By Ron Clarkeback text2ps

Horses, like people, are living longer. Aging in horses brings with it the same range of inadequacies experienced by any species growing old. While evidence suggests that only about 10 per cent of horses are presently beyond 20 years of age, increasing numbers live into the 30’s. Thanks to improving veterinary care, the geriatric equine can live a comfortable and humane life beyond “normal” retirement, and the dreaded period when end-of-life decisions are called for.

Defining “old” for horses varies greatly by breed and history of use. Pony breeds tend to live longer and often remain useable up to 30. Larger breeds tend to show age earlier. The sway back, drooping lower lip, dull coat, gradual loss of body condition, grey hair, joint stiffness, hoof deformities and inevitable and uneven dental wear are sure signs of advancing age.

Key areas need to be addressed in the quest to keep horses growing old while remaining active and comfortable.



Teeth

Most horse owners know the expression, “No feet, no horse”. The same principle applies to teeth. Although good dental care is a lifelong event, tooth care in the elderly horse is of utmost importance.

The cutting and grinding forces of horse’s teeth is a crucial first step in digestion. Food needs to be crushed by the teeth and mixed with saliva to ensure digestive enzymes work their magic as food passes into the stomach and intestine. If a horse’s teeth are not grinding forage properly, it affects the efficiency of the entire digestive process. Choke, impaction, colic and laminitis are often outcomes of bad teeth. The elderly horse with poor incisors does not thrive on pasture.  Providing a high quality extruded seniorteeth float concentrate is usually necessary as horses lose their ability to adequately chew grasses and hays.

Regular check-ups and dental care by a veterinarian are essential. A complete speculum examination should be performed on all aged horses every 6–12 months. The frequency of checkups will be governed by grazing conditions, physical condition of the horse and type of feed. Although there is compensatory growth as teeth wear, eventually there is no tooth left to descend and irregular wear creates wave mouths, points and hooks. Periodontal disease and loose molars can also cause discomfort when eating. Loose teeth should be removed to improve ability to masticate and lower the risk of choke.

Immune function

Immune function in horses declines with age. Studies in horses have shown that age-related immune changes are common and that age has a detrimental effect on immune competency, or the natural ability to resist disease. For example, experimental infection of young horses with neuropathic EHV-1 generally fails to induce central nervous system signs, whereas 2/3 of inoculated aged mares develop signs associated with brain and spinal cord insufficiency. Aged horses show a blunted response to many vaccines compared to young horses. Susceptibility to diseases is increased in horses with disturbances in pituitary function (PPID), which is not uncommon in old horses. Many chronic diseases of old horses are characterized by increased inflammation. Treatment of inflammatory conditions may help improve the general wellbeing of old horses.

An annual blood test for the elderly horse is a wise investment and provides an overview of general health­—things like red and white blood cell counts, hemoglobin levels and an insight into crucial kidney and liver function.

Body condition

Monitoring body condition is especially important in the older horse. Obese horses are prone to heart disease, laminitis, and a host of medical conditions. On the other side, failing condition indicates problems that need to be identified, things like bad teeth and parasites. Nutrition often lies at the heart of both obesity and poor body condition. Diets for older horses often need adjustment as exercise levels decline and metabolic needs change. Professionals with expertise in nutrition should be consulted.

A key predictable change that occurs with healthy aging of the horse is loss of muscle mass. Horse owners should know how to body score and measure weight using a weight tape. Recording both body score and weight every 30 to 60 days. Digital pictures are also useful to document changes in body condition over time. Slow, progressive loss of muscle mass can be expected in old horses, but more rapid weight loss is a sign of additional disease beyond healthy aging.  

A major risk for the obese horse is laminitis, or founder, which often has a prolonged and lasting effect in geriatric patients. It comes with huge welfare concerns and often precipitates the painful decision to euthanize a trusted friend. Weight control efforts in older animals are often aligned with the seasons. With spring pastures, comes the tendency to gain weight, followed by weight loss through winter. Because older horses tend to be slower eaters, do not paddock them with younger, more aggressive animals. Individual attention to body condition becomes part and parcel of feeding the old horse.

Dr. Dianne McFarlane, Oklahoma State University talked about common diseases of the aged horse at the 2014 Western Veterinary Conference in Las Vegas. During her presentation she emphasized that owners of old horses often mistake chronic or low-grade disease as normal, age-related change. Understanding the common medical conditions of aged horses and the early recognition and treatment of disease is important for increased longevity.

Tuffy2smAn important component of managing the care of old horses is regular exercise. Keep older horses in steady work as long as possible. Warm up, stretch, and cool out the old horse longer than the younger animals. Maintaining the elderly horse in a pasture or paddock is preferred to a stall. Remember, it is more difficult to recondition than to maintain condition. The “use it or loose it” philosophy applies. Even low intensity exercise, like walking, is beneficial.

Lameness is one the most common problems of the aged horse with half of all horses older than 20 years being lame at the trot and almost 90 percent showing a loss of range of motion of at least one joint. Hoof lesions, including white line disease, cracks, under run heels, or laminitis were present in 80 percent of aged horses. Evaluation of soundness should be performed regularly on older horses. Owners should understand what laminitis looks like because it is often subtle and mistaken for other conditions like colic, muscle inflammation and arthritis. The importance of excellent hoof care in the geriatric horse cannot be overstated.

Cardiac abnormalities, especially murmurs, may be present in as many as 30 percent of older horses. The presence of murmurs is usually an incidental finding and not associated with anything serious. Typically, older horses have a more difficult time recovering from exercise than younger horses. Both heart rate and body temperature are slower to return to baseline. Adequate warm up and cool down periods are important parts of a well-regimented conditioning program.

Lung sounds produced by heaves are common. Horses that spend significant time housed inside exposed to potential allergens or irritants such as hay or bedding are more likely to have abnormal airway noises. In England, 25 percent of horses over 20 years had abnormalities when examined by stethoscope. In addition, horses with pituitary dysfunction showed a high prevalence of pneumonia and heaves at necropsy despite the absence of outward clinical signs.

Eye lesions were present in almost all aged horses, with cataracts, retinal degeneration and abnormalities of fluid within the eye found most commonly. Vision defects are often not appreciated by owners, particularly when horses no longer work and are kept in familiar environments. Corneal injuries are often a complication of poor vision. Healing of corneal lesions in old horses is often delayed.

Skin lesions can be found in 70 percent of old horses. Nodular diseases, like melanomas, sarcoids and other tumors are common. Changes in hair coat are frequent — things like long hair coats found with disturbances in pituitary function, or hair loss associated with allergic conditions, anhidrosis (inability to sweat) and a range of infectious skin diseases. 

Older horses have a propensity to develop cecal impactions. Clinical signs of this life-threatening condition are subtle. Horses showing mild depression concurrent with a decrease in fecal output and appetite should have a rectal examination by a veterinarian to rule out cecal impaction. Failure to treat cecal impactions aggressively can result in fatal bowel rupture. 

Esophageal obstruction or choke is one of the most common age-related emergencies. Often dental disorders result in a failure to masticate feed well causing recurrent choke. Nearly all aged horses have some evidence of dental disease.

Weight loss is an expected consequence of aging due to muscle atrophy. However, more extensive weight loss than that expected due to age alone may occur in aged horses due to many causes. Chronic pain, parasitism, malnutrition, malabsorption, PPID, infectious diseases and competition for food can all contribute to weight loss in old horses.

Some studies have shown that neurologic conditions may affect up to 25 percent of all horses at time of death. Spinal instability, especially the cervical spine, can contribute to ataxia or staggering. Infectious neurologic conditions may be more prevalent in aged horses. Older mares have been shown to be more susceptible to equine herpes virus 1. Old horses, when not appropriately vaccinated, appear more at risk of West Nile virus than younger horses.

Owners should work with veterinarians to determine what changes are normal and what are abnormal in aging horses so that early intervention can occur when needed. Recognizing what is normal aging and what is disease is not always straightforward.

In Dr. McFarlane’s view, early intervention is one of the most important principles of geriatric medicine as the aged have less capacity to adapt to change, tolerate stress or recover from disease. Well-designed health programs for the senior horse start before the descent associated with growing old begins.

Ron Clarke graduated from WCVM in 1970 and has spent 43 years working with the livestock industry. He presently does contract writing and editing for veterinary and agriculture related publications.