Omega Fields

  • Complications after colic

    Written By:Erin Malone, DVM, University of Minnesota

    Most colic episodes will fully resolve with no long lasting consequences. However, if toxins are released into the abdominal cavity or bloodstream, or if colic surgery is required, the horse will be at risk for other problems.

    Certain bacteria carry toxins. Many of these are found in the gut normally. If the toxin load overwhelms the usual defense mechanisms or if the gut is damaged and lets the toxins leak out, the horse can become ill. These horses may become shocky (poor blood flow causing an elevated heart rate and cool limbs), have reddened or purplish gums or red lines around the teeth, and may seem very depressed.

    The toxins can cause laminitis, clotting problems, and damage to other organs (e.g., kidneys). When horses are stressed (like from colic surgery), their immune system can be weakened. Many horses carry organisms that can cause diarrhea, in particular Salmonella, but are usually unaffected. When stressed, the immune system can no longer keep these organisms under control and the horse develops diarrhea. This can be a severe complication of colic and can be difficult (and expensive) to treat. Many horses will have diarrhea following intestinal disturbances, so they will be closely monitored for salmonellosis.

    If a horse has colic surgery, he will also be watched for incisional infections, infections within the abdominal cavity, and motility disturbances. Some horses will get motility problems following small intestinal surgery that can significantly prolong nursing care and hospital stays. Performing surgery also places a horse at risk for developing intestinal adhesions. Adhesions may make the intestines stick to each other or the body wall in abnormal positions. Some adhesions can cause repeated bouts of colic. In general, surgery for large colon problems has a greater success rate than surgery for small intestinal problems. Luckily the odds for both are improving all the time.

    Permission granted for reprint of article from University of MN Extension. To read more articles from U of M Extension please visit their A to Z library >>>

    http://www.extension.umn.edu/agriculture/horse/a-to-z/

  • Purchasing and using certified hay

    Written By: Krishona Martinson, PhD, U of M

    There is a growing demand for the use of certified noxious weed seed free forage as a prevention to limit the spread of noxious weeds. Noxious weeds compete against native plants, degrade ecosystems, and ultimately pose a threat to wildlife. A common characteristic of all noxious weeds are their aggressive, competitive behavior. Typically, they steal moisture, nutrients, and sunlight from surrounding plants, and can rob waterfowl and mammals of their food sources, nesting areas, and access to water.

    The certified noxious weed seed free forage program is designated to assure that certified forage meets the minimum standards designed to limit the spread of noxious weeds. The Minnesota Crop Improvement Association (MCIA) has been designated under the Minnesota Noxious Weed Law as the official noxious weed seed free forage certification agency in Minnesota. Forage certified under MCIA is eligible to be shipped into restricted area in the United States and Canada were only certified forages can be used.

    In Minnesota, there are no areas where certified hay must be used. When trail riding and camping in public parks, it is considered voluntary to use certified hay. However, if you are planning a trail ride or camping trip with your horse to Wyoming, Idaho, Kansas, Montana, South Dakota, North Dakota, Nebraska, Utah or Colorado to ride on public lands (like the Black Hills National Forest and Custer State Park in SD) then certified hay must be used. These states are requiring that people use certified weed–free hay on all state wildlife areas. The penalty for using non-certified hay on state properties can range from $68 to $1,370, depending on the seriousness of the violation. The offender could also be responsible for the recovery costs for damage caused by noxious weeds to wildlife habitat.

    In Minnesota, the following producers have applied for certification of noxious weed seed free forage. For a current list of producers, buyers can call MCIA (800-510-6242).

    Home county Forage contents Producer and address Phone
    Marshal Alfalfa Dwight Wahlen 3215 18th Street NE, Manvel, ND 58256 701-696-2388
    Olmsted Alfalfa Russell L. Wright 5510 County Road 103 NW, Byron, MN 55902 507-775-2512
    Pine Hay Gary and Rosi Holmes 47280 Fleming Loggine Road, Hinkley, MN 55037 320-384-7873
    Scott Hay John Schulte 6991 Bridle Path, Prior Lake, MN 55372 952-891-2781
    Stearns Alfalfa Dale Spanier 25827 303rd Avenue, Paynesville, MN 56362 320-567-2164
    Swift Alfalfa James R. Gallagher 107 9th Street South, Daverns, MN 56231 320-567-2164

    Forage producers desiring to have their forage certified must apply to MCIA on an application form four weeks prior to each cutting. In addition to a thorough inspection of each field, adjacent areas and storage sites will be inspected. Reinspections can be made at the request of the applicant. Please visit the MCIA website for more information at www.mncia.org.

    Permission granted for reprint of article from University of MN Extension. To read more articles from U of M Extension please visit their A to Z library >>>

    http://www.extension.umn.edu/agriculture/horse/a-to-z/

  • Colic Examinations

    Written By: Erin Malone, DVM, University of Minnesota

    When your veterinarian arrives to examine a colic, she/he will try to determine the severity and the general type of colic. It is very unusual to be able to diagnose the exact cause of colic, but she/he may be able to determine if it is more likely to be an impaction or gas colic, or if it may involve damaged bowel or toxemia. A routine physical examination will help determine the horse's cardiovascular status and identify signs of shock or toxemia. If the horse is very uncomfortable, the veterinarian may give a short acting analgesic/tranquilizer to aid in performing the examination. Depending upon the situation, the veterinarian may then pass a nasogastric tube (from the nostril to the stomach), perform a rectal examination and/or evaluate the abdominal fluid by doing a "belly tap". The nasogastric tube is passed to make sure there is no fluid build-up in the stomach. If there is fluid, this can be a life-saving measure (to prevent rupture of the stomach). If there is minimal fluid, the tube can be used to give mineral oil to the horse to lubricate any impaction. It may also be used to give water to the horse if it seems to be dehydrated. This has the added benefit of stimulating gut motility. A rectal examination allows the veterinarian to palpate structures in the caudal half of the abdomen. Sometimes an impaction can actually be felt. A rectal examination is always somewhat risky, because of the potential for tearing the rectum. Finally, if your veterinarian is concerned about infection in the abdominal cavity or about damage to the intestines, she/he may stick a needle in the abdomen and try to collect fluid for analysis. This test is most useful for determining if the horse needs surgery and is often not performed unless there is a problem getting the horse to a referral institution or if the colic persists. If you have taken your horse to an equine hospital, other bloodwork and tests (such as ultrasound and radiographs) may also be performed.

    Some people believe that it is important to take a horses temperature if they think the horse is colicking. The general thought is that if the horse has a temperature, then they shouldn't' be walked, if he doesn't, then its ok to walk him. However, this is not really the case. Some types of colic are associated with fevers and it is okay to walk the horse to keep him comfortable while waiting for the veterinarian to arrive. However, diseases such as pleuritis, tying up, and laminitis may show signs similar to colic and walking is contraindicated. Pleuritis is inflammation of the chest cavity (pleurisy). It can be detected by pain when the ribs are pressed. Tying up is due to muscle trauma. Muscles (especially in the hindquarters) may look swollen and feel firm. Laminitis or founder leads to heat in the foot and the horse is often reluctant to pick up either foot since it hurts to stand on the opposite limb. In general, if the horse feels better walking, do it. If walking seems to make the horse worse or if you detect signs of rib pain, foot pain, or muscle pain, then stop.

    Permission granted for reprint of article from University of MN Extension. To read more articles from U of M Extension please visit their A to Z library >>>

    http://www.extension.umn.edu/agriculture/horse/a-to-z/

  • Complications with feeding clover

    Written By: Mike Murphy, DVM U of M

    Clover is a desirable feed source for most horses whether used in pasture or in hay because it provides useful energy and acceptable protein and fiber. Problems may rarely arise with clover, just as they can with most desirable feed sources. Clover may be "too rich" at times for horses. The early rapid growth phase of some clovers, like other forages, may contain high amounts of soluble sugars. The soluble sugar content of the plant will decrease as it matures. These soluble sugars and other carbohydrates are sometimes associated with colics and founder in horses fed only pasture in the early spring.

    Growth of mold on clover is occasionally encountered. Two mold problems are generally associated with the common pasture clovers (red, white and alsike). They are associated with weather above 80°F and humidity above 60%. The most well characterized problem is "slobbers." Horses can literally fill several 5 gallon buckets full of saliva in one day. This condition is caused by slaframine, which is produced when red clover is infested with a mold. The mold is generally a rust color seen on the upperside of the leaf. This mold normally "runs its course" in 2 to 4 weeks, depending on weather conditions.

    The second problem in these clovers, black blotch disease, is not quite as well characterized, but has been reported in Minnesota, Washington, and areas of Canada. The mold literally causes black blotches to occur on the underside of the clover leaves, usually closer to the ground where the humidity is higher. Horses ingesting clover with black blotch have been known to develop excessive "sunburn," which is really a thickening and reddening of the white areas of skin due to liver damage. Black haired horses also get the liver damage but the "sunburn" is not visible.

    A third mold condition affects a different clover both white and yellow sweet clover. These clovers are not common in pasture mixes, but are more frequently seen along roadways. The problem arises not from clover in pastures but if sweet clover is harvested for hay AND gets moldy as the hay is baled. Crimping the sweet clover at cutting reduces, but may not entirely eliminate, this problem. An unknown mold converts the naturally occurring cumarol in the sweet clover to dicumerol a blood thinning drug. Horses may bleed if moldy sweet clover hay is a substantial amount of a horse's diet over a number of days. Dicumerol clears quickly, so taking the horse off the hay is the best choice. Injections of vitamin K or blood transfusions may be necessary in extreme bleeding situations.

    However, even with these potential problems, clover is still considered a desirable forage for horses.

    Permission granted for reprint of article from University of MN Extension. To read more articles from U of M Extension please visit their A to Z library >>>

    http://www.extension.umn.edu/agriculture/horse/a-to-z/

  • Unitended Consequences

    Written By Walt Friedrich

    In an earlier article we examined the horse's natural way of communication with others of his species, and how, by domestication, he uses those same natural ways with us. It's the only "language" he knows, and it's virtually all body language. Because neither of us is perfectly fluent in the other's language, misinterpretations can (and do) occur, and when someone is hurt as a result, it's usually a human. This brief series is intended to suggest some of the conditions that can result in unintended but serious damage to ourselves.

    Since we're not horses, we're limited to "reading" our horse from a human perspective, and we can "get it" wrong - and he can misinterpret us as well. For example, we like to "pet" him with our hands, as a way of showing our love and appreciation of him. But horses are very conscious of their personal space, and except for human and equine “friends”, do not allow others into it without an invitation. Sometimes, our horse rejects what we intend as overtures of friendship and mutual admiration. How often have you raised your hand to his nose, just to render a brief pet, only to have him turn away emphatically?

    His action may not mean that he doesn't want our affection; it usually does mean that we've invaded his private space, and he protects it. Fortunately, most often his reaction is as mild as just turning away - another horse invading his space without invitation may well get at least a nip, possibly much more than that as he defends his personal territory.

    The point is to use caution in treating him as a human or even a pet pooch. Though we may have the best of intentions, his misinterpretation could result in our receiving a serious reprimand in the form of a kick or a nip…or worse.

    He can also do us serious damage with no intention at all to do so. Consider: as prey animals his kind discovered ages ago that long life is much more dependent on an ability to escape danger than to take it on and fight it out. And with threats like perpetual lunch-hunting mountain lions sharing his environment, escaping a threat calls for instant action and great speed, letting nothing stop or even delay him. Horses are huge animals of great power, and they dance to their own music, not ours; his sudden reaction to an unexpected touch of our hand on his nose should be taken as a tiny hint of what can happen if we're in the wrong place at the wrong time.

    His needs are far different from his predatory neighbor’s. He's got some pretty good defenses to keep the big cats at bay; he knows his territory down to blades of grass; as a healthy adult he's faster than the big cats (except for the cheetahs, but they don't share his territory); and he's extremely quick to react to danger. Instant escape and tremendous speed and endurance are his only true defenses, and he takes no chances.

    To illustrate the difference between him and us, consider this hypothetical: you and I and a horse are standing in a pasture, chatting, all nice and close to each other, when a prankster sets off a firecracker just behind the horse. Your reaction and mine is to immediately look toward the sound to determine what it was, and then decide if we need do anything about it. In other words, we think about it, just for a second or two. But what does the horse do? He's instantly at full speed, running like blazes at virtually the moment of the sound, because his instinct yelled, “mountain lion!” - no time for thinking. If you or I are in his path, too bad for us - he runs right through us to escape, and we could be just lucky to survive.

    Why on earth is there such a different reaction? You and I can tell very quickly whether or not a sudden situation is an emergency, because rather than to run, our first reaction is to look and evaluate, and then take whatever action we deem necessary. But that takes time. In his case, survivors of his species learned through the millenia that the sudden presence of a predator means they'll either get moving or they'll be the mid-day meal. No time to think, even a few milliseconds can make the difference, so he doesn't bother to look, he's just gone.

    Good thing, too, because his vision, although superb, has an "Achilles Heel”. A brief explanation here of equine vision: with eyes located on the sides of his head, a horse has almost 360 degree vision. Each eye "sees" independently of the other, affording him superior peripheral vision; but while monocular vision is great for awareness, it has no depth perception, meaning the horse has difficulty in determining distance using just one eye. (He switches to binocular mode by turning his head to view with both eyes simultaneously, resulting in superb vision - in 3-D and with depth perception.) Further, his monocular vision is slow to focus, meaning it takes measurable time for him to see clearly, and although it's a matter of just milliseconds, it's too long when the view is of a mountain lion.

    And so because his inability to recognize and identify instantly what he sees can be dangerous for him; his instinct is to move first and look back later, from a safe distance. The problem for us is that when we’re near him when he spooks, we’re in danger of his taking us out as he escapes – and he’ll spook from many more causes than just the sudden bang of a firecracker. You can't stop him from running through you; it can happen much quicker than you can react to avoid it.

    But you can prevent it; he's your horse, and you want to spend quality time with him and not be paranoid about it. So when you're with your horse, it's excellent practice to form the habit of being always aware of your surroundings, and never in his potential flight path if he were to spook. We all know that hanging around his butt puts us in the line of fire from his howitzers (hind feet), but pay attention to his front as well, because that's the way he'll run. When you're dealing with his feet, stay on yours - don't sit as you do footwork on him, but rather, bend - even though it can be hard on the back. Don't daydream when you're on saddle - pay attention to your surroundings. And it's always wise to avoid cramped quarters when you and your horse are together -- his reaction to a fly bite can be enough to get you squashed and stomped.

    This has been Part 2 in a series of writings intended to explain some fundamental differences - those that can get you into trouble -- between your world and your horse's. Please watch for future explorations of these differences.

  • Just Being

    Written By Jenny Pavlovic

    Earlier this year I wrote about taking a therapy dog class with Cay, and how far she’s come since she first arrived here as a practically-feral adolescent 8 years ago. I had decided to enter Cay in the class because of the response she’d shown to my niece’s children, fetching the ball over and over for a 3 year old boy, when she had never fetched the ball for me. She came alive while playing with those kids, and I thought she might like to become a library dog, like Chase, and have kids read to her.

    In the therapy dog class, Cay made many friends and learned to do all of the exercises required to pass the Pet Partners therapy dog test. She sat on command, came when called, walked nicely by my side, and walked through a crowd. She let a stranger brush her and touch her. She even learned to be calm around wheelchairs and funny noises and people who move differently. She did very well, considering she was afraid of practically everything when I first met her.

    After graduating from the class, we were scheduled to take the Pet Partners test the following week. Cay seemed to be ready for the real test since she had passed all of the exercises in class. But she had hurt her leg and was limping, so she was unable to take the test. We rescheduled at a later date and Cay and I continued to practice.

    When the big day came, we started out well enough. But when I told Cay to sit, she just looked at me. She knows the word and knows how to sit, but for some reason she didn’t want to. We tried again and she just didn’t do it. Isn’t it odd that she didn’t do the exercise that most dogs know, the one that was supposed to be the easiest?

    I wasn’t particularly nervous since I’d easily passed the test with both Chase and Bandit in the past. I just wanted Cay and me to give it our best shot. Still, I could tell she was stressed by the test environment, with everyone in the room focusing on her. When we were in the class, with other teams in the room the attention was divided.

    I thought about the test and what was different and how I might have helped Cay better. I tried to stay relaxed, perform my part consistently and do my best to support her. I even gave her calming signals. The message I got from her is that she really wasn’t that interested in doing the exercises. After working with Bandit, a dog who competed in multiple types of performance events for many years and always did what I asked, and then with Chase, who is a natural therapy dog who has always done what I asked, I had to pause and think about what was happening with Cay. Although she had done very well in the class, she wasn’t comfortable in the test environment. I had to listen to what she was telling me.

    Cay doesn’t want added stress in her life. She doesn’t want to work to become anything, she just wants to be herself. She wants to hang out together, go for walks on the hill and by the river, and not strive for anything in particular. She wants to enjoy one another’s company, enjoy the day, and celebrate life. We can all learn from her.

    Each dog has lessons to teach us. I thought Cay wasn’t hearing me when I told her to sit, but maybe I wasn’t listening to her. And she’s right. We could all use more time to just enjoy the day.

    You could say we failed the therapy dog test. But I learned to listen better. Take it from Cay: Don’t let the whole summer get away from you without taking time to relax and enjoy the day with your pups. Cay has come a very long way over the years and I think she would be a great therapy dog. I may consider taking the test with her again in the future, but that will be up to her. I’ll keep listening and we’ll see. For now, we’re taking time to celebrate life.

    With all that’s happening here this summer, Cay has taught me a valuable lesson. In August the kids will visit and Cay will get to play ball with them. Who knows, maybe they’ll even read to her.

    …….

    Cay has allergies this time of year. Omega Fields Canine Shine and Omega Nuggets keep her skin and coat healthy and keep her from feeling itchy.

  • Make better use of round-bales

    Written By: Krishona Martinson, PhD, University of Minnesota

    Drought conditions have severely reduced the supply of hay and other feedstuffs, escalating the demand and driving up prices. Horse owners can reduce hay waste by using feeders and properly storing hay, especially when feeding round-bales.

    In a study conducted in MN, feeding round-bales to horses without a feeder resulted in 57% waste. All nine round-bale feeders tested reduced hay waste, and ranged from 5 to 33% hay waste.

    Research has shown outdoor hay storage losses can range from 5 to 35% depending on precipitation, storage site, and original condition of the bale. For example, the outer 4" layer of a 6' diameter round-bale contains about 25% of the total bale volume, and is most likely to be damaged by weather if stored improperly or unprotected.

    There are a number of techniques that minimize outdoor storage losses:

    1. Bale (or buy) a dense bale as the bales will sag less and have less surface area in contact with the ground.
    2. Use plastic wrap, net wrap, or plastic twine. Research showed that net wrapped bales reduced grass hay dry matter losses by 32% compared with twine bales when stored outside.
    3. Store bales on a well-drained surface. A well-drained, 4-6" coarse rock base will minimize bottom spoilage, as well as using wooden pallets.
    4. Never store bales under trees.
    5. Storage losses are usually reduced by approximately two-thirds with indoor storage and by one-half with good plastic covering (i.e. a tarp) outdoors.

    Permission granted for reprint of article from University of MN Extension. To read more articles from U of M Extension please visit their A to Z library >>>

    http://www.extension.umn.edu/agriculture/horse/a-to-z/

  • Chokecherry

    Written By: Krishona Martinson, PhD, Lynn Hovda, DVM, Mike Murphy, DVM, PhD, and Patrick Weicherding, PhD, University of Minnesota

    chokecherry in bloom

    Chokecherry in bloom

    fall leaf color of chokecherry

    Fall leaf color of chokecherry

    Chokecherry: Prunus virginiana

    Origin: Native to Canada, chokecherry is a widely planted species that has been cultivated since 1724.

    Lifecycle: Chokecherry is a perennial tall shrub or occasionally a small tree.

    Identification: Chokecherry reaches a mature height of 6 to 10 feet and has an irregular, rounded top, often with a crooked or leaning trunk. The leaves are toothed and usually ovate. The long spikes of flowers bloom in June and the “cherries” ripen in August.

    Distribution: Found from Newfoundland to Saskatchewan and south to North Carolina and west to Kansas.

    Habitat: Chokecherry commonly grows on open sites with rich, moist soils, such as along fence rows and streams, on cleared land, and bordering wooded areas. It is relatively intolerant of shade.

    Control: All chokecherries, and other cherry species, should be removed from horse pastures. Do not plant cherry species in horse pastures.

    Toxin: Cyanide.

    When toxic: Cyanide is released from the cyanogenic glycoside (precursor to cyanide) after chewing the forage or seed, or wilting of the forage (i.e., after a frost). The cyanogenic glycoside may be present in higher concentrations in the forage of a young or rapidly growing plant.

    Toxicity: Members of the Prunus (cherry) genus of plants have varying amounts of cyanogenic glycosides in the leaves and seeds of the plants. The Agucatillo (P. brachybotrya), cherry laurel (P. laurocerasus), black, wild, or rum cherry (P. Serotina) and chokecherry (P. virginiana) tend to have more cyanogenic glycoside in the foliage. Apricots (P. armeniaca) and peaches (P. Persia) tend to have more cyanogenic glycoside in the seeds.

    Signs and effects of toxicosis: Animals are most commonly found dead within minutes to a few hours of ingestion of the plant. Rarely, terminal seizures may be observed.

    Treatment: The opportunity for treatment is rare. Sodium nitrite and thiosulfate may be administered in an attempt to treat cyanide toxicity.

    Other information: The fruit of chokecherry (and other cherry species) is not poisonous to humans and is commonly used for making jams, jellies, pies, sauces, and wines.

    Thanks to the following fact sheet reviewers: Ron Genrick, Assurance Feeds and Harlan Anderson, DVM. Photos provided by Krishona Martinson, PhD, University of Minnesota.

    Permission granted for reprint of article from University of MN Extension. To read more articles from U of M Extension please visit their A to Z library >>>

    http://www.extension.umn.edu/agriculture/horse/a-to-z/

  • Carbohydrates: the good, the bad, and the ugly

    Written By Marcia Hathaway, PhD, University of Minnesota

    It is usually the amount of carbohydrates fed at one time, not the inclusion of carbohydrates, that causes problems.

    Carbohydrates are a hot topic in the horse industry. Carbohydrates are essential in all horse's diets. There are, however, different kinds of carbohydrates found in horse feeds.

    The good: The most common kind of carbohydrate is cellulose present in forages. Cellulose is digested by microbes that reside in the horse's hindgut. The microbes break the cellulose down into individual sugars; using the sugars themselves. As a by-product of that process. they produce volatile fatty acids which the horse can absorb and use as its primary energy source. In many cases, all of a horse's energy requirements can be met by forages.

    More good: Another common kind of carbohydrate is starch; present in high quantities in cereal grains, like oats, corn and barley. Starch is digested into individual sugars by enzymes produced by the horse in its foregut. There, the individual sugars can be absorbed by the horse and used as an energy source if the horse requires more energy than can be provided from forages alone.

    The bad: If the horse's capacity to digest and absorb the sugars from starch is not adequate, the sugars pass from the foregut to the hindgut. The amount of starch that can be digested and absorbed in the foregut depends primarily on the amount of starch fed and the amount of time it spends in the foregut, before it is pushed along the gastrointestinal tract and into the hindgut. A general rule of thumb is that no more than 0.5% of the horse's body weight in cereal grains should be fed in one meal. For a 1,000 pound horse, it can digest and absorb the sugars from 5 pounds of cereal grains at one time. To feed more than that amount runs the risk of overwhelming the horse's digestive and absorptive capacity of the foregut and consequently having starch overflow into the hindgut. If more than 5 pounds of grain is necessary per day, it should be divided into two feedings per day.

    The ugly: If starch overflows the foregut and enters the hindgut where microbes utilize it as their personal energy source, the by-products produced in this scenario result in a more acid environment that alters the microbe population and the integrity of the lining of the hindgut. Both of these changes are hazardous to the health of the horse and can potentially lead to laminitis and founder.

    Take home message: it is usually the amount of carbohydrates fed at one time, not the inclusion of carbohydrates, that causes problems in the healthy horse.

    Permission granted for reprint of article from University of MN Extension. To read more articles from U of M Extension please visit their A to Z library >>>

    http://www.extension.umn.edu/agriculture/horse/a-to-z/

  • Carpometacarpal syndrome

    Written By:Erin Malone, DVM, University of Minnesota

    carpometacarpal syndrome

    In recent years, researchers at the University of Minnesota Veterinary Medical Center have identified a crippling form of arthritis that seems to primarily affect Arabian horses, at least in the upper Midwest. This syndrome involves apparent instability of the carpus (foreleg "knee"). This eventually leads to a bony reaction that resembles the callus from a healing fracture and can be seen on the inside of the leg.

    The bone tries (and occasionally succeeds) to bridge the lowest joint in the carpus in order to increase its stability. This is a low motion joint and would not be missed if it were to fuse but the inflammation affects the upper joints. In other words, by the time the lower joint fuses, the upper joints are also arthritic.

    Horses have a gradual onset of increasingly severe lameness that seems to coincide with the development of the bony protruberance on the inside of the carpus (see photo). The affected horses resent flexion of the carpus (i.e. can be sore after farrier work). Most affected horses are lame enough that they cannot be ridden.

    To further investigate this, we found 31 horses with the unusual form of carpometacarpal joint arthritis. 74% of the affected horses were Arabian. The problem affects older Arabians, and the average age at presentation for the initial diagnosis was 14.4 years. It seemed to affect mares and geldings at even percentages. In 7 horses, both forelegs were affected. Two horses were still in work when evaluated but the others were too lame for riding. None of the horses had previous leg surgery but 8 had known episodes of trauma to the carpus. At the time of the study, 10 horses had been euthanized for severe lameness. Five horses lived over 5 years after being retired from riding. Four of the affected horses were necropsied (autopsied), and the anatomy of the carpometacarpal joint was examined.

    During the necropsies, two different types of connection between the medial splint bone and the cannon bone were found. In most horses, these bones contact each other at two sites. In some, the caudal articulation (back connection) is missing, leaving a gap between the bones. In Minnesota, 46% of Arabians and 13% of non Arabians are missing this articulation and have the gap. When horses in California and Florida were examined, this type of anatomy was not seen. When the bones were examined, the Arabians in California did not have a missing connection.

    Based upon our work, we suspect that horses having a gap in the back part of the carpometacarpal joint cannot withstand trauma to the carpus as well as other horses. Injury could then lead to instability and arthritis. Obviously injuries cannot be prevented (particularly in horses) but the increased risk in Arabians makes it important that we recognize the problem and deal with carpal injury more aggressively than is routine. Surgery to fuse the lower joint may help prevent the continued joint degeneration and allow these horses to remain in work.

    Permission granted for reprint of article from University of MN Extension. To read more articles from U of M Extension please visit their A to Z library >>>

    http://www.extension.umn.edu/agriculture/horse/a-to-z/

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