1,000 racehorses a year in UK abattoirs. Shocking failures in checks. How do we know thoroughbreds aren't in our food?

Officials at Aintree racecourse, home of the Grand National, have been forced to deny that fatally injured horses could have entered the food chain (Getty Images; EPA; AP)

The monitoring and tracking of horse numbers in Britain and Ireland is so lax that tens of thousands of animals may have been exported illegally and entered the food chain, experts have warned.

The Independent has also established that more than 1,100 racehorses were slaughtered in abattoirs in Britain in 2011, raising the risk that unscrupulous meat trade middlemen have diverted thoroughbreds for human consumption.

Officials at Aintree racecourse, home of the Grand National, have been forced to deny that fatally injured horses could have entered the food chain after it emerged that the owner of a Yorkshire abattoir raided and closed down this week on suspicion of supplying horsemeat to a Welsh processing plant has a contract to remove destroyed animals from the course. There is no evidence that the horses collected from Aintree entered the food chain.

Up to 7,000 unauthorised horse passports have been in circulation since 2008 after documents continued to be issued in the name of an organisation – The Spotted Horse and Pony Organisation – after it had its licence withdrawn. About 75 different organisations are authorised by the Department for Environment, Food and Rural Affairs to grant the passports, which critics say makes the system chaotic and vulnerable to fraud.

Animal welfare campaigners said that up to 70,000 horses have been exported from the Irish Republic and Northern Ireland, some of them with records showing they are unfit for human consumption wiped clean with falsified documents.

One of Britain’s leading public health experts said that ministers were wrong to state that horsemeat poses no risk to human health. Professor Hugh Pennington said that the potential involvement of back-street or poorly run abattoirs in supplying illegal horsemeat raised the danger of contamination by bacteria such as salmonella in processed food products: “There are issues at the bottom end of the market with meat going under the radar, like the horse meat has been doing.”

The Food Standards Agency (FSA) has sought to quell concern about the presence of a veterinary drug - phenylbutazone, or "bute" - in horsemeat that may have entered the food chain after it revealed that bute had been found in eight out of 206 carcasses tested in a seven-day period this month.

Officials said three of the carcasses had since been sent to France and could have entered the food chain but an individual would need to eat several hundred horsmeat burgers in a single day to obtain a single human dose of bute.

The Ulster Society for the Prevention of Cruelty to Animals said it believed horses in Ireland worth as little as £10 (because they have been treated with veterinary drugs such as bute) were being sold on to slaughterhouses for up to £400 by criminal gangs falsifying horse passports and inserting new identification microchips. The charity’s research indicates that up to 70,000 horses could now no longer be traced in the Irish Republic and Northern Ireland since 2010, many of them racehorses or other leisure animals bought during the economic boom which led to a glut of unwanted animals when the downturn struck.

Experts said there was a separate issue on the British mainland of the alleged overproduction of racehorses, leading to surplus animals being sent for slaughter. Figures published by the British Horseracing Authority show that 1,127 thoroughbreds were killed in abattoirs in 2011, an increase of 126 per cent on 2010, when the number was 499.

Andrew Byers, a specialist in the equine breeding industry at Nottingham Trent University, said: “These unwanted horses, which are unable to race or compete, end up being sent for slaughter.”

It is legal for racehorses to enter the food chain as long as they are properly slaughtered and have not been treated with medicines, such as bute, which make them unfit for human consumption. The BHA, which denies that there is an overproduction of racehorses and points to fall of nearly 30 per cent in thoroughbred foals born in the last five years, said the use of legitimate veterinary drugs in racehorses means virtually all are excluded from the food chain.

Dean Stansall, horseracing consultant for Animal Aid, said: “We have seen in recent days that the system once they reach the slaughterhouse is in a mess – there can be no guarantee that some of these animals are entering the food chain.”

The BHA said it was subject to some of the tightest regulation in any equine sport and an abattoir often represented the most humane way to end an animal’s life. It said the regulation and operation of slaughterhouses was a matter for the FSA.

It has emerged that up to 7,000 unauthorised horse passports have been in circulation since 2008 after documents continued to be issued in the name of an organisation – The Spotted Horse and Pony Organisation – after it had its licence withdrawn. About 75 different organisations are authorised by the Department for Environment, Food and Rural Affairs to grant the passports, which critics say makes the system chaotic and vulnerable to fraud.