5 Things You Need to Know: Senior Horse Dental Care

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Choose Tendon Injury Cases Carefully for Stem Cell Success

  

With any new veterinary treatment approach there come research studies, experiences, and opinions about what works best and why. Stem cell therapy is no exception. One veterinarian recently reported that at least for tendon injuries, the cases practitioners choose to target with stem cells and how they prepare those cells have more bearing on treatment success than the stem cell source they select.
Roger KW Smith, VetMB, PhD, DEO, FHEA, DECVS, MRCVS, professor of Equine Orthopaedics at the Royal Veterinary College, in Hatfield, U.K., shared this and more about what he and his colleagues have learned about stem cell treatment at the 2014 American Association of Equine Practitioners Convention, held Dec. 6-10 in Salt Lake City, Utah.
Mesenchymal stem cells (MSCs) can come from a variety of sources, though practitioners most often use bone marrow or fat (also termed adipose-derived stem cells). Umbilical cord cells and fetal tendon cells have come on the scene more recently, he added.
Cells can come from the horse that’s being treated (autologous therapy) or from a bank (allogeneic), though veterinarians in the U.K. are restricted to autologous because the U.K. does not currently allow allogeneic stem use, as the United States does.
But he does choose his cases. “The only requirement, really, for this particular treatment is a contained defect in a tendon or ligament,” he said. In other words, he and colleagues ideally want to treat a structure with a “central cavity surrounded by intact tendon tissue that can act as a receptacle” for the stem cells. The superficial digital flexor tendon (SDFT) is ideal because injuries to this structure generally meet this description and “because it’s the most common and for which we had comparative outcome for other treatments.” There is no minimal requirement for lesion size but veterinarians don’t generally inject smaller lesions because they have a better prognosis and are more difficult to inject. Stem cells are often focused on the most severe injuries.
Smith avoids treating traumatic injuries--those associated with external trauma to the leg, such as a cut or blunt trauma, rather than an overstrain injury due to overloading of the limb with prior tendon degeneration--with stem cells because studies have shown that open defects in tendons do not retain any implanted stem cells. However, if he feels there is enough time for a granulation tissue bed to form in the defect, then treatment is possible and can be effective. Timing is important; generally, the earlier he treats the injury with stem cells, the better the outcome.
Access to allogeneic stem cells would mean that, yes, he could implant them earlier. But the lag time before first treatment with autologous cases (about three weeks, due to the time it takes to aspirate bone marrow and expand the cells in the lab) isn’t all bad news because it gives the body a chance to establish a vascular supply to support cells after implantation. This usually happens within one or two weeks after injury.
As for selecting MSC cell type, again, he focuses on preparation rather than source. Smith classifies MSCs as either minimally manipulated stem cells (which is often the case with fat-derived) or enriched stem cell products (when MSC populations are expanded by culture in the laboratory). Then he looks at what the case requires. “Culture and expansion is necessary if it is deemed important to produce an abundant and homogenous stem cell preparation because of the low numbers of MSCs in the source material,” he noted, mentioning that only one in 100,000 of the nucleated cells (cells that have a nucleus—in blood these are usually white blood cells, as red blood cells have no nucleus) in bone marrow is an MSC, hence the need for culture/expansion.
Smith uses cultured bone-marrow-derived MSCs in his practice and reported that he has increased his standard dose to 20 million cells (at a concentration of 10 million cells/mL) with the option to increase this twofold for larger lesions, “because of the large loss of cells post-implantation and clinical outcome analysis has indicated better outcome with this large number.”
Smith summarized the techniques he uses to aspirate (both from the sternum and the tuber coxae--the bony prominence of the hip behind the flank) and administer bone-marrow-derived stem cells to treat tendon injuries. Some of the tips he included were to:

• Be sure the entire needle is visible on ultrasound to avoid inadvertent perforation of the deep surface of the tendon where cells would leak out.
• Inject stem cells into one to five sites, depending on the nature of the core lesion. An injury further along in healing will require more injection sites because the cells cannot spread as well through echogenic (more filled in) tissue.
• After administering MSCs, apply stable bandages to maintain the limb's temperature to maximize healing. “This is more important in cold climates, as distal limb temperature is then several degrees below core temperature and most cells are happiest at 37 degrees C (98.6 degrees F),” said Smith.

After implantation, his patients begin a rehab program just as if the tendon had been managed without stem cells. He said there’s no current evidence that stem cell treatment shortens the rehabilitation process because, in the end, he noted, “the mechanism of stem cells is likely to be a modulation of repair rather than being truly regenerative.”
As is the practice at this peer-reviewed meeting, Smith disclosed that he was formerly a director and technical advisor of VetCell Bioscience Ltd and is currently a scientific advisor for Recellerate Inc.

About the Author

 

Stephanie L. Church, Editor-in-Chief

Stephanie L. Church, Editor-in-Chief for The Horse, received a B.A. in Journalism and Equestrian Studies from Averett College in Danville, VA. Her background is in eventing, and she enjoys photography, cooking, cycling, swimming, riding her friends’ and family’s horses, and traveling in her free time.

Mending Tendon and Joint Injuries with PRP

  

The horse resumes active rest with a graded rehabilitation program aimed at getting the horse back to full work in four to six weeks for a joint injury and three to six months for a tendon injury.

Photo: Thinkstock

What makes recommendations for regenerative therapies such as platelet-rich plasma (PRP) inexact is that these approaches are based in biology, not chemistry, said Lisa A. Fortier, DVM, PhD, Dipl. ACVS, of Cornell. Each preparation is just as variable and unique as one horse is to the next. Recognizing this can go a long way in setting clients’ expectations for treatment success using these therapies and also in understanding the controversy that surrounds the best ways to use them. All veterinarians can do for the moment is choose cases carefully, extrapolate from current evidence when formulating treatment plans, and be sure to use traditional rehabilitation techniques as well.
“These are not drugs, they are not perfect, and they are not going to work when all of your other approaches fail,” said Fortier, who is professor of large animal surgery at the university’s vet school, in Ithaca, New York. She summarized current research on PRP and what she’s learned using it at the 2014 American Association of Equine Practitioners Convention, held Dec. 6-10 in Salt Lake City, Utah.
The “tremendous degree of variability” among PRP preparations has to do with platelet and leukocyte (a type of specialized white blood cell that aids in healing) concentrations. Current evidence suggests that PRP preparations with platelet concentrations two- to fourfold over what's found in blood and low numbers of leukocytes are optimal for increased tissue repair.
Veterinarians initially used PRP for treating tendons and ligament injuries, but Fortier said there is now evidence it can help heal joint injuries as well. Research has shown that PRP can increase synovial cells’ synthesis of hyaluronic acid (HA, an important cartilage component that helps maintain hydrostatic pressures to resist weight-bearing forces) and decrease joint pain and inflammation, making it a promising approach for enhancing early return to activity. Therefore, she recommended only using it in mild to moderate joint disease and pointed to human research: “PRP didn’t do anything to help regrow cartilage in human knees, but it did help with pain and returning people to functional activity.”
Additionally, long-term, PRP was as—or more—effective than HA in restoring function and decreasing pain in human knee arthritis cases, but the effect lasted longer (a year or more vs. six months for HA).
She said PRP injections can increase tendon matrix production and decrease inflammatory mediators associated with matrix degradation. As with other therapies, however, one of the keys with PRP treatment is treating an injury early—injecting it into a lesion within a few days of injury can stop the progression and growth of a lesion and avoid scar tissue formation.
Fortier reviewed a few questions she commonly fields about PRP:

• What’s the time frame for successful intervention? It depends on the site and injury severity, but is likely limited to three- to six-month-old injuries.
• Do I need to add thrombin (an enzyme involved in blood clotting) to activate PRP before injecting it? No, she says. “When you put PRP into tissue, it clots naturally.”
• After preparing it, how do I know if I actually have PRP? “Make a smear of whole blood and the PRP, let them air dry, come back and count platelets and stem cells; there should be more in your PRP smear compared to the blood smear,” she suggested. “Some (horses) are going to be super PRP makers, and others are not.”
• How long can PRP sit out at room temperature? “It’s safe to draw the blood, do a couple of more farm calls, and then go back and inject the PRP,” she said. “You can store it for about a year in the freezer without problems.”
• What size needle should I use, and how much PRP should I inject? Fortier uses a 23-gauge needle to minimize damage to tissues. For lesions, she simply fills them up with PRP. For joints, Fortier injects 1-3 mL for smaller joints and 3-5 mL for larger ones. But it is important to point out that if injecting stem cells, you need a larger needle—nothing smaller than 21-gauge to avoid killing the stem cells.
• What’s the horse’s level of activity following treatment? The horse resumes active rest with a graded rehabilitation program aimed at getting the horse back to full work in four to six weeks for a joint injury and three to six months for a tendon injury. An attractive aspect to this treatment, she said, is that the horse can go back to work relatively quickly.

Ultimately, Fortier uses PRP as her first line of therapies for both joints and ligaments. She cautions veterinarians that—as with all other treatments in veterinary medicine—PRP doesn’t always work. “If you don’t get a response for your first injection, you’re not going to get a response for a second,” so move on to other treatment options.
She also said to remember that even PRP applied early will not cure the horse without other rehabilitation techniques, which include controlled exercise, weight loss, and consistent and good shoeing.
Fortier acknowledged it is unclear which biologic approach is best for certain injuries, given the variable nature of biologic therapy, but veterinarians are commonly using a dual PRP/stem cell approach to counteract the time and performance lost with musculoskeletal injuries.
As is practice at this peer-reviewed meeting, Fortier disclosed she is a consultant to Arthrex Inc.

About the Author

Stephanie L. Church, Editor-in-Chief

Shipping Horses Long Distances

   

Schedule rest stops every four to six hours, and offer your horse fresh hay and water.

Photo: iStock

I’ve recently begun searching for a new horse to welcome into my life, and I find myself looking at animals farther and farther away from of my home state of Texas. The process has reminded me how important climate and other considerations can be when shipping horses long distances. The following are some factors to consider when transporting horses afar, be it to a show or to a new home. 

If you’re planning to ship a horse for more than three to four hours, think about his health first. Practice proper preventive care, vaccination, and deworming prior to travel. If your horse isn’t a frequent shipper, you might need to update his vaccines and have your veterinarian perform an overall health check at least two weeks before hitting the road. Your vet might also recommend doing blood work to determine if your horse is healthy enough to undertake long-distance travel or getting an updated Coggins test if your horse’s is more than 6 months old. Some states require proof of a current negative Coggins pulled within the prior 6 months for travel across their borders. 

If your horse requires vaccination, schedule it early enough that the horse’s immune system gets a boost before the stress of shipping—which provides its own set of challenges to even a healthy immune system—and any disease exposures off the farm. This is also a good time to talk to your veterinarian about health certificate requirements and any concerns he or she might have about your horse’s destination, as animal health regulations can vary from state to state and often change depending on disease outbreaks. 

Keep an organized folder of vital paperwork such as vaccine history, Coggins test results, health certificates, and registration papers while traveling. Talk to your veterinarian about preparing a first-aid kit to keep on your trailer in case of emergency. If you already have one, make sure all medications contained in it are labeled and have not expired.

If hauling your own horse rather than hiring a shipping company, it is important to make sure your truck and trailer are ready for long-distance travel. Check your tires and lights to ensure all are in good working order. Give yourself time to repair any potential issues so you are not in a last-minute rush. This is also a good time to clean out the trailer and pack it with necessities such as enough water for your horse to consume during the trip. Water in different parts of the country can taste significantly different, and some horses are very picky about the water they drink. The last thing you want to deal with on a long road trip is a horse that suffers an impaction colic because he does not want to drink water along the way. I also recommend taking enough hay to cover your travel needs plus at least a couple of days. Just as with water, hay and hay quality can vary greatly throughout the United States and other countries. 

If possible, do not restrict your horse’s head or neck position during long trips (six or more hours) because researchers have linked upward head restraint with compromised lung clearance and an increased risk of shipping fever. Also remember that ventilation is vital to healthy travel, and horses locked in a trailer with no air flow can become very hot, especially during summer. On long trips schedule rest stops for your horses and, if possible, time for them to unload and drink water. Offer your horses good-quality hay and water at least every four to six hours during travel (every three to four hours in summer). If you are able to unload horses during stops, this is also a good time to remove any manure and urine-soaked bedding from the trailer so horses are not breathing ammonia-filled air any longer than necessary. Another good idea for long-distance travel is to plan overnight stopping points along the way. Many farms are willing to rent space to owners traveling with horses. Scout these facilities out ahead of time, and have a backup plan in case there is a problem with your first choice.

After arriving at your destination, allow your horse sufficient recovery time before asking him to work or perform. For travel times under 12 hours, 24 hours of rest is typically adequate for recovery. Horses shipping for longer than 12 hours or by plane often require at least two to three days of rest and recovery. During this period watch your horse for any signs of illness, such as nasal discharge or coughing, inappetence or poor water consumption, and abnormal manure production. Call your veterinarian should you note any of these problems, as they can indicate shipping fever or colic post-travel. 

With proper preparation and planning, you and your horse can have an easy and enjoyable long-distance trip.

About the Author

Kristen Slater, DVM

10 Early Warning Signs of Laminitis

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Horses developing laminitis might shift the weight off their feet twice as much as they do normally.

Photo: iStock

Your horse's best chance of overcoming this hoof disease might lie in your ability to catch it early

It’s a painful condition that veterinarians, farriers, and horse owners have been racking their brains about for decades. Laminitis—the separation or failure of laminae, which connect the hoof wall to the coffin bone within—can cause permanent structural changes in a horse’s foot, leading to repeated bouts of disease and lasting lameness. In severe cases the pedal (coffin) bone in the hoof rotates downward, potentially even puncturing the sole and prompting the decision to euthanize. But get this: Watchful handlers can actually detect signs of laminitis in its early stages and intervene before the condition becomes debilitating.

“Everyone talks about laminitis being a lameness issue, but we know that horses start to get damage at a microscopic level before they show any lameness,” says Andrew van Eps, BVSc, PhD, MACVSc, Dipl. ACVIM, senior lecturer and specialist in equine medicine at The University of Queensland Equine Hospital, in Gatton, Australia. 

Therefore, keeping an eye out for minute changes in your horse’s health is key to maximizing his likelihood of recovery, says Tom Ryan, FWCF, a researcher and farrier based in Bedfordshire, U.K. “You have to be proactively thinking ahead,” he says. 

To help you catch this devastating hoof disease while your horse still has a chance to avoid suffering its consequences, our sources have helped us come up with a list of 10 early warning signs. Regardless of the type of case (-supporting-limb, systemic inflammatory response syndrome, or endocrine disease-related), these red flags could indicate laminitis is setting in—even before you see any signs of lameness. So alert your veterinarian as soon as possible if you detect one or more of the following:

1. A strong/bounding digital pulse 

Slide your hand down the side of your horse’s lower limb where the digital artery runs through the groove between the flexor tendons and the suspensory ligament. Where the artery continues down the back of the fetlock you should be able to feel his pulse. Normally, the pulse should be faint or even seem absent, says Ryan. But in laminitic horses it will be stronger and is often referred to as “bounding.” How do you know what’s strong or bounding? “You kind of have to feel to know,” he says. Ideally, you should get to know what’s normal for your horse’s digital pulse. A strong digital pulse can indicate other foot pain, as well, but a bounding digital pulse in both feet is a major clue that laminitis is to blame.

2. A hoof that’s hot for hours

Healthy horses can have hot hooves, says van Eps, but not for long periods of time. It’s normal for horses to experience large influxes of blood into their feet periodically, which causes hoof temperature to rise. But the body regulates this heat, and it should only last a couple of hours at most—unless it’s hot outside. In other words, there’s no need to panic if your horse has been standing in a sunny field on a 90-degree day and his hooves are hot. The time to worry is when hooves reach 91.4°F (33°C) for several hours in a row and the outdoor temperature is lower than 77°F (25°C). “That’s a sign they could be getting laminitis, and that’s what we’ve seen experimentally,” van Eps says.

That increased temperature, says Ryan, is the hoof’s response to the trauma within the laminar tissues. 

Sometimes lameness follows quickly. “We see lameness begin eight to 12 hours after that temperature increase,” van Eps says. If you don’t think you can estimate surface temperatures well with your fingers, van Eps recommends using an infrared surface temperature gauge from a hardware store. 

3. A distorted hoof shape and/or unusual rings 

Healthy hooves grow faster in the dorsal (front) part of the hoof and slower in the quarters, says Ryan, creating smooth, wide, evenly spaced growth rings across the front of the hoof wall that curve downward at the quarters toward the heels. With laminitis, that growth pattern no longer applies; the horse develops wider growth rings at the heel than at the toe (because growth has been compromised at the toe—where most of the damage has occurred—more severely than at the heels). If toe growth goes unchecked, it might curve upward much like a cow’s horns do.

This altered pattern causes the hoof’s rings to curve upward and abnormal rings to develop on the hoof wall surface, which can precede lameness sometimes by months or years, says Donald Walsh, DVM. Walsh leads the Animal Health Foundation, in Pacific, Missouri, which funds research and education projects related to laminitis.

Ryan believes abnormal hoof growth starts before all evidence of pain, due to the laminae being traumatized by the hoof changing shape around it. He’s been investigating the pain-relieving effects of farriers or veterinarians cutting vertical grooves into laminitic horses’ coronary bands to relieve pressure. “Early grooving appears to protect the laminae from more severe effects,” he says, adding that research is pending on this theory. “Our experience indicates that if you can do it very early on, you can see pain relief within hours.” 

  

4. An increased heart rate  “We used to think that heart rate was not a very sensitive indicator,” van Eps says. “But we found that in our clinical patients the most sensitive indicator (for pending laminitis) is probably an increase in heart rate.” Most horses maintain pretty consistent resting heart rates of 30-40 beats per minute (BPM). But van Eps has noted that heart rates of -laminitic horses tend to rise a day or so before lameness sets in. “A mild increase in heart rate of even 6 bpm can be a significant early indicator that your horse is getting uncomfortable,” he says.

“A lot of people have dismissed small heart rate changes, but actually they can be very useful warning signs if the horse’s normal heart rate is known,” he adds. You can measure heart rate with a stethoscope or by feeling for the pulse under the jaw or at the pastern, as described before. Exercise, excitement, and ambient temperature can also increase heart rate, however, so keep these influences in mind when interpreting results.

5. Too little—or too much—foot lifting

Horses rely on movement to get blood flow and the nutrients within to hoof tissues, says van Eps. But if a horse is injured in one leg, he might bear weight for too long on the opposite limb, causing a phenomenon called “supporting-limb” laminitis.

“Consider putting these horses in a sling so they can take weight off that foot,” suggests Walsh. With your veterinarian’s direction you can also try to get horses with leg injuries out of the stall to move around. “Even if the horse is hopping, it’s producing enough movement to prevent laminitis from occurring.”

On the flipside, a horse that picks his feet up too often might also be showing early signs of laminitis, van Eps says. “Horses normally shift their (weight between) feet about two or three times per minute,” he says. “We noticed an increase of three to five times that weight-shifting when they were developing laminitis.” 

If the feet get painful enough, the horse will begin to change his stance, shifting his weight back to his haunches, along with stretching his legs out in front of him in the classic laminitis pose.

6. Apparent stretched and/or bleeding laminae 

As laminae start to stretch, they separate from the hoof wall, explains Walsh. A gap becomes visible along the white line, where the sole and hoof wall meet. This white line widening is known as “seedy toe,” and you can see evidence of this in the trimmings from a laminitic horse’s foot during a farrier visit. He adds that if you notice spots of blood in the white line when you pick up your horse’s foot, it doesn’t mean your horse has been quicked by the farrier; it means the laminae are hemorrhaging, which is a sure sign of laminitis.

Owners can check trimmings each time the farrier comes and begin to recognize what’s normal and not normal for their horses—something farriers might miss, says Walsh.  

Laminar stretching also increases the distance between the external hoof wall and the front of the coffin bone, which can be seen on lateral radiographs (X rays), says van Eps. “That space is normally 18 mm, but it will increase as the laminae stretch,” he says. “There won’t be any rotation of the bone yet, just that lengthening that could go to 20, 21, sometimes even 22 mm.”

7.  A shortened stride 

A laminitic horse starts shortening his stride before he begins limping, says Ryan. Stride changes are more obvious on hard surfaces, especially when turning at the walk.

“Not many other conditions will make a horse lame on a circle on a hard ground at the walk in both directions,” van Eps says. Know your horse’s typical stride length at the walk so you’ll recognize when those steps get shorter. And watch for signs of pain when the horse turns at the walk; these can range from the horse pinning his ears to a reluctance to move. “A horse that looks fine on a straight line on soft ground could look very different on hard ground in a circle,” he adds.

8. Increased insulin levels  

Insulin, a normal hormone released in the body to regulate blood sugar, activates a particular growth factor (IGF-1) in the laminae, causing them to grow. “But the laminae aren’t supposed to grow,” Walsh says.

A basic insulin reading by a veterinarian should show 20 units or lower, Walsh says. If it’s over 40, you need to take action to get that insulin down before laminitis hits. In the “gray area” between 20 and 40, Walsh says he recommends performing an oral glucose test, in which the horse receives a weight-calculated dose of corn syrup that causes insulin levels to spike. In healthy horses these levels should return to normal within 60 to 90 minutes. In insulin-resistant horses they’ll stay elevated for much longer. 

If your horse is already experiencing a bout of laminitis, however, it’s important to wait until it has subsides to test for IR.

Walsh says he sees “storms” of laminitis cases caused by high insulin in spring, when horses are turned out on sugar-rich pastures. Even so, rich spring pastures won’t affect all horses—just those genetically inclined to insulin resistance. These animals need low-sugar diets and plenty of exercise—even if they’re -laminitic—to lower their insulin levels, Walsh says. 

9. Obesity 

An obese horse is more likely to be an insulin-resistant one, say our sources. Obese horses’ feet also bear more weight, which contributes to the mechanical changes in hoof shape. “Physical weight could cause the hooves to grow abnormally,” says Ryan.

The excess weight can also send conflicting messages to farriers, says Walsh. “A lot of farriers will think the horse is wearing his feet down from being overweight,” he says, when in reality, “the horse is breaking his foot down, not wearing his foot down, due to first the stretching of the laminae. Then the excess weight helps to break the foot down.” 

First and foremost, it’s important to recognize if your horse is fat. “Owners are generally blind to how overweight their horses are and don’t appreciate how much they’re overfeeding,” says Ryan. And, secondly, reduce the horse’s calorie intake and increase his exercise, Walsh adds.

10. Diarrhea, infection, or inflammatory response

Systemic inflammatory responses can trigger laminitis, says Walsh. “If the horse is developing a high fever and diarrhea, then laminitis is next on the plate, and you have to be proactive in thinking about that,” he says. “These horses are engaged in massive destruction of the laminae, which occurs because of enzyme reactions in the feet due to the inflammatory response.”

A good way to keep laminitis at bay in these types of cases is packing the horse’s feet in ice, Walsh says. Work with a veterinarian to keep the horse’s legs at a maximum of 41°F (5°C) all the way up to his hocks and knees, starting immediately. If you wait to do this until clinical signs of laminitis appear, you’re often too late to prevent damage.

Take-Home Message

Laminitis starts at a microscopic level well before actual lameness sets in. Careful horse owners can learn to recognize the subtle signs caused by microscopic changes, call their veterinarian, and take steps to prevent the laminitis from worsening. Although these microscopic changes might not be reversible, it’s possible to stop the disease before it becomes debilitating. “Laminitis is all about ameliorating or halting the progression,” van Eps says. “If it’s very early and quite mild then you can go on to have a horse with no functional disruption.”

Researchers recommend getting an idea of what’s normal for each horse—how he walks and turns, how he stands, what his posture is like, and his normal hoof temperature and heart rate. “Once you do that,” van Eps says, “you’ll be well-equipped to detect what’s not normal and instigate change.”

Understanding Forages

  

Forage should be the basis of any equine diet.

Photo: Photos.com

We’ve said it before; we’ll say it again: Forage should be the basis of any equine diet. So understanding pasture, hay, and other fiber sources is an important part of your everyday management. So, too, is knowing which fiber sources are appropriate for your horse.
Forage can be loosely defined as any feed made up of the stems, leaves, and stalks of plants, and which has a minimum fiber content of 18% and a relatively low dietary energy (DE) content. The most natural, least expensive, and safest feed for horses, forage provides the bulk of nutrients horses require for their everyday maintenance metabolism and stimulates the muscle tone and the activity of the gastrointestinal tract. Horses with inadequate amounts of forage in their diets run the risk of colic and founder, as well as stable vices derived from having too little to chew on.
Although horses have been known to nibble on tree leaves and branches, they’re primarily grazers, not browsers like deer, and grasses make up most of their natural diet. If you live in a temperate climate with no chance of drought, your horses might have the luxury of nutritious grazing—fresh forage—year-round. But for most North Americans, there’s a good portion of the year when good pasture is just not available, and hay—grasses and/or legumes that have been sun-cured, dried, and baled for convenient feeding—picks up the slack.
Hay, the most common type of forage fed to horses, averages 28% to 38% crude fiber and has a DE level of about 1.95 to 2.5 Mcal per kg. (Cereal grains, by contrast, contain between 2% and 12% crude fiber and have a much higher DE, averaging 3.3 to 3.7 Mcal/kg.) Hay is high in calcium (Ca) and low in phosphorus (P)—and happily, grains are generally high in phosphorus and low in calcium, so a horse being fed both hay and grain usually ingests a Ca:P ratio that “balances out.” Hay also contains high levels of potassium and vitamins A, E, and K—and if sun cured, high levels of vitamin D as well. (Vitamins tend to break down over time, so the more recently the hay was cut, the higher the vitamin content; by the time baled hay is a year old, it might contain no appreciable amount of vitamin A.)
Hay can be extremely variable in protein content. Legume hays (such as alfalfa or clover) might contain 20% crude protein or even higher while grass hays (such as timothy, bermudagrass, or orchardgrass) average about 11% to 14% protein and can go as low as 4%. The protein content of hay is largely determined when it is cut—the younger the hay, the higher the protein. Hay cut past the mid-bloom stage (when about 50% of the plants have flowered and gone to seed) is a good deal lower in protein content, and mature (full-bloom or past-bloom) hay might be inadequate to meet an adult horse’s nutrient requirements for maintenance.
Cereal grain hay, is rarely fed to horses in North America as it is not terribly economical. Cereal grain hay is hay cut from grains such as wheat or barley while the plant is still green and before the seed is harvested. It is nutritionally similar to grass hay, and the more grain (seeds) the hay contains, the higher its nutritional value. (If the seed heads are lost in harvesting, only straw remains; it makes good bedding but poor feed.)
Far more common are grass hays and legume hays. Of the legumes, alfalfa, also called lucerne, is the most popular crop; it’s estimated that more than half of the hay harvested in the United States is alfalfa or an alfalfa/grass mix. Other legume hay includes clovers, birdsfoot trefoil, lespedeza, cowpeas, vetch, and even soybeans. Horses almost always prefer legume hays over grass hays, and this type contains two to three times the protein and calcium of grasses, as well as more soluble (non-fibrous) carbohydrates, beta-carotene (the precursor of vitamin A), and vitamin E. Because of these qualities, they’re the preferred hays for young, growing horses as well as lactating mares. But legumes are generally more costly, and in some parts of North America might be infested with poisonous blister beetles.
There are also a number of different types of grass hay, with timothy being the most widely grown across North America; it’s an easy crop to establish on most soils, and tolerates cold well, beginning to grow actively early in the spring, weeks before most other hay crops. But timothy doesn’t cope well with extremes of heat and humidity, so in the central and southern United States, growers sometimes may turn to alternatives such as quick-curing coastal bermudagrass (a variety developed to grow tall enough to harvest as hay, unlike its cousin, common bermuda, which suits better as a lawn), brome (drought resistant and hardy, and also cold tolerant, but less palatable than some other grasses, and so usually grown in combination with alfalfa), or orchardgrass (a very drought-resistant species that can be productive even on poor soils). Bluegrass, fescue, reed canarygrass, and ryegrass are some of the other varieties of grass hays fed to horses. Not only do grass hays not harbor blister beetles, but they often are less dusty than legume hays, making them a preferred choice for horses with respiratory problems. And their more modest protein content makes them a better choice than legumes for mature horses not being used for breeding.
You can distinguish a grass hay from a legume by looking at the stalks and leaves: Grass hays grow tall, upright stalks and long, slender leaves that sheathe the stalk itself, rather than branching out on stems the way legume leaves do. Legume stalks are often coarser, and the leaves are less firmly attached—which leads to increased wastage after harvest, when the dry leaves tend to shatter and crumble out of the bale. The seed heads of grass hays, however, can vary a great deal, from the narrow, cattail-like structures of timothy, to the branched, tree-like fronds of bluegrass and orchardgrass and the elaborate tufts of brome. Some grasses create a thick, underlying carpet of roots and connecting runners called rhizomes, which protect the ground from water runoff and traffic damage; this makes them a preferred crop for pastures.
There are considerable advantages to growing grass and legume hays together as one crop. First, horses consider legumes tops in the palatability sweepstakes, so combining the two might encourage a horse that would turn his nose up at straight grass hay to accept and consume a mixed flake. Second, a lower-protein grass hay might help “balance out” the high protein level of a legume and create bales that are appropriate to feed to mature horses—and more marketable for the farmer. And third, the addition of nitrogen-producing legumes to a grass hay crop actually helps fertilize the field and increase the yield of the grass hay. In many parts of North American, mixed hay is the preferred feed for horses—though the mix can be any of a number of combinations of legumes and grasses, depending on the climate, soil type, and demand.

Why We Love Horses

t's Valentine's Day, and whether you get swept up in the spirit, avoid it like the plague, or just wait around for discounted chocolate on Feb. 15, one thing is certain. We all love our horses. And what better day to focus on that fact than this day devoted to love?
We asked members of our Horse Illustrated Facebook community to tell us why they love their horses. Here are some of their responses.

Tank

My palomino Quarter Horse, Tank, will always be my Valentine. He is loving and true, always happy, even when I'm down. He has the soul of an angel and I am blessed to have him.
— Penny Jean K. My beautiful Oscar is a genuine good soul. I always say he's simply a good person and a perfect gentleman. He is always calm and gentle with everyone—people, dogs and other horses. There is no better place to be when I'm upset than at the stables with his muzzle on my shoulder. He'll stand like that for hours.
— Janine V.
Both of my horses, Joe and Louie, are rescues. Joe was starved of both food and attention, and Louie was abused and starved. However, after being rescued they are both the most lovable and most trusting horses I have ever met.
— Tiffaney K.
I love that my horse is silly and sweet with a little bit of sass. We've been together for over 18 years now and I have never had a bad day at the barn with him! He's my best friend and wouldn't trade him for anything!
— Ginny W.
My old horse with endless patience and a huge heart came into my life at a dark time, and she taught me how to live and laugh again. She is 40 years old now and lives the good life. She's still my therapist!
— Michele C.

Beauty and her flock

I love my horse's little soft high pitched "purr-nicker" at feeding time.
— Teresa C. I love Beauty's capacity to love. In her retirement, she has adopted a flock of sheep and loves them all like they're her own. She watches over them and their babies day and night and calls to them when we go out around the farm.
— Juliet O.
My horse gives ME a job to do. Retirement wasn't for me and I purchased a beautiful Paint. He and I learned together. He gave me purpose. Love my big boy. We might not win or place a lot, but we sure have fun.
— Darlene J.
My favorite thing about Cinnamon, my very first horse, is her ability to overcome her past and trust me more each year. She may have a lot of sass but she has learned to love more than I thought possible!
— Kim H.
I love all my horses. They are all my best friends especially when in need. They are what get me up in the morning. They make me want to live my life to the fullest. No matter how many mistakes I make, they forgive me and help me move on and learn. To me that is so very important. Love them all to pieces!
— Nikki G.
My horse, Mystic, was a rescue horse who had severe trust issues. The day I met her I knew I couldn't leave her. She and I bonded immediately and even though I have owned her for just over a year, she has become a huge part of my life. She has shown me that love and trust are not just shared between humans but also between humans and animals. She has overcome her fears with a lot of patience and love that I have provided for her. She is my therapy and I am hers.
— Shelly G.

Bold and Melissa

He's a great mountain horse. He'll go over anything. He also makes me laugh. Mickey is such a clown. If anything is amiss in the pasture, I know he did it.
— Sara L. My horse can read my mind and my heart. We have both been through our share of illnesses and hospitalization over the past few years and each time we have been there for each other during some long recovery time. I recently had to make the hard decision to retire both him and me from active riding. We are beginning a new chapter in our lives and I feel no sadness or regret. My horse has taken me to places I only could dream about as a child and our journey has included some very special people I would not have met without my beloved Bold. I look forward to the future with joy because he is my best friend.
— Melissa G.
Share what you love most about the horse in your life in the comments below, or join the conversation at Facebook.com/HorseIllustrated.
Further Reading
Be My (Horse Loving) Valentine