The future success of a racehorse can be detected in the animal’s gut when it is just one month old, research suggests.

A recent veterinary study analysed horses’ poo, measuring the bacteria in the digestive systems of more than 50 thoroughbred foals over the first three years of their lives.

The study found the more types of gut microbes a foal had at just four weeks old directly correlates to its future health, and its success on the racecourse.

The findings, published in the journal Scientific Reports, add to an emerging biological picture regarding the importance of the trillions of microbes that live inside young animals’ digestive systems – and their role in long-term health.

“Gut health is absolutely critical,” said lead researcher Chris Proudman, a professor of clinical veterinary science at the University of Surrey.

“There is a growing understanding that what happens in human guts and in animal guts – horses, in this case – has a profound influence on many aspects of health and disease.”

“It’s also about timing,” he explained. “The nature of the gut bacteria in those first few weeks of life predicts the future health, and the future performance, of these horses.”

Young racehorses provide veterinary scientists with an ideal opportunity for studying the gut.

Breeders and trainers of thoroughbred foals typically keep highly detailed records of each animal’s birth, diet and health, as well as any veterinary care they receive.

“Anything we can investigate – to help them be in as good shape as possible – is a really good opportunity for us,” said Jane Black, co-owner of Chasemore stud farm in Surrey, which bred some of the foals involved in the research.

Over the course of three years, owners and trainers recorded how their horses performed on the racecourse, including where they placed and how much prize money they earned.

Meanwhile, scientists regularly collected faecal samples – by collecting horse poo from the stables – from each of the 52 young horses involved in the study.

Researchers were then able to “DNA fingerprint” the samples, providing a regular read-out of the bacteria inside each animal’s gut.

“We can see the amount of bacteria present and identify the different types,” explained Prof Proudman.

“Then we compared that with our health data, and with our racing performance data.”

The study concluded that the more diverse the gut bacteria in a four-week-old foal, the fewer health problems – particularly respiratory diseases – the horse suffered in later life.

Researchers also found a direct relationship between the number of different types of gut bacteria in a month-old foal and its performance on the racecourse when it was older.

The team of scientists also investigated the long-term consequences of young foals being treated with antibiotics.

Foals treated with antibiotic drugs had fewer types of bacteria in their guts, and subsequently went on to win less prize money in their racing careers compared to horses that had not received early antibiotic treatment.

Prof Proudman said the discovery raised questions about the use of antibiotics, both in animals and in humans, in early life.

“We need to think about things that happen in those first few weeks of life – to make sure that animals and humans’ gut bacteria are in a good state at that stage.

“That appears to set them up for a healthy life in the future,” he said.

Professor Roberto La Ragione, also at the University of Surrey, said:  “The next part of our study will examine how we can minimise disruption of gut bacteria when antibiotics have to be used to treat infections [early on].”