Should I Deworm My Horse in the Winter?

Q. - Is it worthwhile to deworm my horses during the winter? I've heard that internal parasites aren't around this time of year.

A. - Yes, you are correct that we recommend deworming horses during the active grazing season rather than during the winter. The reason is that the small strongyles tend to arrest their development over the winter at the larval stage. Most of the available dewormers have no effect against these arrested larvae, and the few that do are only partially effective. 

The arrested development can lead to an accumulation of small strongyle larvae in the mucosal walls of the large intestine. If a large number of these larvae are present in a horse, deworming it at this time might actually cause more harm than good. Most dewormers mainly act on the adult parasites present in the lumen of the intestine, and removing these may activate the arrested larvae and cause them to mass emerge from their encysted stage. This can lead to serious diarrhea. 

There are situations where it can be necessary to deworm a horse during the winter months, such as if the horse hasn’t been dewormed adequately during the latter part of the grazing season. Other examples of winter deworming include foals that harbor ascarid parasites, which aren't seasonal to the same extent as the strongyles. In both cases you should consult with your veterinarian regarding your choice of dewormer.

We find that horses actively shed parasite eggs year-round, but there is a tendency toward lower counts in the off-season months. This makes sense from the parasite's standpoint, as winter conditions do not favor parasite transmission. 

So the bottom line is that we don't typically recommend treatments directed at strongyle parasites during the winter months in the colder climates. Remember, though, that in warmer climates (i.e., the southern United States) parasite transmission is more likely to occur during the winter than in the hot summers. Most importantly, make sure your dewormers are working by running fecal exams to determine parasite egg counts before and after treatments.

Electric Fencing

Q. - We just got a four year-old stallion at our barn, and I wanted to know if even with electric fencing will he be able to break out to get in with the mares that are in the paddock next to him? Electric wires are the only thing separating him from the geldings and mares. The mares are just coming into heat, and he has been smelling the air. Otherwise, he’s really quiet.

A. - Electric fence is not my favorite fencing option for many reasons. Even though it may be just fine for some stallions, I would not depend on an electric wire as the only barrier between a stallion and geldings and cycling mares. More effective fencing options include 6-foot-high sturdy post and board (with boards on both sides of the posts), especially if lined with stallion-safe diamond mesh woven wire. The best option is a double line of fencing with an alley between.

Participation Sought on Performance Horse Management Survey

University of California, Davis (UC Davis), researchers are seeking participants for an online survey regarding performance horse management.

Claudia Sonder, DVM, director of the UC Davis Center for Equine Health, is conducting a study that she hopes will help identify links between performance horse management practices with musculoskeletal health, injury, and performance.

"The survey contains questions about the management practices of horse owners and how they might relate to the musculoskeletal health and performance of their horses," Sonder said. "The findings will be used to design research studies to fill gaps in knowledge and establish science-based recommendations for preventing injury in equine athletes."

And, she said, advancing scientific knowledge that can help prevent injury in equine athletes benefits everyone: the horses, the owners, and the industry.

"We need input from a large population in order to identify any trends in human behavior that could be correlated with the health and performance of horses," Sonder added.

The study, which takes about 10 minutes to complete, is available at http://tinyurl.com/qzm3pws.

 Navicular Disease and Fracture

Q. - I have a 17-year-old Paint who was diagnosed with navicular disease when he was 2. Recently I had him X rayed again and found out that he has a fractured navicular bone that has calcified. I have seen magnetic bell boots available on the market and was wondering if these would help with the pain. Also, is there any type of treatment or surgery that can repair this?

A. -  Navicular syndrome, a degenerative disorder of the navicular bone and the surrounding heel structures, is one of the most common causes of lameness in horses. The navicular bone is a small bone that lies within the horse’s hoof, behind the coffin joint and near the back of the heel. The deep digital flexor tendon runs down the back of the limb and behind the navicular bone, using it as a fulcrum to flex the coffin joint. Navicular syndrome generally causes a chronic lameness affecting both forelimbs, though the horse is often more sore in one foot than the other. Owners may notice that their horse has a stiff or shuffling, short-strided gait. A mild intermittent lameness may be present first, along with difficulty turning sharply, but the lameness can worsen to severe and debilitating over time. Several factors can contribute to navicular syndrome development, including poor conformation, heavy work, and improper trimming and shoeing. 

 

Navicular syndrome is managed rather than cured. Therapeutic hoof trimming or shoeing is a cornerstone of treatment, and your veterinarian and farrier should work together to restore hoof balance, reduce strain on the navicular region, and protect the injured areas. Joint and/or bursa injections might help reduce heel pain and inflammation. Non-steroidal anti-inflammatories such as phenylbutazone can provide occasional pain relief. Sometimes other medical treatments are used, but no single treatment works for all horses. Palmar digital neurectomy, a surgical procedure to cut the nerve that provides sensation to the heel, should be used as a last resort for pain control. This procedure may have several adverse effects and does not offer a permanent solution to lameness, as many horses regain sensation in two to three years.

 

To fully understand your horse’s condition, it would help to know how lame he currently is and the fracture’s configuration, because those will affect the treatment options. One fracture type involves small oval or round fragments on one or both sides of the navicular bone’s distal (lower) border, embedded within the impar ligament. These distal border fragments are pieces of bone that have pulled off of the navicular. They are found in 24-40% of horses with navicular syndrome and are likely a result of the bone degeneration I described earlier.

 

Another type of fracture occurs due to trauma, such as when a horse kicks a wall. Most of these break in a vertical direction, causing the bone to split into two parts. Unlike the progressive bilateral lameness of navicular syndrome, a horse with a traumatically fractured navicular bone has acute lameness that affects only the fractured limb and may be severe. 

 

Conservative treatment for a fractured navicular bone involves an extended rest period and corrective shoeing to stabilize the foot and relieve stress on the bone. Even after a prolonged healing period, the navicular bone often heals with fibrous tissue instead of a true bony union. The prognosis for return to soundness is unfavorable, and a neurectomy is often necessary if athletic work is the goal. Surgical repair using a screw is an option to provide greater stability and healing potential, but the procedure requires a facility with special equipment. With surgery the outlook for athletic use is still guarded, but pleasure riding may be possible.

 

There are no published scientific studies that show magnetic bell boots help treat lameness. Published, peer-reviewed studies will need to demonstrate a value to these products before the majority of the veterinary community will endorse their use. I recommend working with your veterinarian to develop a treatment plan to manage your horse’s lameness.

Increased Incidence of Twins

Q. - I read the article about twins ("Seeing Double," TheHorse.com/33858) and would like to ask a question: If research shows that Thoroughbreds and Warmbloods are more likely to have twin pregnancies, could this be in relation to the number of mares that receive injections (of ovulation-inducing agents such as human chorionic gonadotropin [hCG] or deslorelin acetate) to encourage ovulation?

I allow my mares to breed naturally (live cover rather than by artificial insemination) with no interference apart from ensuring a clean uterus prior to breeding. To date I’ve not had any twin pregnancies. I would love to know if the injections can cause the release of two eggs around the same time.

A. - his is an interesting question. In fact, there have been at least a couple of studies that looked at whether inducing ovulation could contribute to increased incidence for twins. It is logical that the risk for twinning will increase if there are two follicles present and we encourage both of them to ovulate by administering hCG or deslorelin. Yes, there is a risk that subordinate follicles that would normally regress over time would be induced to ovulate. This is why when managing mares with hormone treatments or otherwise, it is very important to determine the ovaries’ follicular situation and follow up with examination after ovulation.

It is important to remember, however, that administering hCG or deslorelin does not cause a new follicle to develop but just encourages ovulation of any follicle that is present.

Can Fodder be Included in a Horse's Feeding Program?

Q. - I would like to learn more about barley fodder, which in essence is the same as barley sprouts for human consumption. No soil involved—just trays, seeds, and water—and seven days later you have feed. All the sites that advertise ready-made setups to grow your own fodder for your animals don’t really talk about the sugar contents; they only say it is good for your animals, cuts your feed bill by one-third to one-half, and increases nutrition for your horses. I have geriatric ponies, and I am concerned about laminitis. What can you tell us horse owners about this grow-your-own fodder for horses?

A. - Feeding fodder to horses and other livestock classes is not a new idea but one that has gained interest recently. Fodder is commonly comprised of cereal grains that are grown hydroponically (in nutrient solutions rather than soil), and when the plant sprouts the forage material is harvested and fed to the animal(s). It takes seven to 10 days for the material to grow, depending on the system and the plant material used. As mentioned, cereal grains such as barley or oats are most commonly used, but in some cases legumes such as alfalfa or clover may be grown.

The fodder produced has a high average moisture content of 90%. This is somewhat like lush spring grass. This moisture content can affect a horse’s nutrient intake due to significant water consumption while eating the fodder. While water intake is a good thing, it does limit the intake of other nutrients. For example, if a horse ate 10 pounds of fodder he would really be consuming 1 pound of dry matter and 9 pounds of water. The nutrients in that 1 pound of dry matter will vary depending on the crop. In the analysis reports I have seen, the crude protein generally ranges from 18-28% for cereal grains and more than 30% for legumes such as alfalfa. The other nutrient values and sugar levels (an overabundance of which can lead to laminitis) are similar to those of other forages.

How fodder can fit into a feeding program depends on the individual horse’s nutrient needs, the other feeds available to him, and the fodder’s nutrient content. If considering feeding fodder to older ponies, you need to consider that these ponies have lower nutrient needs and factor your concern about founder into your feeding decision. This feed might not be the best choice for this group of horses.

As for the cost of the feed, you need to consider the expense of the grow unit, any added utility costs, and the labor required to grow and harvest the feed in a timely manner. Include your horse’s needs and the costs to supply the feed into your decision of whether or not to incorporate fodder into your feeding program.

Swollen or Filled Legs: What’s Wrong With Your Horse?

Horses can rapidly develop swelling or “filling” in one or more legs. Is it serious? What causes it?

A common reason for filling is inactivity in a horse that is accustomed to moving around. An example might be a horse that is usually turned out in the pasture but has been kept in a stall overnight, maybe at a show or in preparation for an early ride the next day. The owner notices that the horse’s rear legs are puffy and swollen as he’s led out of the stall. The legs are not uncommonly warm, and the horse may move somewhat stiffly but is not truly lame. Caused by inactivity and reduced lymph flow, this “stocking up” is usually not serious and will dissipate as the horse is exercised. It’s more common in older horses and can affect all four legs, though stocking up is often seen only in the hind legs.

If your horse has leg swelling accompanied by lameness, warmth in the leg or hoof, or an elevated body temperature, it’s time to call the veterinarian. This is more than simple stocking up.

Swelling in a single leg is likely to signal a serious condition. Horses can “blow up” a leg in response to a scratch, cut, or puncture wound that may be so insignificant that it’s hard to find. The leg may be warm in addition to being swollen. This swelling isn’t likely to go down until the wound is cared for and any infection is treated.

A horse that has significant swelling in all four legs may have some type of systemic illness. This could be a sign of heart trouble, liver or kidney disease, or a bacterial or viral infection. It’s definitely a situation that calls for a veterinary examination.

Bonding With a Trail Buddy

Q. I took my best trail and traveling horse, a 7-year-old Tennessee Walking Horse gelding (gelded at age five), on a trail ride recently. He has been on other trips of similar distance and length of stay and has always been great in groups, even very large ones. He is very tolerant of other horses around him. On this trip, my friend took her well-behaved Spotted Saddle Horse mare. The horses had met briefly in the past, but do not live/board together.

This was a gathering of approximately 50 to 75 horses, so all trail rides were large. On the first ride, my friend and her mare opted for the longer ride, and I took my less conditioned gelding on the shorter ride. As the "long ride" group separated from my group, both of our horses displayed separation anxiety by crow-hopping, jigging around, calling to each other--behaviors that were unusual for both horses individually. Once we got moving, my horse settled down and was the trail-savvy boy I am used to.

When in their accommodations (10x10-foot stalls--both are used to much larger areas), my boy became very aggressive toward other horses coming near "his mare" and bit a gelding to one side as well as the mare (no stitches required, but still extremely unsettling to all humans). He even kicked at me once, which he has never done to horse or human (he loves people to scratch, or horses to scratch or nibble, on his butt). That was immediately punished.

When we did ride together, he didn't want to let the mare out of his sight, and would pin his ears and act aggressively toward other horses that came near "his" mare.

I am trying to give as many details as possible because I will do anything possible to avoid another situation like this again. I felt this was way beyond bad manners and that herd and possibly hormonal influences were at work. He had trailered with a gelding this same distance previously and none of this behavior happened, so I am assuming it was in large part due to the mare/gelding pairing. I have shared this story with several people who, surprisingly, have told me that they've had this same problem, even with two geldings.

I would greatly appreciate any advice about this situation. I will definitely not trailer any distance with a mare in the future, but would like to know of anything to discourage this bonding and behavior. It made for an extremely stressful week.

A. First, your suggestion that the basis of your gelding's behavior is probably due to natural bonding behavior of horses--either the strong motivation for horses to "buddy up" or a male-female attraction--sounds right on track. Part of the herd instinct of horses is for any small groups, particularly for isolated individuals, to band together and protect one another. In the case of your gelding and this mare, as you suggested, their behavior likely included male and female bonding, and for your gelding the protective behavior of a harem stallion to a newly acquired mare.

One trailer ride, a few hours, how could they bond so fast? As your friends have experienced, the basic bond of two horses, even two geldings, can form quickly and can be very strong. The same can occur among mares, and in the wild, two non-harem stallions, or bachelor stallions, can become very close affiliates in a very short time.

One of the fascinating observations of domestic horses is how well horses immediately can revert to natural social organization and survival behavior.

You also mentioned hormones. If your gelding was completely castrated, the gonadal hormones that drive his male sexual behavior are no longer present. While gonadal hormones certainly influence the level of male-type sexual, aggressive, and other social behavior, they are not necessary. Even geldings castrated at a very young age can retain high levels of each of these types of male behavior.

What can you do? Well, your decision to avoid one-on-one opportunities for your gelding to bond with a mare is probably a good strategy if you can do that. But if you can't, or if the problem should arise again, there are some things that have been judged helpful in some cases.

If you must travel, or house your horse next to a potential "mate," one thing to try is an odor-masking agent. There is one product made specifically for this called Acclimate. This is a waxy ointment with anise oil that is rubbed onto the nares (nostrils). The strong odor of the anise is meant to reduce the effectiveness of the social odors of inter-male aggression and male sexual response to females. In my experience, this product or other similarly smelly ointments applied to the nose usually don't completely eliminate social interest, but for many horses that approach does seem to dull their response a bit. It's probably worth a try.

To get to the point of being fairly compliant with domestic life, as it sounds like your gelding has been for you before this incident, requires considerable behavior modification. Your gelding has already suppressed a lot of natural urges, many of which would be much stronger than bonding. With the usual discipline and training, most horses can learn to suppress these natural tendencies, too. Should this type of behavior occur again, letting him know what is expected is likely to get his focus back on you. Even stallions can learn to suppress their sexual and aggressive urges.

We often recommend specific schooling in which the horse is worked on a longe line or in a round pen. The social challenges are presented, and the horse is kept going forward, paying attention to the handler. Discipline is usually more effective when the horse is in your control, for example, under saddle or in hand than when they are in a paddock or stall. But there, too, he could be schooled to come to you at the door and pay attention rather than kicking at you.

Swelling in the Girth Area

Q. My horse is swollen under his girth area on both sides of his body. There isn't a sore; the area just seems very tender when I groom it. The girth does not seem to be rubbing. What could be causing this problem?

A. This is not an uncommon finding you are describing with your horse but one that can be a bit tricky to figure out.

Though you mentioned it does not appear to be the result of rubbing, I would check your tack closely to make sure that excess pressure in the cinch or girth is not occurring at the swelling site.

If you ride in a western saddle, the length of the cinch can sometimes create pressure at the “D” ring where the latigo attaches to. Even an otherwise properly fit saddle can create “hot spots” or pressure sores in the girth region related to the contact site with the cinch.

These scenarios are less likely to occur with an English saddle, but still worth a closer inspection.

I have also seen horses develop allergic reactions (contact dermatitis) to a cinch based on their makeup (cotton, neoprene, etc.).

During this time of year, a horse’s longer coat can trap in moisture underneath tack leading to higher incidence of skin reactions or dermatitis. Sometimes an obvious rash is not always present. Even irritation from tack pulling on the coat can lead to inflammation and irritation of the area. This will hopefully improve within a week or two if the horse is not saddled during this time.

It is also recommended that you contact your local veterinarian to get his or her advice. A bacteria or fungal infection is possible in that location (including ringworm) and treatment will depend on many variables, including the horse’s general health, age, and geographic location. Please have your veterinarian examine the horse if you continue to have concerns.

Rude for Food

Q. My yearling colt came from a place where he was kept with a group of yearlings.  All were fed their grain in buckets along a fence line, with the buckets hung on posts. I now have him in with one other yearling, a filly that I got at the same time from the same place.  When I go out to feed, they both run up anxiously awaiting their stipend.  The colt is very impolite. He lays back his ears and turns his hind end toward me offering to kick me. Of course, I immediately put down his bucket to get him to stop.  Then I proceed to the filly. How do I change this rude behavior without scaring him away from me? I would like him to allow me to approach him. He is still quite leery of me.

A. What a great description of a common problem scenario.  This food-related aggression is a natural behavior for achieving access to a highly palatable limited resource (the grain). This behavior has been inadvertently reinforced by a continuous schedule of giving the grain. In the colt's mind, he learned that he has to be aggressive in order to get his supper. Even though the behavior does seem rude and frustrating, it probably represents a healthy ability to learn by association.  That means he should be able to learn alternative behavior that will be more "gentlemanly" and safe.  The procedure I have used to correct it will simultaneously eliminate the aggressive behavior and overcome the leeriness.  As a bonus, he will learn to tie and to stand quietly on command.  This is my usual recommendation for the procedure.

Start by haltering the colt. Attach a short catch-cord (24-inches or so of lightweight string or leather strap) from the halter's lower ring (under the chin).  At feeding time, go out to the pasture area with the bucket of grain. Leave the bucket outside the pasture, a few paces from the gate. Stand at the gate and hold a few grains of sweet feed in an outstretched hand. Just stand quietly waiting for the colt and/or filly to investigate.  When one or the other takes the treat, close the gate, say "good," then go get a handful of grain and return. Repeat the handout gesture several times. Every time feed is taken from your hand, say the word "good" in a calm and consistent tone. Do this until all of the grain is gone. It might take 30 minutes the first time.  The point of the first lesson is for the colt and filly to come to you and to learn the conditioned stimulus "good," and to do something quiet and positive for the feed reinforcement. I recommend feeding them the entire supper from your hand on this Day 1 of the procedure.

On Day 2 repeat Day 1, but after a few hand-fed handfuls, try quietly and calmly to get a hand on the colt's halter (or on the catch-cord).  The first couple of times you might have to feed and catch simultaneously.  If he is leery of being caught, you can say the word "good" to reassure him. He should by now associate that word with a positive result. If you're not successful with the catching, return to more hand-feeding for awhile, then go back to trying to catch him. Once you are successful with catching the colt, repeat the hand-feeding, each time waiting until he will allow you to catch him before the feed is given. Continue to say the word "good" each time the colt is taking the feed. Repeat until all the feed is gone.  The lesson will reinforce and extend the lessons of Day 1 to include approaching you calmly, head first, and offering to be caught in order to get a treat.

On Day 3 continue as on Day 2, but after a few handfuls, lead the colt to a fence post, reinforcing him for each step with a handful of his supper and the word "good." Once he is near the post, feed him the rest of his supper one handful at a time. If he hasn't already, he might start getting grabby for handfuls. In a calm, pleasant voice say "stand," wait until he stands quietly, then give the grain.  The point is for him to go to the post with you and to learn to stand there.  The previously learned lessons also will be reinforced.

On Day 4 stand by his post with an outstretched hand, and wait for the colt to come to you.  When he gets there, attach him to the post with a tie (with a quick-release of some sort), say "stand," and give him a handful of feed. Do the same for the filly. (I would always tie the colt first; since he seems to be the more aggressive, he might attack her when she's tied).  Then attach each of their supper buckets to a post.

Gradually, you can use the word "good" intermittently without the grain treat. You will see that it has taken on special reinforcing qualities and can be as nearly effective in reinforcing the desired behavior as the grain itself. It will be a handy tool when you don't have grain or don't have a free hand to dispense grain.  Actually, you can choose any word to be the conditioned reinforcer. You just have to use the same word in the same tone of voice.

You can stop here or continue to teach all sorts of lessons within the context of this feeding ritual. For really aggressive horses, I also have taught the "back" and "stand" command sequence to get them to back up a few steps and wait for me to present the feed bucket.  A horse cannot lunge forward for feed or turn and offer to kick while it is backing up.

Teaching the horse to stand calmly or to back up a few steps and to stand instead of charging in order to get his feed is called counter-conditioning.  This behavior modification procedure simply involves eliminating an undesirable behavior by teaching another behavior that is counter to it. Counter-conditioning typically is more effective than you would intuitively expect with aggressive horses. It always seems easier for them to do something else rather than to stop doing something and just do nothing.

There is a newly popularized procedure for horses known as clicker and target training that long has been used with schooling performing wild animals, and more recently with dogs.  The learning principles are the same.  The clicker is the equivalent of the conditioned reinforcer "good." It is unique, not threatening, and a very standard auditory stimulus that the horse associates very quickly with the food reward.  The target can be used as the equivalent of the feeding post in our example.  The horse learns to go to or follow the positive target.

Hope this goes as smoothly for you as it has for me and other clients with whom I have worked in person.

(from the horse.com)

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.