With today's horses living much longer than previously, researchers are beginning to address the physical and mental health issues that develop with longevity.
It stands to reason ailments that affect geriatric seniors will also be more prevalent, such as Cushing’s disease, osteoarthritis, gastrointestinal problems, and chronic pain. But what about mental decline? Can horses be affected by senility or dementia, similar to elderly humans?
A question of dementia in older horses
It has long been established that cats and dogs can suffer from dementia; autopsies of both species show the same type of brain lesions as Alzheimer's patients, so it makes sense that horses could be similarly affected.
Surprisingly, there has been very little medical research done in this area. “Although research has been done on the older horse, it is really in its infancy,” says equine geriatric specialist Dr. Mary Rose Paradis, associate hospital director at Massachusetts’ Cummings School of Veterinary Medicine, in her essay, Biology of Aging in Horses.
It has long been established that cats and dogs can suffer from dementia; autopsies of both species show the same type of brain lesions as Alzheimer’s patients. If other animals can experience this form of cognizant deterioration, it makes sense that horses could be similarly affected.
According to the Canadian Alzheimer’s Society, human dementias “are fatal, progressive and degenerative diseases that destroy brain cells. They are not a normal part of aging.” Owners of older horses may note the following changes which are all hallmark signs of human dementia: uncharacteristic forgetfulness, confusion, unusual dependency on companions, aimless wandering, depression and even mood changes such as grumpiness.
Dementia is not a condition strictly reserved for older horses, however; it can affect even younger animals if they contract encephalitis, suffer head trauma or an embolism, develop a forebrain lesion or a number of metabolic disorders.
In a paper on Forebrain Diseases by Robert J. MacKay, BVSc, of the College of Veterinary Medicine at the University of Florida, he explains that the temporal lobe of the cerebrum controls learning-based behaviour and that any structural, metabolic, or psychological disturbances affecting this area may result in dementia. He goes on to define dementia as “changes in normal habits, personality, attitude, reaction to the environment, or loss of learned skills.”
Symptoms may include disorientation in a familiar environment, failure to recognize a handler or object, inability to be led, frequent yawning, head-pressing, irritability, unprovoked kicking or biting, compulsive walking or circling, and dramatic changes in eating or drinking habits.
Dr. Paradis suggests that owners who feel that something is mentally amiss with their horse, regardless of their age, should not adopt a “wait and see” attitude. The problem could be caused by a condition such as loss of vision, brain tumours or liver disease. If the onset of confusion or disorientation is sudden, it could also herald something extremely serious such as Eastern equine encephalitis, West Nile virus or even rabies.
Even severe vitamin B deficiency can cause dementia. “If people start to see changes in their horse’s personality or something that might appear as confusion, they should call their veterinarian to do a thorough exam and blood work,” advises Paradis.
Research into the physiological changes in the older horse, specifically examination of the horse’s brain as it relates to age-related degeneration, is still relatively uncharted territory. “I have never seen any pathology reports that have extensively looked at the horse’s brain in regards to changes that we see in humans with aging,” says Paradis.
“Strokes are very rare in the horse; I’ve only seen one on post-mortem. They don’t develop high cholesterol or plaque in the arteries like humans, which is probably related to their diet and environment. It would be very interesting to actually do a study that looked specifically at sections of old horse brains to see if there are any aging changes.”
In 2010, Italian researchers published a study in the Journal of Comparative Pathology, undertaken because, according to the scientists, “Many age-related changes are described in the nervous system of different species, but detailed studies of brain lesions in aging horses are lacking.”
They identified lesions in the brains of 60 horses aged from seven to 23 years in order to determine whether these changes could be distinguished from pathological (disease) processes in future studies.
As reported in Horse Canada, ff tests show that a horse is, indeed, displaying signs of dementia, there are a number of steps a horse owner can take to make the horse as comfortable as possible for its remaining years:
- Try to keep the feeding and turnout routine the same daily
- Only turn him out with a kind and familiar companion
- Lead him directly into his stall or paddock – don’t leave him up to his own devices to find his way around.
- Make sure that when turned out he is actually using the run-in or other shelter; the concept of staying dry or out of the sun will likely be lost. Blanketing may be necessary in cold weather.
- Monitor his paddock time to make sure he is not being bullied or chased from his food.
- Address any pain issues with medication; discomfort can add to distress and disorientation.
- Don’t ignore him – even old horses need love and regular grooming, even if he has no recollection of who you are.
While euthanasia may be inevitable, judicious caretaking can make an older horse’s life more bearable. He will let you know when it is time.