A retrospective case series of 66 foals with presumed acute interstitial pneumonia

Summary Background There is limited literature describing acute interstitial pneumonia (AIP) in foals. Objectives Description of clinical and ultrasonographic findings in 66 foals affected by AIP. Investigation into whether the number of AIP cases is associated with specific climatic conditions. We also investigated whether clinical, haematological and sonographical findings on the day of diagnosis differ between survivors and foals dying of AIP. Study Design The current report was designed as a retrospective case review. Methods Foals aged 30 days to 6 months, born at one stud between 2008 and 2020, and affected by AIP were included. Inclusion criteria were dyspnoea, high numbers of comet tail artefacts at thoracic ultrasonography and treatment with glucocorticoids. Foals with moderate or severe bronchopneumonia were excluded. Clinical and ultrasonographic findings were evaluated from the individual file of each foal. These findings were compared between survivors and non‐survivors of AIP. Climatic conditions of the 3 days prior to diagnosis were also selected. Results Forty‐one of the 66 foals with AIP analysed survived and 25 did not survive the disease. The foals developed AIP at an average age of 2.3 months. The body temperature was significantly lower in foals surviving compared to those not surviving. The AIP was developed mainly in warm and dry weather conditions, with a higher incidence in the months of June to September. Main Limitations This is a purely descriptive report based on retrospective data collection. Conclusion When respiratory distress and hyperthermia occur in association with a thoracic ultrasonography dominated by comet tail artefacts, the diagnosis of AIP should be considered, especially if these signs occur on warm and dry days.