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Wondering about the location of myofascial trigger points (MTPs) in dogs with osteoarthritis?

So, did a Brazilian group of veterinary researchers.

Formenton M, Fantoni D, Gauthier L, et al.  Prevalence and Location of Myofascial Trigger Points in Dogs with Osteoarthritis.  Front Vet Sci.  V ol12, Jan 14, 2025.

https://doi.org/10.3389/fvets.2025.1488801  

Methods: 

Thirty-five dogs were selected and examined for the presence of MTPs using palpation. Assessments were performed independently by two examiners. Correlations between age, MTP number and location, and the site of osteoarthritis were also investigated.

Results and discussion: 

Thirty out of 35 dogs (86%) had at least one MTP and only 5 (14%) had none. A total of 177 MTPs were identified in dogs in this sample. The prevalence of MTPs was higher in the longissimus thoracicae (40% and 43%; left and right side respectively), followed by the quadriceps femoris (40% and 31%), longissimus lumborum (20% and 23%), gluteus medius and deltoid muscles (14%; left side only), and the pectineus muscle (11%; right side only). The number of osteoarthritic joints was not correlated with the number of MTPs or age. However, age was positively correlated with the number of muscles affected by MTPs. Correlations between the presence of MTPs in muscles surrounding and the affected joints were also lacking.

Further breakdown:

Ninety (51%) out of 177 MTPs were located on the left (L) and 87 (49%) on the right (R) side. Most MTPs (95/177; 54%) were located on the back. Remaining MTPs were located in hind limb muscles (64; 36%), front limb muscles (16; 9%) or head and neck muscles (2; 1%).

Age was positively correlated with the number of MTPs per dog (r2 = 0.56, p = 0.0005) but not with the number of osteoarthritic joints (r2 = 0.23, p = 0.1772). The number of MTPs was not correlated with the number of osteoarthritic joints per dog (r2 = 0.04, p = 0.8021).

The group evaluated MTPs found in muscles surrounding each specific joint.  For example, the muscles considered to be relevant to the shoulder joint were: Masseter, Brachiocephalicus, Sternocephalicus, Trapezius pars cervicalis, Pectorales superficialis, Pectoralis profundus, Supraspinatus, Infraspinatus, Trapezius pars thoracica, Latissimus dorsi, Longissimus thoracicae, and Serratus ventralis thoracis.  The muscles considered to be relevant to the carpus were:  Extensor carpi radialis, Extensor digitorum communis, Extensor carpi ulnaris, and Flexor carpi ulnaris. Based on the researchers evaluation of joint-muscle MFT correlations, the percentage of dogs with OA and MTPS is 1.81%. Myofascial TP location was not correlated with the presence of OA.  (PS. I have thoughts on this one!)

Conclusions:

The prevalence of MTPs in dogs with osteoarthritis seems to be high. Most dogs (86%) had at least one MTP, the longissimus and quadriceps femoris being the most commonly affected muscles. The number of MTPs increases with age.

Laurie’s thoughts:

Firstly, I am happy that research such as this is coming out.  Relevant to rehab!  Well done.

When reading the findings and conclusions that the MTP location did not correlate with the OA joint, that’s where I had to dig deeper (into the supplemental information).  This is where I found the information above regarding which muscles were ‘presumed’ to correlate with the joint location.  Now, think about your own body.  If you have a painful elbow, and you therefore have to compensate for that elbow with every movement you do that involves your arm.  It is not the biceps and triceps that become overworked (and hence prone to MTPs).  It is instead the muscles that move the joints that are compensating (i.e. those around the shoulder and neck).

Think about a dog with tarsal or stifle pain.  It compensate.  It might shift its weigh forward, thus increasing use of shoulder muscles and triceps.  It uses its front legs to help pull itself up from lying and sitting, using latissimus dorsi and teres major as an example.  It rounds the back, holds the leg in slight flexion, and offloads to the other three legs.  So I would not expect the correlating MTP to be localized in many cases.

I would love to see this study targeted to MTP correlations to OA in specific joints.  The authors did bring up this same point in their discussion as warranting of further investigation.

All in all, I declare this study as “Research that Matters”.

Until next time,

Cheers!  

Laurie