Control of Strangles
Isolate clinically affected animals or identified carriers immediately in a quarantine area, and clean and disinfect their water buckets or feed containers daily. Bedding can be burned or alternatively composted under a plastic sheet (to prevent spread by flies). Scrub with water and detergent any areas contaminated by infected horses, then disinfect by steam cleaning and/or applying effective disinfectants. Fly control is required to prevent spread during an outbreak.
Have quarantine area staff change their coveralls and boots before leaving the quarantine area, and wash their arms and hands carefully with chlorhexidine soap.
Under optimal conditions, the bacteria can survive probably 6–8 weeks in the environment. Jorm (1991) has shown that S. equi survived for 63 days on wood at 2°C and for 48 days on glass or wood at 20°C. (6) The organism is readily killed by heat (60°C) or disinfectants (particularly povidone iodine, chlorhexidine). Rest contaminated pasture areas for 4 weeks, since the natural antibacterial effects of drying and of ultraviolet light will kill the organism
Approaches used to control strangles will depend on the circumstances of the individual horse or horse farm, but all people involved with horses need to maintain constant vigilance. These approaches involve a combination of knowledge of the history of individual animals and their source of origin, general hygiene, quarantine, and immunization, with appropriate action if an outbreak occurs.
Farms with large populations and movement of horses, particularly of older foals and yearlings, will want to maintain a routine immunization program of all horses to reduce the incidence and severity of disease. On these farms, depending on the vaccination program including the type of vaccine used, all incoming horses should be isolated for 2 to 3 weeks and, although expensive, a series of nasal or preferably nasopharyngeal swabs taken during this time for demonstration of the organism or its DNA. Only then should these isolated horses join the rest of the group.
Where a few adult horses are kept together and are uncommonly mixed with other horses, immunization may not be required since all immunization carries a slight risk of adverse effects. Incoming animals should be quarantined for 3 weeks, during which time nasal swabs should be assessed for the presence of the organism.
Strangles is a highly contagious and serious infection of horses and other equids caused by the bacterium, Streptococcus equi. The disease is characterized by severe inflammation of the mucosa of the head and throat, with extensive swelling and often rupture of the lymph nodes, which produces large amounts of thick, creamy pus.
Strangles is caused by Streptococcus equi subspecies equi, better known as Streptococcus equi (S. equi). The organism can be isolated from the nose or lymph nodes of affected animals, and is usually readily identified in the laboratory by simple sugar tests.
All precautions should be taken to prevent the spread of Strangles, in the event of a confirmed case the relevant private yard/riding centre/facility centre should be closed to movement of all animals. Staff should take extra hygienic precautions using overalls, clean clothes, disinfected boots and constant hand and arm washing.
Contact your vet for further precautions and advice.