By Karen E. Davison, PhD, and Katherine K. Williamson, DVM
A horse’s outside appearance can be an indicator of his inner health. A shiny hair coat, strong muscle tone, good-quality hooves, and ideal body condition reflect a strong, healthy horse that should be ready to work. Health and nutrition both come into play in supporting a horse to consistently perform at his best. This becomes especially evident in events that require repeated runs in a single day or hard work several days in a row.
Horses in less than top condition cannot sustain top performance. Some horses will compensate and manage for a while but at some point might become irritable when saddled, nervous or anxious when ridden, and eventually stop performing well at competitions. The most noticeable sign of a horse in less-than-ideal body condition is visible ribs. If the problem continues beyond what body fat stores can cover, muscle tissue will break down to generate the calories needed for work. This loss of muscle tissue usually first occurs over the back and loin, or topline, and will eventually affect the neck, hindquarters, and shoulders. Sometimes what owners mistake for muscle creases or definition is really lack of fat cover and muscle mass beginning to diminish.
If there are no other health issues at play, you might be able to improve your horse’s body condition through diet alone. The first step in determining why your horse is not eating well, losing weight, or failing to thrive would be to examine his nutritional program, which is one of the easiest things to change. Here are some basic questions to ask yourself:
- Is my horse chewing and swallowing both forage and grain properly? By observing your horse eating hay, grass, and feed, you might find that while he is taking in food, he might not be chewing and/or swallowing it properly. This is especially common in older horses with poor dentition that are quidding forages or dropping feed. The horse appears to be eating well, but the forage or feed is actually balling up in his cheeks and then dropping on the ground. Have your veterinarian evaluate your horse at any indication of dental problems.
- Is the forage high-quality and available in sufficient quantities? It is not uncommon to find hay and pasture that appears to be of good quality, but is actually poorly digestible or low in certain nutrients. It’s a good idea to have your hay and pasture grass tested so you can assess its nutrient content and digestibility, but horses themselves can often tell you about hay quality. When hay quality and digestibility decreases, the amount a horse is willing to eat also decreases. So if your horses aren’t eating all their hay, chances are you’re either feeding too much or feeding low-quality forage. Additionally, most people feed hay by the flake and do not weigh it. A hay flake’s weight varies considerably depending on hay type and baling. Weighing hay is a good way to determine that you are feeding enough. While it is not possible to weigh the grass your horse consumes, do inspect your pastures to ensure they have adequate edible grass present.
- Am I feeding the right type of concentrate for my horse’s lifestyle? Horses in different stages of life and with different levels of activity have different nutrient and caloric requirements. Choosing a high-quality feed that fits your horse’s age and activity level will help ensure those requirements are being met.
- Am I feeding enough of the right type of feed? Because most people feed by the “scoop” rather than by weight, if is often easy to under- or overestimate the amount of feed you are providing. Weighing your feed with a scale will help. Additionally, be sure to review the feeding directions on the feed bag or tag. Most manufacturers formulate feeds to be fed at a minimum rate of three to four pounds per day for an adult 1,100-pound horse in light work in order to provide the basic nutrients and calories he requires. If you are feeding less than that amount, chances are you won’t meet your horse’s protein, vitamin, and minerals needs, even if the animal is maintaining adequate body condition. In those cases, a more concentrated ration balancer feed might be the best choice. If your horse is on the thin side, you might need to increase the volume you feed him. Sometimes you’re feeding the right feed and simply need to adjust the amount you provide to support the level of work or to compensate for lesser quality hay.
If you’ve determined that your horse’s nutritional program is adequate but his body condition still doesn’t look right, the next step is determining if your parasite control program is effective. Parasite resistance to dewormers and the high prevalence of parasites not routinely detected in fecal examinations (including tapeworms and encysted small strongyles) now make it important to consult with your veterinarian to determine if your parasite control measures are appropriate and effective.
Once you have ruled out nutritional deficiencies and parasite issues, start exploring the possibility that a medical issue could be the source of your horses’ poor body condition or performance. One of the most common manifestations of health problems in horses is poor feed consumption and weight loss.
Following are some common medical causes of poor feed intake and weight loss. Always consult with your own veterinarian for help diagnosing each horse’s individual issues.
Medications—Many medications, particularly non-steroidal anti-inflammatory drugs (NSAIDs) and antibiotics can have adverse effects on the gastrointestinal tract and other organ systems.
- NSAIDs—Drugs in this category include phenylbutazone (Bute), flunixin meglumine (Banamine), ketoprofen (Ketofen), naproxen (Equiproxen), and firocoxib (Equioxx). These drugs are often used in combination, particularly in athletic horses, to treat musculoskeletal inflammation and pain. Problems sometimes encountered when using these drugs include inadvertent overdosing, chronic use, multi-drug interactions, and hypersensitivity in some horses. These drugs can produce oral, esophageal, gastric, and colonic ulcers. They can also produce kidney damage and liver toxicity. Clinical signs associated with adverse effects to these drugs include weight loss, diarrhea, inappetance, colic, poor hair coat/hoof quality, anemia, and low protein (hypoproteinemia).
- Antibiotic Therapy—Veterinarians use antibiotics to treat a wide range of bacterial infections. Commonly used antibiotics in adult horses include penicillin, trimethoprim/sulfa, metronidazole, ceftiofur (Naxcel, Excede), enrofloxacin (Baytril), and gentamicin. Adverse effects can include allergic reactions, diarrhea, renal damage, and liver toxicity, all of which can result in poor appetite and weight loss. Certain antibiotics, including trimethoprim/sulfa and penicillin, are more commonly associated with diarrhea in horses than other drugs; however, any antibiotic can potentially induce this adverse effect.
Medical Conditions—Many medical conditions can result in poor feed intake and utilization. Common ones include:
- Oral/Dental Conditions—Oral ulcers, oral defects (such as parrot mouth or missing incisors), jaw injuries, wave mouth, dental hooks and points, retained caps, and missing molars can all affect chewing and grinding essential to proper feed utilization in the gut. Additionally, some injuries and neurologic conditions can impact the lips, tongue, and cheeks, making it difficult for the horse to pick up feed and chew adequately.
- Esophageal Abnormalities—Tumors, ulcers, erosions, strictures (particularly those associated with prior episodes of choke), and neurologic abnormalities affecting swallowing and peristalsis (passage of feed down the esophagus and into the stomach) can all affect feed consumption.
- Gastric Issues—Ulcers, cancer, and delayed gastric emptying can greatly affect appetite and intake amounts leading to weight loss.
- Small Intestinal Abnormalities—These issues can lead to maldigestion and malabsorption of nutrients, preventing the horse from utilizing food effectively. These conditions could be infectious or inflammatory in origin, or due to cancers such as lymphoma. Many are chronic.
- Colitis—This is a very broad term for inflammation of the large intestine. Colitis causes can be infectious, parasitic, or toxic and usually result in at least some degree of diarrhea and protein loss into the gut.
- Colic—Horses that have had severe episodes of colic or undergone colic surgery commonly experience restricted access to feed, inappetance (sometimes prolonged), poor gut motility, poor absorption, and fragile bowel tissues, along with an increased energy demand due to the healing process. Lack of intake in the presence of increased energy demand can result in very rapid and often profound weight loss.
- Age—Aging horses can experience many problems resulting in poor intake and weight loss, including, but not limited to, pituitary pars intermedia dysfunction (PPID, or equine Cushing’s disease), diarrhea due to poor water absorption in the large colon, dental issues such as tooth loss and wave mouth, decreased saliva production leading to difficulty swallowing and poor feed digestion, pain associated with arthritis, chronic kidney and liver disease, and loss of nutrient absorptive capacity in the small and large intestine.
- Respiratory Diseases—Long-term respiratory diseases such as recurrent airway obstruction (RAO, or heaves) greatly increase a horse’s caloric needs (due to increased work of breathing and high inflammatory states) while at the same time often suppressing appetite. Additionally, horses with RAO frequently have dietary restrictions with regard to dusty hay and grains—many RAO horses fare better when dusty feed is eliminated from the diet. Further, some of these horses are so severely affected that they must be kept outdoors at all times, where they could be exposed to inclement weather even when proper shelter is provided; this could further increase caloric demand. The end result could be significant loss of body condition.
- Chronic Diseases—Many chronic diseases result in poor feed efficiency and some loss of body condition. Melanoma, lymphoma, liver and kidney disease, for example, can affect horses of all ages but are most prevalent in senior horses and can lead to ill thrift, poor body condition, and a poor hair coat.
- Chronic Pain—Do not underestimate pain’s effect on horses’ appetite and calorie needs. Laminitis, osteoarthritis/degenerative joint disease, fractures, tendon and ligament injuries or degeneration, and navicular syndrome are just a few examples of musculoskeletal disorders that can result in sustained pain and lead to dramatic weight loss. Horses that hurt are often harder keepers than sound horses.
Keep in mind that sick, hurt, or underweight horses are often a bit lethargic, especially if they’ve been on a low plane of nutrition. When they get healthy, stop hurting, and are fed properly, they could start feeling much better and initially feel like they have more energy than you want. The nervous energy of a horse that is feeling better generally subsides in 30 to 45 days.
Weight gain and bloom are achieved not only through calories but also from providing a diet complete with essential amino acids, fatty acids, vitamins, and minerals. All these nutrients play a role in hair coat, muscle tone, hoof quality, immune function, and overall appearance and health. Calories replace body fat but regenerating lost muscle and improving hair coat and hoof quality requires complete and balanced nutrition. Whether you prefer sweet feeds or pelleted rations, there are numerous commercially available products designed to provide the calorie and nutrient level needed to support weight in horses at all life stages and activity levels. Remember, ideal condition isn’t just about a horse’s outside appearance; it’s about what goes on inside.