“MUSCLE PAIN AND INJURY are poorly recognised as a cause of lameness and poor performance in the horse,” according to Dr Tracy Turner of Turner Equine Sports Medicine and Surgery in Minnesota.
Speaking about the diagnosis and treatment of muscle injuries at the 2016 American Association of Equine Practitioners’ Convention in Orlando in December, he said that muscle conditions such as fibrotic myopathy, stringhalt, tying up, and post-exercise fatigue were better recognised than general muscle injury in horses.
The first two are more usually associated with gait abnormalities and the latter two considered specific physiologic disturbances, he said.
Noting that muscle injuries frequently cause lameness in human athletes and racing greyhounds, he said that similar injuries would be expected in horses.
Horses are frequently exposed to several factors known to predispose to muscle strains and injury, including cold, impaired circulation, muscle fatigue, poor training and so on, so why, he asked, do vets not diagnose muscle injuries more frequently?
He believed the reason was the diagnostic process and the fact that diagnosing muscle injuries in horses was very challenging.
Radiographs and nerve blocks are not helpful and ultrasound is only useful after locating the injured muscle.
Palpation could be useful but not in cases where the muscle injury was only painful during exercise or movement and not when the horse was standing still. “Many muscle injuries causing lameness or poor performance are likely to go undiagnosed and are treated using rest, pain killers, and antiinflammatories.”
A proper diagnosis has to start with a thorough history of the problem, he continued, to determine whether there was a history of a fall or other trauma, the duration of clinical signs, the presence of swelling, and whether lameness or poor performance has been documented.
He urged vets to stand the horse squarely and look and palpate for signs of muscle atrophy, fibrosis, tension, spasm, defects or pain.
Look inside to locate
Dr Turner advocated the use of thermography if the injury could not be located, as the images reflected alterations in circulation of deeper tissues, including muscle, and muscle injury could be detected as either a temperature increase or decrease.
An increase suggested vasodilation associated with inflammation while a decrease indicated chronic scarring, reduced circulation, local oedema, swelling, and vascular stasis due to severe inflammation.
Once the site of injury has been located, ultrasound can be used to evaluate muscle fibre alignment and look for haemorrhage, he said. Sites at which muscle injuries have been located include both the forelimbs and hindlimbs, haunches and the back, with localised muscle soreness readily induced by a poorly fitting saddle or poorly balanced rider.
Once the injury has been found, the next step is rehabilitation, beginning with stretching – so long as this can be done without causing pain.
Other options include: massage (to relax the muscle, loosen and help prevent scar tissue formation, and encourage blood flow and healing of the muscle); therapeutic ultrasound (to speed up the healing process by increasing blood flow to the affected area, decreasing pain by reducing swelling and oedema, and gently massaging muscles to loosen scar tissue); shock wave therapy; electrical stimulation (either transcutaneous electric nerve stimulation or functional electrical stimulation); and pulsed electromagnetic field therapy.
