Pioneering treatment for arthritis may improve equine welfare and reduce wastage
Dr Jason Lowe BVSc, Cert EP
Equine veterinarians have a range of options to treat lameness in horses caused by osteoarthritis (OA) and practitioners use all means at their disposal to ensure horses are exposed to the absolute least amount of discomfort and pain, and potential for injury, while under their care.
Intra-articular (IA) corticosteroid administration is one of the most commonly used treatments, employed principally for their immediate and powerful anti-inflammatory effect. However, these, and non-steroidal anti-inflammatory drugs (NSAID’s), treat the symptoms and provide temporary pain relief without addressing the underlying cause of the painful and debilitating condition.
Arthramid Vet is now registered for veterinary use. It was introduced to veterinarians in New Zealand (2019) and Australia (2020). A unique, patented product, Arthramid® Vet, that is not a pharmaceutical and has a completely different mechanism of action to conventional treatments. Arthramid® Vet is an inert and biocompatible hydrogel consisting of 2.5% polyacrylamide and 97.5% sterile water. The 2.5% PAAG gel, a porous biomaterial for intra-articular injection, is neuro-innocuous, safe and stable with great tissue integration in joints from various species, including horses. Its 3D network of cross-linked polyacrylamide polymers forms a “scaffold” inside the joint working to improve the joint capsule elasticity lost during the osteoarthritic process.
According to Dr Jason Lowe BVSc., managing director at Innovative Medical Solutions, “the 2.5% PAAG gel integrates into the joint and produces synovial hyperplasia, forming a thick, cushion-like membrane that increases the elasticity and tensile strength of the joint, reducing the pain and inflammation of synovitis and restoring long-lasting joint function.”
Research suggests 2.5% PAAG is more effective in treating OA than conventional treatments and its adoption by veterinarians will allow a progressive reduction in the use of corticosteroids, such as triamcinolone, and other anti-inflammatories in horse racing and other competitive horse sports.
This evidence is supported by multiple clinical trials; Tnibar et al. (2014) directly compared the efficacy of 2mls of 2.5% PAAG with 12mg of triamcinolone acetonide (TA) and 20mg of hyaluronic acid (HA), when injected into a metacarpal / metatarsophalangeal (fetlock) joint, in 40 warmblood horses used for dressage, show jumping or eventing. Twenty horses were assigned into 1 of 2 treatment groups after clinical examination, intra-articular anaesthesia, radiological and MRI assessment, and were clinically evaluated at 1, 3 and 6-months post-treatment. The proportion of lame-free horses were 55%, 65%, and 75% respectively in the 2.5% PAAG treated group and 15%, 40%, and 35% in the control (TA-HA) group. The study concluded that horses treated with 2.5% PAAG were significantly less lame (p<0.001) than those receiving positive control treatment (TA-HA).
Lowe and de Clifford, (pending publication), conducted a prospective double-blinded positive-control study to investigate the efficacy of a 2.5% polyacrylamide hydrogel (Arthramid® Vet) in the management of inter-carpal joint lameness in thoroughbreds. Thirty-three flat-racing thoroughbreds in full training at a single training facility with lameness (AAEP 1-3/5) localised to the inter-carpal joint by intra-articular anaesthesia and radiological assessment were enrolled. Horses were randomly allocated to be treated intra-articularly with either 2mls of 2.5% PAAG, 12mg of triamcinolone acetonide or 20mg of sodium hyaluronate (followed by two further intravenous treatments of 40mg, at weekly intervals), by a treating veterinarian blinded to the examinations at enrolment. All horses were rested for 48 hours’ post-treatment before re-entering an unaltered training regime. Compared to the horses that received triamcinolone acetonide or sodium hyaluronate, horses treated with 2.5% PAAG showed a higher probability of resolution of lameness, joint effusion and reaction to flexion at 4 (P<0.05) and 6 (p<0.05) weeks, with no difference seen between groups at two weeks. There was no significant difference between the triamcinolone acetonide and sodium hyaluronate groups at any time point. Of the horses treated with the 2.5% polyacrylamide hydrogel, 8/12 (67%) were lame free at 12 weeks. This report concluded that 2.5% PAAG could be used in the management of joint lameness in racing thoroughbreds and is superior to and longer lasting than both triamcinolone and hyaluronic acid.
A case study report from three prominent equine practices in the UK using 2.5% PAAG in 341 mainly in-work thoroughbreds (804 various joints) indicated that in 88.9% of cases when no concurrent medication was used, the anticipated outcome of 2.5% PAAG was achieved within 2 months of the initial treatment. Of the 341 horses treated with 2.5% PAAG, 210 horses (61.6%) were known to still be in work after more than 2 years in most cases from the date of initial treatment.
New technologies now give us the means to improve the safety and well-being of our equine athletes and to reduce the potential for injury – all it takes is knowledge and a change in mindset – a sentiment agreed with by Dr Florent David, an equine specialist in Surgery, Sports Medicine & Rehabilitation, and Diagnostic Imaging, who says “Veterinarians and horse owners need to keep in mind the delayed response to PAAG treatment. This delay is normal, but it’s not what clients are accustomed to with joint treatment. PAAG’s take three to four weeks, and sometimes up to six weeks, to take effect. They are not anti-inflammatory drugs or painkillers and, as a result, it requires a different mindset of the trainer and owner expectations, compared to traditional therapies”. He says, “There is mounting evidence that these new products (PAAG’s) are a game changer in the management of joint pain in osteoarthritis, and I’m very glad we have those products available”.
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