- Jun 1, 2005
Whether you consider a horse to be old at 18 or 25, at some point, senior horses are going to start showing clinical signs of aging--moving more slowly or stiffly, becoming unthrifty, developing a dull coat, or displaying subtle or obvious signs of a disease process. Here are some of the common problems you could encounter in your aged friend and what you should know about those topics to help him through those golden years.
"Older horses, in general, do not commonly develop life-threatening or career-limiting cardiac problems," reports Laurie A. Beard, DVM, MS, Dipl. ACVIM, associate clinical professor at Kansas State University's College of Veterinary Medicine. "Nevertheless, a decrease in aerobic and exercise capacity occurs in older horses. Older horses are not as able to run as fast or as long as younger horses."
Unfit older horses do not thermoregulate as well as unfit younger horses; thus they can become overheated or chilled more easily. The cause of altered themoregulation is unknown, and it's also unknown if training helps improve the age-related decline in these values, Beard says.
Although usually of little consequence, older horses commonly develop aortic regurgitation. "This is a result of slow degeneration of the aortic valve, leading to leaking of blood across the valve when it shuts," Beard explains. "The majority of older horses with aortic regurgitation are clinically normal and do not have exercise intolerance. There is no treatment, as this does not appear to result in any significant problem. The prognosis for older horses with aortic regurgitation is excellent."
Beard notes that in very rare cases, the volume of regurgitant blood can be large enough to enlarge the chambers of the heart, resulting in heart failure. "If a murmur consistent with aortic regurgitation is noted, a physical examination should be performed every 6-12 months. Enlargement of the heart chambers can lead to congestive heart failure, which has a poor prognosis for life."
"Older horses can be more prone to impaction colic," says Bill Hope, DVM, Dipl. ABVP, associate professor (clinical track, equine ambulatory) at Purdue University. "Their digestive systems don't adapt as well as younger horses."
Reduced ability to handle certain types of feed and reduced water consumption in the winter can lead to constipation, then impaction, then colic. Clinical signs include abdominal discomfort or pain (stretching, lying down and rolling, getting up and down, and restlessness).
Treatment depends on the severity of the impaction. "In mild cases, we often administer warm water and mineral oil through a nasal gastric tube to try to loosen up the impaction, or sometimes Epsom salts by stomach tube; it will take about 12 hours or so for the impaction to pass," says Hope. "We also provide pain relievers to keep the horse from lying down or rolling while this process is going on."
If that doesn't work or for more difficult cases, the next step is over-hydrating the horse with IV fluids to try to pull water into the bowel and break down the impaction.
Should that fail, the only option left is surgery. Unfortunately, older horses do not recover as well from colic surgery, although with today's advanced anesthestic techniques, it is less risky than in the past to put an older horse under general anesthesia.
Recovery from anesthesia can be an issue. "Older horses tend to have brittle bones," Hope says. "Sometimes when recovering from anesthesia, they can break a leg because they get up too quickly, then fall, put excess strain on a leg, or bend it back in the wrong direction."
To minimize colic, provide equine senior feeds, which can be more digestible, and encourage water consumption by increasing salt consumption (i.e., add a little salt to the feed, put a salt block beneath the feed in the feed bunk, or provide separate salt blocks). Try to keep drinking water temperate in the winter.
Compromised Immune Function
The field of immunology in older horses is just beginning to be evaluated, says Meri Stratton-Phelps, DVM, MPVM, clinical assistant professor of large animal medicine at the University of Georgia and owner of All Creatures Veterinary Nutrition Consulting Service. "Research performed in humans has demonstrated that the immune systems of elderly people may be disregulated, resulting in an increased incidence of cancer and autoimmune diseases. To date, with the exception of secondary disease processes that occur in older horses, veterinarians have not yet identified a group of diseases that specifically occur in elderly horses due to immune system dysfunction."
Clinical signs associated with secondary disease processes, i.e., malodorous nasal discharge with tooth root infection, sole abscesses and lameness with Cushing's disease, weight loss, chronic skin infection, etc., might indicate that an elderly horse has a compromised immune system. Treatment is currently directed at the secondary disorders.
"The prognosis for recovery from disease in an elderly equine patient depends on the inciting cause of the disease, and in the horse's ability to respond to the medical treatments," Stratton-Phelps states. "Each case must be evaluated as an individual patient."
Equine Cushing's disease (ECD, or pituitary pars intermedia dysfunction) is commonly diagnosed in aged horses, says Rachel Jahnke, BSc, DVM, of Wisconsin Equine Clinic & Hospital in Oconomowoc, Wis. Due to a tumor that forms in the pars intermedia of the pituitary gland, Cushing's results in excess production of cortisol hormone, which in turn leads to hirsutism (a long, often curly hair coat that does not shed out well), laminitis, lethargy, excessive drinking and urinating, muscle wasting (especially over the topline), increased appetite, and recurrent infections.
Management is multifaceted and includes good-quality feed, deworming, regular dental care, routine farrier work, good grooming, and, if needed, antibiotics and drug therapy.
"Horses with ECD are prone to laminitis," Jahnke explains, "so diet is very important; feeding lots of high-energy hay/grain may complicate laminitis. Make sure fresh water is always available as horses with ECD drink more."
Because ECD horses do not shed out well, prevent over-heating by clipping the hair coat in spring and several times throughout the summer, and by providing adequate ventilation such as a fan to keep the horse cool.
"Avoid making the horse sweaty, as this will promote skin infections," says Jahnke. "The owner may want to body clip the horse, then blanket in winter."
Drug therapy includes antibiotics to manage recurrent infections or pergolide, bromocriptine, and cyproheptadine to treat clinical signs of ECD. Jahnke notes that acupuncture combined with Chinese herbs has also yielded beneficial results for some horses.
Prognosis varies. "If managed well, these horses can live several years as very functional, happy horses," Jahnke says. "For some horses, the clinical signs--especially laminitis--become difficult to control and the horse might need to be euthanatized. Occasionally the pituitary tumor becomes large enough that neurological signs are observed and euthanasia might be indicated."
Degenerative Joint Disease
Degenerative joint disease (DJD) refers to destruction of joint cartilage. Often accompanied by inflammation, the disease is progressive and commonly occurs with aging.
"In feral horses, there is a pattern of DJD which is age-related," notes Antonio Cruz, DVM, MVM, MSc, DrMedVet, Dipl. ACVS, ECVS, assistant professor of large animal surgery at the Comparative Orthopaedic Research Laboratory, Ontario Veterinary College, University of Guelph. "However, the way we use horses--strenuous exercise, working on hard surfaces, insufficient rest following strains or injuries--can accelerate degeneration."
Typically, DJD presents as lameness, stiffness, joint swelling, and moving slowly or reluctantly.
"Once the degenerative process begins, there is no return," Cruz states. "Joint cartilage does not regenerate. We can only try to slow it down and to make horses usable and comfortable."
Management techniques include using analgesics on a short-term basis (long-term use might be associated with adverse side effects such as gastric ulcers), anti-inflammatories, joint medications such as hyaluronic acid or glycosaminoglycans, providing a cushiony bed (deeply bedded stall or run-in shed) to minimize pressure on painful joints, good footing for exercise (avoid surfaces that are slippery, deep, or really hard), and proper management of the feet (improper balance places additional strain on the joints). Maintain some degree of activity to prevent stiffness, Cruz advises. Some horses can still be ridden lightly, while others do best with just turnout or hand walking. Soreness after exercise suggests over-use or an ongoing problem that needs to be investigated.
The rate of joint degeneration varies. Good management can keep many horses comfortable for the remainder of their days; other horses reach a point where uncontrollable pain is too overwhelming and there is no quality of life. In those situations, Cruz recommends euthanasia.
Many horses develop periodontal disease or lose teeth prematurely, not as a condition of aging, but from years of neglect. "This is a major issue in older horses," says David O. Klugh, DVM, Fellow in the Academy of Veterinary Dentistry and owner/practitioner of Equine Dental Associates, a referral practice in Newberg, Ore. "It's a common misconception that it's normal for a horse to have its teeth run out. Although the rate of tooth eruption in older horses slows down considerably, it doesn't quite stop completely. Horses should have all their teeth for all of their lives, regardless of how old they get."
With periodontal disease, the health of the gum deteriorates, so inflammation starts to occur between the teeth, leading to infection and loosening. When teeth become too loose, tooth extraction is usually the only viable option.
Signs of dental problems include dropping feed out of the mouth, bad mouth odor, difficulty chewing, swelling on the side of the face, and bitting problems. Gradual depression, an increased quietness or sedentary behavior, or other behavioral changes can also be associated with dental disorders.
"Frequently, by the time you see clinical evidence of a dental problem, the dental problem is pretty severe and may be beyond help, other than extraction," Klugh says. To prevent these problems from occurring, older horses should have their teeth examined at least once a year during a physical exam, but the more frequent the exam, the more likely a problem will be caught before it gets too severe.
Horses that lose so many teeth that they can't effectively grind their feed should be given complete feeds (pellets or grain) softened by water, Klugh suggests. A high-energy equine senior feed is helpful for horses that have difficulties masticating feed such as grass hay.
The bowels of older horses often experience age-related changes that result in chronic diarrhea. Diarrhea can be caused from any number of maladies, including various infections and disease processes; therefore, it's important to differentiate between chronic "old age" diarrhea and disorders due to underlying causes. Hope says that generally age-related chronic diarrhea presents where the horse is basically happy and in good weight, but with loose stools. Diarrhea accompanied by serious weight loss and stools that are watery or bloody suggests an underlying disease.
One major assist to these horses is to provide a more digestible diet. "A pelleted or complete feed can help," says Hope. "Avoid rich hay; grass hay is a little easier to digest. During bouts of diarrhea, give the horse Kaopectate or something similar to coat the digestive tract, and probiotics, acidophilus, or yogurt to restore normal or 'good' bacteria back into the digestive tract."
"Any older animal will eventually develop age-related ocular disease," says Ursula M. Dietrich, DrMedVet, Dipl. ACVO, ECVO, assistant professor in the department of small animal medicine and surgery at the College of Veterinary Medicine, University of Georgia. "This is due to the biologic clock ticking and decline of the cells' regeneration capacity, but it is not known if the aging process may also be influenced by environment, nutrition, care, etc. Treatment of some ocular diseases in horses can be costly and difficult, and they may take many weeks to heal."
In horses, the most commonly seen eye disorders are nucleus sclerosis, corneal problems, and vitreous/retina changes. Cataracts, on the other hand, may be age-related, but are most commonly seen with chronic uveitis (moon blindness) in the horse.
Nucleus sclerosis occurs when lens fibers, which grow throughout life, become more densely packed within the center of the lens. "This gives the lens a less clear appearance and a little bit of a bluish sheen," says Dietrich. "However, the animal is still able to see. There is no therapy indicated."
"Cataract unrelated to other ocular disease is less frequently observed in horses than it is dogs," explains Dietrich. "However, secondary cataract due to chronic inflammation (e.g., equine recurrent uveitis) is more commonly diagnosed. The longer the inflammation persists in the eye, the more likely is the development of a cataract."
Cataract surgery can be done if the cataracts are primary (unrelated to other ocular disease)--usually in very young horses. If the cataracts are secondary to inflammation, surgery is not advised, as inflammation can worsen with the surgery.
Corneal edema occurs when cell layers that protect the cornea on the inside and outside become less efficient. This allows fluid to get into the cornea, Dietrich says, causing corneal edema (fluid accumulation). Chronic inflammation inside the eye can also cause corneal edema. Clinical signs are usually a bluish-whitish haze in the cornea that can affect part or all of the cornea.
"If the edema becomes chronic, corneal ulcers could occur," Dietrich warns. Edema due to age-related degeneration cannot be resolved, but prophylactic treatment is warranted to help prevent an ulcer formation.
Corneal ulcers in horses are caused by age-related changes, trauma, or other conditions. Those ulcers can become secondarily infected with bacteria or fungus. "Corneal ulceration is usually a very painful disease," says Dietrich. "The horse is squinting, tearing, and the conjunctiva is usually very red." Prognosis is best in superficial ulcers that are treated quickly. However, age-related ulcers might take a long time to heal and can recur. Deeper or unresolved ulcers can result in perforation of the cornea and loss of the eye.
Treat ulcers with topical antibiotics and anti-fungals to prevent secondary infection. "If the ulcer is deep, surgery such as a conjunctival flap may be necessary to give mechanical support and promote healing," says Dietrich.
Vitreous/retina changes occur with aging. As the horse gets older, vitreous (the gel that fills the eyeball between the lens and the retina) liquefies and horses start to have "floaters" or loose fibers in the eye. "It is difficult to objectively say how much this affects horse vision," Dietrich says. "Very severe vitreous degeneration will certainly affect vision; in some cases horses are spooking or refusing to jump."
Aging horses often experience slowed hoof growth, a more boxy hoof shape, or flares, says Henry Heymering, Certified Journeyman Farrier, Registered Master Farrier, and president of the Guild of Professional Farriers. "Sidebones, ringbone, and arthritis tend to make the hoof boxy. Various aches and pains can cause flares--for example, hip and/or pelvis pain will cause flares to the insides of the front feet (particularly common in older broodmares), while shoulder tightness or soreness can cause flares to the outsides of front feet. Treating these hoof conditions isn't necessarily a problem--most everything can be managed with care."
Due to degenerative joint disease or other lameness problems, older equines can have trouble tolerating farrier exams and hoof work. "Joints don't bend so well," Heymering states. "Horses can't flex as far or stand as long with one foot up. The farrier may have to shoe the horse without putting the hoof between his legs, and by working on each hoof a little at a time instead of completing each hoof in turn."
For these situations, Cruz suggests administering anti-inflammatories and analgesics a few days prior to farrier work.
The most common reproductive problems seen in older mares involve intrauterine cysts and problems with uterine defense/clearance mechanisms. Older stallions frequently experience reduced semen motility.
Intrauterine cysts occur inside the horns of the uterus, explains Hope. "Smaller cysts can look like pregnancies at early stages, while bigger cysts interfere with the mare becoming pregnant simply by occupying space." There are no clinical signs; cysts are detected via ultrasound.
Treatment consists of puncturing the cysts or removing them with a laser. Although affected mares usually form more cysts within a few years, removal does extend the period of fertility. "Remove the cysts a couple of months prior to breeding to give the uterus a chance to recover," Hope advises.
Inefficient uterine defense mechanisms and poor uterine clearance hinder mare fertility. When either mechanism fails, debris, bacteria, and fluid accumulate in the uterus, hindering pregnancy. Uterine discharge suggests a problem, with ultrasound and culture confirming the diagnosis.
To treat, the veterinarian flushes the uterus to rid the mare of as much bacteria as possible and uses appropriate antibiotics. "Some bacteria don't present a lot of problems, but some bacteria can be very stubborn, somewhat resistant to some antibiotics, and more difficult to clear up," Hope says. It can take a month to restore the uterine environment, so treatment should be done at least one month prior to breeding.
Reduced motility of sperm can be age-related. "Oftentimes, aged stallions do not have a good concentration of semen," Hope says. There is no treatment, although reducing the number of breedings per day helps preserve better concentration.
Arthritis can take its toll on any stallion. The physical strength required to mount a mare on a regular basis is great, and stallions with large books that have to mount mares several times a day will eventually begin to show wear and tear. Joint injections and anti-inflammatories can help make stallions more comfortable, as can mounting a dummy or learning to be collected from the ground.
Recurrent airway obstruction (RAO) or heaves (chronic obstructive pulmonary disease) is a common pulmonary problem in middle-aged to older horses. The cause of RAO is believed to be due to a hypersensitivity reaction to hay and dust, says Beard. "Clinical signs of RAO (during an episode) include a chronic cough, dilated nostrils, increased effort to expire (breathe out), and in some cases a nasal discharge."
Management consists of reducing exposure to mold or dust by keeping horses outside, wetting down hay, and/or eliminating hay completely (switch to complete pelleted feeds). "In moderate to severe episodes, glucocorticoids and bronchodilators may be beneficial," Beard says. "Use only when necessary, as glucocorticoids can result in immunosuppression, laminitis, and adrenal suppression, while bronchodilator drugs lose effectiveness if used for more than a few days."
Prognosis depends on the ability of the owner to change the environment, and the severity of the disease.
Weight loss in older horses occurs for several reasons, including underlying disease, bad dentition, and impaired ability to absorb nutrients; it's imperative to identify the cause of weight loss in order to initiate proper treatment. Treatment and prognosis depend on underlying cause. A good, well-balanced diet can help, Hope states. (See page 95 for more information on feeding older horses.)
It's an unhappy fact of life that sooner or later disease, injury, or euthanasia will claim your horse's life. But by scheduling regular wellness exams with your veterinarian, practicing good management, monitoring physical and behavioral changes, and initiating prompt veterinary attention when changes occur, you can optimize the quality and quantity of your aged equine's life.
TIPS FOR KEEPING OLD HORSES HEALTHY: Prevention Helps Keep Horses Alive Longer
Practicing prevention and wellness throughout a horse's life and during its senior years can help minimize or delay the onset of various "old age" disorders. Our experts offer the following tips:
- Monitor for changes in body condition, behavior, and attitude, suggests Philip J. Johnson, BVSc (Hons), MS, Dipl. ACVIM, MRCVS, professor of equine internal medicine in the College of Veterinary Medicine at the University of Missouri-Columbia. "Failure to maintain satisfactory physical condition could be implicative for many different problems."
- Provide seniors with adequate exercise to maintain muscle tone and flexibility of joints. Says Johnson, "Carefully observe the horse's reaction to work and use common sense. Different horses seem to 'age' at different rates. Some individuals are clearly capable of a higher level of sustained exercise than others. Exercise is also beneficial in order to promote insulin sensitivity in horses that might also be affected with insulin resistance issues."
- Don't overdo exercise or rush a recovering lame horse back to work, regardless of any age, warns Antonio Cruz, DVM, MVM, MSc, DrMedVet, Dipl. ACVS, ECVS, assistant professor of large animal surgery at the Comparative Orthopaedic Research Laboratory, Ontario Veterinary College, University of Guelph. "Horses that have been heavily exercised in the past may develop arthritis quicker and sooner," he says. "Exercise control and management, adequate farrier work, and adequate exercise surface are very, very important. If a horse is getting lame, give him the rest he deserves. Even with medications, it still boils down to resting the horse with an injury for the appropriate period of time."
Maintain regular oral exams. "Careful dental examinations are very important, and appropriate action should be taken as problems are recognized," Johnson says. "If the teeth are maintained as comfortably as possible (i.e., minimal sharp edges that might cause pain during mastication), modern feed products are wonderful for geriatric horses with advanced dental attrition. Note that dental attrition is faster in horses that had been fed grain-rich rations throughout their lives; this phenomenon results from the increased grinding down of the teeth by relatively hard grains."
Explains David O. Klugh, DVM, Fellow in the Academy of Veterinary Dentistry and owner/practitioner of Equine Dental Associates in Newberg, Ore., "Green grass pasture helps keep the chewing surfaces even and allows for normal chewing motion; this translates to normal rates of attrition and eruption in the teeth. The mechanical effects of attrition and force delivery to the tooth haven't been addressed in feed."
- Keep up with your deworming program. Even though most older horses have developed "immunity" against parasites, their immune systems begin to decline as they age, making them more susceptible.
- Aid immune health by providing proper nutrition, advises Meri Stratton-Phelps, DVM, MPVM, clinical assistant professor of large animal medicine at the University of Georgia and owner of All Creatures Veterinary Nutrition Consulting Service. "Balanced nutrition is essential for horses of any age, but is especially important in elderly horses that may not be able to masticate and digest their food as well as younger horses," she says. "Use of dietary supplements should be approached with caution, as some nutrients can be toxic when fed in excess of the horse's requirement (i.e., selenium). Antioxidant supplementation may help to enhance immune system function, but research into this area still needs to be performed before appropriate dosages and treatment regimens can be recommended."
- Groom your horse regularly to inspect surface condition. This is especially helpful if the winter coat is very thick.
- Promote mare reproductive health, advises Bill Hope, DVM, Dipl. ABVP, associate professor (clinical track, equine ambulatory) at Purdue University. Avoid dystocia (be present at delivery to assist with any problems that can help prevent uterine damage), flush out the uterus with saline a few days postpartum (gets rid of infection-causing debris), and culture mares before rebreeding (catching and treating infections early reduces damage from inflammation).
- Minimize the onset of recurrent airway obstruction by improving barn ventilation, recommends Laurie A. Beard, DVM, MS, Dipl. ACVIM, associate clinical professor at Kansas State University's College of Veterinary Medicine.--Marcia King
ADVICE ON MANAGING OLDER HORSES: Modify His Environment
As your horse moves through his senior years, he'll likely need modifications in his environment and routines to keep him happy and healthy. Karin D. Bump, MS, PAS, professor of equine studies at Cazenovia College in Cazenovia, N.Y., offers the following advice:
Introduce new routines and activities slowly--Consistency is important for the older horse. Sometimes horse owners feel that turning a horse out to pasture after a long life in the show ring is the best way to thank their horses. For some horses, however, this might not be the best approach. Behaviorally, horses become accustomed to their surroundings and their routines; a dramatic change can be a hard adjustment for an older horse. Introduce new routines and activities slowly, gauging how they are responding with each change.
Provide more bedding for sore joints--Extra bedding can be very helpful for the older horse, particularly in cold climates, but watch to see if the extra bedding impedes his ability to get up and down or to move around.
Turnout changes--The geriatric horse has a higher probability of dropping down in pecking order status. This becomes important if his feed intake is reduced because other horses are keeping him away from the feed area. But unless you see pecking order aggression, don't automatically remove the senior horse from other horses of younger age. A personal example: We had one old gelding who was the best baby-sitter for the newly weaned colts and for the 2-year-olds in training; when weaning and training time rolled around, he was in his best spirits and condition. Continually evaluate each horse individually.
Provide appropriate exercise--Although older horses usually become more limited in what they can do, exercise is still important. Monitor your horse's condition and soundness, then modify his routine as necessary. Lots of walking, light jogging, and slow longe work on a large circle are good forms of exercise beyond the exercise afforded by turnout. For a show horse that's behaviorally accustomed to the showing lifestyle, maintaining the habit of some type of show preparation can keep him feeling like he has a job to do.
Pay attention to weather--In cold weather, the horse should either have an ample winter coat or blankets if he's been clipped. Horses stay healthier when the barn temperature is not dramatically different than the outside temperature, as it's hard on a horse to go from hot temperatures to cold. During hot weather, dehydration, electrolyte loss, bugs, and skin problems can be issues: Provide ample, free-choice water and electrolyte solution, groom regularly to pick up on skin and dehydration issues, and provide fly protection or turn-out during times when insect activity is reduced.--Marcia King
About the Author
Marcia King is an award-winning freelance writer based in Ohio who specializes in equine, canine, and feline veterinary topics. She's schooled in hunt seat, dressage, and Western pleasure.
POLL: Colic Surgery