Joint hypermobility syndrome or JHS is a disorder affecting the connective tissue that leads to joint laxity. It has been widely studied in humans and features of the disorder include:

• Joint – joint laxity, myalgia, subluxation, osteoarthritis and pain.

• Soft tissue – ligament, muscle, meniscus tear, bursitis, tendinitis. In humans with JHS muscle strength and function are impaired along with their balance.

• Spine – Disc prolapse, spondylolysis, spinal abnormalities

In humans extra articular features of JHS include, chronic pain, IBS, constipation, anxiety, depression, bruising, cardiovascular issues, and reduced proprioception.

In human studies, there is an association between joint hypermobility syndrome (JHS) and anxiety. People with JHS experience increased fear, agoraphobia and pain. The strongest association between JHS and psychological conditions is with anxiety disorders.

In humans, it is thought there are two possible mechanisms for the association between joint hypermobility and anxiety disorders. Firstly, it is thought that patient’s autonomic responses are dysfunctional with the following regions of the brain being affected: insular cortex, amygdala and anterior angulate cortex. These brain regions are linked to autonomic arousal and heightened emotional states.

The second proposed mechanism is the link between anxiety, pain and the perception of joint instability. Patients with JHS have increased exteroception (perception of their environment), nociception (perception of pain), somatosensory amplification and decreases proprioception (leading to coordination difficulties).

Does joint hypermobility occur in dogs?

While JHS has been studied in humans, little research has been performed in other species including dogs. A retrospective study of guide dogs and assistance dogs has found similar associations between excitability and joint hypermobility to those identified in human studies.

The study reviewed data collected from 2001 – 2014 by guide dog organisations. Two forms of data were analysed for the study:

• PennHip assessment for hip distraction performed when dogs were approximately 18 months old.

• C-BARQ behaviour assessment performed when the dogs were approximately 12 months of age.

In total, 2,381 cases were analysed.

The cohort was clustered into four groups based on their PennHip assessment scores and analysis performed to identify behaviour and demographic factors of the groups with the highest and lowest levels of hip hypermobility.

Demographic factors affecting hip hypermobility in dogs

In this cohort, female dogs were 3.66 times more likely to have high hip distraction scores than males.

Analysis of the correlation between breed and high hip distraction scores indicated that Golden Retrievers were 8.58 times more likely to have high joint hypermobility scores compared to other breed groupings. On the other end of the scale, Labrador Retrievers and German Shepherds were 5 times more likely to be in the lower hip distraction cluster.

Behavioural factors affecting hip hypermobility in dogs

In terms of behaviour, dogs in the highest joint hypermobility cluster also had higher incidence of excitability and aggression toward familiar dogs.

Excitability

This study draws a link between excitability in dogs and similar emotional responses in humans with JHS. When assessing a dog’s emotional response to a stimuli, two dimensions need to be considered:

• Valence – A determination of the character (positive or negative) of the response.

• Arousal – The intensity of the response.

In dogs, excitability can be defined as the ease with which the dog enters a high state of arousal (regardless of valence) in response to an external stimuli. Signs of excitability in dogs may include:

• Marked behavioural arousal

• Barking or yelping

• Rushing toward or around the source of excitement

• Difficulty calming down

For each one point increase in C-BARQ excitability scores, the dog was 1.26 times more likely to be in the highest joint hypermobility cluster.

This study links high levels of arousal in dogs with signs of anxiety in humans. It is thought that high levels of arousal impairs cognitive function which can lead to the development of anxiety disorders. Based on this association, this study’s findings aligns with the findings in human studies of the link between anxiety and JHS.

Aggression toward familiar dogs

The second set of behavioural traits analysed was the association between C-BARQ scores on aggression toward familiar dogs with joint hypermobility scores. The study used the “aggression toward familiar dogs” C-BARQ trait as an indicator of the dog’s anxiety level. The reason for the link between aggression and anxiety was based on thinking that the dog’s level of anxiety or ambivalence in a group of dogs factor affects intra-group aggression. Therefore, the higher the level of aggression the higher the anxiety levels.

The study found that for each one point increase in C-BARQ aggression to familiar dog score, the dogs was 1.7 times more likely to be in the highest joint hypermobility cluster. As an indicator of anxiety, this finding aligns with those of human studies of JHS.

Pain

Another influencing factor on anxiety in humans with JHS is pain. In this study, the differences in behaviour of dogs with high joint hypermobility could not be attributed to pain due to the absence of differences in behaviour traits typically associated with pain including:

• Touch sensitivity

• Energy level (lower levels of activity indicator of pain)

• Aggression in other situations

This study concluded that similar to findings in human studies, there is a link in dogs between joint hypermobility and emotional arousal states.

Treatments for joint hypermobility

In humans with JHS, there is evidence that physical therapies that address muscle strength and function are beneficial to keep patients active and participating in regular exercise. Additionally, manual therapy that address motor control are effective in restoring proprioception, balance and co-ordination.

Further, manual therapy and relaxation training in humans that addresses the emotional states linked with JHS have some benefits.

Likewise in dogs with joint laxity, the goals of therapy would be similar and include:

• maintaining the strength of muscles that support the joint

• maintaining proper joint function to address balance and co-ordination and maintain a normal gait

• managing pain or discomfort

Full Stride provides myofunctional treatments to keep dogs active by maintaining muscle strength and function and assist in managing pain.

Until next time, enjoy your dogs.

Sources:

Bowen, J., Fatjó, J., Serpell, J. A., Bulbena-Cabré, A., Leighton, E., & Bulbena, A. (2019). First evidence for an association between joint hypermobility and excitability in a non-human species, the domestic dog. Scientific reports, 9(1), 8629.

Bulbena-Cabre, A., & Bulbena, A. (2018). Anxiety and joint hypermobility: an unexpected association. Current Psychiatry, 17(4), 15.

Engelbert, R. H., Juul‐Kristensen, B., Pacey, V., De Wandele, I., Smeenk, S., Woinarosky, N., … & Simmonds, J. V. (2017, March). The evidence‐based rationale for physical therapy treatment of children, adolescents, and adults diagnosed with joint hypermobility syndrome/hypermobile Ehlers Danlos syndrome. In American Journal of Medical Genetics Part C: Seminars in Medical Genetics (Vol. 175, No. 1, pp. 158-167).

Image by Rachel Scott from Pixabay