VETERINARY
Streptococcus zooepidemicus
The bug that can place bets WORDS: PROFESSOR CELIA M MARR/AnDREW S. WALLER, AnIMAL HEALtH tRuSt/JOSH SLAtER, ROyAL VEtERInARy COLLEgE MAIn PHOtO: SHuttERStOCK
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The Horserace Betting Levy Board (HBLB) has invested over £7 million to protect racing and ensure horse welfare by disease surveillance and research on prevention of equine infections over the last decade. Infection with bacteria is one of the important causes. One bug in particular that can be found in many cases is Streptococcus zooepidemicus. We know that horses can develop immunity to this species of bacteria. However, we also know that this bacteria can be found in horses that are healthy without necessarily causing any harm. The reasons for this inconsistency are being investigated thanks to new research funded by the HBLB.
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ESPIRATORY disease affects a large proportion of young horses around the world, reducing performance with significant disruption to training and racing schedules. Inflammatory airway disease affects young horses in particular and it generally causes mucus in the trachea. Some estimates suggest that in British Flat racing yards, for every 100 horses, each month there will be nine cases. Coughing and nasal discharge can last around eight weeks and some animals are affected again and again. All of which leads to significant cost to the racing industry. As a result, this problem has been a longstanding focus of attention for the Horserace Betting Levy Board’s (HBLB) veterinary research efforts.
Bacterial genetic code One reason why bacteria from the same species might affect horses differently is that there are different strains within a bacterial species. This is rather like different breeds of horses – a Falabella pony is the same species as a thoroughbred – but it looks and acts very differently. All living things, from human to single-cell algae in the ocean, have a genetic code written in DNA. Understanding this genetic code can reveal how organisms live and function. An HBLB-funded collaborative team working in Dr Andrew Waller’s lab at the Animal Health Trust and Professor Josh Slater’s lab at the Royal Veterinary College have set out to unlock the genetic make-up of different strains of Streptococcus zooepidemicus in order to understand better if some strains of this bacteria cause disease while others are relatively harmless. The researchers also looked at how different strains of Streptococcus interact with the horses’ immune system. The ulitmate goal of this research is to gain the knowledge which will lead to new vaccines. Left: S. zooeopidemicus colonies grown on a blood agar culture plate Below: The build up of mucus in the trachea (below) of infected horses found on endoscopy, which is typical of inflammatory airway disease. (Photos courtesy of Dr. Richard Newton, Animal Health Trust)