Epidemiology of equine influenza, risk by age, breed and sex.
D000367:Age Factors; D000818:Animals; D005260:Female; D006734:Horse Diseases / Q000453:epidemiology*; D006736:Horses; D009980:Influenza A virus; D008297:Male; D009976:Orthomyxoviridae Infections / Q000453:epidemiology / Q000662:veterinary*; D012189:Retrospective Studies; D012306:Risk; D012737:Sex Factors; D013045:Species Specificity