Horse Health
Help for sterile and subfertile studs
Experts suggest methods to help some stallions conquer problems with libido and low fertility
by Denise Steffanus
Thoroughbreds are at a disadvantage in the breeding shed because of the Jockey Club rule banning conception by any means other than live cover. While other breeds, including racing Standardbreds, can take advantage of the benefits of progressive technology in reproductive medicine, Thoroughbred breeders are faced with some of the same obstacles that have impacted their livelihood for decades, possibly even centuries.
For Thoroughbred mares, innovative methods of diagnosing and treating certain problems have improved fertility, but relatively few advances have been made to assist stallions in getting mares pregnant via live cover.
No cigars
Cigar, North America's all-time leading money earner, is perhaps the most famous sterile stallion. In 1997, when the two-time Horse of the Year was diagnosed with fertility problems, Assicurazioni Generali SpA paid a reported $25-million fertility-insurance claim to Cigar's owners and took possession of the horse. The Italian underwriter then enlisted the help of Philip McCarthy, V.M.D., a Central Kentucky practitioner whose focus is stallion reproduction, to see if anything could be done to improve Cigar's fertility. Unfortunately, despite McCarthy's best efforts, Cigar remained sterile and now resides at the Hall of Champions at the Kentucky Horse Park in Lexington.
Most recently, Irish and English highweight George Washington (Ire) was yanked out of Coolmore's breeding shed and sent back to trainer Aidan O'Brien when the multiple Group 1 winner was found to be subfertile.
While the causes of Cigar's infertility and George Washingston's subfertility may never by known, academic authorities are examining how stallions are managed and the possible effects on fertility.
Dickson Varner, D.V.M., a board-certified reproduction specialist at Texas A&M University whose focus is stallions, was the expert called in to evaluate George Washington.
Varner said fertility problems in a stallion could be congenital, acquired, genetic, or environmental. He is most concerned with environmental factors, including medications that may temporarily or permanently damage fertility, and pesticides.
One drug of primary concern is methotrexate, a human chemotherapy drug and arthritis treatment.
In humans, methotrexate is used alone and coupled with the drug RU-486, the so-called "French abortion pill," to terminate pregnancy. When administered as chemotherapy or to treat arthritis, the law requires patients to be informed that methotrexate "É may cause sterility, which could be permanent."
"In some instances, horses have received that medication in race training, and it's hard to say why," Varner said. "It's probably because it's an anti-inflammatory that could possibly be a replacement for phenylbutazone, but the difference is that it has a very detrimental and probably permanent effect on semen quality."
He added, "And, of course, drugs like anabolic steroidsÑEquipoise is the biggest one, one that's given repetitivelyÑcan have a deleterious effect on testicular size, semen quality, and sperm-production rates."
Varner said that when administered to young horses nearing puberty and continued through puberty, drugs such as Equipoise and Regu-Mate could permanently impact fertility.
"The pubertal period is a very critical period in the stallion's life, and if anything damages the testes when they're going through puberty, it's more likely to have a permanent effect," he said.
Varner also questioned the use of cimetidine, which is prescribed by some veterinarians to protect the horse's stomach as an inexpensive but less effective alternative to omeprazole (GastroGard).
"If you go to the literature, you'll see that cimetidine has been associated with reduced fertility and libido," Varner said. "I think in dogs it's been associated with Leydig cell tumors in the testes."
Varner also is concerned about pesticides and other chemicals used in pasture management because studies in other species have shown their deleterious effects on fertility. Bred for speed
McCarthy believes the predominant cause of fertility problems in stallions (and mares) is that the trait they are selectively bred to achieve is speed, not fertility. "We've always selected them in the Thoroughbred business based on performance on the racetrack," McCarthy said. "There is very little attention paid to reproductive performance. So, occasionally, you'll get a horse that's a superior athlete but he's missing some of the qualities you'd like to see in terms of reproductive performance. When those two spheres collide, you get problems with reduced fertility and then you see the consequences."
Varner said certain bloodlines in Thoroughbreds have reduced fertility, but he declined to identify which lines.
"We don't like to release information like that and startle the industry," he said. "We identified a specific defect a number of years ago in a number of Thoroughbred stallions, and all of them were of similar lines." Not in the mood
McCarthy regards low libido, not sperm production, to be the most limiting factor for stallion fertility. One problem he cited is the ever-increasing number of mares a stallion is expected to cover in a breeding season.
In the 30 years since his residency at the University of Pennsylvania, McCarthy said he has observed stallions' books increase dramatically from about 40 mares to up to 300 mares for some dual-hemisphere stallions. And many of those mares do not conceive on the first cover.
"There are many more problems that we have in getting the stallion to come in and service those mares twice and three times a day," McCarthy said. "And in many instances the stallion has plenty of spermÑplenty of capability of rendering mares pregnantÑbut they are just not that interested in breeding. I personally think it is a behavioral issue."
Sue McDonnell, Ph.D., founding head of the Equine Behavior Program at the University of Pennsylvania's New Bolton Center, is considered the foremost authority on stallion behavior. She believes it is important to assure the stallion's first experiences in the breeding shed are positive. This means keeping the stallion under control while not over-disciplining him so that he infers that breeding is an undesired behavior.
McDonnell said stallion handling is a lost art, but consultants are available who can observe and suggest solutions to most stallion-handling problems. New Bolton also offers a two-day course titled "Just Stallion Handling." McDonnell urged early intervention before the behavioral problem becomes ingrained.
Most Thoroughbred stallions live in a barn with other stallions with no mares in sight. While this may be a good idea for most stallions to keep them calm, McDonnell said some stallions might need a harem to improve their libido and subsequently their fertility.
She suggested placing such a stallion in a sturdy paddock adjacent to a band of mares. McDonnell believes this will have a threefold benefit: the stallion will increase his amount of exercise by running up and down the fence, his libido will improve, and both these benefits will improve fertility.
"Sitting in a stall is not good for libido, so if they can be out and run up and down the fence line next to their mares, it's better to be lean and fit than a couch potato," she said.
Reinforcement breeding
One of the most promising techniques available to the Thoroughbred breeding industry is reinforcement breeding, the practice of collecting semen from the exterior of the penis when the stallion dismounts the mare and then mixing it with prewarmed semen extender and infusing it into the uterus of the mare just covered.
While McCarthy said he cannot endorse the practice until it is validated by controlled studies, Varner was enthusiastic about its use.
Varner said he conducted a private study of reinforcement breeding at a Thoroughbred farm in Kentucky a few years ago, and then one of his colleagues at Texas A & M, Terry Blanchard, D.V.M., did a follow-up study after he became resident veterinarian at John G. Sikura's Hill 'n' Dale Farms in Lexington.
"We saw up to a 20% improvement in pregnancy rate per cycle, so I think that is an exciting area in the Thoroughbred industry," Varner said of his original study. "It doesn't mean that every stallion needs to have reinforcement breeding, but if you have problems with a horse, that's a very good treatment strategy."
At last year's American Association of Equine Practitioners convention, Blanchard reported: "Mares receiving reinforcement breeding had a greater chance of getting pregnant than mares that were not reinforced; this resulted in an average increase of a 12%-per-cycle pregnancy rate in eight of 13 stallions in the study."
Blanchard said stallions whose impregnation rates increased with the use of reinforcement breeding during the first season it was employed also experienced a similar increase when it was used in subsequent years. Some stallions, however, did not benefit from reinforcement breeding.
Supplementation
Researchers are looking at Omega-3 oils as a possible nutritional support for stallion fertility, in particular docosahexanoic acid (DHA).
Researchers at Texas A & M fed a DHA-enriched nutraceutical to stallions to study its effects on sperm motility. The study, which focused on the motility of sperm contained in cooled or frozen semen and used for artificial insemination, showed that supplementation with DHA benefited motility. But would the same DHA-enriched diet hold benefits for Thoroughbreds, which breed by live cover?
"There are three studies done: one at Texas A & M, one at [University of] Arizona, and one at Colorado [State University]," said Ed Squires, Ph.D., professor of equine science and reproduction specialist at Colorado State. "Although we looked at fresh semen, cooled semen, and frozen semen, there were some occasions when even in the fresh semen, motility looked a little better in certain stallions. Also, the sperm numbers were higher in some of those horses. So I don't think it has to be just an [artificial insemination] situation.
"Since that sperm membrane is made up of fatty acids, I think all we're doing is helping the sperm to make them a little better," Squires said. "They should try it [for subfertile stallions], and even if they have a fertile stallion, it might make him a little better, particularly those horses that are being heavily used. There is some suggestion, at least in pigs and boars, that it actually increased sex drive."
In an informal survey of people who had used the DHA supplement last year, Squires asked the question, "Did it affect sex drive?"
A lot of people thought it had some positive effect on sex drive, so I think if I had a problem stallion, I would certainly use it. And if I had a horse that was heavily working or maybe a little slow in the [breeding] shed, I'd probably try it on him." However, McDonnell cautioned stallion owners about some nutraceuticals marketed to help fertility without any studies to back them up.
"You'll find things that are specifically developed for stallions that are totally bogus," she said. "They're meant to enhance fertility and libido, and whenever we've tested them, they actually adversely affect both fertility and libido." McDonnell would not name the products but added, "The important thing people ought to know is that they have not been tested for safety or efficacy. A lot of these things have 'sperm' in the name."
Call for research
Varner said he would like to see more research aimed at helping Thoroughbreds.
"With Thoroughbreds, our efforts really need to be dedicated to understanding the molecular science behind testicular function and sperm function, so we can devise ways to possibly do some gene therapy to enhance the fertility of horses. It's not something that's outside the realm of possibility."
Denise Steffanus is a contributing editor of Thoroughbred Times who writes frequently on veterinary and farm management topics
Walk this way
Veterinarian and blacksmiths design ambulatory sling to enable horses with severe fractures to exercise and thereby avert laminitis
by Denise Steffanus
The deadly specter of laminitis hovers over every horse that suffers a severe orthopedic injury. As in the case of Barbaro, even when heroic efforts achieve successful healing in the injured leg, the horse may be lost to catastrophic laminitis in its other limbs, which causes the hoof capsule to slough off.
For many years, equine surgeons have tried to find a way to avert laminitis while a horse recuperates. Now a collaboration between Roger Murphy, D.V.M., in Lexington and blacksmiths Beach and Tyler Faulkner has produced an ambulatory sling that enables a horse to be walked 20 minutes per day using all four limbs while recuperating. The inventors have dubbed the device the "Faulkner walker," a tribute to the father-and-son team's remarkable mechanical ability that made it possible.
The original idea for the device came to Murphy in one of those rare, middle-of-the-night epiphanies. He and his wife had taken in a severely malnourished mare that had been confiscated in an abuse case. The mare was down and too weak to get to her feet, so it was essential for her survival to get her up and moving. Murphy awoke from a troubled sleep with this thought: There's no reason we can't put some wheels on a set of stocks and suspend a sling from the stocks and let her move around.
"I jotted down the idea on a piece of paper on my bed stand and drew a little picture," Murphy said. "I called Beach [Faulkner] the next day, and I said, 'This is what I'd like to do.' "
Faulkner was head farrier for Spendthrift Farm in the 1980s when Murphy was resident veterinarian during the farm's heyday. Representing the fifth and sixth generations, respectively, of a family of blacksmiths, Beach and Tyler Faulkner count Claiborne Farm and Gainesway among their current clients.
The Faulkners immediately began to design and construct the device. The next morning they already had produced a crude version of the current Faulkner walker.
Murphy and the Faulkners placed a sling around the mare, then rolled the walker above her, hooked the sling to the walker's winch, and lifted her to her feet. In the following days, the three rolled the mare out of her stall and around the driveway surrounding the barn for 20 minutes daily while she walked cooperatively along, suspended in part by the sling. Finally, the mare was turned out to graze in the walker as she gradually regained strength.
"About 12 days into that, she could support her own weight, and we took her out of it," Murphy said.
The Faulkners continued to refine their walker, improving the strength and design of the wheels and inventing a folding winch lift to raise and lower the horse in the sling. With the assistance of Steve Snapp of Snapco in Cynthiana, Kentucky, who helped find the right parts to accomplish the job, they constructed a second, bigger walker to accommodate an adult, Thoroughbred-size horse.
One of the advances the Faulkners made was to retrofit a two-horse trailer to accommodate the walker. An onboard winch draws the walker, with a horse in the sling, up the ramp and into the trailer, where it is secured for transport. In this manner, the Faulkner walker and trailer can be used as an equine ambulance.
Acid test
On January 4, Standardbred broodmare Classical Lin was found down in a paddock at Starmaker Farm in Cynthiana. Kristina Lu, V.M.D., a field veterinarian with Hagyard Equine Medical Institute in Lexington who was called to assist, determined that Classical Lin had sustained severe, multiple fractures to her right hock. Lu splinted the leg and had the mare transported immediately to Hagyard's Davidson Surgical Center, where surgeon Robert Hunt, D.V.M., awaited her arrival.
"It was a complicated fracture," Hunt said. Classical Lin had sustained fractures of the large bone that makes up the point of the hock (sustentaculum talus), the large bone above the hock (tuber calcaneus), and multiple small fractures of the central tarsal joints, and a luxation (displacement of the bones) of the joint.
Hunt, assisted by surgical intern Megan Parker, D.V.M., realigned the hock joint and fused it with ten screws and a six-inch plate. But, despite the successful surgery, Classical Lin's chances were slim.
"Low; very low," Hunt said of the typical survival rate after this type of catastrophic injury. "Everything needs to go right. ... If you can't reduce the fracture [pull the pieces together] and get everything lined up, you may as well not even recover the horse [bring it out of anesthesia]. We got lucky in this situation and were able to get it reduced and get the implants all in place and very stable."
But Classical Lin had more than luck on her side. In addition to being a talented surgeon, Hunt is an authority on laminitis, and he knew about the work Murphy and the Faulkners had done. So he suggested recuperating the mare in the Faulkner walker.
"My big fear initially, rather than just laminitis, was that she was going to tear the implants up," Hunt said. "She couldn't get up and down on her own, so she was, at best, going to tear the fixation apart."
Classical Lin was placed in the Faulkner walker two days after surgery, and she adapted to it immediately, perhaps because of her experience pulling a sulky, in addition to her intelligence and tractable nature. Parker, Starmaker foreman Alvin Stamper, and the Faulkners helped the mare to get 20 minutes of exercise daily by guiding the walker as the mare strode out enthusiastically, up and down the driveway at Starmaker.
Eight weeks after surgery, Classical Lin's hock was healing well and her feet were in good conditionÑtwo weeks after signs of laminitis typically appear in cases such as this.
"I'm cautiously optimistic, barring any setbacks, but it could happen any day, as far as backsliding or encountering problems with laminitis," Hunt said. "But she's done well so far and she's remained evenly loaded on her legs. The big part is using the limbs evenly. We're able to take the weight off her, and she's still able to load the legs without overloading anything."
Classical Lin's progress
Parker, a 2006 graduate of Michigan State University, has been the primary physician for Classical Lin since her surgery.
Classical Lin underwent three cast changes since the initial one was applied after surgery on January 4. At nine weeks after surgery, Parker planned to wean the mare out of her cast and then gradually wean her out of the walker. The process includes cutting the cast vertically in the front and the back, then creating a hinge using Elastikon medical tape that enables Parker to remove the cast for periods of time until the mare is comfortable going without it completely. Classical Lin then is expected to spend periods of time out of the walker until Parker determines she is stable enough to function completely without its help.
One major concern throughout the mare's ordeal was her quality of life.
"This walker allows her to get out and move around, rather than having her in a sling in a stall," Parker said. "It actually allows her to get out, walk, graze if she wants to, and it brings her attitude up. It also facilitates, in combination with the tube cast, strengthening of the soft-tissue structures around the hock. This means having that additional strength will make the support system greater for the fusion of the hock joints and potentially speed up the healing process. So, instead of having lax and atrophied tissue and tendons, you have tissue that has had normal physiological stress to promote the strength of the support system. So it's hopefully going to be good all around.
"Being a normal horse really helps her, not just her attitude. Depression and stress play a role in injury, and I think that's really important. Yes, she's a stoic mare, but she's still in a stressful situation, and this helps her pretend to be a normal horse and allows her to get out there and bring her attitude up and keep the blood flowing."
Parker said the success of Classical Lin's case offers hope for horses that sustain other types of catastrophic injuries.
"By showing that a horse can use this walker to its advantage to help prevent laminitis in such cases as a hock fusion is huge," she said. "You can deduce that other injuries also could be helped by this walker."
Parker added that it takes a horse with the right personality to adapt to the walker, be comfortable in the sling, and have the proper attitude to cooperate with treatment.
"I wouldn't say we're out of the woods yet," Parker said on February 20. "I won't be able to say that until she's walking and able to get up and down on her own and is comfortable. But the key factor is that we're seven weeks out from surgery right now, and she's still comfortable and she's walking. And every time we walk her, she walks a little bit better, and she adapted so well to this walker that sometimes it's like she's not even in it. So, taking all those factors into play, the chance for the better outcome is here for us."
Andrew Fabian, D.D.S., and his wife, Linda, from McMurray, Pennsylvania, bred, own, and raced Classical Lin. The Fabians have been involved with Standardbreds for 30 years, and they have eagerly awaited a foal out of the homebred mare named for Linda Fabian.
Because of a series of circumstances, Classical Lin cannot maintain a pregnancy, so she must rely on a surrogate mare to carry her embryo, which is allowed by United States Trotting Association rules. The Fabians hope Classical Lin's foal, by 1998 Hambletonian winner Muscles Yankee, due on June 1 will duplicate the efforts of another of their homebreds from the same bloodline, Miss Wisconsin, who earned $525,551, an enviable sum in Standardbred circles.
Fabian has received regular progress reports from Starmaker farm manager Mike Polston.
"Mike called over the weekend and said they walk her out, and you can just see that she's a pretty game mare, which is no surprise," Fabian said. "Hopefully, she's going to pass that on to her foals."
'Beach's contraption'
Everyone who talks about the Faulkner walker invariably refers to it as "Beach's contraption." In the early 1900s, contraption was the term used to describe Henry Ford's motorcar and the Wright brothers' flying machine. Where would we be without them now? In the near future, placing an injured horse in the Faulkner walker may be as commonplace.
Faulkner said constructing the walker was just a matter of assessing what was needed and then figuring out a way to accomplish it. He and his son believe the crucial element is to find the right type of person to implement and operate it.
"Finding someone with vet knowledge, mechanical ability, and horsemanship is the key to it being successful," Beach Faulkner said. "That person has to know how to use a winch and how to operate the folding winch lift. Dr. Parker is good at that, and so is Dr. Hunt."
A lifelong horseman, Faulkner said his emotions at being able to help Classical Lin to survive go beyond words. "The people at the farm have expressed their gratitude over and over," he said.
With patent approval pending, Murphy and the Faulkners have decided to produce the walkers on a custom-built basis. Meanwhile, Murphy is putting together a presentation to submit to the American Association of Equine Practitioners discussing the walker's use in several different scenarios and cases, including that of Classical Lin, so veterinarians across the nation will know that help exists for debilitated horses and those with severe fractures.
"We developed this walker because it was something that was needed at the time, and there was nothing like that available," Murphy said. "We try to find a place where we can do the most good, and I think there is definitely a place for this walker and some definite benefits for cases like Classical Lin and probably horses like Barbaro, too."
"I'm just tickled to death to be a part of saving Classical Lin," Faulkner said. "And I can't say enough about Dr. Parker and her ability to work with the machine."
"It's going to be an incredible tool as long as we learn, as surgeons, to implement it in the right situations," Hunt said. "Not every horse's behavior is going to allow it, but for those that will and those that will allow you to work with them, there is no reason we should be tolerating contralateral limb laminitis with the technology we have today. If we have the ability to unload, or take the weight off, the limb that's going to be sustaining all the load of the horse, this is a very good measure to prevent it. It's the most effective measure we'll ever have at preventing laminitis. There's not a shoe or any type of foot device that's going to prevent it."
Denise Steffanus is a contributing editor of Thoroughbred Times who writes frequently on veterinary
and farm management topics