Many clients with senior dogs initially sought treatment because their dog was limping on a front leg. We typically think of the hips and knees as being the source of weakness as we age (and this is indeed true in terms of age related muscle atrophy) however a recent study indicates the greatest loss of joint mobility in older dogs is in the front legs.

Study design

The study sought to investigate the extent of the influence of the aging process on dogs’ locomotive system, in the absence of disease. By knowing which joints are most affected, dog owners and physical therapists are able to develop targeted therapy regimes.

Ten Beagle dogs participated in the study (the small number of participants is a potential limitation and needs to be considered when reviewing the results). Five dogs had an average age of 2 years and were categorised as the “young” group. The remaining five dogs had an average age of 10.4 years and were known as the “old” group.

All dogs were fitted with bio-markers attached to their limbs and backs so their joint kinematics could be recorded and analysed. Dogs were trained to trot on a treadmill.

Results

Joint mobility in the forelimb of older dogs

• Carpal joint had less extension and less flexion. The joint’s range of motion was less than in younger dogs.

• Shoulder joint had less flexion.

• Elbow joint had decreased range of motion.

The study found that all dogs in the old group demonstrated restricted joint mobility in the forelimb but particularly in the carpal joint.

Joint mobility in the hind limb of older dogs

• Hip joint – Reduced extension

• Stifle (knee) joint – Reduced extension but greater range of motion.

• Tarsal joint – Greater maximum flexion than younger dogs and greater range of motion.

Findings

The study found that the greatest loss of joint mobility was in the forelimbs. The forelimbs bear approximately 60% of the dog’s body weight so the study surmised that the greater proportion weight bearing increases the attrition of these joints over time. Further, the greater range of motion in the tarsal and stifle joints in the older dogs is theorised to be a compensatory mechanism for the restricted joint mobility in the forelimbs or restricted function of the hip joint.

Finally, it is thought that these findings may be more pronounced in large and giant breed dogs where the loss of articular cartilage may be greater. It is also thought that dogs under greater physical stress such as running at speed or uphill running may exhibit greater levels of joint restriction.

Why do dogs slow down when they age?

The main reason for reduced mobility as dogs age is the reduction in body tissues. Sacropenia or the loss of muscle tissue affects the strength and function of muscles. Muscles atrophy and lose tone as dogs age.

Reduction in body tissues also affects connective tissues such as ligaments, tendons and the fascia. These tissues are required to stabilise the musculoskeletal system including joints and muscle bundles. Connective tissues are also integral to locomotion.

Finally, reduction in body tissues affects joint capsules. As dogs age, less chondrocytes are produced which leads to thinning of articular cartilage (which lubricates and protects the joints) and in turn the formation of periarticular osteophytes (bone spurs), joint capsule thickening, and synovitis. The reduced concentration of chondrocytes progressively leads to the onset of age related degenerative joint disease.

How to treat restricted joint mobility in older dogs?

This study recommended that older dogs participate in physical and exercise therapy that targets all joints. As altered joint mobility causes adaptations to the functioning of the muscles in the limbs and trunk, the study recommended that therapies address the whole dog with particular attention being given to examining and treating the distal limb segments namely the carpal and tarsal joints.

Full Stride provides massage, passive range of motion and exercise therapy treatments to dogs of all ages and breeds. I practice on the north side of Brisbane, Australia, so give me a call or email to discuss how a treatment may benefit your dog.

Until next time, enjoy your dogs.

PS: You may also find these related articles useful:
http://www.fullstride.com.au/blog/muscle+atrophy+in+old+dogs
http://www.fullstride.com.au/blog/passive-range-of-motion-exercises-for-dogs

Source:

Lorke, M., Willen, M., Lucas, K., Beyerbach, M., Wefstaedt, P., Murua Escobar, H., & Nolte, I. (2017). “Comparative kinematic gait analysis in young and old Beagle dogs”. Journal of veterinary science, 18(4), 521-530.