Trailer Troubles

Q. - My 16-year-old mare has been horrible about trailer loading since the day we purchased her 11 years ago. That day it took three hours to get her in the trailer, and the only other time we’ve been able to get her in a trailer it took several more hours. We’ve tried what feels like everything—from putting the rig in her field and feeding her in the trailer to sedation and veterinarian assistance to help overcome—or even improve—the problem with no avail. She needs to move in a few months, and I’m concerned about getting her in the trailer. Do you have any recommendations for how we can load her, and is there anything we can do to help her overcome her trailer loading problem?

A. - At this point, my recommendation would be to seek the help of a certified applied animal behaviorist (CAAB) who practices all-positive reinforcement methods of trailer loading for horses. This way you and your horse can start fresh. If you can’t find a CAAB to train you and your horse on-site, you might be able to work long distance either by communicating with the behaviorist on Skype or another video service or by using video and written training materials. These days you can quite easily incorporate such a video communication link. Or you might be able to add the help of a local trainer the behaviorist recommends or supervises.

A word of caution, though: Positive reinforcement methods are not yet well-understood in the mainstream training world. Plenty of misinformation remains in the media, and even in academic equine programs, confusing positive and negative reinforcement. It’s no wonder we get so confused about very simple, effective methods! Offhand, resources I can recommend for training materials and local referrals for truly all-positive reinforcement-based trailer training and rehabilitation include Shawna Karrasch of On Target Training and Evelyn Hanggi, MS, PhD, of the Equine Research Foundation—both in California—and our behavior lab here at the University of Pennsylvania School of Veterinary Medicine. All offer courses and consult on individual cases.

Club Foot Heritability

Q. I work on a Thoroughbred farm, and they have a mare there with a club foot. Her mother did not have a club foot, but I am told her sister did and her yearling colt did. I know in the Quarter Horse world, when looking to breed, it is common to breed to a horse that has better conformation than what your horse has. What I would like to know is with carefully resourced breeding could this mare throw a foal without club feet, or is she destined to always pass this on?

A. Club foot is a term commonly used to describe an abnormally upright front foot conformation. It can be a congenital (born this way) or developmental (acquired early in life during foalhood) issue, or it can occur later in life due to chronic lameness or injury that causes the horse to not bear weight fully on the affected limb. In those cases, the underused foot eventually becomes steep and narrow while the healthy foot becomes splayed and flat.

Congenital club foot can range from a mildly upright hoof to one where the dorsal hoof angle (that the front of the hoof makes with the ground) approaches or is beyond vertical. These are commonly termed “flexural deformities” because the deep digital flexor (DDF) tendon and the associated inferior check ligament are abnormally tight in these animals. This creates excessive contraction at the DDF attachment to the bottom of the coffin bone, resulting in downward rotation of the bone. The normal alignment of the short pastern bone and coffin bone is a straight line visible on X ray, but in a club foot the coffin bone angles downward relative to the pastern (a “broken forward” axis).

Researchers have tried to prove the degree of heritability of many orthopedic issues in horses, including osteochondritis dissecans (OCD) and navicular disease, but it is surprisingly hard to prove a link between genetics and certain problems once all of the variables are factored in. Despite the lack of scientific backing, many experienced horse people believe certain traits tend to be passed down through certain lines, and I do believe that congenital club foot runs in certain families, even if the parent does not show the trait. If this mare has thrown multiple offspring with the same problem (and I have often found it will be the same foot affected in every foal), there is a good chance she will continue to do so, especially if bred to the same stud. Even when you “breed the best to the best and hope for the best,” you never know what you are going to get. It is likely that even with careful pairing, there is an increased probability she will continue to produce some babies that have a club foot, although not every one of them will have this trait due to the variability of each mating.

Age to Breed a Colt

Q. How young is too young to breed a colt? We have a coming 2-year-old who acts like he is ready to breed.  We don't have any mares to breed to him, but the question came up for discussion last night among a group of guys.  This colt was out there showing his stuff along the fence near the fillies.  Among us we had strong opinions about how young horses could breed, how young they should breed, and how young they could be fertile.  Some of us thought that it was okay, and others thought it might mess them up for the future to start too early. If a colt appears to be breeding, does that mean he is mature enough to impregnate the mare?

A. Most yearlings and two-year-olds can and will breed under good circumstances.  There's probably not a horse practice without a firsthand story of the pregnant filly that was only with a colt until a year of age.  So for sure, many fairly young colts can be fertile.  Some young colts are quite mature behaviorally, looking like old pros before the age of two if given access to fillies or mares. Others might be awkward and slow but given ample opportunity, particularly with young mares of their size, will have no problem mounting, inserting, and ejaculating normally.

One common attribute of young colts is that their endurance and confidence might be much less than those of a three- or four-year-old. If you hand breed them, they might be shy, easily distracted, or overly put off by correction.  That is probably the basis of concern about "messing up" a stallion by breeding him too young. It is not wise to count on a two-year-old being able to handle a busy breeding or semen collection program.

We have studied colt development in our semi-feral pony herd here at New Bolton Center. In that herd and in other herds of horses that have been studied under natural social conditions, the yearling and two-year-old males do most of the breeding of the young fillies.  The young fillies are often still living for the most part in their natal band (band in which they were born) with their sires and dams at the time of their first estrus.

As estrus begins, the young fillies wander from the family band up to several times a day to join roving bands of young bachelors.  The fillies seem to actively solicit attention from the young males.  The young males take turns breeding the fillies. They tolerate each other's awkward "schooling" mounts, and seem to wait their turn patiently. So even though stallions might take years to get their own established harem, most young males have some of this style of breeding before the age of two.

The maturation of sperm production and behavior often don't coincide.  That means a young colt might be very willing to breed and have nearly perfect form as much as a year before his testicles and sperm production have developed.  Similarly, a colt might have apparently maturing testicles but be immature behaviorally.

Another concern we hear from time to time is whether early breeding influences a colt's manners and studdishness in non-breeding situations. One episode is probably not going to mean much, but if a young colt is allowed to breed frequently, research suggests that his hormonal and behavior maturation might be accelerated.  That means he might be more "full of himself" at an earlier age.

While we're on the subject, many horse owners are alarmed when a colt mounts his mom during foal heat.  This normal behavior is seen in almost every colt at the time of foal heat. In fact, almost all of the normal sexual behaviors --teasing, marking, flehmen response, erections, mounting, sometimes weak thrusting --are seen within the first week of a colt's life.  They are sometimes not in the "adult" sequence, and they might be subtle or interspersed with action play sequences. But if you look closely, they are there. Colts do a lot of sexual play with filly and colt playmates.  They achieve erections but rarely ejaculate in the play form of sexual behavior.