강아지 진균성 호흡기 감염(아스페르길루스) 증상과 원인, 진단·치료와 관리 포인트 총정리

Comprehensive Guide to Canine Fungal Respiratory Infections (Aspergillosis): Symptoms, Causes, Diagnosis, Treatment, and Management

RespiratoryDiseasesMeongsiljang Veterinary Advisory Board

Aspergillosis, a fungal respiratory infection in dogs, occurs when airborne spores invade and proliferate in the respiratory tract, leading to chronic nasal discharge, coughing, and difficulty breathing. Early diagnosis and appropriate treatment are essential.

Canine fungal respiratory infections (aspergillosis) are infectious diseases caused by airborne spores invading and proliferating in the respiratory tract.

Microscopic structure of Aspergillus spores in a dog’s nasal cavity

Canine fungal respiratory infections caused by Aspergillus occur when airborne Aspergillus spores are inhaled and proliferate primarily in the nasal cavity and frontal sinuses. Sinonasal aspergillosis, which affects the nose and sinuses rather than the lungs, is the most common form and is frequently observed in young to middle-aged dolichocephalic (e.g., German Shepherd) and mesocephalic (e.g., Labrador Retriever) breeds. The primary causative agent is Aspergillus fumigatus, a saprophytic fungus widely distributed in soil. This condition can develop even in dogs with normal immune function, and tissue damage is known to be more closely associated with the host’s excessive inflammatory response than with the fungus itself. Early stages may present with mild nasal symptoms, but if left untreated, the condition can progress to chronic nasal discharge, sneezing, and epistaxis (nosebleeds), making early detection and appropriate diagnosis and treatment essential.

The primary causes are the invasion of airborne Aspergillus spores and decreased immunity.

The primary cause of fungal respiratory infections in dogs is Aspergillus spores, which are commonly present in the air. These spores are widely found in soil, damp environments, and places conducive to mold growth, and they enter and establish themselves in the nasal cavity and sinuses when dogs breathe. The main causative agent is Aspergillus fumigatus, a saprophytic fungus common in soil, and this condition is frequently seen in dolichocephalic (long-nosed) and mesocephalic (medium-nosed) breeds. This infection can occur even in dogs with normal immune function, meaning immunosuppression is not a prerequisite for infection. In fact, it is known that the host’s excessive inflammatory response plays a greater role in causing destruction of nasal and sinus tissues than the fungal colony itself. Symptoms primarily manifest as inflammation of the nasal cavity and sinuses, and can also be influenced by environmental factors and the localized characteristics of the lesions.

A dog coughing in a humid indoor environment

Main symptoms include chronic nasal discharge, coughing, difficulty breathing, and weight loss.

The main symptoms of fungal respiratory infections in dogs include persistent nasal discharge, sneezing, nosebleeds (epistaxis), and pain around the nose. The discharge may come from one or both nostrils and can be mucoid or thick and pus-like; it may sometimes contain blood or lead to nosebleeds. Depigmentation, or lightening of the skin color, around the nostrils may also occur. In rare cases of invasive infection that spreads systemically, nonspecific signs such as decreased appetite, weight loss, and lethargy may accompany these symptoms. If nasal symptoms persist for more than two weeks, a veterinary visit is essential.

Symptoms Requiring Immediate Veterinary Attention

If your dog experiences severe, persistent nosebleeds, facial swelling with significant pain, or neurological signs such as seizures, decreased consciousness, or disorientation, immediate veterinary attention is required. These symptoms may indicate that the lesion has spread beyond the nasal cavity and sinuses to involve adjacent structures like the skull or cribriform plate, so prompt evaluation by a veterinarian is essential.

Diagnosis is performed through nasal endoscopy, imaging studies, and biopsy.

Diagnosing fungal respiratory infections in dogs involves a combination of nasal endoscopy, imaging studies such as head and nasal CT or MRI, and cytology, histopathology, and fungal culture of nasal tissue. - Nasal Endoscopy: This procedure allows direct visualization of the nasal cavity, helping to identify destruction of the nasal turbinates and the presence of white, green, or black fungal plaques. - Imaging Studies: CT or MRI scans of the nasal cavity and frontal sinuses are essential for determining the extent and location of lesions, including turbinate destruction, cavitation, and bone hyperostosis. - Histopathology and Culture: Tissue samples taken from fungal plaques are examined via cytology and histopathology. Because Aspergillus can resemble Penicillium under microscopy, fungal culture is necessary for a definitive diagnosis. - Serology: Antibody tests may be used as an adjunct, but they are prone to false-positive and false-negative results, making them unreliable as a standalone diagnostic tool. Since no single test is sufficient for confirmation, a combination of diagnostic methods is required.

A veterinarian performing a nasal endoscopy on a puppy

Treatment involves antifungal medication, surgery, and immune modulation.

Treating fungal respiratory infections in dogs centers on local (intranasal) therapy, which involves directly instilling antifungal agents into the nasal cavity and sinuses. Veterinarians commonly use endoscopy to deliver antifungals such as clotrimazole or enilconazole into the nasal passages and frontal sinuses. Success rates improve when this is combined with debridement to remove fungal plaques and necrotic tissue. If the lesions are extensive or do not respond well to treatment, additional interventions may be necessary, and the duration of therapy varies depending on the extent of the disease and the patient’s response. Systemic antifungal medications may also be used concurrently, but the specific drugs and treatment duration are determined by your veterinarian based on your dog’s condition. In cases of severe inflammation, steroids may be used as an adjunctive therapy. Regular examinations and monitoring are essential throughout the treatment process, and you must consult your veterinarian before discontinuing any therapy.

Home management focuses on environmental hygiene and immune support.

Managing fungal respiratory infections in dogs at home focuses on environmental hygiene, overall conditioning, and consistent monitoring during treatment. It is important to reduce indoor humidity and ventilate frequently to minimize the accumulation of mold spores. Regularly wash your dog’s bed, toys, and food bowls, and avoid areas with high levels of dust or mold. Providing a balanced diet and nutritional supplements when needed helps maintain overall health, while reducing stress, ensuring regular walks, and allowing ample rest can positively support recovery. However, since Aspergillus is a common environmental mold, it is difficult to completely eliminate exposure through environmental management alone. Regular veterinary check-ups are necessary after treatment to monitor for recurrence, and you should visit the clinic immediately if symptoms reappear.

A clean indoor environment where dogs can live comfortably

Breed-Specific Precautions and Recurrence Prevention

Dolichocephalic and mesocephalic breeds, particularly German Shepherds, may be relatively susceptible to Aspergillus infections. This susceptibility may be related to the nasal anatomical characteristics of these breeds, but there is insufficient clear evidence that reduced immune response due to genetic predisposition plays a role. Moreover, this infection can occur in dogs with normal immune function. Early diagnosis and comprehensive treatment, including surgical debridement, are crucial, and regular check-ups are necessary after treatment to monitor for recurrence. If infection is suspected or nasal symptoms persist, immediate veterinary consultation is essential.

Reviewed by a veterinarian

Dr. Tony — Punnawat Phongkittirak

Veterinarian

A veterinarian who majored in veterinary medicine at Khon Kaen University, Thailand, and completed the IVSA program at North Carolina State University in the United States. Drawing on clinical experience at animal hospitals, he works in the pet healthcare field and is dedicated to building a digital care environment that connects pet parents with veterinarians.

Frequently Asked Questions

Can fungal respiratory infections in dogs be transmitted to humans?

Aspergillosis is not known to be directly transmitted from dogs to humans. However, since Aspergillus is a common environmental mold, people with weakened immune systems (such as cancer patients or those taking immunosuppressive medications) are at risk of infection from the environment itself, so caution is advised.

How long does the treatment period last?

The duration of antifungal treatment varies depending on the extent of the lesions and the response to therapy. Even if symptoms disappear, do not stop treatment on your own; follow your veterinarian’s instructions and attend regular check-ups.

Is Aspergillus infection curable?

If the lesions are localized and appropriate treatment is administered, a full recovery may be possible; however, some cases may not respond well to treatment or may recur. The prognosis can be poor if the infection spreads systemically or involves the nervous system. Overall prognosis depends on the dog’s immune status, whether the lesions are localized or systemic, and the timing of treatment.

Can it be prevented?

Aspergillus is commonly found in the environment, making complete prevention difficult. However, you can reduce exposure by controlling indoor humidity, ventilating regularly, and maintaining a clean environment with minimal dust and mold. Brachycephalic and mesocephalic breeds are especially at risk, so it’s important to recognize early symptoms such as nasal discharge, sneezing, or nosebleeds promptly.

If your pet has a persistent runny nose or keeps sneezing, is it necessary to visit the vet?

Yes, if nasal symptoms such as runny nose, sneezing, or nosebleeds persist for more than two weeks, it could indicate several nasal conditions, including Aspergillus infection. It’s important to visit a veterinary clinic right away for a proper diagnosis.

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References

[1] Gelatt K, McGill L, Perman V. (1973). Ocular and systemic cryptococcosis in a dog. J Am Vet Med Assoc 162:370-375.

[2] Clercx C, McEntee K, Snaps F et al. (1996). Bronchopulmonary and disseminated granulomatous disease associated with Aspergillus fumigatus and Candida species infection in a golden retriever. J Amer Anim Hosp Assoc 32:139-145.

[3] Lisciandro G.R., Fulton R.M., Fosgate G.T., Mann K.A. (2017). Frequency and number of B-lines using a regionally based lung ultrasound examination in cats with radiographically normal lungs. J Vet Intern Med 14:534–541.