Without a doubt, Sir for Sure stole the show during the Plate Trial Stakes while The Minkster, a top Queen’s Plate contender, settled for a sixth-place finish. But was The Minkster’s performance simply lacklustre in light of his competition, or did something else prevent the son of English Channel from securing the limelight that day?

The Minkster’s trainer, Danny Vella, believes a case of the thumps could have hampered the colt’s ability to hit the board.

“On the way back to the barn he was pretty exhausted. He was suffering from the heat, so we obviously got the hose on him, cooled his body, cooled his head, and tried to get the circulation regulated.

“At the same time he had what we call the ‘thumps’, which stems from an electrolyte imbalance and causes their diaphragm to pulsate a little bit. It’s really not harmful, it doesn’t really hurt a horse terribly, but they feel uncomfortable. He wasn’t quite himself. Whether it started during the race or after the race is the tricky part to decide … the way he finished I would say something was going on during the race.”

What causes thumps?

Thumps, which is also technically known as synchronous diaphragmatic flutter (SDF) is caused by an electrolyte imbalance. Matt Nugent, a commission vet at Fort Erie Race Track who also runs Nugent Veterinary Services in Niagara, notes that, “Usually, its calcium that does it. If it’s low, when the horse needs it at the time of exertion, they just can’t mobilize it. But sometimes you can have too much calcium in their diet if they are being supplemented.”

“I can’t think of any breed dispositions to it. Typically, you see it in higher-end athletic horses, like racehorses or eventers, that kind of thing,” said Nugent. (Watch a video of a pony with the thumps here.)

Keeping fit is an essential aspect of the game, but nutrition is also crucial, especially when it comes to electrolytes. Saravanan Moorthy, a vet at Woodbine Racetrack, highlights several electrolytes that play an essential role in a horse’s life.

“The major electrolytes would be sodium, calcium, magnesium, phosphorous, and potassium, then the minor or trace elements: iron, copper, cobalt, zinc, selenium, manganese, iodine. If there’s a calcium deficiency, it makes the phrenic nerve a lot more irritable, and that is what causes the SDF,” said Moorthy, who runs Moorthy Equine.

An electrolyte imbalance can be triggered in racehorses when they are physically exerting themselves. “Exercise, sweating, especially if they’re training on Lasix [furosemide] on hot summer days – it definitely aggravates the situation,” said Moorthy.

Lasix is an anti-bleeding medication that’s administered approximately four hours prior to a horse’s race. It is also a diuretic and can cause fluid and electrolyte loss.

How thumps looks

Thumps could be compared to humans experiencing hiccups. Of course it’s not the same, but the spasm and uncomfortable feeling for both horse and human are somewhat relatable.

“It’s like a hiccup. It’s in the diaphragm, just like a hiccup is, but it happens during extreme exertion, like in a race,” said John LeBlanc, a trainer at Woodbine who has dealt with ‘thumpers’ in the past. “The vets always tell us it’s an electrolyte imbalance. However, we’ve tried all kinds of different things, and you may help deplete the severity, but some horses just learn to deal with it and run with it. I’ve seen them pull up after a race and not present thumps, but when I get back to the barn, and as they are cooling out, the thumps occur. So it may not be happening in a race itself, but during the recovery period if the body is just over-exerted,”

Although humans getting the hiccups can be embarrassing or awkward, the thumps can profoundly impact racehorses.

“Normally they take a breath with every stride, so if their diaphragm goes into a fluttering state, they won’t be able to breathe normally and get the oxygen they need to feed their muscles and the rest of their body that they need to perform,” said Nugent.

In some instances there are noticeable signs. “Basically, there are two ways of knowing a horse has thumps. One, you can actually hear it. If you squeeze their nostril, you can hear this noise, it’s almost hiccupping. The other is if you look at their abdomen and their stomach is vibrating; it’s not just like when a horse is inhaling and exhaling, it’s kind of spasming. It can be very painful for them,” said Josie De Paulo, who experienced the situation with previous runners such as Eminent Force.

Vella believes this was The Minkster’s first case of thumps.

“First time I’ve seen anything. I mean, he’s undefeated up until then. Basically, it’s from the extreme heat which changed a few days ahead of the race. The horses take longer to climatize than we do, so if it’s hot for a few weeks in a row, they get used to it, whereas with this situation, it only had been hot for a few days, and he probably wasn’t fully climatized. The race didn’t go his way. That probably puts him off a little bit. He wanted to be in front earlier, and there was a bit of speed inside. Part of it’s mental from frustration and part of it’s the heat situation.”

On Sunday, July 24, the day of the Plate Trial Stakes, the senior stewards report listed the temperature as 27 degrees Celsius; according to the website timeanddate.com the humidity was listed at 72%.

Vella notes the champ was back to normal the day after the Plate Trial. “I was exhausted thinking about it, and he was definitely himself, so that’s a very good sign. He wasn’t moping around; he wasn’t tired at all. It was just like any other day for him. I believe there is no long-term effects from this type of thing. Of course, if he was to repeat it continuously, that’s different, but most horses don’t. Usually, once you adjust accordingly you can control it with very few problems. As far as how he bounced out of the race, the next day he seemed himself and you have to go by what they tell you.”

Treating and preventing thumps

Holding your breath, placing a penny between your toes, or someone scaring you are some go-to methods to remedy a case of human hiccups. However, for a horse prone to thumps, the best way forward is to correct the electrolyte imbalance by administering electrolytes or adjusting the feed program.

“Usually, we can correct these problems with extra electrolytes. Sometimes feeding them a little differently so that they maintain a higher liquid content in their stomach before and during the race. We’ve talked to the veterinarians and to the feed people, and we are going to adjust accordingly. Hopefully, we can solve the problem; usually, you can,” said Vella in relation to The Minkster.

A ‘calcium jug’ might be used to manage a thumper, which is comparable to a human patient being administered an intravenous saline drip at the hospital.

“It’s a bag of fluids with either added calcium or you can add different electrolytes in with the fluid jug as well as vitamins ‒ DMSO could be added,” said LeBlanc, who has experienced thumps with runners such as Green Doctor.

“Green Doctor at one point in time started getting the thumps. I couldn’t take her off of Lasix, because at times she did have a bleeding issue, but I tried different electrolytes, different balances of calcium, and she still thumped occasionally.”

Josie and Mike De Paulo have seen horses with thumps and provides some insight on treatment.
“Ideally, when we had race-day medications, you had no issue with it because you could give them a calcium jug [intravenously]. Now we pre-race horses with extra electrolytes to stop them from getting it. It does stop on its own in time.”

Woodbine-based trainer Sandy McPherson is quick to add his two cents. “We supplement them with calcium and take them off Lasix, and generally that does the trick.”

Note that the AGCO Thoroughbred rulebook states that a horse receiving Lasix must remain on the Exercise Induced Pulmonary Hemorrhage program (EIPH) for 100 days, after which the horse may be removed from the program.

There are a variety of electrolyte supplements such as electrolyte paste or Equi Jugs that can be orally administered to horses. On Woodbine’s backstretch, horse supply stores such as Merrill’s and Greenhawk provide a bevy of such options. Dan Colangelo, a Woodbine Equine Veterinary Services vet, also notes you can use an oral supplement known as Calf-Lyte. “Basically, it’s a supplement that you would give young calves that have diarrhea, as they lose a lot of electrolytes and it replenishes it. It was basically formulated for that, but it’s a been very good source of electrolyte rebalancing [in horses].” It is added to the feed as a top dress.

The Lasix question

Colangelo notes that in addition to race day, Lasix is sometimes used on horses for a prep work leading up to a race.

“A lot more trainers and vets are advocating for use of Lasix to prevent bleeding when they work. Often you work a week to ten days before a race; if the horse gets Lasix then it puts them into a negative electrolyte balance, and then they run again seven days later. So now they’ve had two doses of Lasix in about a seven-day period, and that exacerbates the electrolyte imbalance in some horses.”

The thumps and Lasix discussion is not a new one, nor is it restricted to the racing industry. An article posted on the Federation Equestre International (FEI) website ‒ the governing body for global equestrian sport ‒ four years ago entitled ‘All About Thumps’ also noted that ‘Lasix or other diuretics, frequently used in racing, may exacerbate loss of hydration.’

The use of Lasix is also a divisive issue. “Lasix is something that we raced without for a long time and the sun came up every morning,” remarked McPherson. “Right now in the U.S. in the big races they are running Lasix-free. A lot of people can’t deal with that because they think it stops horses from bleeding. I don’t think it stops horses from bleeding. It may stop some; it may have that effect occasionally. But horses bleed through Lasix.”

As of last year, several big races (Breeder’s Cup Challenge races) at Woodbine are also run Lasix-free, including the Woodbine Mile, and the Natalma and Summer Stakes.

Vella acknowledges that several factors can impact a horse’s race day hydration status. “Lasix does dehydrate a horse. So Lasix does not help a horse that has problems with thumps, that’s for sure. What also comes into the play is the limitations we have on electrolytes and race day medications that we didn’t have before.”

As it stands, racehorses in Ontario cannot be administered certain electrolytes within a specific time period before a race day. This limitation stems from an AGCO directive back in early 2019, which prohibits race-day medications, drugs, and substances “for any horse entered to race starting 24 hours prior to the post time of the first race of the day.”

When asked for further clarification on whether electrolytes can be administered on a race day, Raymond Kahnert from the AGCO communications team offered this response:

“Electrolytes that are voluntarily ingested by horses on (a) race day are not prohibited. However, two examples of prohibited methods are nasogastric tubing of electrolytes (referred to as milk-shaking) and intravenous administration of electrolytes.”

The Canadian Pari-Mutuel Agency (CPMA), which oversees the post-race equine drug testing program, was asked how nasogastric tubing  or intravenous administration of electrolytes adversely affects the post-race testing process: “Electrolytes do not affect the post-race testing of substances for which official samples are tested for under the CPMA Equine Drug Control Program. However, they may have an effect on the TCO2 levels of racetrack samples taken either pre- or post-race. Testing for TCO2 is a provincial program. For this reason, and in an abundance of caution, horsepersons may want to refrain from administering electrolytes on race day to avoid the inadvertent administration of undeclared alkalinizing agents.”

Meanwhile, for The Minkster only time will tell whether his electrolytes are back in balance and there are no ‘hiccups’ in his connections’ plans as the clock ticks closer and closer to the Queen’s Plate.