Ask Your Veterinarian: What Are Hoof Growth Rings?

by | 01.10.2019 | 3:06pm

QUESTION: What are hoof growth rings and what does it mean when you see them on a horse at sale?

DR. SCOTT FLEMING: Growth rings are externally visible ridges in the hoof that indicate differences in the rate of growth or quality of a horse’s hoof wall. The appearance and number of rings can vary from several consecutive rings to a single or widely intermittent pattern. Growth rings can be indicative of a problem within the hoof capsule or may just be an external map of changes in activity, nutrition, or a systemic disturbance that altered hoof growth at one time.

The average hoof on a healthy adult horse will grow from the coronary band to the ground in approximately one year. Alterations in hoof growth or quality such as laminitis can greatly affect growth rates. For example, the hoof wall at the toe may grow slower than the heels in both laminitis and clubfooted hooves while exhibiting a similar dished appearance. Both conditions may take much longer for the toe to grow to the ground.

 

Visually, the growth rings will appear small and tightly spaced at the toe and become wider and more pronounced toward the heels where the growth rate is more rapid. We describe these growth rings as being divergent. They are wider in one part of the hoof than another region. They can be divergent in several planes, such as those described previously, or wider at the toe than heels or even wider on the outside of the hoof than the inside or vice versa. These patterns tell us something about the hoof and what forces, either internal or external, are causing growth differences in the hoof. Wider (faster growth) at the toe than heels can mean the heels are compressed or compromised in some manner. We often see this pattern with negative palmar/plantar angled coffin bones.

The hoof may also exhibit a rounded “bullnosed” appearance and the angle of the coronary band is higher than a normal hoof. Rings that are divergent from one side of the hoof compared to the other may result from differential loading due to conformation or can result from more significant insults such as medial sinking or failure of the internal suspension of the hoof. Divergent rings can often result from overloading or imbalance of one portion or structure in the hoof and can be improved through trimming and shoeing that reduces stress in the affected region.

Reading growth rings offers valuable information but is only part of the picture to overall hoof health. The rings that are visible, are a history of where that hoof has been recently, but internally, a hoof can be catastrophically failing without external signs having shown in the wall itself. Physical evaluation, a detailed history, and radiography remain the cornerstones for diagnosing hoof problems.

Scott Fleming, originally from Northeast Texas, grew up riding Western performance Quarter Horses and working with cattle. Upon graduating from high school, Fleming attended farrier school and maintained a quarter horse centric farrier business in Northeast and central Texas until moving to Lexington. He also served in the Marine Corps Infantry for four years.

Fleming graduated from veterinary school at Texas A&M University in 2013. He then completed an internship at Rood & Riddle in 2013-2014, continued at the hospital as a fellow, and is currently an associate veterinarian at Rood & Riddle.

Outside of Rood & Riddle, Fleming enjoys spending time on the farm with his wife, Tina and their two children, Callie and Case . A special interest for Dr. Fleming is participating in Equitarian Initiative trips to Central America to help working equids in the region.

Do you have a question for a veterinarian that you’d like to see in Ask Your Vet? Email natalie at paulickreport.com

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Pregnancy Problems: How to Increase Your Chances of Delivering a Healthy Foal

By Jen Roytz

What could be that difficult about breeding? You select a stallion that suits the mare and your goals, breed your mare, then keep her fed and watered for 11 months until you’re rewarded with a healthy foal.

If only it were that simple.

There are many reasons a mare can prove difficult to get into foal, or to stay in foal. It could be as simple function of age. It could be results from a complicated delivery. Or, it could be a multitude of other reasons.

Regardless, now is the time breeders should be paying special attention to preparing their breeding stock for the upcoming season, and for those with known issues there are added safeguards and steps breeders can take she gave themselves and their horses the best chance at a successful pregnancy.

Issues that Can Impact Conception

There are many reasons a horse may have issues getting impregnated, the most basic of which are her age, not breeding her at the appropriate time during her cycle, or poor reproductive health of the mare or stallion.

A typical mare’s ovum, or egg, begins to lose viability within just five to six hours post-ovulation, and typically loses all viability within 24 hours. While a stallion’s semen typically remains viable for 48 hours, a reduced number and quality of a stallion’s semen can limit its viability to just a few hours. Age can negatively impact these timeframes for both sexes.

The mare’s body condition can also play into her chances of becoming pregnant. Most veterinarians recommend mares to rank around a 5 or a 6 on the Henneke Body Condition Score (BCS). When a mare’s weight and overall health decline, so too does their reproductive efficiency.

Outside of age and general health-related issues, endometritis is the most common reason for infertility in mares. This condition, which is an infection or inflammation of the lining of the uterus caused by foreign contaminants such as bacteria or spermatozoa, can either be acute as a result of breeding (both artificial and natural), reproductive examination or as a result of poor conformation.

“There are simple, but important steps one can take to improve the chances of conception, including a physical examination of both the mare and the stallion, a careful and thorough reproductive exam of the mare prior to the breeding season and during the estrous cycle during which breeding is to occur and to optimize the overall health of the horse,” said Kristina Lu, VMD, an equine reproductive specialist with Hagyard Equine Medical Institute.

Early vs. Late Term Pregnancy Loss

Just as there are a number of reasons a mare can be difficult to impregnate, the same can hold true for keeping her in foal. Most pregnancy losses occur in the initial weeks and months of pregnancy.

Again, age can play a role. As mares age, they may experience uterine fibrosis, which can lead to a placenta that is less-efficient in getting nutrition to the growing fetus.

Other causes for early-term pregnancy loss can be unavoidable complications, such as genetic defects or embryonic abnormalities. They can also be due to uterine infections that may have been low-grade and undetectable at the time of breeding/conception but proliferate in the subsequent weeks and months.

Late-term losses can have their own set of culprits.

“Placentitis, umbilical cord torsion, systemic illness can all cause late, and in some cases mid-term abortion in mares,” said Lu. “Diseases such as leptospirosis, equine herpesvirus 1 or 4 and equine viral arteritis are threats to a healthy gestation as well, some of which can spread quickly through a herd and may not generate obvious clinical signs other than abortion.”

Then there are also those mares that have little trouble carrying a foal to term, only to be prone to dystocias (difficulty giving birth), which can be caused by congenital abnormalities, such as contracted limbs that prevent the foal from properly fitting through the birth canal. This, in turn, can lead to oxygen deprivation in foals.

Safeguards to Protect Both Mare and Foal

While some complications are simply unavoidable, there are safeguards and protocols that can be implemented to support the gestation and delivery of a healthy foal.

“Some simple things horsemen and women can do to protect their mares and future foals are to maintain good general health of a mare, conduct thorough reproductive examinations, monitor the mare’s reproductive tract before and after breeding, ensure regular core vaccinations, consider screening for placentitis if the mare has a previous history and consider vaccinating for herpes or leptospirosis if appropriate,” said Lu. “Breeding as close to ovulation as possible can also be of benefit. On the other hand, repeated breeding during an estrous cycle (average 21 days) may increase opportunity for endometritis in some mares.”

Above all else, staying in regular communication with your veterinarian is one of the best forms of protection one can afford their mares.

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Bad Bedding? Straw Hard On Equine Lungs

by | 12.27.2018 | 11:21am

Straw bedding and dry hay can be risk factors for inflammatory airway disease (IAD) in performance horses, a new study shows.

Julie Dauvillier, Fe ter Woort and Emmanuelle van Erck‐Westergren, who represent the Equine Sports Medicine Practice in Waterloo, Belgium, studied the role of fungi in IAD. Horses affected with IAD generally have poor performance, a cough and excess mucus in the airways.

The researchers used 731 horses that were used for racing, sport and leisure riding in their study. The trio collected data, observed environmental conditional and collected samples from bronchoalveolar lavages and tracheal washes. Fungal cultures were positive in 55 percent of the horses; horses that had fungal elements in their tracheal wash samples were twice as likely to have IAD.

Horses bedded on straw were 90 percent more likely to have fungi in their tracheal wash than those bedded on other materials; horses bedded in wood shavings had only a 40 percent risk of fungi in their wash.

Hay and straw are naturally contaminated with fungal spores during harvest; storage can increase fungus proliferation. Steaming did help reduce the fungal particles hay, but soaking did not decrease the amount of fungal spores dramatically.

Read more at HorseTalk.

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When Laminitis Strikes, What’s Your First Line Of Defense?

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Barbaro, Edgar Prado, and Dr. Dean Richardson at New Bolton during the Derby winner’s treatment for laminitis

The most important time to take action against laminitis is when a horse shows early signs or a high-risk event occurs that might trigger laminitis. Triggers for laminitis range from exposure to black walnuts to injury to physiological disruption from colic, high fever, retained placenta, or carbohydrate overload. In essence, anything that causes a horse significant trauma might set in motion a cascade that ends in laminitis.

Laminitis is regarded by many in the veterinary field as the most horrific disease to attack horses because in severe cases, it literally causes the hoof capsule to slough off when the laminae that make up the connective tissue between the interior structure of the hoof and the hoof wall die. Theories about what actually happens to the horse physiologically to cause laminitis are numerous, and researchers still seek answers to many questions about the disease.

Dr. Hannah Galantino-Homer is the director of the Laminitis Laboratory at the University of Pennsylvania’s New Bolton Center. The laboratory is part of the Laminitis Institute founded by the university after the tragic death of 2006 Kentucky Derby winner Barbaro. The colt was euthanized after an eight-month battle against laminitis at New Bolton Center after fracturing his right hind leg at the beginning of the Preakness Stakes.

If you think laminitis is a threat, call your veterinarian immediately. Time is of the essence.

Galantino-Homer said several things can be done while waiting for the veterinarian to arrive. First, move the horse to a confined area with soft footing. This can be a round pen with a deep sand base or a stall with at least six inches of bedding, either shavings or several bales of scattered straw.

“This allows them to distribute the weight more, and it encourages them to lie down if their feet are really sore,” she said.

Next, ice the horse’s feet. Studies show that cryotherapy reduces pain and inflammation. This can be done by standing a horse in ice and water, using ice boots, packing crushed ice in a bag and securing it to the horse’s foot with bandage, or pulling pantyhose over the horse’s lower limb and filling it with ice. If you are fortunate to have a Game Ready system, this is an ideal use for it.

More importantly, icing can slow down the cascade of events.

“Any kind of damaged tissue tends to compound the damage by releasing more things that cause more damage, more inflammation,” Galantino-Homer said. “You’re slowing all that down. You’re slowing the metabolism of the white blood cells that have been activated by tissue damage going on. So you’re trying to slow all that down.”

Administering a nonsteroidal anti-inflammatory drug is the next measure but be sure to get your veterinarian’s approval first. The horse’s history, current medical condition, and potential cause of laminitis must all be factored into what the horse should receive.

“Veterinarians have preferences for what they use,” Galantino-Homer said. “For a horse owner in a first-aid situation, it would be whatever you have on hand—Bute, Banamine. It’s medical management for painkilling and inflammation, and it is going to depend on other clinical aspects. Such as a horse with colitis, you have to worry more about kidney damage. So they may manage pain differently.”

When your veterinarian arrives, he or she will examine the horse to determine the best course of treatment. This commonly includes tubing the horse with mineral oil and activated charcoal to protect the intestinal mucosa, particularly in the case of carbohydrate overload. When colitis is a threat, your veterinarian may recommend Bio-Sponge to combat bacterial overgrowth, Galantino-Homer said. Developed by the late Dr. Doug Herthel’s Platinum Performance laboratory, Bio-Sponge oral paste is an intestinal adsorbent that grabs onto damaging agents and carries them out of the horse’s body when it defecates.

Because laminitis is a complex disease and every horse is an individual, no set plan of treatment can be applied to every horse. Long term, expect the horse to require the care of a farrier knowledgeable about laminitis and therapeutic shoeing. Your veterinarian also may recommend management changes for the horse, including a nutritionist to modify the horse’s diet.

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Does Your Overweight Horse Have An Insulin Problem?

by Eleanor M. Kellon, VMD

 

Easy keepers and overweight horses and ponies have been around forever. Laminitis has also always been with us, and it’s no secret that overweight animals are at high risk. We now know that the vast majority of laminitis cases are caused by high insulin levels – hyperinsulinemia. Does this mean being overweight/obese causes insulin problems?

 

It might seem that way superficially but the logic is faulty.

 

There is an important principle in science which states, “Correlation (or association) is not causation”. Observing that things occur together does not mean one causes the other. Let’s say that the native horses of the country Muropa are observed to regularly consume the leaves of the Bajunga plant, which only grows in Muropa. It has also been observed that Muropa horses never develop sweet itch. Does this mean Bajunga protects from sweet itch? While there could be a link, this doesn’t prove it. It could be a genetic factor protecting them – or simply that there are no Culicoides midges in Muropa!

 

Many horses that develop laminitis are overweight or obese. We know that the vast majority of laminitis cases are caused by high insulin levels. The correlation has always been obvious and it didn’t take long for an assumption to arise that obesity is a laminitis risk factor and causes elevated insulin. There’s just one thing: It’s not true.

 

A study (Bamford) published in the Equine Veterinary Journal in 2015, fed horses and ponies a control diet or one designed to cause obesity, by feeding either excess fat or excess fat and glucose. The weight gain did not reduce insulin sensitivity in either group. Dr. Bamford has also clearly shown that insulin responses to oral or intravenous glucose have marked variation by breed in horses of normal weight. You can read all of Dr. Bamford’s work in detail in his thesis here: https://minerva-access.unimelb.edu.au/bitstream/handle/11343/148423/Bamford%20PhD%20Thesis.pdf?sequence=1.

 

Selim, et al., 2015, followed two groups of Finnhorse mares on either native pasture or intensively managed improved pasture. At the end of 98 days of grazing, the mares on improved pasture went from a body condition score of 5.5 to 7 and gained 145 pounds; but this was not associated with insulin resistance.

 

If obesity isn’t a cause, why is more insulin resistance seen in obese horses – 25 to 50% IR depending on the study versus 10 to 15% of horses in general? The answer is simple. The IR increases appetite and weight gain. Yes, there is an association between obesity and high insulin but obesity is the result, not the cause.

 

This is more than just splitting hairs. If you think obesity is a cause, then weight control becomes a treatment — even possibly a cure. When you realize it is a consequence, not a cause, expectations for results of weight loss become more realistic. There are many benefits to weight loss and it should be aggressively pursued, but it won’t make insulin resistance go away.  Approximately 50% of IR horses are normal weight.

 

 

About ECIR Group Inc.

Started in 1999, the ECIR Group is the largest field-trial database for PPID and IR in the world and provides the latest research, diagnosis, and treatment information, in addition to dietary recommendations, for horses with these conditions. Even universities do not and cannot compile and follow long term as many in-depth case histories of PPID/IR horses as the ECIR Group.

 

In 2013 the Equine Cushing’s and Insulin Resistance Group Inc., an Arizona nonprofit corporation, was approved as a 501(c)3 public charity. Tax deductible contributions and grants support ongoing research, education, and awareness of Equine Cushing’s Disease/PPID and Insulin Resistance.

 

THE MISSION of the ECIR Group Inc. is to improve the welfare of equines with metabolic disorders via a unique interface between basic research, and real-life clinical experience. Prevention of laminitis is the ultimate goal. The ECIR Group serves the scientific community, practicing clinicians, and owners by focusing on investigations most likely to quickly, immediately, and significantly benefit the welfare of the horse.

 

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Hay! Are You Getting What You Pay For?

Today’s high forage prices are an extra incentive to understand hay quality.

 

by Stephanie Davis DVM 

 

July 31, 2018 – In most instances, I would argue that the idiom, “You get what you pay for,” is almost always true. Especially as U.S. hay prices have escalated significantly, it would be great if that were true. However, when it comes to buying hay, it’s not that simple.

Just because the hay is expensive, looks or feels good, or is a “heavy bale,” does not automatically mean it’s of high quality. Although hay is most typically sold by weight, much of that weight could be due to a high percentage of ash in the hay.

Ash is the total mineral content divided into two types: internal ash (from the plant) and external ash (dirt and dust from harvesting and storage). So, you could literally be paying more for a bale that essentially has more dirt than another one. A ranch manager in Central California recently paid $345 a ton for the “high quality” alfalfa she requires for a band of senior equine citizens, up from $190 a ton 10 years ago. Fuel prices involved in that hike make it an extreme example, but, at any price, you don’t want much of it going toward external ash.

Therefore, weight is not a good way to determine if the hay is of high quality. It’s important to know if the hay is actually of high quality as well as what factors can affect the quality and nutritional value.
The main factors affecting hay quality include: the type of hay, soil, weed contamination, rain (moisture), and how the hay is cut, dried, and baled. As the buyer for our horses, we cannot control any of these factors. Even if we have a great relationship with our hay supplier, they can only control so much themselves depending upon the weather and the type of equipment they use to bale the hay.

The only definitive way to know the quality of your hay is to have it tested. There are feed companies that will test your hay for you at a very reasonable cost. Additionally, some of the best hay providers will have the hay tested before they sell it to you. The more often you test your hay, you will be surprised by the differences in the nutritional profiles.

In a perfect world, your hay has been tested and shows an excellent nutritional profile with a low ash percentage and has a high leaf-to-stem ratio. If this is the profile of your hay, then why would the hay need to be steamed? There are two simple reasons: mold spores and external ash. Mold spore count can also be tested by a laboratory. They are measured in “colony forming units per gram” (cfu/g). If hay has over 1 million cfu/g, you have a high risk of causing respiratory problems with your horse. Even though the hay has a high nutritional profile, it could still have a high mold spore count.

Unfortunately, as the grass itself grows, there are a number of bacteria and fungi that will grow on the plant naturally. As the hay is cut and dried, certain types of bacteria and fungi will die off but others may thrive in a lower moisture environment. That is why the drying stage of making hay is so very important. However, even if the processing of the hay goes exactly to plan, a certain number of mold spores remain and will inevitably invade your horse’s airway. Second, is the issue of the external ash. Even with a low percent, there will still be an amount of dust and particulate matter that will remain on the hay and become airborne once the horse pulls on the hay to break it apart to eat.

Therefore, regardless of the quality of the hay, all hay will have mold spores, dust, and particulate matter that can insult the horse’s airway. The best way to combat those problems is to steam the hay from the inside-out using a high temperature hay steamer. This is scientifically proven to kill mold spores and reduce the dust and particulate matter.

 

Article provided by Haygain as part of our Horse Health Library, and photos are available on request. For more educational articles on a variety of conditions our products address, please contact Kim F Miller at kimfmiller1@mac.com.

 

Haygain is committed to improving equine health through scientific research, product innovation and consumer education in respiratory and digestive health issues. With offices in England and the USA, Haygain distributes products for healthier horses to 19 countries, including its Haygain® Hay Steamers, ComfortStall® Orthopedic Sealed Flooring System, ForagerTM Slow Feeder and Flexineb® Portable Equine Nebulizer. Visit www.haygain.us for more information.

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Ask Your Veterinarian: How Much Does Environment Influence OCD Lesions?

by | 07.09.2018 | 2:38pm

Question: What do we know about environmental factors that could make a horse more or less likely to get OCD?

Answer: Osteochondrosis (OC) is widely understood to be a disturbance of endochondral ossification (the formation of bone from cartilage) and is arguably one of the most clinically relevant developmental orthopedic diseases in the equine patient. Although it was once thought that OC lesions were static, sequential radiographic studies on foals, weanlings, and yearlings revealed that the characteristic lesions of OC could increase in size or completely regress (“heal”) up to 12 months of age. The timeline of this lesion formation and regression is different for each joint, and has supported the idea that there are number of environmental factors, in addition to genetics, that play a role in the progression of osteochondrosis.

Although no definitive cause of osteochondrosis has been determined, factors such as nutrition and exercise have been shown to play a role in the development and progression of OC lesions. Of these possible etiologies, the role of nutrition has been most closely investigated. Initial research into the effect of diet on OC focused largely on dietary energy level, usually in relation to a high growth rate.  Although the results of many of these studies seem to be conflicting, many support the conclusion that high growth rate (a combination of genetics and diet) is associated with an increase in the severity of OC lesions. It is important to note, however, that this is a combined effect: decreasing nutritional plane below maintenance levels will not decrease the incidence or severity of OC lesions and can lead to other dietary imbalances.

Studies investigating the role of trace elements (copper, zinc, calcium, and phosphorus) have determined that low copper levels (which can be induced by increased zinc) are linked to decreased resolution of OC lesions, and copper supplementation, to a certain extent, was able to reduce the severity of cartilage lesions. Investigations into the role of calcium and phosphorus in OC have determined that high calcium diets failed to produce OC lesions, whereas high phosphorus diets (five times NRC) reliably produced lesions in foals.

The role of exercise in the formation of OC lesions seems intuitive; it is well known that exercise is vital to the formation of a functional articular cartilage surface and OC is a developmental defect in articular cartilage. Investigations into the exact role of exercise in OC however, have yielded conflicting results.  In some studies, increased exercise was correlated with decreased incidence in OC, whereas other research was unable to find decreased incidence in OC lesions with exercised horses but did notice a decrease in severity of existing lesions. As with nutrition, it is clear that although exercise can play a supporting role in decreasing the incidence or severity of OC, no single factor is responsible for the course of the disease.

Since the process of cartilage metabolism and bone formation is highly dynamic, especially during the first year of age, it is widely thought that there are certain periods of times (“windows of susceptibility”) during which environmental factors can play a pivotal role in the severity of OC lesions. Research investigating these developmental periods, as well as the exact pathogenesis of osteochondrosis, will yield more answers and recommendations in the future.

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Can Bandages Cause Tendon Damage In Racehorses?

by | 06.11.2018 | 1:19pm

Many racehorses have their legs bandaged in an effort to reduce the chance of overreaching and injury when they are worked or exercised; many sport horses and those ridden for pleasure have their legs bandaged or wrapped by owners who believe they are providing support to equine legs. In horses that are not racing, the chance of injury from interference is much lower as they are not working at racing speeds.

British veterinarian Dr. Campbell Thompson of Nantwich Equine Vets is urging horse owners and riders to carefully consider if their horses should wear leg support while being ridden. The former vet of the British Olympic team, Thompson warns that horses’ legs can overheat if the horse is worked hard or if the weather is hot. This overheating can make horses susceptible to tendon damage in the legs that are wrapped, he says.

While open-front boots, like those worn by horses that jump, are not potentially harmful, bandages that completely encase the horse’s legs, like those used on racehorses, can cause overheating and potential for injury, Thompson said. Additionally, he does not feel that any wraps provide support for the horse’s limbs.

Read more at Horse & Hound

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Ask Your Veterinarian: Recovery Time After Long Hauls

by | 05.02.2018 | 11:40am

Kentucky Derby Champion Nyquist is escorted off the van by groom Elias Anaya after arriving at Monmouth Park July 27 ahead of the Haskell

QUESTION: When a horse ships long distances to race, why do some lose so much weight…and how long does it take them to recover fully?

DR. PETER MORRESEY: Transportation causes stress in horses. Many things are done to minimize this, but stress cannot be eliminated completely and like people, horses respond individually. Many studies have been performed to assess metabolic and physical changes in transported horses.

During transport, heart and respiratory rates increase. The stress hormone cortisol is released, promoting breakdown of body tissue and energy stores. The levels of other hormones involved in metabolism (e.g. thyroid hormone) are also altered.

Transportation also results in the horse constantly needing to preserve balance, requiring energy from his muscles. This is most needed during acceleration and deceleration of the transport vehicle, so the skill of the driver also affects body condition.

All of these alterations to the daily needs of the horse over and above maintenance consume energy. In addition to this, exposure to new horses and novel environments provide an infectious challenge; this, too, has an energy cost to defend against.

During transportation, horses vary in their water and food intake. If the horse eats and drinks adequately, losses will be comparatively small and easily made up. When the horse cannot or will not eat enough due to circumstance or personality, these reductions compound the loss of energy stores and body condition (muscle, fat).

Recovery time varies between individuals. Time taken to recoup losses depends upon the ability of the horse to resume intake adequate to replace losses and meet ongoing needs. For some horses this is not difficult and they rapidly adjust with minimal outward signs. For others, situations of stress resulting from a new environment, altered social setting, and variations in the food offered due to different hay/concentrates and water source (which can greatly affect taste) mean many days may be needed to regain body condition and energy stores depleted on their journey. There is no set period over which this may occur. Special attention should be paid in the days following transportation to the vital signs of the horse, with alterations in respiratory rate or effort, or elevations in rectal temperature, requiring prompt veterinary attention.

Opportunities to ease the stress and resulting losses due to transportation include acclimating the horse to trailers or stalls well in advance of the time of transport, progressively altering food offered to match that available during their journey, and ensuring in the initial period after arrival that routine and feedstuffs to as great of a degree as possible do not deviate any more than necessary from that which the horse might expect.

Dr. Morresey began his career in New Zealand as a mixed animal practitioner following graduation from Massey University in 1988. He completed a theriogenology residence at the University of Florida and spent time as part of clinical faculty at the University of Pennsylvania. Areas of interest include reproduction, internal medicine, neonatal medicine, veterinary business and Chinese medicine.

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Possible Link Between Selenium and Cribbing In Horses

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Stereotypic behaviors such as weaving, cribbing, and stall-walking occur commonly in high-performance horses as well as many companion horses. In addition to being unsightly, potentially damaging to the barn, and raising welfare concerns, stereotypic behaviors also result in important health issues such as dental disorders, temporohyoid joint damage, poor performance, weight loss, and colic.

“Cribbing is the most troublesome of these compulsive behaviors. It involves grasping a fixed object with the incisor teeth and aspirating air with an audible grunt,” explained Kathleen Crandell, Ph.D., a nutritionist for Kentucky Equine Research.

The exact reason horses crib remains unknown. Some suggest that cribbing horses have unmet dietary or management needs. Others believe that altered biological functions are the culprits, such as decreased antioxidant levels or increased oxidative stress.

Because trace elements such as selenium, zinc, manganese, and copper protect the body from oxidative stress, one research group* recently explored the hypothesis that oxidation status may contribute to cribbing. To test this theory, blood samples were collected from horses during or immediately after an episode of cribbing and when cribbers were resting. Control horses with no known history of cribbing were also tested. Samples were analyzed for various markers of oxidation.

“The most important finding in this study was that serum selenium concentration was significantly lower in cribbing horses than in controls, with the lowest levels measured while horses were actually cribbing,” Crandell said.

Based on these data, the researchers concluded “that alterations in serum selenium, an important component of the antioxidant system, may play a role in the pathophysiology of cribbing behavior in horses, adding further evidence to the theory that cribbing may be related to increased oxidative stress and alterations in essential trace elements.”

Micronutrients imbalances can affect many physiological processes, which is one reason why Kentucky Equine Research nutrition advisors are available for consultation. They can help with feed analysis, recommend ration fortifiers containing vitamins and minerals such as Micro-Max (Gold Pellet in Australia), and antioxidants such as Nano•E, a water-soluble, natural-source of vitamin E, and Preserve PS (Preserve in Australia) to provide natural-source vitamin E, vitamin C, and other antioxidants.

“Management also plays an important part in minimizing stereotypic behaviors. Strategies such as providing environmental enrichment tools, offering free-choice hay or prolonged grazing, and allowing direct visual contact or prolonged turnout time in groups are thought to improve the welfare of affected horses,” Crandell mentioned.

*Omidi, A., R. Jafari, N. Saeed, et al. 2018. Potential role for selenium in the pathophysiology of crib-biting behavior in horses. Journal of Veterinary Behavior 23:10-14.

Article reprinted courtesy of Kentucky Equine Research (KER). Visit equinews.com for the latest in equine nutrition and management, and subscribe to The Weekly Feed to receive these articles directly (equinews.com/newsletters).   

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