The Horse

SEP 2018

The Horse:Your Guide To Equine Health Care provides monthly equine health care information to horse owners, breeders, veterinarians, barn/farm managers, trainer/riding instructors, and others involved in the hands-on care of the horse.

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20 TheHorse.com THE HORSE September 2018 Are Horses Living Longer? Paradis looked at age demograph- ics in a 2003 study she completed with Margaret Brosnahan, DVM, PhD, Dipl. ACVIM, a clinical assistant professor at Midwestern University, in Glendale, Arizona. They found that the percentage of horses older than 20 in the university's annual caseload increased from 2.2% in 1989 to 12.5% in 1999—an almost sixfold increase over a decade. While Paradis studies horses within a hospital setting, the National Animal Health Monitoring System (NAHMS) surveys horse owners, industry stakehold- ers, and government officials periodically to gain an overview of the horse industry based on responses from farm owners with more than five horses. Paradis says NAHMS results likely underestimate older horse numbers because many re- tired horses live on smaller farms. In its 1998 study the NAHMS program unit found that 7.5% of U.S. horses were 20 or older, while in 2015 it found that 11.4% of U.S. horses were 20 or older. Of that 11.4%, 1.5% were 30 or older. This could lead to today's supposition that horses are living longer. Leading Senior Horse Health Issues When we think about the top senior horse health problems, we need to con- sider whether a condition is truly one of only older horses or whether it's a disease that has worsened over time and appears more prominently in old age. "I think the biggest health issue is the fact that we hardly ever see one thing in isolation," says Ann Dwyer, DVM, a pri- vate equine practitioner at Genesee Valley Equine Clinic, in Scottsville, New York. "When you are older, every single system in your body has undergone the changes that the years bring." Paradis says older horses are usually seen for veterinary care because of the gastrointestinal, musculoskeletal, and respiratory systems. Endocrine Issues Paradis says the disease most commonly associated with old age in the horse is pituitary pars in- termedia dysfunction (PPID), commonly known as equine Cushing's disease. While horses as young as 5-7 can have PPID, she says a large percentage of senior horses develop it, as risk increases with age. This incurable but treatable disorder of the pituitary gland's pars intermedia is characterized by excessive hair coat, delayed shedding, muscle wasting, abnor- mal fat distribution, laminitis, recurrent infections, and more. Musculoskeletal Issues Dwyer sees many musculoskeletal conditions in older horses, usually from a combination of arthritis and soft tissue diseases such as tendonitis or desmitis (tendon or liga- ment inflammation, respectively). Musculoskeletal problems were the second-most-common problem reported in the Brosnahan study. Of the horses seen by university veterinarians for lameness, 37.5% had the hoof disease laminitis (mostly secondary to PPID, she says), while 55% had lameness classified as degenerative disease. Paradis says some older horses might experience progressive degeneration of the suspensory ligaments (which attach at the top/back of the cannon bone, split two-thirds of the way down the cannon, and attached to the sesamoids) in the hind limbs or be predisposed to osteo- chondral disease caused by stiff and brittle cartilage. Gastrointestinal Issues "Colic is always a big fear for the (owner of the) older horse," says Paradis, who says 44% of small intestine problems found in her se- nior horse research were due to lipomas. Dwyer sees many of these strangulat- ing fatty tumors, which wrap around the small intestine and cut off circulation or cause an obstruction. She calls peduncu- lated lipomas (benign fatty masses origi- nating from the mesentery, a membrane that supplies blood to the intestines and connects them to the body walls) one of the two most common life-threatening or -ending emergencies she sees in older horses. The other is severe arthritis in the spine or other skeletal region, which can prevent a horse from rising. Dental Issues In 2012 British research- ers found that 95% of horses over 15 years of age have dental abnormalities; however, owners surveyed in that study reported that only 10% of the horses had dental disease. These conditions include a smooth mouth (where the teeth are worn down to root level), wave mouth (unven wearing of the cheek teeth), step mouth (where The Price of Longevity In one study research- ers found that 95% of horses over 15 had dental abnormalities.

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