Online Reprint: Pet Projects at New Bolton Center

(Deirdre Biles profiles the University of Pennsylvania New Bolton Center in this article from the August 26, 2000 issue of The Blood-Horse.)

With their shaggy manes and stocky bodies, they look like children's pets. They are the kind of animals that make people coo and exclaim, "How cute!" But the semi-feral ponies that roam the spacious pasture at the University of Pennsylvania's New Bolton Center (NBC) are the subjects of serious scientific research. Left to their own devices, the ponies organize their own family groups, eat when they want to, and breed whenever the desire strikes. Sometimes, the pint-sized stallions rise up on their hind legs and fight furiously. By studying how the ponies act, Dr. Sue M. McDonnell and her associates have gained valuable insights into equine behavior and used them to solve the problems of horses that are managed in a more traditional style. In many cases, the environments created by man are at odds with the natural equine way of life. "

For example, a very simple thing we've learned is the more a stallion is exposed to mares, and the less he is exposed to other stallions, the more fertile he will be and higher his libido will be," said McDonnell, who heads the equine behavior program at the NBC. "The presence of other stallions is suppressive. So, on a farm where there is a problem horse, we might recommend moving him to a barn where there are no other stallions. If the farm has nice, safe, double-fenced paddocks, we might recommend locating some mares nearby as long as the stallion doesn't go bananas and hurt himself. For some horses, all you may have to do is give them more contact with their mares in the breeding shed before they are asked to mount them."

McDonnell's pony herd is just one example of the many innovative equine research projects under way at the NBC, the 600-acre rural campus of the University of Pennsylvania's College of Veterinary Medicine. Located in Chester County in Southeastern Pennsylvania, the NBC is the home of the George D. Widener Hospital for Large Animals, which serves more than 6,000 equine patients annually. Its staff includes veterinary specialists in orthopedic and soft tissue surgery, neonatology, reproduction, nutrition, and cardiology.

In all, there are more than 70 buildings on the NBC property, ranging from straw-filled barns to sparkling-clean laboratories filled with the latest high-tech equipment needed for nuclear scintigraphy, thermography, and color-enhanced Doppler echocardiography. Its facilities also include an evaluation center for performance horses that is equipped with a high-speed treadmill and a unique recovery pool system where large animal surgery patients can safely emerge from anesthesia while supported by a special raft.

Many of the clinicians and researchers who work at NBC are internationally known in their fields of expertise. The results of their work appear in numerous scientific publications and are presented at veterinary conferences around the world. They have developed bonded horseshoes that do not need nails and an external skeletal fixation device for horses that suffer severe leg fractures. They also have completed studies that indicate the popular bleeder medication furosemide (Lasix) is a performance enhancer.

One area of the NBC's research that has received wide publicity in the Thoroughbred industry involves the prevention of bucked shins in young racehorses. Over the years, the scientists involved in the project have developed and refined a training regimen they claim cuts down on the number of injuries.

"We recently had a paper published on a study where we looked at several hundred horses trained in different manners," said Dr. David Nunamaker, the Jacques Jenny Professor of Orthopedic Surgery. "In studying the effect of classical training versus high speed works, we showed that breezing is actually beneficial in that it reduces the incidence of bucked shins. Galloping, at least in the amounts that were used in this study, was detrimental and increased the incidence of bucked shins. The incidence in horses that were trained classically was nearly 50% compared to only about 9% in the horses whose training included workouts twice a week."

Other scientists at the NBC are studying such equine health issues as heart abnormalities and pregnancy loss. They also are experimenting with a variety of cutting-edge surgical techniques.

Dr. Virginia Reef, a professor of medicine, is a specialist in the imaging technique of ultrasound. She is one of the pioneers in the study of the medication Bapten as a treatment for bowed tendons. That research has been expanded to include suspensory ligament injuries, and "we've had pretty good results with our Thoroughbred racehorses, with a number of them going back to run successfully," she said.

Reef and her colleagues also are studying heart problems in horses. In one project, they are looking at a new marker for myocardial injury in the horse. The protein under scrutiny is released when muscle cells in the heart are damaged.

"In humans, this type of marker is effective in identifying subclinical or early myocardial injury," said Reef, who is the section chief for sports medicine and imaging. "In horses, we're looking at colic patients because some of the horses that have gastrointestinal disease actually develop clinical cardiac problems. It would be helpful if we could pick up these kinds of things earlier. We're also looking at septic neonates and horses that are being evaluated on our high-speed treadmill because of performance problems."

In addition, Reef and her staff are studying the prevalence and types of cardiovascular disease in breeding stallions. They also are exploring the possibility of treating some of the horses suffering from such problems with a type of anti-hypertensive drug known as an ACE inhibitor.

"ACE inhibitors are used in people with valvular heart disease or congestive heart failure to enable the heart to eject more of its blood volume more effectively," Reef said.

"In people who are placed on ACE inhibitors, there is a significant improvement in their echocardiograms three to six months later, and it's felt these medications probably prolong the time until they would need a new heart valve. Obviously, a horse is not going to get a new heart valve, but if we could prolong the useful breeding life of a valuable stallion one to two years, that would make a significant difference to an owner or a syndicate."

Dr. Patricia Sertich, an associate professor of reproduction, is involved in a three-year study to identify the causes of abortion and pregnancy wastage of horses in Pennsylvania. Much of the data is gathered by examining aborted fetuses, which farm owners and their veterinarians are asked to send to the NBC. When that is not possible, study participants can submit the results they obtain using a special necropsy kit that was assembled especially for the study.

"Most of the information in the literature about pregnancy loss and abortion in horses is coming out of Kentucky and was collected on intensely managed, closely grouped farms," Sertich said. "Although there are some things that are similar, there are a lot of aspects of the horse industry in Pennsylvania that are quite different. We thought it would be important to find out exactly what our problems here are and to get an idea whether we were managing those problems appropriately.

"One thing we've already learned," she continued, "is that there are a lot more herpes abortions than what people thought and many of these mares that aborted had been vaccinated. As a result, maybe we'll find out we need better vaccines or a different vaccination protocol."

In another area of reproduction research at the NBC, Dr. Regina Turner is using molecular biology techniques to study proteins and genes that are involved in sperm motility. One day she hopes it will be possible to improve motility by simply infusing a mare's uterus with extender containing an important component that is missing in a subfertile stallion's sperm.

"The groundwork has been laid in other species, so it should be relatively easy to translate into the horse," said Turner, who is an assistant professor of reproduction. "It might be possible to develop screening tests to identify stallions that are carrying sub-optimal genes and help predict whether they or their offspring will be more or less fertile as a result. Reduced sperm motility is one of the biggest factors we see associated with infertility in horses."

Eric Parente, an assistant professor of surgery, uses a diode laser to perform various throat and soft tissue operations. One of the biggest improvements recently in technique involves the use of an endoscope (which is passed through the equine patient's nostril) to carry the flexible fiber that transmits a laser beam to the surgical site. Such an approach means that an incision is no longer needed in many procedures involving the throat.

"Because the surgery is minimally invasive, there is a quicker recovery time," Parente said. "The horses can go back into training in about two weeks. Before we did it this way, it was probably closer to four weeks. The other big advantage is there is no risk from general anesthesia. We do the surgery in a standing horse that is sedated and has been given a local anesthetic."

The trend toward less invasive techniques also is seen in the work of Dr. Dean Richardson, the Charles W. Raker professor of surgery. In orthopedics, such operating strategies can help reduce the risk of infection and lessen the damage to soft tissue near the injuries.

"I'm interested right now in putting in bone plates through stab incisions," said Richardson, who also serves as the NBC's chief of large animal surgery. Like Parente, he also has tried performing operations in standing horses without subjecting them to general anesthesia.

"The very simplest arthroscopic procedures can easily be done this way," Richardson said. "Most of the ones we do are for ankle chips, and it takes five to 10 minutes. It's very controversial; there are a lot of people who don't think it's justified. But we did report on over 100 cases of ankle chips at an American College of Veterinary Surgeons meeting last year, and our results were identical to everybody else's results under general anesthesia.

Dr. Mike Ross, a professor of surgery, heads the NBC's nuclear scintigraphy program. Scintigraphy is a sophisticated diagnostic technique in which radioactive material is injected into a horse and images are produced that show the distribution of the material in tissues.

"We are not pioneers by any stretch of the imagination in this technology," Ross said. "But we do find it to be a very useful tool in lameness diagnosis, and we have published a number of papers about it."

According to Ross, "There is a common condition in racehorses, usually two to four years of age, that affects the fetlock joint in both the front and hind limbs and can cause lameness. When we scan these joints, we find a lot of hot spots and areas of increased uptake; the X-rays are usually negative. It's a stress-related event that involves bone underneath the cartilage, much like bucked shins. With these horses, you back off their training or their racing, you use intra-articular therapy, and you assess their progress based on scintigraphic changes."

Ross and his co-workers also have studied pelvic injuries using nuclear scintigraphy, discovering some that had not been described before in the veterinary literature.

"The occasional Thoroughbred racehorse will back up against the starting gate or fall down in the gate and fracture or injure the point of the rump," he said. "His trainer notices a lingering hind limb lameness he can't figure out. When he brings the horse up here and we scan it, we find problems in that area. We usually recommend rest, probably for three to six months."

When not studying the NBC's semi-feral ponies, McDonnell has plenty of other work in the field of behavior to keep her busy. She is especially interested in stallions that shuttle between the Northern and Southern Hemispheres, and how such trips effect their fertility and libido.

"Beginning with the 1999 breeding season, we just started getting good data on how stallions in this country are handled using different managements and different breeding schedules," she said. "Some of those stallions were shuttle stallions; some were not. Traveling with the shuttle stallions is our next step. It will probably be three or four years before we have something we want to hang our hat on."

McDonnell also has been involved in developing treatment protocols for the problem known as a stereotypy, the frequent, almost mechanical repetition by a horse of a movement or behavior. Feeding the nutritional supplement l-tryptophan, which occurs naturally at high levels in grass and grass hay, is one strategy. Administering anti-obsessive-compulsive, psychotropic drugs is another.

But in the end, the best solution may be to try to incorporate as many natural elements as possible into the horse's management. McDonnell takes her cues from the semi-feral ponies; instead of endlessly pacing, weaving, and cribbing, they munch contentedly on their grass or interact with their pasture mates.

"You can greatly relieve stereotypes and other undesirable behaviors by manipulating what the horse eats," McDonnell said. "This is not always possible with the equine athlete, but in general, you should try to move more toward a natural diet of grass and hay. If you go cold turkey, and cut out all their grain, it's hard to watch over the short-term because they will lose weight. But eventually, their hind gut flora will get back to normal and their appetite will kick in. They'll get a nice kind of beautiful, well-balanced look to them, and they'll turn into a sensible animal.

"Very often," she added, "we get horses donated to our teaching program because they are so bad. We save them up for the clinics we conduct, and we'll just turn many of them out in a pasture and leave them alone. After a couple of weeks outside, there is no problem horse to show the students. They just self-correct. They lock in on the grass, and their motivation to eat seems to overpower all their undesirable behaviors."

Click here to read Deirdre Biles; profile of Dr. Jon Palmer, director of neo-natal care at New Bolton Center.