Do Horses Need Magnesium Supplements?

Magnesium has an important role in muscle and nerve function. Horses that are deficient inmagnesium may be unusually spooky and excitable, and they may have muscle tremors or cramping. However, this deficiency is rare because grass and hay normally contain sufficient magnesium to meet the horse’s requirements. Giving a horse too much supplemental magnesium may have no effect at all on nervous behavior or muscle cramping, and may cause serious digestive and metabolic problems.

There are several factors that can decrease the magnesium content of pasture plants. If the soil in a region is deficient in magnesium, growing plants will have a lower content. Lush spring grass has a high moisture content that tends to dilute other nutrients, so each mouthful of this grass will have less magnesium than what would be found in a similar mouthful of summer grass. Diets that are unusually high in potassium can reduce the horse’s ability to absorb magnesium. Finally, intensely exercised horses lose some magnesium in their sweat.

Even if one or more of these conditions exists, horses are not likely to need much, if any, supplementary magnesium. A veterinarian can draw blood for analysis to see if the horse is low in magnesium, and an equine nutritionist can suggest the best way to supplement if this is needed. Because horses are always replenishing magnesium as they graze or eat hay, owners who decide to supplement this nutrient should err on the low rather than the high side to avoid diarrhea and other problems in their horses.

SOURCE: KER

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Vital Signs: Know What’s Normal for Your Horse

When you read a book or magazine article that talks about a horse’s vital signs, the normal rates are almost always given as a range rather than a single number. That’s because an individual equine’s pulse, respiration, temperature, and other signs will be influenced by the horse’s age, stress level, location, health status, fitness, and the time of day, to name a few factors. A young horse taken to its first show or trail ride might have a much faster pulse than an older horse that’s relaxing in its familiar stall at home, and a horse with an infection would probably have a higher temperature and faster breathing rate than one in good health.

When a veterinarian is called to examine your horse for any reason, he will probably check these vital signs and use the results to help determine what may be wrong. You should know the ranges that are normal for your particular horse in order to compare them with whatever the veterinarian has found. To learn about your horse’s vital signs, it will be necessary to take several readings at various times and note any changes you observe.

Checking heart rate is easiest with a stethoscope placed on the girth line just behind the horse’s left elbow. You may have to move the stethoscope around a bit to find the “lub-dub” sound that the heart makes. You can also slide your fingers under the horse’s jaw and feel for the pulse; keep checking by pushing your fingertips outward against the jawbone. The horse’s pulse will rise when you enter the stall, especially if you are carrying tack or are accompanied by a stranger. It will also be higher when the horse is excited or stressed for any reason such as being at an unfamiliar location, in the presence of strange horses, or faced with an unusual stimulus of any kind. The pulse will generally rise with fever, pain, fear, stress, or exertion. It may be lower in horses in top athletic condition and also in horses that are in shock or hypothermia. The normal range is from about 30 to 45 beats per minute for mature horses; foals will have a more rapid pulse.

Counting respiration can be done by watching the ribcage expand and contract, by seeing the horse’s nostrils flare, or by cupping a hand loosely over a nostril and feeling the exhaled breath. The normal range is about 8 to 16 times per minute, generally faster in horses that are nervous or in pain and slower in those in shock, hypothermia, or drug-induced depression. Fit horses also breathe somewhat more slowly; those with colic, discomfort, or heat exhaustion breathe faster, as do horses that have been exercised recently.

Finding the horse’s temperature is probably the simplest chore because a digital thermometer is used for this reading. While someone else is holding the horse, pull the tail out of the way with one hand and slip the lubricated tip of the thermometer about two inches into the horse’s rectum with the other hand. Don’t let go; the thermometer can disappear if the horse tightens its sphincter muscles! When the thermometer beeps or indicates the reading is complete (this make take a minute or two), withdraw the thermometer and check the temperature. The normal range is about 99.5 to 101.5 degrees F, but can be higher in horses with infection, pain, or exposure to strenuous exercise. Horses that have been exposed to high environmental temperatures may also show a rise in body temperature. Lower readings will be seen in horses that are in shock or have hypothermia.

If you have trouble checking your horse’s vital signs, ask your veterinarian to help you learn the proper procedures. You can also find out how to check gum color, dehydration, gut sounds, and the horse’s digital pulse (taken at the fetlock). Knowing the normal readings for your equine will help you and your veterinarian determine what may be wrong with the horse.

Source:KER Newsletter

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

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

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

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

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

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

Source: KER Newsletter

Importance of Vitamin E for Horses

Vitamin E has numerous functions in the body, many of which are still not completely understood. Vitamin E is essential for the integrity and optimum function of reproductive, muscular, circulatory, nervous, and immune systems.

Its action as a natural antioxidant is seen as the underlying factor of most vitamin E functions. Vitamin E is considered to be the most effective natural lipid-soluble chain-breaking antioxidant. The action of vitamin E is very important in cell membranes, protecting them from peroxidative damage. This is especially important in the mitochondrial membrane, where enzymes involved in respiratory chain energy production are located. Selenium, like vitamin E, also acts to prevent lipid peroxidation, but with differing mechanisms. The two complement each other, one appearing to be able to compensate for the absence of the other to a certain extent. Signs of vitamin E deficiency, such as nutritional muscular dystrophy, are often the same as those seen with selenium deficiency. Other diseases associated with low serum vitamin E include degenerative myelopathy and degenerative myeloencephalopathy.

There are at least eight forms of vitamin E found widely distributed in nature: four tocopherols and four tocotrienols. The majority of vitamin E activity in animal tissues is generally assumed to be alpha-tocopherol and when it is present it is used preferentially. Tocopherols are extremely resistant to heat but readily oxidized. Natural vitamin E is subject to destruction by oxidation, a process that is accelerated by heat, moisture, rancid fat, and certain trace minerals. Horses have the capability to store much less vitamin E than vitamin A. However, stores are thought to be able to compensate for about four months or more of inadequate vitamin E intake.

Vitamin E is abundant in green growing pastures, particularly in alfalfa (lucerne). The content diminishes with maturation, especially after the plants go to seed. Harvesting the forage diminishes the quantity of vitamin E present, and storage of the hay further decreases the amount of vitamin A by as much as 50% in the first month. Vitamin E is abundant in the germ of grains and oils pressed from the germ. Vegetable oils such as corn and soybean oil are relatively high in vitamin E. In practice, the vitamin E content of other feedstuffs is variable and not readily predictable because of handling and storage time. Therefore, it is common practice to supplement animal feeds with vitamin E. Since esterification stabilizes vitamin E, commercial supplements usually contain tocopheryl acetates.

Vitamin E appears to be the most researched vitamin at this time in production animals. Several studies have reported evidence of oxidative stress occurring with exercise in both humans and rodents. Since the main function of vitamin E is to protect the cell against peroxidative damage, lipid peroxidation as a result of exercise may be influenced by the concentration of vitamin E present in the diet. Signs of vitamin E toxicity in the horse have not been produced.

Back Pain in Horses

Wringing the tail, throwing the head, jigging, bolting, not standing still to be tacked up or mounted, refusing to pick up a lead or a gait…these are only a few of the behaviors horses might show when they have back pain. Some of these signs are more subtle than others, and they may come and go over the course of time, making it difficult for owners to pinpoint what is causing them. A veterinarian can often diagnose back pain in a horse, but in some cases, even a professional may have trouble telling just where the horse’s pain is.

Back pain in horses can be caused by a number of factors includingarthritis, malformed vertebrae, injuries, overwork, or a training program that asks for a higher level of performance than the horse has been prepared for. Horses that develop back pain from being ridden may have strained some of the muscles that help to move and stabilize the back. When pain and inflammation restrict the action of these muscles, the job of stabilizing the back falls to other muscle groups that are less able to perform this function.

In horses, the longissimus and iliocostalis muscles lie parallel to the spine for the entire length of the back. These muscles function to flex the horse’s back in both horizontal and vertical planes. The multifidus muscles form a deeper layer and instead of influencing the whole back, each one of these shorter muscles controls only a few vertebrae and the joints between them. When pain occurs, the multifidus muscles fail to stabilize the intervertebral joints as efficiently as they should, and they tend not to recover full function even after the pain has been relieved. Over the course of time, instability increases the horse’s risk for developing arthritis in these joints.

A veterinarian should always perform an examination of a horse that shows signs of back pain. Because back pain can be indicated by a range of behaviors, owners should consider the possibility that back pain might be a cause of resistance, other training problems, or lameness elsewhere, such as the hocks. Ruling out this factor may clarify training decisions such as whether to give the horse a break or try a different approach to teaching a new skill.

Humans recovering from back injury have benefited from physical therapy aimed at reactivating muscles that stabilize the vertebrae. Hilary Clayton, a professor in the equine sports medicine department at Michigan State University, has conducted research that shows the same effect can be achieved in horses. If the examining veterinarian feels that stretching exercises would help a horse build or regain strength and flexibility in its back muscles, the owner can incorporate these exercises into the daily schedule. Commonly known as “carrot stretches,” the activities involve the owner holding a carrot or other enticing treat just out of reach to encourage the horse to stretch its neck and back both lengthwise and laterally. Beginning exercises should ask for just a little bend or stretch to be held for a few seconds before allowing the horse to reach the treat (wear gloves to protect fingers from enthusiastic carrot eaters!). Each session should ask for a small increase of effort.