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Changing approach to pet mobility

01 May 2009, at 12:00am

At the WSAVA conference in Dublin last year, the Hill’s Mobility Award was given to Professor David Bennett of the Institute of Comparative Medicine at the Glasgow veterinary school, for his outstanding work as a clinical researcher in the field of canine and feline orthopaedic medicine and surgery.

At the WSAVA conference in Dublin last year, the Hill’s Mobility Award was given to Professor David Bennett of the Institute of Comparative Medicine at the Glasgow veterinary school, for his outstanding work as a clinical researcher in the field of canine and feline orthopaedic medicine and surgery.

 Through improvements in the mobility and quality of life of pets, Professor Bennett’s research was judged to have contributed significantly to the well-being of pets’ lives and to the humananimal bond world-wide.

 Veterinary Practice asked Professor Bennett what the award meant to him and how he envisages the approach to pet mobility changing in the future.

How did it feel to be the recipient of Hill’s Pet Mobility Award? 

“I feel very proud indeed and honoured to have been given this award and in particular to be the first ever recipient, when I know there are so many deserving candidates from all over the world. It means a great deal to me to be recognised by my peers and profession in this way.

 “I would like to pay tribute to the many clinicians, scientists, nurses, technicians and students that I worked with over my many years and who have helped me to achieve this award, which very much reflects an enormous team effort and is as much for my colleagues as it is for me.” 

What initially drew you to study mobility problems in greater depth? 

“My initial interest in the musculoskeletal system was stimulated whilst I was still an undergraduate student at the Royal Veterinary College and this was due to two excellent teachers who became my mentors: Professor Leslie Vaughan and Gary Clayton-Jones.

 It was their enthusiasm and clinical skills, together with their devotion to clinical research that provided the initial stimulus. The recent death of Prof. Vaughan is a great loss to the profession – he really cared for his students.

 “I was able to consolidate my undergraduate interest by working as a house officer with my two mentors before moving to the University of Glasgow as a young lecturer in veterinary orthopaedics.

 It was there that it became apparent to me that diseases of joints, in particular arthritic conditions, were the most significant as far as mobility problems in small animals was concerned and after forming a collaboration with the Centre for Rheumatic Diseases at the Medical School I was able to setup a research group into joint diseases.

 “I later moved to the University of Liverpool where I created the Arthritis Research Group with Professor Stuart Carter and together we were able to investigate the molecular events occurring with different arthritic conditions. It was in 1996 that I returned to the University of Glasgow and I have continued my studies into the molecular pathogenesis of arthritis in small animals under the umbrella of the Comparative Molecular Medicine and Therapeutics Research Group.” 

What in your opinion have been the major advances in the care of pets with mobility problems in the last five years? 

“I think it is true that clinicians have become more aware of how important it is to control the pain which many of our patients with mobility problems, particularly osteoarthritis, are suffering and this is to be applauded. We now have a number of non-steroidal antiinflammatory drugs available for longterm use in the dog and very recently we have had one introduced for longterm use in the cat.

 “The recent identification of feline OA as a major clinical problem has been a significant development. We continually make the mistake of believing that cats are small dogs and this has so often slowed our research into this important species. Cats very seldom limp with their OA as dogs do; instead they show life-style and behavioural changes, particularly reduced activity levels (playing, chasing and hunting) and unwillingness to jump.

 “There has also been an increased interest in the nutraceuticals and the role that they play in the treatment of osteoarthritis, although there is still debate, both in human and veterinary rheumatology, as to how effective these are and exactly how they should be used.

 “A very important development has been the application of special diets to help control the inflammatory load within arthritic joints. The Hill’s j/d diets are available for the dog and cat and are based on increased levels of certain omega-3 fatty acids. These have undoubtedly helped us to reduce the inflammation and pain within osteoarthritic joints.

 The novel research supported by Hill’s has increased our interest in and understanding of nutrigenomics, the science concerned with the effects of specific nutrients on gene expression. The fact that nutrients such as the EFA can reduce the expression of MMP and COX genes in chondrocytes is of enormous therapeutic significance.

 “As a trained surgeon I must also acknowledge the significant improvement in mobility that prosthetic joint surgery has made to arthritic dogs. Total hip prostheses are now well tried and are an excellent way of treating endstage disease. Prostheses are now also available for the stifle and elbow but further development and refinement is probably required for these.” 

What do we have to look forward to in the next five years in terms of innovation in the care of pets with impaired mobility?

 “This is a difficult question to answer but I can certainly have a go at gazing into my crystal ball. Worldwide, there is a great deal of interesting on-going research into various aspects of osteoarthritis (the commonest cause of impaired mobility in both the dog and cat) and it is difficult to know which will translate most into positive effects at the patient level.

 “I do feel that the current interest and research into rehabilitation programmes for the OA patient will affect our treatments in the future. I also feel that the recent trend to use multimodal drug therapy in arthritic dogs and cats will become a more established approach especially in the more severely affected patients; we will not just rely on our NSAIDs but use combinations of drugs that affect the pain pathways in different ways and will thus work together in a synergistic effect, having an overall more beneficial effect, at the same time perhaps reducing the dose of individual drugs which are required and thus reducing the tendency for toxicity problems.

 “I also think that the many current studies into stem cells and how they can be differentiated into cartilage cells for example, will increase our understanding of the biology of the chondrocyte and this will lead to a better understanding of the pathogenesis of disease and how it should be treated. Whether these studies will ever lead to effective cartilage re-surfacing technology, I am not so sure.

 “It is clear that the natural ageing process has an effect on our ability to repair damaged tissues, including cartilage. We also know that this ageing process is accelerated in an inflammatory environment such as occurs with OA, mainly through oxidative stress.

 “Expression of cell cycle inhibitors is increased and there is a significant loss of telomere lengths, both of which speed up senescence and reduce the metabolic activity of chondrocytes and thus their attempts at repair. Research into the ageing process will be an important area over the next five years and perhaps lead to new approaches to slow down the process at a local level (i.e. the joint) and increase the anabolic activity of cartilage cells.

 “I also think that there will be a move towards biological therapies, which is already occurring with the equine and human species, to help control the inflammatory cytokines and matrix metalloproteinases which play a major role in the degradation of cartilage. These biological therapies will include gene therapy, where specific DNA is introduced into the patient’s cells to create a therapeutic effect.

 “I also think current studies into the effects of obesity on osteoarthritis and mobility will also improve our understanding of the disease and help in our treatment. There is some evidence in the human patient that obesity may actually initiate osteoarthritis through the actions of adipokines (such as leptin, adiponectin and resistin) which are released from the white adipose tissue of obese patients and lead to cartilage and ligament degeneration.

 “Clearly, osteoarthritis in dogs is generally initiated by other problems such as elbow dysplasia, hip dysplasia and cruciate failure and it is difficult to show that obesity pre-dates the OA in dogs and so it is perhaps unlikely that obesity is a primary initiating factor but it could certainly contribute to the problem. Interestingly, it has been shown in people that there are increased fat deposits in the bone marrow of arthritic joints even though the patient may not be clinically obese.

 “Osteoarthritis in the cat is much more similar to the human than is the case with the dog and I think studies on the pathogenesis of the disease in the cat may well help us to understand the condition in the human. The cat suffers mainly a primary or idiopathic form of OA and like the human, this might represent a systemic disorder. The effect of obesity on osteoarthritis in the feline species is currently being researched and this should provide interesting data and perhaps help us to manage and treat the disease better in the future.

 “We are now, of course, in the postgenomic era and the complete feline and canine genomes have been sequenced and thus we can identify all the genes present in an individual. Although OA is a complex disease, we are gradually unravelling which genes may be involved in the disease process and this will undoubtedly provide important information in the future on which to base new therapies.

 “It is important to study genes which are ‘switched on’ and ‘switched off’ in the diseased joint compared to the normal. I also genuinely believe that it will be genetic studies in the cat rather than the dog which will give us the more valuable data since we do not have the many underlying causes such as elbow dysplasia and cruciate disease which of course have their own genetic influences.” 

Are enough people bringing their mobility impaired pets forward for treatment? Do you feel that the problem gets adequate attention from owners? 

“I think the simple answer to this has to be no and this is particularly relevant I think for the cat. As far as the cat is concerned, we now know that older cats (seven years or more) will suffer arthritis but they seldom show lameness. They are more likely to show the lifestyle and behavioural changes which I have already mentioned and the owners generally feel that these reflect a cat that is ‘just getting old’. They are thus unlikely to seek veterinary advice.

 “Certainly, lameness is most often associated with osteoarthritis in dogs and generally when an owner notes a limp, he or she will seek veterinary attention. However, even with dogs there are undoubtedly animals (particularly with bilateral disease where both limbs are affected to the same degree) that are in pain and just show a stiffness, perhaps with behavioural/lifestyle changes, that the owners do not realise are suffering chronic pain.” 

How important is owner education about the problem? 

“Owner education is paramount in raising the profile of mobility problems in small animals. Osteoarthritis is often a condition that they can relate to in that it is the commonest of all diseases in all species, including the human, and most owners will either suffer the disease themselves or know of relatives and friends who do. It is important that not only do owners realise how common the problem is in their pets and how it can be recognised but also the fact that it is a disease which has to be managed rather than cured. Owner’s expectations are often in excess of what can be achieved by our currently available treatments.” 

Should practices be doing more to help restore mobility in pets? Can you suggest one thing that all practices should start doing today to improve the level of care? 

“This question touches on the previous one. I think all practices should increase the awareness of mobility problems in cats and dogs by improving communication. This can include simple measures such as wall charts, well-being/health check clinics, nurse screening clinics and client-based questionnaires. For example, the owners of all cats over seven years of age should be asked to complete a questionnaire on the lifestyle and behaviour of their cat; this is the only way OA and chronic pain will be recognised in cats.

 “As far as one particular step that a practice could take, if not already routine, it would have to be the weighing and body scoring of all dogs and cats registered with the practice and at regular intervals! Any over-weight animal can then be managed in the appropriate way. Weight reduction is still the single most important factor in managing OA. Trained nurses can be very helpful in this initial screening process.”