muscle | Horse Racing Free Tips

Study: Majority of Horses Considered ‘Lefties’

Wither measurements of 490 horses taken with a flexible tracing tool have shown that the majority of horses have larger measurements on the left side of their withers as compared to their right, suggesting they are “lefties.” Dr. Katrina Merkies, with the University of Guelph, and a team of undergraduate students digitized and compared years of measurement data to come to this conclusion.

The study included a variety of breeds, including finer-boned breeds like Thoroughbreds and Arabians to heavier breeds like Warmbloods and draft horses. Overall, 60 percent of study horses had larger muscles on the left sides of their withers.

[Story Continues Below]

Merkies and her team considered laterality as a possibility for why horses have a tendency to build muscle on the left. Laterality refers to a horse's preference for using one side of his body. The right side of the brain controls the left side of the body and this is where fearful stimuli are processed, the team reported. Merkies noted that horses will often look at an object they are afraid of out of their left eye or step off trailers with their left front leg first, both of which reinforce the notion that these horses are “lefties.”

While examining differences in body sizes and shapes, the scientists also found that horses of medium height were more likely to have more-curved backs than their brethren of other sizes. The team hypothesize that this is because medium-sized horses are often ridden by adults, whose saddle might not properly fit, being too long in the seat and applying pressure to the lumbar region.

Pressure from an ill-fitting saddle can cause pain and affect performance, as well as prevent the muscles from building in a symmetrical way. Merkies stated that proper and twice-yearly saddle fittings are imperative for equine comfort and the development of balanced muscles.

Noticing Asymmetry Under Saddle? The Solution Could Come From A Single Bell Boot

Though all horses have some degree of asymmetry, a rider can make a slight asymmetry better by placing something loose around the fetlock of the weaker leg, according to a report from the archives of The Horse. The horse will feel it and work harder to engage his limb, said Dr. Adrian P. Harrison, who works with Copenhagen University in Denmark.

The fix could be as simple as occasionally using a bell boot on the weaker leg; the boot uses proprioception to remind the horse that the weaker leg is still there. Proprioception is the awareness of body parts, and knowing and remembering where they are and what they are doing. The bell boot helps a horse “remember” his leg is there.

[Story Continues Below]

This correction could resolve issues relating to an old injury or dominant limb. Old injuries can sometimes cause horses to be unwilling to fully engage a limb for fear of pain; the bell boot trick helps them realize they are pain free.

Harrison created a study using eight sound dressage horses that had slightly weaker left hind limbs when measured using acoustic myography (AMG). AMG measures how muscle and ligament fibers move, and how much power the central nervous system must exert to get a muscle to contract.

Riders of the horses placed a cob-sized bell boot on the horse's weaker limb when the horse was ridden for 60 minutes every three days for six weeks. At the end of the study, AMG shows that the asymmetries had resolved.

Diet And Exercise Key To Managing Tying Up From PSSM

Polysaccharide storage myopathy (PSSM) is a glycogen storage disorder in horses that causes muscles to cramp. It occurs primarily in horses with Quarter Horse bloodlines, like Paints and Appaloosas, but it can also occur in draft horses, draft crosses and Warmbloods.

In normal horses, insulin goes from the blood and is stored as glycogen in the muscle and liver cells. In horses affected by PSSM, a large amount of sugar (glycogen) is stored in the muscle and up to four times the typical amount of polysaccharide (an abnormal form of sugar) accumulates in the muscles.

Horses with PSSM are generally in good weight and have a quiet temperament. They often experience a PSSM episode when they begin training or go back into training after a layup, when their movement is restricted. The episode normally comes on after the horse has been walking and trotting for about 20 minutes.

When a horse has a PSSM episode, their muscles get very stiff and hard, especially over their hindquarters; they will sweat profusely, refuse to move, and their flanks may tremble. When they stop moving, the horse may stretch out as if urinating. Foals with PSSM often show signs of muscle pain and weakness when they have diarrhea or an infection like pneumonia.

Horses that have PSSM should not be fed sweet feed, wheat, oats, barley, molasses or feeds high in starch. They should also be exercised daily. Exercise encourages the body to use glucose properly and improves energy metabolism in skeletal muscle.

Researchers have found that if horses have only their diet adjusted, about 50 percent will improve. If both diet and exercise are adjusted, more than 75 percent of horses with PSSM will have few or no tying-up episodes. Though it may seem counter-intuitive, horses should be turned out and encouraged to move as soon as a PSSM episode has dissipated.

3-D Printer Makes Equine Neck Replica To Train Veterinarians

Similar to doctors in human medicine, veterinarians spend hundreds of hours honing their skills in laboratories before they begin practicing in the field. Learning how to administer joint injections is no different. The equine neck has a complex set of muscles and vertebra, but a new 3-D printer is making it easier for vets to learn how to precisely place ultrasound-guided injections.

Veterinary students typically learn how to do this procedure on equine cadavers, which have a limited shelf life and also have a delay in getting injection results to learn what may have been done incorrectly. To see if 3-D models might be a useful teaching tool, Dr. Alex zur Linden, radiologist and Ontario Veterinary College researcher, joined Dr. John Phillips, an engineer and director of 3D printing in the University of Guelph's Digital Haptic Lab.

Watch a video on how the 3-D models are created below.

Once a CT scan of an equine neck is complete, computer software will highlight the part or parts of the scan that will be printed. The printing takes between three and six hours. The team tested 13 different materials and printers to determine which one best simulated real bone using ultrasound; six of the materials worked for simulating bones or joints.

The model vertebrae were then embedded in ballistics gel that simulated the soft tissue around the bones. The models give vet students the ability to practice procedures with instant feedback; they're also efficient and reusable. Once the lab is complete, the model can be melted down and used again.

The research team is hopeful that the models will become a resource for the scientific community and spur the creation of other3-D models for horses and other animals.