The Ahern Procedure: Vet hopes to educate on breathing issues

27
Oct

Over the past 30 years, long-serving equine veterinarian Dr Tom Ahern has been sought out world-wide for his innovative throat surgery that has literally breathed new life into racehorses across the globe, however he feels that the involvement of the pharynx in breathing issues is still quite confusing to many industry participants.

The experienced surgeon hopes to educate trainers, owners and his colleagues alike with the aim of promoting the procedure he developed, the oral palatopharyngoplasty, which is currently only performed by a handful of vets around the globe due to the often-reported high degree of technical difficulty and the potential to permanently damage the airway.

Ahern’s surgical journey began when he graduated veterinary school in Sydney in 1978 before landing a job in Perth. A short time later and his revolutionary operation was unexpectedly born within his first decade of practice. He first published his surgery in 1992 before publishing the theories behind the procedure, titled ‘Pharyngeal dysfunction during exercise’, in the United States seven years later.

The operation was founded after renowned late trainer Peter ‘Porky’ Graham, a client of Ahern’s, approached him in the 1980s regarding a horse who had previously won a race but had since been banned from racing after refusing to jump from the barriers in races or trials. “Porky said to me, ‘we’ve got to do something about this horse’,” Ahern said. “I just laughed and said, ‘I’m not a psychiatrist!’

“Then he replied with, ‘no, I think it’s a physical issue and he’s struggling to breathe because I had a noseband and tongue tie on, which worked for a while, but now he’s refusing’.” Ahern was of the opinion that the available surgeries at the time were a waste so, in an attempt to satisfy the trainer, he said he would try to think of a different approach.

As he reflects on the events leading to the creation of the ground-breaking surgery, Ahern recalls a float arriving at his practice 10 days after his conversation with Graham and a grey horse being unloaded. “I asked what horse it was and they said, ‘it’s Porky’s horse, he said to do whatever you’d thought of’,” he said. “So, I went home that night to do some serious thinking.”

That evening, Ahern recalled having seen the beginning of numerous horses’ palates billow noticeably when intubating them through the throat and decided to focus on that area, rather than the opposite end where traditional procedures were being performed. After experimenting with the tightening of the region in order to reduce the palate billowing, Ahern was pleasantly surprised to see it ultimately resolve the horse’s issues.

“That horse ended up racing again and won eight or nine races,” Ahern said. “That was my first and biggest lesson in understanding the association between altered behaviour and breathing issues. “After that it was a matter of trial and error, as is the case with developing any new procedure. “Since then, I’ve done thousands of surgeries in a dozen countries and horses have won stakes races everywhere.

“In Europe, patients have won the English Derby, Golden Jubilee Stakes and the Prix de l’Arc de Triomphe, and most stakes races in WA have been won at least once by my patients and sometimes three or four times. “These days, the procedure is presented in all the major equine surgery textbooks around the world and it’s essentially regarded as a form of plastic surgery, like the human equivalent, as there are often only millimetres between success and failure.”

Ahern concedes that the common mentality towards throat surgeries is largely dismissive due to the varied success of traditional procedures, such as laryngeal surgery, otherwise known as a ‘tie-back’. However, he makes mention that there are up to 30 different variations and combinations of throat operations performed on horses, which must be assessed individually.

His own procedure is yet to undergo critical assessment as other surgeons have struggled to reproduce it but, in 1993, one of the many research articles that have been published by Ahern found his operation to result in successful race performances in 75 of the 100 horses across three states that were used in the study.

According to Ahern, since returning from the United Kingdom in 2008 the surgery has resulted in 420 individual winners of at least 1,200 races on WA tracks alone, averaging out to approximately two wins each week. Successful patients include Railway Stakes winners Machine Gun Tom and Welcome Knight, as well as current Ascot 1200m track-record holder, Danny Beau, but Ahern said he couldn’t name other patients for reasons of client confidentiality.

“A horse is an obligate nasal breather, meaning they are designed to only breathe through their nose, as they need to be able to eat and run if suddenly confronted with a predator,” Ahern explained. “However, if for whatever reason the horse feels that this nasal supply is inadequate, then it can cheat by sneaking some emergency air through its mouth.

“When a horse is galloping, their soft palate should sit on the tongue and this contact between the tongue and the soft palate creates a seal, referred to as the oropharyngeal seal. “This seal prevents the horse from taking air through its mouth and the palate moving up and narrowing the airway, which can then result in the palate displacing. “So, if for whatever reason they don’t feel their air supply is adequate, they can cheat by flattening their tongue and breaking the seal to enable them to breathe through their mouth.

“The epiglottis is then the only thing left holding the palate in place but, if it is very small or weak, the palate will displace and a gurgling sound may be heard.”

In 2012, an article was co-published by Adelaide Veterinary School’s Associate Professor Samantha Franklin who, in the United Kingdom 13 years prior, had taken up Ahern’s theory about the oropharyngeal seal mechanism with a view to either supporting or refuting his claims. Her study, ‘Characteristics of palatal instability in thoroughbred racehorses and their association with the development of DDSP’, appeared to support what Ahern had been preaching for the previous two decades.

“They spent 10 years observing the movements within the pharynx and associated changes in airway pressures,” Ahern said. “The disruption of the oropharyngeal seal, which they now referred to as palatal instability, was shown to significantly affect a horse’s air supply and their ability to perform. “Horses experiencing palatal instability often don’t displace their palates, so they don’t gurgle. “They either make no noise at all or produce a harsh inspiratory sound which sounds like air being dragged through the mouth.

“The UK team scoped horses while they were exercising on a treadmill and could observe when the seal broke and then see the palate start ballooning into the airway. “They measured this billowing to come up with different grades of PI. “Palatal instability is now the most common upper airways issue diagnosed in thoroughbreds and the only procedure that was specifically designed to reduce the incidence of palatal instability is the oral palatopharyngoplasty.”

Ahern says that studies have shown around seven per cent of thoroughbreds experience better-known laryngeal problems, such as semi-paralysis of the arytenoid cartilage, with such horses often referred to as ‘roarers’ or ‘broken winded’. However, he feels racing participants may be surprised to learn that palatal instability is thought to effect up to 33 per cent of thoroughbreds. “With laryngeal problems, you get grades of weakness and this is usually picked up at the yearling sales, or when being vetted,” Ahern said. “But the pharynx dysfunctions while the horse is working, so you can’t really assess it unless you have a dynamic scope performed during exercise.

“In a UK study, they took 70 yearlings from one yard that had passed the sales scope, so the larynx appeared to be good. “They weren’t broken-in, so they put a dynamic scope on and lunged them and a third of them showed evidence of airways collapse, including palatal instability. ”Ahern asserts that recent findings debunk the age-old perception that breathing issues are only probable if an abnormal noise is prevalent. “Traditionally, a trainer would ask the rider if the horse made a noise during work,” he said. “These might be a rattling, roaring, whistling or gurgling noise and, if the answer was no, it was assumed the horse didn’t have a breathing problem. “That’s now untrue and there are articles that have found between 25 to 30 per cent of cases with breathing issues have no history of abnormal noise.”

Ahern also notes the growing number of horses being diagnosed with lower airway issues and feels that, in some instances, there may be a direct correlation between these and palatal instability. He says the mechanics of a horse mouth breathing in order to allow greater air supply after the oropharyngeal seal is broken means that other foreign material located in the mouth, such as saliva, bacteria and feed material, can be sucked into the airway with inspiratory efforts. “As a result of this contamination, a lot of lung samples will come up positive and these horses are subsequently treated,” Ahern said. “As long as the treatment is successful and the issue doesn’t reoccur then other factors, like palatal instability, are unlikely causes.

“But if the problems reoccur when work pressure recommences, then palatal instability should always be considered and at least eliminated from the equation.”

Ahern adds that continued contamination will lead to the deterioration of lung tissues which may cause additional issues down the track, such as exercise-induced pulmonary haemorrhage (EIPH) otherwise known as ‘bleeding’. “During a race, there are enormous internal pressures being exerted on very thin blood vessels in the lungs which have been described as ‘waiting to burst’,” Ahern said. “If you add significant suction pressure to these vessels, which is what happens when the upper airways are narrowed or collapse, then logically you will increase the chance of vessel rupture and bleeding. “I do oral palatopharyngoplastys on a significant number of two-year-olds each season and it is rare that any present with serious bleeding issues during their racing careers.”

Group 1-winning WA trainer Ross Price has been a client of Ahern’s for more than three decades and has enjoyed great success with a substantial number of horses that have undergone the Ahern Procedure. The widely-respected veteran horseman fondly recalls taking advice from Ahern in the early 1990s and the decision inevitably paying dividends. “Tom rang me from South Australia and said, ‘Ross, there’s a horse here that they’re putting up for sale and it needs its throat doing, but they don’t believe it does because it’s never made a noise’,” Price said. “It was just about barred from the barriers over there, but Tom really believed it was a good horse and encouraged me to buy him. “He said, ‘he’s won nine races, so he’s an open-class horse, but they want $60,000 for him’.” Hesitant at the seemingly-hefty price tag at the time for a five-year-old horse with a lengthy stewards’ rap sheet that included trying to leave the course half way through a Flemington straight-six race, Price says he was lucky a stable client of his thought differently. “I spoke to one of my owners and he had a different philosophy to me,” he said. “He said, ‘that’s not a lot, I bought a yearling for $100,000 this year and I don’t even know if it can gallop’.

“So he went over there and bought it and Tom did the operation on it straight away and sent it over. “I started training it and that horse was Welcome Knight. “I won a Railway Stakes with him and retired him when he had his 20th win at 11 years-of-age.

“Because he couldn’t breathe, he got into a really bad habit of not wanting to go out onto the track over there and they even struggled to load him onto the truck.” Price adds that the theory behind the surgery is surprisingly straightforward but can have a remarkable impact. “It’s such a simple thing,” he said. “You’ve got an airway that might be an inch in diameter where the air sucks down and then the palate gets loose and knocks it off, so you’ve only got half the diameter there and can only get half the air down. “It’s as simple as tightening it all up and letting the lungs get the air.

“It’s a feather in Tom’s cap because he developed the surgery from nothing and, put it this way, it’s such a good surgery that if it doesn’t work, they’re no worse off than they were before. “I’d say 90 per cent of them do work and, the biggest issue I think, is that people do them on horses that might not have much ability anyway.”

ORAL PALATOPHARYNGOPLASTY CHEAT SHEET:

As told by Dr Tom Ahern

WHY DOES PALATAL INSTABILITY OCCUR?

In simple terms, PI is the event that occurs when a horse decides to ‘cheat’ or ‘supplement’ its normal nasal supply with air acquired through its mouth. Anything that causes or leads to a narrowing of the airway can trigger this response. The upper airway is maintained by muscle tone and reductions in tone will lead to narrowing of the airway. Skeletal muscles can fatigue due to unfitness or reduced oxygen supply and, along with this, the throat muscles will also fatigue. This reduction in muscle tone can then lead to upper airways narrowing and reduced air supply.

WHY IS THERE SUCH A HIGH INCIDENCE OF PALATAL INSTABILITY?

Well, one could ask why is there such a high incidence of knee injuries in professional football ranks? The answer is that you expect these with ‘elite performance’. The same principle applies in elite equine athletic pursuits, which include racing and cross-country events. That elite pressure is not only applied to skeletal musculature, but also the horse’s pharyngeal and laryngeal muscles. The important thing is to firstly recognise these issues and then treat them.

INVESTIGATING PALATAL INSTABILITY:

Things to look for which might suggest an over-ground scope might be a good idea. Abnormal behaviours like not wanting to go on the track, not wanting to load onto the float on race days or being nervous or wound up before a race. However, not all horses that play up when being loaded onto trucks or into barriers will have breathing issues and there are a number of other explanations for this behaviour.

Occasionally horses will also throw themselves on the ground when asked to move on or pull up abruptly without warning during a workout. Others will simply refuse to put in an effort at the serious end of a race or event, whilst others will ‘over-race’ which, in some cases, appears to be an attempt to get the event over and done with.

PERCEPTION OF THROAT SURGERY:

The problem is that, when you mention throat surgery to trainers and owners, their opinions are often skewed by their experience with other procedures. In actual fact, there are 25 to 30 different types of throat surgeries, all of which have varying success rates. Judging whether a surgery is successful or not based on whether they make a noise has never been reliable. Laryngeal surgery, or a tie-back, is a perfect example because usually the vocal folds are actually removed, which are the main source of the noise.

OTHER METHODS:

The Cornell collar and the tie-forward procedure are both based on the theory that the larynx sits too far back, so they aim to position the larynx in a more forward position. This theory is different from that proposed by research into the oropharyngeal seal and palatal instability.

Laser firing is performed on the opposite end of the palate to the OPP procedure, while thermal firing is performed on the same tissues as the OPP procedure and relies on scar tissue formation to increase tension. Thermal firing is banned in many countries, including Australia. Results with these procedures are well documented and your surgeon will of course usually speak from their own experience with any procedure.

There are also numerous varieties of gear, such as tongue bits, nosebands, tongue ties, and bitless bridles that reputedly help a horse to breathe. However the thing that I find myself saying most often is, ‘as much as they may help, even be it temporarily, none of these actually improve a horse’s airway’. Only surgery can do that.

OTHER SYMPTOMS OF PALATAL INSTABILITY:

A lot of horses don’t make a noise but they regularly or intermittently pull up with an elevated heart rate or respiratory rate after fast-work or a race. For example, when a trainer feels that they have done plenty of work with a horse and it should be fit, but it still blows hard and has an elevated heart rate after its workouts. In the absence of any other obvious issues, the simple answer is that if the oxygen supply is inadequate or suddenly interrupted, then you can expect the recovery to be extended.

Another useful tool is to examine the inside of the cheeks between the molars at the back of the mouth. If they are breathing through their mouth, they will create a negative or suction pressure, called the inspiratory phase, which tends to draw their cheeks onto the cutting edges of their teeth. I suggest hosing their mouth out, putting a gag on them and looking at the inside of their cheeks near these molars. If you see wounds or scars where their teeth have been cutting, then palatal instability should be considered amongst other possible causes. With palatal instability, having their teeth filed will reduce the severity of these abrasions but will not eliminate them. However, not all cases of palatal instability will present with these lesions.

MATURITY:

It has often been proposed that horses ‘mature’ out of these issues. In my experience and that of numerous high-profile international trainers whose opinions I have canvassed, only a small proportion ‘grow out’ of these issues. More often they will learn to work around the issue often by not exerting themselves when put under pressure.

WHEN TO OPERATE:

As time goes on, many horses with palatal instability will experience progressive deterioration of the lower airways. This can lead to deterioration of lung function and more serious episodes of exercise-induced pulmonary haemorrhage or ‘bleeding’. Their attitude to racing will also deteriorate and can lead to emotional issues and altered behaviours that will also need to be overcome post-operatively. So, very simply, intervene as young or as early in their racing careers as possible before these other factors become overwhelming.

POST-SURGERY:

The surgery is just stage one in a horse’s recovery and, when I deal with people, there is an agreement. How they’re worked afterwards and how they’re ridden post-operatively are also very important in the recovery process as you have to get the horse’s confidence back. You also don’t want them to be over raced in that first crucial recovery preparation. We normally give them three or four runs and they go out for a six-week spell and, after that, they resume normal racing. It’s like coming back from a tendon injury, you’re not going to give them 20 runs in their first prep.

OVERGROUND SCOPING:

It is important to realise that a negative OG scoping does not rule out breathing issues. A gallop is not a race! Numerous horses have been found to have significant issues following a negative test.

Trainers and owners looking for more information are encouraged to contact Dr Tom Ahern direct on 94784029 or 0423246144 or by visiting   www.drtomahern.com

Michael Heaton