Aging is an inevitable and natural process, but it is never easy. In both humans and it is characterized by diminishing of strength and flexibility. Further, the ability of the body to cope with infection and stress also reduces. Activities become harder and less enjoyable, injury and sickness become more frequent and may be harder to bring under control.
But every horse ages in his own way, and whereas the aging signs may be obvious in some aging steeds, they may be unnoticeable in others. According to Karyn Malinowski, a professor at Rutgers Equine Science Center, scientists have determined that horses physiologically show signs of aging when they attain 20 years and over. During an exercise research trial that took twelve weeks, she detected only a few of these signals. She remembers seeing the horses queuing up at the gate to exercise before they later started bucking, kicking, rearing and running around in the pastures. Malinowski is convinced that the horses were happy to exercise their aging joints.
Likewise, Malinowski’s horse, a standardbred horse called Magic was happy to foxhunt while a senior but she could not bear to look at the images when she X-rayed his legs. She advises that horses need to be kept moving for as long as possible, regardless of their age. Leaving a healthy old horse standing in a stall does not do him any favors.
Yet, irrespective of how energetic your senior horse may seem, the aging process continues, and he will get on better if you identify and respond to the effects of aging in the right way.
Set a Baseline
If the normal TPR (temperature, pulse, and respiration) measurements of your horse are already posted in a place that you and your vet can easily access them, great. If they are not, this is the opportune time to get and record them. Obtain an even more comprehensive picture of his general health by incorporating two additional numbers: weight (computed using a weight tape and horse weight calculator as shown on TheHorse.com) and body condition score (from one to nine). In addition, take a photo of him from a number of angles and archive the pictures in a place where they are easily accessible.
Consequently, rather than relying solely on memory, you can refer to images and reference data when you are evaluating your horse in the future. Many of the age-related changes occur too gradually for you to notice if you interact with your horse daily. But if you can compare the initial and current figures and appearances on a regular basis, say, the first day of each month, you are better able to identify even slight differences. Talk to your vet about these changes and they may assist you to counteract or slow down some of the negative effects of aging.
Conduct Frequent Checkups
It is important that your horse gets an in-depth veterinary checkup every year, including a full oral examination. Adult teeth continue to emerge gradually from the gum as they wear down. They normally last a lifetime, but horses that are very old may have very little parts of one or more teeth that remain that they are no longer attached to the gums. These loose teeth affect chewing and cause pain. Such teeth must be pulled out for the horse to be comfortable again.
As your horse grows old and particularly if health problems crop up, ask your vet if it is advisable to carry out more frequent checkups. Call when questions arise in between the visits.
If an older horse has a problem that can only be rectified through surgery, you need to ask yourself if the benefits of such a procedure are worth the costs. According to Amy Johnson of New Bolton Center (NBC) in Pennsylvania and the University of Pennsylvania, when it comes to colic, research can provide guidance when making the decision. She cites a study conducted done in 2010 by Louise Southwood, her colleague at NBC, which showed that older horses that have undergone colic surgery for particular conditions, in fact, turn out as well as younger horses. She adds that people may be reluctant to consider colic surgery with an older horse due to the fear that the animal may do poorly afterward. Obviously, there may be other reasons why surgery may not be pursued, but the assumption that the prognosis may be worse is generally incorrect.
Malinowski notes that just like humans aging horses have a tendency to replace muscle mass with adipose tissue (body fat). This is problematic for two reasons:
First, the majority of horses aged over 20 years old suffer from some level of arthritis. When they carry excess weight, this aggravates the problem. As Malinowski says, if you are overweight, the knees are the first body parts to be affected. It is, therefore, a good idea to keep the horse fit and maintain the body condition within a range of 5 to 7 to reduce the weight on the joints.
Secondly, the aging of the body comes with increasing insulin resistance. Insulin helps to control blood sugar levels by signaling the liver, muscle and fat cells to convert glucose and then store it in form of glycogen. The reduced insulin sensitivity weakens the body’s ability to break down glucose. This condition is akin to the diabetes type 2 in humans which is also worsened by excess body fat.
Malinowski explains that the response to exercise by a healthy horse is to produce more cortisol, a hormone that mobilizes the stores of glycogen. This results in a production of more glucose to refuel the working muscles so that the horse can recover more quickly, and it also functions as an anti-inflammatory agent.
However, research studies have indicated the cortisol level of older horses does not go up due to exercise as is the case in younger horses. An older horse does not have the same anti-inflammatory properties and its glycogen-metabolism cycle does not kick in as much. As a result, recovery from exercise takes longer in the older horses.
The Stamina of Older Horses
In spite of a horse’s extraordinary ability to exercise, Malinowski points out that aerobic performance diminishes after age 20. Both the stroke volume (quantity of blood ejected by the heart after each heartbeat) and maximal heartbeat start to decrease. This means that the total cardiac output (stroke volume × heart rate) of a horse over 20 years old is considerably lower than that of a younger horse.
As such, she explains, it is crucial to take care when you exercise an older horse in hot, humid conditions. His heart beats harder and his internal temperature reaches 40 degrees Celsius (105 degrees Fahrenheit) earlier than his younger colleagues. She also adds that even though the horse is sweating adequately, he cannot go as far or as long.
Malinowski opines that researchers in Rutgers have also observed that ten minutes after stopping an exercise there is no difference in the heart rate between younger horses and older horses and recovery is quick for both categories. The cardiac output of an older horse is enough to thermoregulate its body while carrying on in the heat. The older horse has the same ability as younger horses to stand around sweating during hot weather. But this does not hold when it comes to thermoregulating and exercising.
Malinowski advises that the ability of the horse to respond to diseases and infections is reduced after age 20. Luckily, because the older horse’s risk of getting exposed to disease-causing organisms may be reduced since he is not frequently going to shows, mixing with unfamiliar horses and inhabiting unfamiliar barns. But new visitors to your home barn may hold infectious agents. Keep any strange horses away from your senior horse whether on turnout or inside the barn and do not share equipment such as blankets, tack or water buckets.
Malinowski also advises that vaccines for things like influenza can work with older horses but the level of antibody production is not as a high as with younger horses. But it is not known if a higher vaccine dosage can make up for the deficit.
Until this is clarified by researchers, she recommends giving older horses their normal vaccinations in spring and then a booster for diseases like encephalitis in late summer or early fall for preventive purposes.
According to Malinowski, older horses need to be dewormed first when necessary and depending on the kind of parasite observed. Due to cold temperatures, there is no need of deworming in midwinter since it is difficult to find parasites crawling on the grass. With wet conditions and warm soil, one should deworm. But it is advisable to have a vet count the fecal eggs and identify the parasite present so you can know which dewormer to use.
Malinowski says that if an old horse has some degree of arthritis, his movement and performance depends on how comfortable he feels in his joints. To prevent Magic from getting any probable aches, she gives him one gram of phenylbutazone before going to foxhunt and one more gram once he gets back. Overusing non-steroidal anti-inflammatory medicines like phenylbutazone can irritate the stomach lining.
Vets report some success in using joint supplements like chondroitin in horses suffering from osteoarthritis, but she warns that these products may not be up to the required standards. She adds that frequent mild exercises can help to ease aches sometimes.
Malinowski advises that older horses staying in a stall need to have deep bedding so as to be comfortable - but it should not be too deep that it prevents them from getting up easily. She adds that rubber mats are wonderful.
According to Johnson, the right diet for an aging horse depends on the individual. The condition of the teeth does play a part and whatever else happening inside his body is also important. Some horses can eat the same diet all their lives, but horses suffering from laminitis may require low-sugar/low-starch diets. This may include hay that is tested to ensure it has low sugar and starch.
Those with weakened dentition--normally characterized by quidding (when a horse chews and drops food, instead of swallowing), dribbling food from the side of the mouth, weight loss and slowed eating, may need their food to be processed into a slurry or gruel to prevent choking and make the nutrients more accessible.
Malinowski says that foods by Dr. Green Pasture are the best option for horses with good teeth and are not obese or susceptible to laminitis. Good quality roughage, or fiber, must be present in a horse’s diet regardless of his age. The type of fiber will depend on the dentition.
Jack Easley, a vet who is an expert in equine dentistry in Shelbyville (Kentucky) advises that geriatric horses with serious tooth problems need food that is basically prechewed. The grain, minerals, hay and everything needed by a horse is ground and made into dissolvable pellets that do not need to be chewed. This is what constitutes senior feed, and they can be used to ensure correct feeding and extend the life span of a horse to point where he does not have any teeth.
Johnson adds that so long as the senior horse is fed properly, mineral and vitamin supplements are not required since many supplemented grain diets and good forages include these. But a horse on a restricted grain diet might need a form of ration balancer to ensure he gets the right amount of vitamins, especially if the hay is not of high quality. However, do not overfeed the horse on minerals and vitamins since any excess will be eliminated as urine.
Discuss with your vet about formulating the most appropriate ration for your senior horse. In addition, monitor the feed bucket - if your horse is having a lot of leftover food, you may need to change his diet.
Further, observe how your horse keeps body weight and condition during the cold winter and summer heat. Malinowski advises that these conditions stress older horses and they may require calories to be added to their diets.
The Bottom Line
Even a very healthy horse will not live forever. But you can give him the best chance of living comfortably for the longest time possible by monitoring his body changes and staying in contact with your vet. Also be on the lookout for any signs of ADR (ain't doing right).
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