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SyncThermology Blog

The Effect of Obesity on Joints

Sunday, October 23, 2016  ‹ Back To Latest News List

This week our blog is written by our North West equine and canine technician Kat, we hope you enjoy!

Nearly 30% of the world’s population is now classed as over-weight or obese, which no longer comes as a surprise to many of us. In UK, this epidemic is even worse. According to the Global Burden of Disease study- 62% of the adult population is over-weight. It’s also well known that the generous waist line trend has been carried over to our beloved pets. Whether equine, canine or feline… It’s commonly believed that 50-60% of our pet population is carrying some extra pounds.

Obesity obviously increases the pressure put on the joints during movement, but there’s another aspect to obesity which often goes unnoticed by some owners. Aside from the mechanical stresses, there are a whole host of molecular events taking place in our animal’s joints. Unlike mechanical pressures, these events are affecting the joints all the time - including non-weight bearing structures.

Adipose tissue - or put simply, fat tissue, was once thought to be a simple storage solution for unused energy which just happened to gather around all the wrong places. I’m sure many of us will agree! Research has shown us otherwise though. Fat tissue is actually highly metabolic. It’s very capable of producing and releasing its own signalling molecules such as Adipokines, Cytokines and Chemokines which affect the whole body. Their function just like classic circulating hormones - is to travel through the blood stream binding to some of the cells passing messages.

We now know that excess Adipose tissue is causing a whole range of issues such as systemic low-grade inflammation, systemic insulin resistance, changes to the expression of obesity-related genes and altering the balance of cell growth and division which might lead to carcinogenic changes. Putting it in very simple terms- fat tissue is an acting organ. It doesn’t sit quietly around its neighbouring organs minding its own business. It slowly puts an additional stress on the whole system and other organs increasing the chances of pathogenic changes.

Looking specifically at the link between obesity and joint health, Adipokines play an important role as they influence cartilage and bone homeostasis. Many molecules are produced by the fat tissue and their function is complex - some of these molecules can have both protective as well as damaging effects. Fat tissue also produces more pro-inflammatory molecules rather than anti-inflammatory ones and that in itself leads to imbalance and systemic inflammation.

Let’s say we have a joint. There is normal articular cartilage which is built from chondrocytes and collagen. These are metabolically active cells which amongst other functions, produce extracellular matrix with enzymes responsible for remodelling of cartilage and other connective tissues. This joint is healthy, remodelling the tissues when it’s deemed necessary. Now let’s imagine that the body in which our joint lives, becomes overweight and fat tissue is now causing low-grade inflammation. There’s also an increase of molecules involved in destruction of articular cartilage (such as IL-6 and TNF-α). The process of inflammation produces by-products which can alter enzymes keeping the cartilage and other connective tissues healthy. Together with effects of IL-6 and TNF-α the joint becomes unstable and is now breaking down the bone and connective tissues quicker than it can remodel it. This will continue slowly leading to degeneration of articular cartilage with loss of collagen and new bone growth which are vital for remodelling the joint. We now have a degenerative joint disease (DJD) or osteoarthritis (OA) which I’m hoping you can now see- fuels its own progression.

I would like to point out that joint disease doesn’t have to be caused by obesity. Acute injuries, bone incongruities (where the bones doesn't fit together), natural 'wear and tear' can all create degeneration. However, statistics are pretty damning… Prevalence of DJD in obese dogs is 83%. Various studies have found that we, as owners, are in denial about the weight of our pets. As many as 76% of canine, 69% of feline and 60% of equine owners believe their pet were at a healthy weight when in fact they were not.

It’s not all doom and gloom though! Even if your animal suffers from DJD, even a relatively small reduction in body weight can result in significant improvement in clinical signs and their quality of life. The cost saving of limiting treats or food can soon mount up and pay for some hydrotherapy sessions or that new bridle you’ve been day-dreaming of. Next time your vet sees your animal, ask for their opinion. Go and see the veterinary nurses in your practice - many are now running special weight clinics. Weigh or measure your animal each month to make sure you stay on track.

By limiting weight gain you are improving and extending their life!