"Paul said he started to neigh," Terry Biddlecombe, husband of Best Mate's trainer Henrietta Knight, said, "which is usually the sign of a heart attack."
Carberry's worst fears proved justified, and from that moment on it was the most bewildering of days. For a while after Best Mate's passing in the Haldon Gold Cup there were strange, rather unreal reactions among some of his connections.
Jim Lewis, the owner, behaved as we might do ourselves, running up the course as soon as he realised there was something wrong with the prince among his string, bursting into tears when the extent of Best Mate's condition became apparent.
Terry Biddlecombe was also trademark, the grizzled veteran unfazed by the calamity around him. "He'll be missed, for sure," he said. " For the last four years, for the public, he's been the horse. He's gone out today with no pain.
"I wish I could say he was better than Arkle, but we'll never know because he hasn't won a fourth Gold Cup. I was going to say his heart was his greatest strength, but it's gone and given out today. But he was an exceptionally good horse, a tough horse. Arkle is past and now this horse is past. We've got to find another one now."
The manner of Henrietta Knight, Best Mate's trainer and Biddlecombe's wife, was the strangest. It seems she was touched by the same emotions as Jim, but felt she had to behave like Terry.
In the paddock before the novices' chase which followed the Haldon Gold Cup, Knight could be seen smiling happily with Timmy Murphy, the jockey. Rather spookily, Racing Demon, the gelding which his trainer had called the new Best Mate, won the race. It was here we recognised just how much Knight had been thrown off kilter, as, for the first time in her life, she ran up the racetrack to greet a winner.
In the immediate aftermath of Best Mate, Knight had hidden behind the old countryman's attitude, the stoicism that life can be taken just as easily as it is given. "We all have to go sometime," she said. "Dick Hern once said to me that you have livestock and you have dead stock, which may not sound very nice, but it's true.
"It's probably harder for people watching who are not so close to racehorses than it is for us. We work with animals. It's best to try to think forwards. It's best not to dwell on things too much."
The facade cracked, however, in the Racing Demon press conference, when the thought of carrying on without Best Mate had his now ex-trainer choking. Yes, this was just the death of a horse, but it was also the death of a champion, an equine athlete which had just about carried his version of the sport for the last four years. "We will never replace Best Mate," Knight added. "He put our yard on the map. He was a great horse. He's a legend and he'll remain a legend."
Lewis was the most emotional of Best Mate's connections. His voice almost hoarse with feeling, he said: "What a pleasure he was for everybody. How much it meant. He made a lot of difference to a lot of people."
Lewis revealed Best Mate will be buried at Exeter. "This is where it all began with him," he said. "He won his first chase here and was never beaten here before today. It seems like the right place. This has been a terrible day, but I am still very, very proud of him and there won't be many who did what he did."
His sentiments were echoed by Edward Gillespie, managing director of Cheltenham racecourse, where Best Mate enjoyed so much success. "We are all very shocked here and saddened for everyone in jump racing," Gillespie said.
"Mostly for Henrietta, Terry, Jim and Valerie [Lewis], who were closest to him, but somehow it is different because Best Mate attracted so many people to pay attention to the sport who would otherwise not even look at the racing pages.
"He had the most impact on the sport of any horse in the last 40 years, there can be no question of that. We don't lose many really high-profile horses in such a way: I suppose One Man of the jumpers would be the first I can remember, but Best Mate was higher profile. I feel so sorry for everyone, we waited 40 years for one like him and he was great."
Gillespie's sentiments were both genuine and understandable because each time Best Mate went to Prestbury Park for the Cheltenham Gold Cup it seemed to be an uplifting experience, not least because Knight responded to victory with such unabashed delight.
For her, the memory of Best Mate's third and final Gold Cup triumph remains the best. "The last one [is my favourite] because of the pressure and people said we couldn't do it," she said. "That was his best performance in my opinion because it was his third Gold Cup. They may not have been the best horses he beat, but it was fantastic to win it for a third time."
Had he survived yesterday, Best Mate would have relinquished one record, that of not being out of the first two in 21 outings over fences. Yet even at the last there was a reminder of what had made him so great, an easy style and a most rare fluency at his obstacles. Best Mate flowed over his fences like river water over a stone.
Some had imagined that Best Mate would come here for little more than a racecourse gallop, that he would doddle around at the rear before being allowed to pass through a few horses in the straight.
That notion was dispelled immediately as Paul Carberry forced his mount near the head of affairs from the start.
It was rather dispiriting to see Best Mate beaten off quite so easily in the middle of the race, but no post-mortem will ever tell us at which part his old heart started to give out.
In a scene horribly reminiscent of Ascot last year, Best Mate, like Persian Punch of the Flat before him, made the death of a celebrity the most public of exhibitions, crashing to the floor as he approached the stands.
The full merit of Best Mate's achievements has also been questioned by proponents of Arkle, an earlier triple Gold Cup winner, from 1964 to 1966.
Now Best Mate himself will have the booster of nostalgia. He will live in the mind of all who witnessed his fleetness over ground and obstacle. He will live always in the mind of Henrietta Knight, the good memories preferable to the dark flashbacks that could come from the first day of November.
"I've been on a horse when it died of a heart attack and it was remarkably like that," she said. "The legs went, he wobbled, and then he went down. And that was it. He died beside me.
"I was numb at the time and it was only afterwards that it started to hit me. But I'm proud of the horse. He looked an absolute picture today. I felt he was enjoying what he was doing and, at least, he never got beaten in the Gold Cup."
Equine heart attacks leave vets baffled
About 275 horses died on British race tracks last year. These fatalities emerged from a total of 92,000 runners during those 12 months, amounting to a death rate of fewer than three out of every 1,000 runners.
But even in death, Best Mate was amongst the special ones. Injuries such as fractures result in by far the highest number of casualties. Sudden deaths from suspected heart failure are uncommon - and remain something of a mystery to the veterinary world.
Racehorses run a far higher risk of a heart-related sudden death than human athletes, Lesley Young, the equine cardiologist at the Animal Health Trust in Newmarket, said yesterday.
"When humans die in these kind of circumstances, it is usually because of some congenital problem, perhaps heart disease," Young said.
"Between 15 and 20 horses die each year after an exercise-related collapse, entirely separate from falls or other accidents. Best Mate is one of these.
"About one third of them suffer a severe haemorrhage, usually when a main blood vessel, such as the aorta, for some reason just ruptures and the horse bleeds out. It is very distressing.
"The other two-thirds have no obvious cause of death, except that it must be heart-related. What we don't understand is that this happens with apparently healthy horses, who have even been ultra-sounded and thoroughly examined and do not seem to have any heart problem at all. It is strange and a mystery we are trying to solve."
The risk to horses of heart-related sudden death during racing has been assessed as being about 50 times higher than with human athletes. The statistics deal with men and women of college age - the equivalent to the usual age of racehorses. Young said that vets are anxious to discover the reason for this problem.
"Why do horses have this higher risk of abnormal heart rhythm during fast exercise? We think that some have had a heart attack, but only because nothing else seems to be wrong with them - even when a post mortem has been carried out," she added.
Four leading horses that died on the track
ONE MAN (trained by Gordon W Richards)
Greys like One Man have always attracted an emotional following and the northern-based chaser was arguably the best horse never to win the Cheltenham Gold Cup. One Man's successive victories (1995-96) in the King George V1 Chase stamped him as one of jumping's greats. He was killed in a fall in the 1998 Melling Chase at Aintree, just 16 days after winning the Queen Mother Champion Chase at the Cheltenham Festival.
NODDY'S RYDE (trained by Gordon W Richards)
Spectacular front-running two-mile chaser whose promising career came to a premature end in the autumn of 1984. Noddy's Ryde had the race won only to slip on landing after the final fence and break his off hind in the Haldon Gold Cup at Exeter - the same race in which Best Mate met his end yesterday. Noddy's Ryde won eight times before finishing second in an epic duel with Bobsline in the 1984 Arkle Chase at Cheltenham.
TEN PLUS (trained by Fulke Walwyn)
Desert Orchid, the brilliant grey, won the 1989 Cheltenham Gold Cup but tragedy struck with the fall of Ten Plus at the third-last, when he was arguably going better than Desert Orchid. The bay had won his previous four races. He was a nine-year-old but had been lightly raced and was full of potential. Ten Plus was always prominent in the 13-runner field and led at the 14th until tumbling three from the finish. He had broken a leg and was put down.
DUNKIRK (trained by Peter Cazalet)
Dunkirk was himself an electrifying jumper but he died trying to match the legendary Arkle in the King George VI Chase at Kempton. The Boxing Day contest in 1965 saw Dunkirk crashing headlong over the 14th fence, fracturing rider Bill Rees's thigh and effectively shattered the royal jockey's career in the saddle. A year later Arkle suffered a fractured pedal bone in the same race but survived for retirement.
'We waited 40 years for one like him and he was great'
Henrietta Knight, Trainer
"I was on the track where he came down and I was the first one there. I knew immediately he had died. He was a very popular horse with a tremendous following and now there is a big vacuum."
Jim Lewis, Owner
"He was a great racehorse - there can have been very few in the world like him. What a pleasure he was to own and how much he meant to me. I will never forget him."
Terry Biddlecombe, Knight's husband and assistant
"Paul [Carberry] knew something was wrong. The only consolation is it was pretty instantaneous and he wouldn't have felt any pain."
Edward Gillespie, Cheltenham managing director
"Best Mate attracted so many people who would otherwise not even look at the racing pages. We waited 40 years for one like him and he was great."
John McCririck, Racing pundit
"The memory of his silky fencing and love of attention are what he leaves behind. We will now never know if even better was to come."Reuse content