Cause & Mechanism of Repair
A muscle strain, or pulled muscle, occurs when a muscle is overstretched or torn. This usually occurs as a result of overuse, improper use or fatigue. Strains can happen in any muscle, but certain muscle strains are more commonly associated with certain disciplines.
Patients often lose a degree of strength and range of motion with a muscle injury and there may be some associated internal bleeding from the injured area. Muscle strains can also be very painful. The severity of the injury can be assessed by how much strength and range of motion they lose, and this can provide an idea as to how long it will take to recover. Muscle injuries can be categorised into three grades; 1 being a mild strain through to 3 being severe. Grade 1 injuries generally take about 2-3 weeks to improve, and approximately 6 weeks to heal completely. Grade 2 strains can take 2-3 months before the muscle is sufficiently repaired to return to full function. Grade 3 strains refer to a complete rupture of the muscle or the muscle-tendon junction and may require surgical intervention to repair.
When a muscle is initially injured, significant inflammation and swelling occurs in order to protect the area. Following the inflammatory phase, the muscle begins to heal, however the mechanism of regeneration involves the laying down of collagen in the form of scar tissue. Over time, this scar tissue remodels, but the muscle never fully regenerates. Scar tissue is weaker and less elastic and as such can leave the muscle more prone to re-injury.
Treatment and Recovery
The majority of acute muscle injuries are partial thickness tears. In humans they can most often be treated successfully with rest, ice, compression, elevation (also known as RICE), and nonsteroidal anti-inflammatory drugs (NSAIDs). In dogs, it is obviously difficult to elevate a limb, but if possible it is still beneficial to treat the area with ice immediately following the injury if it can be detected and for the first 48 hours. Rest is also an important factor to reduce the risk of further injury to the muscle. It is also advised to take your dog to your vet for assessment and they may prescribe NSAIDs or painkillers.
After the initial inflammatory phase is complete, approximately a week, appropriate gentle massage can be applied in order reduce the formation of restrictive scar tissue and aid in the re-alignment of the muscle fibres. Range of motion techniques should also be conducted to promote gentle stretching and optimise healing and functionality. Exercises may also be advised to encourage the dog to use the muscle correctly again and help to strengthen the area.
A return to full activity is usually allowed when the patient is no longer showing signs of injury, has full range of motion, and full strength. All too commonly we attempt to return to our sport or activity with our dogs before these criteria are met. Returning too soon can result in a high chance of reinjuring the muscle and sustaining a setback. It is important to seek the advice of your therapist as to when and how to re-introduce your dog to exercise.