The present study described the clinical features of 73 confirmed cases of equine influenza in Metro Manila-based horses from September 1997 to December 1998. Records of the results of the hemagglutination inhibition (HI) tests from the Philippine Animal Health Center and individual health records of HI-test positive horses from the stables within the vicinity of San Lazaro and Sta. Ana racetracks were examined.
The predominant clinical signs of equine Influenza positive cases were coughing [73 cases (100%)], inappetence [73 (1000/0)], 38.5-41oC fever [69 (94.5%)] and labored breathing [54 (74%)]. The most common sequel to equine influenza cases was secondary bacterial infection. The ages of 55 horses submitted for HI test were from 1 to 3 years old (65.5%). There were 70 out of 73 confirmed cases (95.9%) that were not vaccinated against equine Influenza. There was a marked decrease in the number of confirmed cases following the disease outbreak of September to December 1997. The different treatment regimens applied to an infected horse were known to be symptomatic in nature. The recovery rate from equine Influenza was 93.20/0.
The study has shown that confirmed equine influenza cases in Metro Manila horses exhibited clinical features of an acute respiratory disease that affected horses of all ages, that It commonly resulted into secondary bacterial Infection, and that the treatment regimen given to cases were symptomatic.