Infectious agents in acute respiratory disease in horses in Ontario.

This research was conducted to identify the infectious agents causing acute respiratory disease in horses in Ontario, using a new nasopharyngeal swab for isolation and serum samples for antibody determination.

Study Design and Implementation

• The study was undertaken in Ontario and focused on understanding the root cause of acute respiratory diseases in horses. The idea was to identify the infectious agents currently responsible for these diseases.
• To help maximize the collection of potential infectious agents, a specialized nasopharyngeal swab was designed. This tool was used to optimally isolate samples which would then indicate the presence of certain viruses, Mycoplasma (a type of bacteria that lacks a cell wall), and pathogenic bacteria (bacteria that can cause disease).

Collection of Serum Samples

• Serum samples were collected from the horses to further confirm the presence and type of infectious agent. These samples were used to determine antibody titers, which are measurements of how much of a specific antibody an organism has produced.
• The specific antibodies they looked for were those that responded to a range of viruses and mycoplasmas like equine influenza virus type A subtype 1 and 2, equine rhinoviruses type 1 and 2, the equine herpesvirus type 1, Mycoplasma equirhinius and Mycoplasma felis.

Results and Findings

• The findings of this research were compelling. They found Equine Rhinovirus Type 2 in 28 out of 92 horses tested, and Equine Influenza Virus type A, subtype 2 in 5 horses. These viruses are known to cause respiratory diseases in horses.
• The researchers also isolated bacteria and mycoplasma commonly associated with nonspecific respiratory issues in horses. However, in 10 of the horses, the researchers identified Streptococcus pneumoniae of capsular type 3, which is uncommonly linked with respiratory diseases in horses. This particular finding could indicate a new or under-represented cause for some respiratory diseases in horses.