Dermatitis, cellulitis, and osteomyelitis caused by Aspergillus nidulans in a horse with pituitary pars intermedia dysfunction.

The article investigates a rare presentation of a fungal disease caused by Aspergillus nidulans in a 12-year-old Quarter Horse with pituitary pars intermedia dysfunction, manifesting as dermatitis, cellulitis, and osteomyelitis. Despite aggressive therapeutic interventions over a year, the disease progression could not be halted and surgical excision at an early stage is suggested for similar cases in future.

Patient Background and Clinical Examination

• The study is centered around a case of a 12-year-old Quarter Horse gelding (a male horse that is castrated) with an existing condition of pituitary pars intermedia dysfunction.
• Detailed clinical and histologic examinations were conducted which revealed dermatitis (skin inflammation), cellulitis (a bacterial skin infection), and osteomyelitis (bone infection) in the horse.

Identification of Fungal Disease

• The cause of these conditions was found to be Aspergillus nidulans, a species of fungus, confirmed through Polymerase Chain Reaction (PCR) assay, a molecular biology technique.
• This fungal disease present in the horse is characterized by aggressive local invasion, and has not previously been reported in equine patients. As such, it represents a novel presentation of equine fungal disease.

Treatment and Outcomes

• The researchers detail various treatment methods that were attempted over a one-year span to curb the disease progression. These included systemic and topical antifungals to combat the fungus, anti-inflammatories to reduce inflammation, and the utilization of cellular matrices—a treatment where cellular structures are applied to aid healing.
• Despite these, the fungal disease did not respond to any medical therapy, showing its resistant nature.

Surgical Recommendations and Postmortem Findings

• While surgical excision (removal of the disease tissues) was not attempted in this case, the study suggests that such an approach should be strongly considered early in the disease process for similar cases in the future, provided clean margins (complete removal of disease tissue) can be achieved.
• Postmortem examination of the horse revealed that the disease was locally aggressive but had not disseminated (spread) to other parts of the body.