Investigations on the ability of clenbuterol hydrochloride to reduce clinical signs and inflammation associated with equine influenza A infection.

The research article explores the effect of clenbuterol hydrochloride, a bronchodilator used in horses, on the symptoms and inflammation of equine influenza A infections. However, the study found no meaningful impact of the drug on the clinical or laboratory measured parameters within a 14-day window following an infection.

Study Design

In this study:

• 24 Quarter Horse and Quarter Horse-cross yearlings were intentionally infected with the influenza A virus (Influenza A/equine/Saskatoon/90 [H3N8]) through a method called nebulisation, which transforms liquid medicine into a fine mist that can be inhaled directly into the lungs. The infection was part of a randomized, double-blind control trial.
• Horses were sorted into three groups, each consisting of eight animals. Group 1 acted as a control group which received a placebo (carrier syrup), Group 2 received the standard labeled dose of clenbuterol hydrochloride, and Group 3 received twice the labeled dosage.
• All treatments were administered orally twice a day for 10 days, beginning from the day of infection.

Methods of Assessment

To determine the effect of the drug:

• The horses’ health was monitored for influenza symptoms for 14 days.
• Bronchoalveolar lavages, a procedure to obtain samples from the lower respiratory system, were conducted 4 days before the infection and on 5 and 13 days post-infection. In these samples, the cell counts and concentration of inflammatory indicators, prostaglandin E2 and F2alpha, were determined.
• Blood samples for hematology and serology were drawn 4 days prior to infection, on the day of infection, and 5, 9, and 13 days after infection.

Results

Findings from the study:

• All horses underwent a typical influenza infection, which involved symptoms like fever, coughing, and secondary bacterial infections mainly comprising of Actinobacillus spp. and Streptococcus spp.
• No statistically or clinically significant impact was observed from the treatment with clenbuterol hydrochloride on any of the monitored clinical or laboratory parameters within 14 days of infection.