By Dr Andy Richardson BVSc CertAVP(ESM) MRCVS, NAF Veterinary Director
There are many conditions in horses where the provision of long-term analgesics and anti-inflammatories is warranted. This can provide much needed pain-relief and help relieve the unwanted effects of chronic inflammation.
It is one of the fundamental animal welfare considerations is that we provide animals under our care with ‘freedom from pain’¹. Veterinary surgeons, other professionals and horse owners all have roles to play in ensuring the correct decisions are made with respect to the provision of pain relief and supporting the body’s response to inflammation.
Short-term vs Long-term treatment options
Veterinary surgeons are frequently required to administer pain-relief and anti-inflammatory medication to counter acute onset injury, illness and disease. This is frequently via intravenous injection to ensure the benefit to the horse is received as quickly as possible.
Examples of when vets would deliver intravenous medication in this way would include colic (abdominal pain), orthopaedic injury or eye pain.
When longer-term medication is required, it is more common for owners to seek a product that can be given orally in feed. The benefits of this would be the avoidance of having to repeatedly inject the horse and also the reduced costs of having an option that does not require veterinary administration.
Oral Anti-Inflammatories for Equine Use
There are two main categories of veterinary prescribed anti-inflammatories licensed for horses that can be administered by the oral route:
1. NSAIDs – Non Steroidal Anti-Inflammatory Drugs
NSAIDs are commonly used in horses to treat pain and inflammation. They can be further categorised as being nonselective or selective – see box below: ‘Cox pathways explained’. There are potential downsides to long term administration of non-selective NSAIDs in particular that includes the potential to cause or exacerbate gastric ulceration, colitis and renal (kidney) disease². Whilst the risk is increased when NSAIDs are used at high doses or for prolonged periods, there is some evidence to suggest the downsides are present even at recommended doses³. Reported side effects of NSAID use include gastric ulcers, diarrhoea, protein loss and colitis. Rough hair and fluid swellings that accumulate at the chest area or lower limbs are visible consequences of protein loss that can result from the damage that NSAIDs can cause to the gut lining³.
COX pathways explained
NSAIDs work by targeting the inflammatory pathways that are stimulated following injury or illness. NSAIDs will inhibit one or both of the Cox-1 and Cox-2 pathways in the body. The Cox-1 pathway is important for maintaining beneficial functions within the body, such as the production of mucus on the inner surface of the GI tract, blood clotting and the ability for kidneys to function effectively. The Cox-2 pathway is responsible for causing pain and inflammation. Therefore, it is beneficial if NSAIDs only target the Cox-2 pathway and leave Cox-1 uninterrupted as much as possible. For this reason, some of the newer NSAIDs on the market are Cox-2 specific, and so achieve just that. They are referred to as being selective. Some of the more traditional NSAIDs are non-selective and inhibit both pathways. For short term use, this is less of an issue as pain-relief is often the main concern. However, when longer term treatment is needed, continued blockage of the Cox-1 pathways increase the risk of unwanted side effects associated with this type of NSAIDs – such as gastric ulceration³.
Just as in other species (including humans), horses can have individual variability to what is an acceptable dose and period for NSAID administration and therefore respond differently. One key message is that horse owners should always base treatment choice, dose and duration on veterinary advice. In a survey of horse owners, it was shown that it was not always the case that NSAIDs were given at the recommended dose. In addition, 82% of respondents used an NSAID without consulting their vet.
2. Corticosteroids
Corticosteroids are another commonly used treatment for inflammation in horses. Corticosteroids do not have any direct analgesic effect, so they are not a useful option for longer term pain relief. They are useful for when short-term reduction in inflammation is required – for example with inflammatory conditions such as acute flare up of allergies or excessive swelling. They are an extremely useful treatment for vets when fast acting responses are needed. Their use should always be discussed in full with your vet, as they have been linked with unwanted side effects such as laminitis, delayed wound healing, gastric ulceration and a reduction in immune function⁴. These side effects are likely to be more prevalent with higher or prolonged doses.
Long Term pain - how to manage
There are many scenarios where the provision of long-term pain relief is extremely important for maintaining a horse’s welfare.
Whilst advances are being made all the time in vet’s ability to treat equine injury and disease, there are unfortunately several conditions of such severity that euthanasia may be the most appropriate course of action. Whilst discussion surrounding this topic is beyond the scope of this article, this decision should always be taken in consultation with your vet.
For less severe chronic conditions, the provision of longer term anti-inflammatory support is of paramount importance. For example, the horse with arthritic or degenerative orthopaedic disease or horses affected with seasonal disorders such as allergic skin disease. There are several inflammatory conditions where continued exercise is beneficial, so being able to provide safe, long-term relief for the horse is of paramount importance.
Consideration should be given to other options that can complement traditional veterinary pharmaceuticals to help control inflammatory conditions and maintain long-term relief. This should be based on a holistic approach to care, involving the different professionals that are relevant for each area:
Veterinary
Farrier
Physiotherapy and Chiropractic
Nutrition
Supplementation
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