Horse health: five conditions named by veterinary and government bodies.

Each condition below is named and summarised from a veterinary, academic or government source. A horse that may have any of them needs a vet, who must be consulted. This page describes no signs to check at home, and no care, treatment, medication or dosing.

Colic

Professor Sarah Freeman's team at the University of Nottingham School of Veterinary Medicine and Science launched the REACT Now to Beat Colic campaign with the British Horse Society on 1 September 2016, describing colic as a life-threatening condition. The Nottingham research reported that:

• colic accounts for one in three emergency veterinary call-outs;
• at least one in ten of those cases may be critical;
• up to 80 percent of critical cases end in death or euthanasia;
• more than 90 percent of horse owners surveyed did not feel confident spotting the early signs.

The campaign name is an acronym the researchers use for the warning signs it covers. The FEI's 2018 hot-weather guidance notes that travel, dehydration and changes in diet can all raise the risk of colic in competition horses. Colic needs a vet.

Laminitis

The British Equine Veterinary Association's weight management toolkit links obesity in horses closely with insulin dysregulation and laminitis. A study by Danica Pollard and colleagues (Animal Health Trust, Rossdales and the Royal Veterinary College, funded by World Horse Welfare; Equine Veterinary Journal, 2018) followed 1,070 horses and ponies in Great Britain for 29 months. A search summary of the Royal Veterinary College's release says the study estimated from owner reports that about one in ten develops at least one episode a year, making laminitis about as common as colic, and that it found no safe season. The release itself refused our request, so those figures are unconfirmed. Laminitis needs a vet.

Strangles

The Government of Ontario (page published 11 December 2023, updated 20 February 2026) describes strangles as a bacterial disease of horses and other equids over one month old, caused by Streptococcus equi subspecies equi. It often swells the lymph nodes of the throat, sometimes enough to interfere with breathing.

• It spreads by nose-to-nose contact and by contaminated objects, hands and clothing. Ontario names the movement of horses, including to competitions, as a major factor in spread.
• About 10 percent of recovered horses become carriers that can shed the bacteria on and off for months or years, often without signs.
• Death is uncommon but possible.
• Strangles became an immediately notifiable disease in Ontario under the Animal Health Act, 2009 in February 2023.

Ontario advises contacting a veterinarian for signs such as fever, nasal discharge or swollen lymph nodes, and doing so immediately for breathing difficulty.

Equine influenza: the FEI's competition rules

The rules below concern whether a horse may compete at FEI events. Whether and when a horse is vaccinated is a matter for its vet.

An FEI presentation by Goran Akerstrom (July 2023) summarises the FEI's eligibility rules:

• vaccinations are checked by the veterinary delegate or another FEI-appointed vet before horses enter FEI stables, and must be recorded in the FEI passport;
• a horse may compete from 7 days after the second vaccination of its primary course;
• it remains eligible for 6 months and 21 days after its last booster;
• it may not compete in the 7 days after any vaccination.

The primary course changed in 2024. The 2023 FEI slide gives an interval of 21 to 92 days between the first two vaccinations. The British Show Pony Society's copy of the FEI requirements (dated 10 April 2024) gives 21 to 60 days for any horse starting a new primary course from 1 January 2024; the FEI's own page could not be read, so this rests on that copy. A search summary also says the FEI moved from annual to six-monthly boosters in 2005, which we could not confirm.

During a vaccine shortage, the FEI temporarily allowed boosters at intervals of up to 12 months for international competition from 1 October 2022 to 1 April 2023, and British Dressage temporarily waived its national six-month booster rule at the same time (British Dressage, 9 September 2022).

EHV-1: the 2021 Valencia outbreak

Equine herpesvirus-1 (EHV-1, also called rhinopneumonitis) caused the outbreak that shut down FEI sport in mainland Europe in 2021. On 1 March 2021 the FEI called the outbreak at the CES Valencia Spring Tour probably the most serious EHV-1 outbreak in Europe for decades, describing the strain as particularly aggressive, with linked outbreaks in France, Belgium and Germany.

A World Organisation for Animal Health (WOAH) webinar case study dated 27 March 2024 gives this account:

• The Valencia event ran over four weeks from 28 January 2021 with 752 competing horses. On 20 February, 20 horses had fever and a horse returned to France was confirmed with EHV-1 neurological disease; the event was cancelled the next day.
• Of 160 horses still at the venue, 118 were infected, with or without signs, and 8 were euthanased there. Overall 20 affected horses were euthanased, and 10 national federations reported linked cases.
• The FEI cancelled competitions in mainland Europe from 1 March to 11 April 2021 (78 FEI events; WOAH describes it as six weeks across 12 countries) and blocked horses from the Valencia, Sunshine Tour, Doha and Oliva Nova events in its database until they met FEI testing requirements, affecting 3,836 horses.
• The FEI formed an Epidemiology Group, sent its veterinary manager to the site and engaged Valencia University Equine Hospital; a laboratory network led by the Irish Equine Centre characterised the virus.
• Events resumed on 12 April 2021 under enhanced biosecurity until 30 May, including mandatory EHV-1 testing before arrival at events with more than 400 horses stabled overnight. The FEI HorseApp was launched on resumption to record horse arrivals and departures for tracing.

The counts grew as the outbreak went on. Eurodressage's report of 1 March 2021 gave 4 deaths at that point, against the WOAH case study's later total of 20 euthanased.

WOAH also records a further outbreak at Oliva Nova, Spain, in February 2023: about 1,000 horses were on site and 4 were confirmed positive. Spanish veterinary authorities closed the venue, and all horses on site were blocked in the FEI system until they met the FEI testing protocol. EHV-1 needs a vet.

For how horses are identified and their vaccinations recorded, see horse passports and identification.