Page 100 - September 2020

VETERINARY VIEWS
Even when a horse is pastured outside, this doesn’t ensure minimal exposure to endotoxin. Both wind and foot stamping by horses congregating in one area tend to stir up manure and dust to expose airways to endotoxin similar to what is experienced in a stall environment.
Restriction of exercise in a young, growing foal retards cartilage development, but is reversible once a foal is provided with pasture exercise.
CONFINEMENT EFFECTS ON GROWTH AND DEVELOPMENT
Many studies have focused on confinement of young horses and how that impacts musculoskeletal development, particularly joints. One overriding conclusion is that restriction of exercise
in a young, growing foal retards cartilage development, but this is reversible once a foal is provided with pasture exercise. The objective is to allow pasture playtime to achieve sub-maximal loading of the joints. Stall confinement of a young
horse can lead to potential cartilage injury, especially if short bouts of heavy exercise are superimposed on unconditioned joints.
A newborn’s joint cartilage is like a “blank” slate, ready for adaptive change. Particularly before five months of age,
juvenile articular cartilage is a dynamic tissue that continuously remodels, gradually assuming characteristics important to joints’ future strength and resistance to injury. Functional adaptation of “impressionable” cartilage progresses via weight bearing to a “mature” state by 18 months of age.
Normal weight-bearing exercise
is necessary for normal equine limb development. Flexural deformities (contracted tendons) can result from imbalances between growth and exercise. If physes (growth plates) or angular limb deformities (crooked legs) generate pain, then exercise restriction is essential. However, normal growth of a young horse requires normal exercise.
This response of cartilage to mechanical stimulation gives an owner an invaluable tool and window of opportunity to “shape” a durable athlete. Normal development of bone, joint, ligament, tendon and muscles are important for adult athletic capabilities and resistance
to injury.
STALL CONFINEMENT AND INTESTINAL HEALTH
Intensive housing and feeding programs enhance the potential for colic problems
as compared to horses living at pasture
with the opportunity to regulate their own feeding patterns. Recently imposed stall confinement is associated with 54% of impaction colic cases; another study found 62% of colon impactions occurred within two weeks of significant management changes, such as stall confinement or transport. “Change” is the most
important factor – changes in feed and housing pose a bad formula for intestinal health. Yet, for a horse that is accustomed to stall confinement and consistent
feeding, additional stall time is not as
big a worry.
For confined horses, minimize changes in feed type, volume, frequency, and water availability. A good tactic is to reduce quantity of feed, especially of concentrates. While free choice forage intake is known to reduce the incidence of developing gastric ulcers, when necessary feed less calorie-rich hay and supplements. To deter gastric ulcer syndrome, find ways to minimize a horse’s overall stress.
Exercise provides multiple benefits
by increasing metabolism and improving intestinal motility. There is evidence that light physical activity (walking) stimulates GI motility. Fiber digestibility increases by up to 20% in exercised horses, promoting greater retention of the fluid part of the diet and shortened retention of the more formed, particulate part of the feed – this helps to deter impaction colic. Just as dietary changes challenge equine digestion, horses with acute decreases in activity – such as might occur with restricted exercise due to lameness – should be monitored closely for digestive problems that can
lead to colic.
PERFORMANCE EFFECTS OF CONFINEMENT
Confinement has other effects on fitness. A study looked at middle-aged (14 years old) horses that had completed 14 weeks of light to moderate exercise in a collegiate riding program and were separated into three groups: a) pastured 24 hours per day; b) stalled with night paddock turnout
and exercise; c) stalled with night paddock turnout and no exercise. The pasture used was somewhat hilly with ample room to run. The small paddock turnout for the stalled horses did not allow them to move at similar speeds to pastured horses.
The findings of fitness indicators (heart
rate, heart rate recovery, rectal temperature, and blood lactate levels) at the end of the study were compared to the start:
• Pastured horses had lower heart rates at trot,
hand gallop and 10-minute recovery points.
• Non-exercised, stalled horses had higher recovery heart rates whereas stalled, exercised horses had
improved hand gallop heart rates.
• Lactate concentrations were higher for non-
exercised, stalled horses after the hand gallop. • Both pastured and exercised, stalled horses
had lower rectal temperatures after the hand gallop and at the 10-minute recovery.
In summary: Horses given pasture and exercise demonstrated improved fitness. Other interesting findings arose from
this study from GPS units that monitored movement. Over a 24-hr period, pastured horses traveled twice the distance of those allowed only paddock turnout at night, averaging 6.7 miles
of travel whereas those in stalls, with or without exercise, traveled 2.8 – 3.2 miles.
Pastured horses had a larger increase in bone density, significantly different from exercised and non-exercised stalled horses. Once stalled horses are turned out, they should improve bone density while confinement of previously pastured horses to stalls could cause loss of fitness benefits.
These findings might be worthwhile considerations, particularly for the young, growing race athlete.
98 SPEEDHORSE September 2020