The Effect of Insect Bite Hypersensitivity on Movement Activity and Behaviour of the Horse.
Authors: Söderroos Denise, Ignell Rickard, Haubro Andersen Pia, Bergvall Kerstin, Riihimäki Miia
Journal: Animals : an open access journal from MDPI
Summary
Culicoides-associated insect bite hypersensitivity (IBH) significantly compromises equine welfare, yet the precise behavioural and activity changes in affected horses remain poorly characterised. Researchers tracked 30 horses across two summers using a cross-over design, combining clinical assessment, skin biopsies for inflammatory markers, and continuous behavioural monitoring (direct observation and motion indices) to establish whether IBH alters movement patterns and scratching behaviour. Whilst total scratching frequency and overall activity levels did not differ between affected and control horses, a striking temporal pattern emerged: IBH-affected animals demonstrated substantially elevated itching behaviours during evening hours, a period that coincided with peak Culicoides activity. Of particular clinical significance, even brief scratching episodes were associated with moderate to severe inflammatory skin lesions on histology, indicating that the damage threshold is lower than might be expected from behavioural observation alone. The practical implications are clear: evening stabling or additional insect protection during high-risk periods offers a pragmatic welfare intervention, whilst a novel repellent showed promise as a non-toxic prophylactic option, though efficacy data require further investigation before widespread recommendation.
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Practical Takeaways
- •IBH-affected horses should be stabled or provided extra protection during evening hours when Culicoides activity and itching behaviours peak
- •Minimize any exposure to biting midges in susceptible horses, as even brief contact can trigger significant inflammatory skin damage
- •New insect repellents may offer a safe prophylactic option for IBH management, though efficacy requires further validation before clinical recommendation
Key Findings
- •IBH-affected horses showed clinical and histopathological signs of inflammatory skin lesions despite no difference in total itching behaviours compared to controls
- •Higher numbers of itching behaviours were observed in IBH-affected horses during evening hours
- •Even short periods of scratching were associated with moderate to severe inflammatory skin lesions in IBH-affected horses
- •A novel insect repellent showed preliminary safety and non-toxicity as a prophylactic intervention to reduce Culicoides exposure