Nicky Grant BSc Hons Physiotherapy, MSc Veterinary Physiotherapy, MCSP, ACPAT A, HCPC, RAMP
We've all seen those dogs on the agility course that have these amazing jump styles, huge hind limb extension and loads of flexibility through the weaves. But have you ever stopped to think what allows this flexibility and also whether it is always a good thing. One of the things that may be going on in this situation is that the dog may be hypermobile. Hyper mobility is well documented in people; it can be tested and measured using a scoring system called the Beighton score. It is a score out of 9 and looks at different joints throughout the body to see if they move more than we would expect. We look specifically at the little fingers, the thumbs, the elbows, the knees and the lumbar spine. Hypermobility can affect a single joint, or multiple joints and the term is used when there is more than what is determined as normal range of movement. It is often termed ‘double jointed’ in people. Joints are given stability by a number of structures but predominantly ligaments; ligaments are fibrous bands that attach bone to bone. For example ligaments running down the side of the joint are often called collateral ligaments so they stop excessive movement side to side of the joint and we've all heard of cruciate ligaments that sit within the knee joint and are vital for stability both in people and dogs. When a joint is termed hypermobile the ligaments are a bit more flexible than normal. This is due to the collagen fibers within the ligaments being slightly different to normal making the ligaments a little bit stretchier therefore allowing more movement in the joint. In some cases the hypermobility can be seen in other connective tissues throughout the body such as the skin. A common area for dogs to be hypermobile is the shoulder. The shoulder is an incredible joint as it relies almost entirely on soft tissue for its stability. If an agility dog is hypermobile in one or both shoulders, the stress of weaving and that side to side movement can cause micro-trauma and ultimately damage to the shoulder joint, often the inside (medial) side of the joint. Even the jumping stress on the front limbs is significant with approximately 4.5 times their body weight going through their front limbs when jumping, this could equate to 80-90kg in a 20kg dog (Pfau et al, 2011). It would be interesting to research the forces on the font legs of a stop contact on an A-Frame wouldn’t it? The wrists (carpi) are another area that can often be affected and these take a huge amount of stress when landing over jumps and coming off an A-Frame. How do you know if your dog might be hypermobile? They may have excessive extension of the lumbo-sacral joint when jumping or going over the top of the A-Frame, this is where their back legs go very high out behind them. It is however important to note that this does not always mean a dog is hyper mobile, it may mean they need to improve their body awareness, improve their strength, work on their jump coordination or retrain their jump style. They may have an unusual weave pattern; slow motion videoing is an excellent way to spot any concerns or abnormalities and also to use as a comparison to monitor for any changes to their action. In some cases, hypermobile dogs can have very stretchy skin, you are able to pick up their skin in handfuls and if feels very pliable. This is not that common but is something worth checking. So how can we manage these dogs and what can we do to help them? Can they do agility? These are both questions I will discuss in my next blog, see you next time ☺ Pfau T, Garland de Rivaz A, Brighton S, Weller R. 2011. Kinetics of jump landing in agility dogs. Vet J. 2011 Nov;190(2):278-83