Muscle strains in dogs – symptoms and treatment

Overview

A muscle injury may be a small, localised fibre injury or an extensive tear that impairs normal muscle function. Mild strains often go without veterinary examination, making their overall frequency difficult to estimate.

Sporting dogs develop both acute injuries and overuse injuries caused by repeated training. Damage may affect the muscle belly or the junction between muscle and tendon.

A common example of a hindlimb injury involves the iliopsoas, a muscle that flexes the hip. Lameness from an iliopsoas injury may be acute or longstanding.

Healing of a muscle and its tendon attachment may require different activity restrictions. The precise location of the injury affects the signs seen in the dog.

Causes

A common cause is overstretching a muscle while running or jumping. The muscle–tendon junction is vulnerable because it is the weakest part of the muscle–tendon unit.

A movement that stretches a strongly contracting muscle can exceed the fibres' ability to withstand the load. Slipping with the back legs splaying outwards can injure the hip flexor.

A direct blow can also damage blood vessels within a muscle. A deep cut or bone fracture can directly tear a muscle.

Torn small vessels bleed into the tissue. Bleeding and swelling may interfere with normal muscle contraction.

Scar tissue forming in the healing area can restrict flexibility. Persistent muscle shortening, called contracture, can eventually impair movement of the neighbouring joint too.

A contusion can also form a haematoma, a local collection of blood within the muscle. Muscle can also be injured during surgery.

The iliopsoas consists of the iliacus and psoas major muscles. These attach together to the lesser trochanter of the femur.

Besides flexing the hip, the iliopsoas helps stabilise the hip and spine.

Risk factors

Intense sport and work expose muscles to peak loads. Agility demands speed, coordination and balance from the muscles.

Racing emphasises speed and power, while pulling work demands endurance. A previously injured muscle is more susceptible to another injury.

Repeated training can cause injury without an obvious single accident. In 72 agility dogs with iliopsoas injuries investigated between 2009 and 2015, ages ranged from 1.5 to ten years.

Injury severity in these dogs was not clearly associated with age or weight. An iliopsoas injury can also develop as a consequence of another limb problem.

In the agility dogs studied, injury severity showed no clear association with sex or breed.

Typical symptoms

• Your dog is lame or takes weight off the painful limb.

• There is swelling around the muscle.

• Bruising develops beneath the skin.

• Handling or palpation causes obvious pain.

• Willingness to train or performance decreases.

• With an iliopsoas injury, the stride may shorten and hip extension decrease.

• An agility dog may extend the back legs less than usual while jumping.

A mild tear may be difficult to notice at home.

A chronic iliopsoas injury can cause recurrent or gradually worsening back-leg lameness.

Local muscle pain and spasms may occur.

Not all muscle injuries cause visible lameness.

During weave poles on an agility course, forward propulsion from the back legs may decrease.

With a scarred shoulder muscle injury, the paw may turn outwards while walking.

Pain may cause a dog to shift weight onto healthier limbs.

Complications and consequences

A severe muscle tear can leave permanent functional impairment. Extensive scar tissue can shorten the working muscle and reduce its ability to contract.

Prolonged complete immobility can predispose a dog to permanent muscle contracture. Scarring of the infraspinatus, a muscle behind the shoulder, may not alter the gait until 2–4 weeks after injury.

The dog may then begin swinging the front leg out to the side to bring it forwards. Improvement in lameness therefore does not always mean that muscle function has returned to normal.

Another muscle injury is possible even after healing. A concurrent knee or hip problem can maintain pain and make recovery harder to assess.

A muscle contusion usually heals without long-term functional impairment.

Diagnosis at the vet

Locating the pain

The vet establishes whether lameness began suddenly or gradually and what the dog was doing before symptoms started. The examination assesses walking and trotting.

Muscles, joints and the back are palpated to locate pain. Neurological function is also examined because nerves or the spinal cord may be responsible for lameness.

The significance of a muscle injury is assessed alongside findings in other tissues. In the case series of 72 agility dogs with iliopsoas injuries, 73.6% had other orthopaedic findings.

In the same series, 27.8% had cruciate ligament instability. An iliopsoas injury was the only identified musculoskeletal cause of pain in 26.4%.

Pain from an iliopsoas injury may become more apparent when the vet extends the hip while rotating it inwards. Cruciate injury and hip dysplasia can coexist with muscle pain.

Sedation may be needed if pain or tension prevents a reliable examination. The limbs are also checked for differences between sides, loss of muscle mass and joint swelling.

The back is examined for pain and muscle tension. When necessary, each limb is examined from the toes up to the hip or shoulder.

Force plate analysis may be used to investigate subtle lameness in a sporting dog. Moving in a straight line and in circles can reveal different ways of adjusting the gait to relieve pain.

Turning increases loading on the inside limbs. The vet also asks about previous medication and its effect on the signs.

Gait assessment may compare walking on different surfaces.

Imaging and the extent of injury

Ultrasound can show disruption of muscle fibres and help locate the injury. Chronic damage at the iliopsoas tendon attachment may appear as calcification on X-rays.

CT or MRI can also help establish the injury's location when needed. A rise in the blood muscle enzyme creatine kinase can support suspicion of muscle injury.

An acute iliopsoas injury often appears as a darker area on ultrasound. Chronic scarring may appear as a brighter, more echo-reflective change.

A mild grade I muscle–tendon injury involves local swelling or bleeding. Grade II involves mild fibre tears and more swelling.

In grade III, damage may involve extensive or complete fibre disruption. Scarring also helps distinguish a chronic injury from an acute one.

Ultrasound findings are always interpreted alongside clinical signs, because a change in the opposite leg may be a symptom-free finding associated with compensation. A tear in the surrounding muscle fascia may form part of a severe injury.

In the same agility dog series, 54.2% had grade I iliopsoas injuries. Grade II injuries occurred in 22.2%.

Grade III injuries occurred in 5.6%. Chronic changes were found in 18.1%.

Bilateral iliopsoas ultrasound changes were seen in 72.2% of dogs in this series. Lumbosacral pain may also lead to spinal MRI to investigate its origin.

Treatment

Initial care

Initially, activity is reduced, pain is treated and cold therapy may be applied to the area. The vet prescribes a non-steroidal anti-inflammatory medicine or other pain relief as needed.

A light compression bandage may be used for some injuries, depending on the muscle's location. Initial care may focus on reducing swelling and inflammation for about two days.

A severe tear may require surgical repair. Planned repair may take place 2–3 days after injury, once swelling has subsided.

Infraspinatus contracture can be treated by surgically releasing the scarred muscle–tendon section. The outlook for return of normal limb function after this procedure is generally excellent.

Rest, controlled movement and rehabilitation

Supervised passive physiotherapy may begin after two days for some injuries. With a mild muscle injury, light controlled exercise may resume after 7–14 days.

Initially, movement is controlled, without running or jumping. A more severe strain may require about three weeks of rest before more active rehabilitation.

An isolated injury to the iliopsoas tendon attachment requires at least four weeks of initial rest. Loading of an operated muscle is carefully controlled during healing.

A rehabilitation plan reduces the harms of excessive immobility. A healing muscle needs an appropriate, carefully controlled amount of loading.

Physiotherapy may continue after initial treatment because of the risk of reinjury. Rehabilitation may also use laser or ultrasound therapy.

Prevention

A gradual warm-up before exercise reduces the risk of reinjury. Training is designed to match the demands of the dog's own sport or work.

The programme includes enough recovery and rest. Avoid repetitive, one-sided heavy training with a growing puppy.

Allow enough time for a muscle injury to heal before demanding activity. Individual exercises and restriction of particular loads can reduce the risk of reinjury.

As well as warming up, the dog's training includes a gentle cool-down after activity. Muscle care should continue after the dog's active career has ended too.

Important for dog owners

A video of lameness filmed at home may help the vet if your dog moves more normally at the practice. Excitement or adrenaline at the appointment can temporarily mask lameness.

Monitoring considers changes in performance and willingness to train as well as walking. Lameness lasting two days needs veterinary examination at the latest; severe or worsening pain needs assessment immediately.

Record when signs began, what your dog was doing beforehand and how rest affects walking. Ask for written instructions on permitted movements, cold therapy, any bandage and rehabilitation exercises. Do not try painful stretches to diagnose the injury at home. Before the appointment, note whether signs are improving, worsening or shifting between legs.

Difficulties on stairs, during jumps and when rising after rest also help describe the problem. A recent accident, training or change in routine may be an important part of the history.

Frequently asked questions

What is the difference between a muscle strain and a muscle tear?

A muscle can be overstretched and partially damaged or torn completely. Signs of a mild injury may be very subtle. A severe tear may require surgery. Treatment is therefore chosen according to the extent found on examination. Ultrasound helps assess damage to muscle fibres.

Does a muscle strain show on a dog's X-ray?

Chronic injury at a tendon attachment may appear as calcification. However, ultrasound shows muscle fibre damage more directly. MRI or CT is also used when needed to establish the injury's location. The method is chosen according to symptoms and the muscle being examined. Measuring a blood muscle enzyme may also support suspicion of injury.

When can my dog exercise again after a strain?

With a mild muscle injury, light controlled exercise may begin after 7–14 days. An isolated iliopsoas tendon attachment injury requires at least four weeks of initial rest. These are different injuries, so check your own dog's activity programme in the treatment plan.

Can a muscle strain recur?

Yes. An injured muscle is more vulnerable to another injury. Gradual warming up and individual exercises can reduce the risk. Ongoing physiotherapy may help. Renewed enthusiasm for training alone does not determine readiness for full activity. Allow enough healing time before demanding exercise.

Can a dog have a knee or hip problem as well as a muscle injury?

Yes. An iliopsoas injury can occur alongside a cruciate injury or hip dysplasia, for example. The examination therefore looks for other sources of pain too. Concurrent conditions can make recovery time harder to assess. Examining the whole dog helps plan rehabilitation. In a referral case series of agility dogs, 73.6% had other concurrent orthopaedic findings.