Strangles - A guide for horse owners and visitors



A guide for horse owners in the New Forest and visitors considering bringing their horses with them on holiday


From time to time an outbreak of strangles occurs in the semi-feral New Forest pony herd.

Strangles is a highly contagious, bacterial, respiratory infection caused by Streptococcus equi.  It affects horses, ponies and donkeys of all ages but young and elderly horses are most susceptible to the infection.  It is always present at a low level within the UK horse population but new cases arise every year.  Whilst occasionally an animal will die as a result of complications, the majority of healthy animals which contract strangles effect a full recovery despite looking quite poorly whilst suffering from the infection.

Fortunately the infection is not airborne, so unlike flu, it will not spread long distances without some kind of direct contact.  It can be transmitted both directly via close contact with an infected horse or indirectly through shared housing, water and feed buckets, shared tack and equipment; and contact with shared personnel.  On the Forest, the most likely way for a riding horse to become affected is to drink or eat whilst it is being ridden, if it comes into contact with any discharge from an infected animal (from a draining abscess or nasal discharge), for example on a gatepost, or by being ridden close to an animal with the infection.

Direct contact between infected horses is the most obvious means of transmitting the infection. The bacterium is discharged (shed) from draining abscesses and the nose, and it may survive in the environment, particularly in water troughs. The incubation period is usually about one week but may be longer. Horses incubating the disease may shed S. equi before the onset of obvious clinical signs and so may spread the infection to in-contacts before the first case becomes apparent.

Unfortunately there is considerable and unjustifiable stigma associated with the condition, with rumours of outbreaks spreading like wildfire.  The Verderers do their best via social media and on their website, to publicise suspected cases of strangles in the Forest herd.

In order to prevent wider infection, it would assist everyone if yards that have an outbreak will also share the news openly.

A small but important proportion of horses that have recovered from strangles become persistently infected (most commonly in their guttural pouches) with S. equi for months or even years. These ‘carriers’ are less susceptible to reinfection, and they may have no obvious clinical signs of disease but can intermittently shed S. equi, which can then infect naive horses. These subclinical carriers are probably the most important factor in persistence of infection and can initiate new outbreaks.

March 2023