve the prognosis. This infection underlines the importance of diagnostic care to avoid misdiagnosis.

Other Significant Fungal Infections

Histoplasmosis

Histoplasmosis primarily targets a dog's lungs after inhaling or ingesting contaminated soil, often with bird or bat droppings. Dogs that spend time outdoors are at higher risk, but indoor pets can also be infected from contaminated potting soil or manure. This infection can cause coughing, lethargy, and more severe symptoms if untreated.

Malassezia Dermatitis

Malassezia is a yeast normally present on the skin and ears, but overgrowth causes painful dermatitis. This leads to greasy, red or darkened skin that's itchy and often smelly. Some breeds, including poodles, basset hounds, West Highland White Terriers, cocker spaniels, and dachshunds, are more prone to this condition. Treatment may involve topical antifungals and managing underlying causes like allergies.

Cryptococcal Infection

While more common in cats, dogs can also develop cryptococcosis, especially after exposure to bird droppings. Dogs inhale or ingest fungal spores that infect the respiratory tract, eyes, skin, and nervous system. Symptoms include sneezing, skin lesions, seizures, and blindness. Early diagnosis and treatment are critical as late-stage infections can seriously affect the dog's prognosis. This infection is rare in the UK but more prevalent in North America.

Prevention and Responsible Care

Preventing fungal infections involves good hygiene, avoiding exposure to contaminated environments, and regular veterinary checks. Responsible pet ownership also means consulting a vet immediately if your dog shows unusual skin lesions, respiratory signs, or other concerning symptoms. Early diagnosis and treatment greatly improve the chances of recovery and reduce the risk of spread.

Always seek professional veterinary advice before starting any treatment. Avoid the use of unproven remedies and ensure environmental cleanliness to protect your dog and household members from contagious infections like ringworm.

Conclusion

Fungal infections in dogs range from common contagious skin diseases like ringworm to serious systemic conditions such as blastomycosis and cryptococcosis. Recognising symptoms early, understanding the risks, and seeking veterinary care promptly can safeguard your dog's health. Providing diligent aftercare and follow-up will support complete recovery and help prevent recurrence.

If you suspect your dog may have a fungal infection, arrange a thorough examination with your vet. Together, you can ensure the best treatment plan tailored to your dog's specific needs.