Abstract
Fetlock joint inflammation is a common problem in horses arising mainly from an overall increase in recreational activity engendered by better veterinary care and increased longevity. Whilst nonsteroidal anti-inflammatory drugs have proven efficacy in reduction of inflammatory symptoms, they are not without risk of significant adverse effects. Alternative phytopharmaceutical treatments exist, but are largely non-researched in vivo. One such candidate molecule is the polyphenolic compound curcumin, found in turmeric, which has known anti-inflammatory properties. In this study six horses with known fetlock joint inflammation were randomly assigned to receive no treatment or 0.05 g/kg body mass high curcumin content turmeric each day for ten days as part of their free-living customary diet. Quantitative measurements of fetlock circumference showed no reduction in the control group but up to a 5.0 mm reduction in inflammation in the test group following turmeric administration. Professional handlers, who subjectively rated the mood and mobility of the horses with initial fetlock inflammation on a daily basis, concluded that the turmeric treatment group significantly improved over the ten-day trial period. Both quantitative and qualitative results strongly suggest that turmeric containing curcumin, is an effective and easily administered phytopharmaceutical which reduces inflammation and improves mobility and mood in horses with fetlock joint inflammation.
Keywords: Inflammation; injury; horses; mobility; fetlock; turmeric; curcumin
Aims
To determine the reduction in the inflammatory response of horses with fetlock joint inflammation and improvement in mobility and mood following administration of high content curcumin turmeric added to the free-living customary diet compared with non-treated horses of similar inflammation.
Introduction
The equine fetlock is a term used for the joint where the cannon, proximal sesamoid and pedal bones meet and is comparable to the ankle joint in humans. Joint inflammation arising either from injury, chronic disease or idiopathy is a common problem in horses (Kahn, 2010), with joint pain being a leading cause of lameness (De Grauw et al., 2006.). However, with improved veterinary care, equine populations are living longer and competing into older ages, but the inflammatory response either due to exercise or injury is poorly understood (Reed et al., 2015). Some estimates indicate that up to 15% of equine populations are older than twenty years of age and more susceptible to exercise injury (McKeever, 2002). Conventional therapy is treatment with nonsteroidal anti-inflammatory drugs (NSAIDs), such as cyclooxygenase inhibitors (Marshall & Blikslager, 2011) and phenylbutazone (Slater et al., 1995). Despite their beneficial anti-inflammatory, anti-pyretic and analgesic properties, NSAIDs are associated with significant and potentially fatal adverse effects. These include vomiting, gastrointestinal ulceration and bleeding, colic, weight loss and diarrhoea. Furthermore, administration of these drugs maybe dangerous in animals who are renally compromised (Kahn, 2010). Alternatives to these drugs are herbal extracts and phytopharmaceuticals, for example curcumin, an active anti-inflammatory component found in the spice turmeric. Turmeric containing approximately 2 – 4% curcumin is extracted from the rhizomes of the plant Curcuma domestica. The extracted spice turmeric also contains the polyphenols α-Turmerone, β-Turmerone, Curlone, Zingiberene and ar-Turmerone, which could be considered to have anti-inflammatory activity (Bisset & Wichtl, 2001). The putative mode of action is the ability to inhibit cyclooxygenase enzyme 2 (COX-2), which mediates the production of prostaglandins responsible for the inflammatory process (Clutterbuck et al., 2009). Curcumin is an active polyphenol (Figure 1.) traditionally used for the treatment of many human diseases.
Figure 1. Chemical structure of curcumin (Bisset & Wichtl, 2001)
Furthermore, it’s safety has been demonstrated in numerous human and animal clinical studies (Gupta et al., 2013). Recent studies have shown that bioactive polyphenols, including curcuminoids, resveratrol, quercetin and pterostilbenes have anti-inflammatory action in vitro in equine blood samples collected from senior horses, aged 20 years or more (Siard et al., 2016). Although in vitro evidence may be promising, there is little clinical in vivo data to support the use of turmeric containing curcumin and other polyphenols as a viable anti-inflammatory treatment in horses. The aim of the present study was to investigate the anti-inflammatory properties of a high curcumin content turmeric extract as a dietary supplement in horses with known inflammatory conditions, notably in the fetlock joint. To test the hypothesis that turmeric has anti-inflammatory properties in horses, six horses were recruited to the study with similar fetlock inflammation. Of these, three horses were observed for ten days with no dietary intervention and three horses had their diets supplemented with 0.05g/kg of body mass turmeric per day. Both test and control horses were assessed after 10 days for reduction of inflammation. The null hypothesis (H0) is that there will be no difference between control and test horses. The alternative hypothesis (Ha) is that horses treated with turmeric will show a reduction in fetlock inflammation.
Methods and Materials
Equine Subjects
Six horses, 4 male geldings and 2 female mares aged between 22 and 36 years were recruited to the study from the population of horses at Old Barn Stables, Waffrons Farm, Woodstock Lane, South Chessington KT9 1UF. Horses were chosen from the same stable yard to ensure any variables in diet and care were constant. Out of thirty horses resident at this yard, six were identified as having abnormal inflammation of the fetlock joint by the yard’s qualified veterinary practitioners (Priory Veterinary practice, Banstead SM7 2NZ) and the yard manager. Of these two had a reduced workload and lower rider weight limit, two were retired and two were in full work. Approval for inclusion in the study was given by the owner and yard manager. Any current treatments administered to each horse as part of their daily routine was recorded. In addition, the age, body mass and breed and daily turmeric dosage of each horse was recorded. Each horse was assigned a trial number one to six.
Test Materials
All horses received a basal diet of Dengie original Hi-Fi chaff (Dengie Crops Limited, Howells Farm, Maypole Road, Maldon, Essex CM9 4SY) appropriate for their weight, height and workload. Four horses trial numbers two, four, five and six also received a soaked sugar beet supplement as part of their free, customary diet (Elm Farm, KT10 0TB). This supplement was given as part the diet in aid of maintaining condition as deemed necessary by the yard manager and was given as part of their primary care and welfare regardless of any study intervention. Turmeric powder containing 3.19% curcumin was obtained from Naturally Animals (The Tannery, Tannery Lane, Gosden Common, Bramley GU5 0AB). Each kilogram of turmeric powder was supplied with 1L cold-pressed linseed oil and 100g black pepper corns as additives to the feed as recommended by the supplier. Linseed oil and black pepper were supplied to aid formulation. In test horses one handful of Hi-Fi chaff was made into a well in the feed bucket. Into this, 15ml of linseed oil was added followed by the pre-measured dosage of turmeric powder, to which 6 grinds of black pepper from a hand mill were added.
Study Design
Of the 6 horses, eligible to participate in the study three were randomly assigned as control subjects and three as test subjects. This was achieved by writing the name of each horse on a piece of paper and blindly picking them out of a riding hat to be assigned horse numbers one to three as controls and horse numbers four to six as tests. Each horse was assessed for fetlock inflammation on day one by taking a tape measure around the widest point of the fetlock and measuring the circumference to the closest 0.5 mm, as recommended by the yard’s veterinary practitioner. Control horses’ numbers one to three did not receive turmeric as a dietary addition over the test period, although their basal diet remained the same as test horses. Test horses numbers four, five and six, received 0.05g/kg body mass turmeric in their feed for ten days in addition to their normal diet. This dose was recommended by the supplier and equated to 1.6mg/kg body mass of the active curcumin per trial day. At ten days, final fetlock circumference in mm was measured as described. After the ten-day treatment period, a subjective visual assessment of fetlock inflammation was made by the investigator and yard manager, this was done by looking for swelling and signs of oedema. Furthermore, independent employees of the stable were asked to assess horse mobility and mood on a daily basis throughout the trial period.
Results
Figure 2. shows the profile of trial horses following randomisation, who were included in the study and their random trial allocation number.
Figure 2. Profile of trial horses
| Control horse number and breed | ||
| 1 | 2 | 3 |
 |
 |
 |
| Shetland Cross | Miniature Toy Horse Cross | Exmoor |
| Test horse number and breed | ||
| 4 | 5 | 6 |
 |
 |
 |
| Welsh B | Highland | Arab |
Table 1. shows the biometrics of horses included in the study. Height is traditionally measured from the horse’s withers to the ground in hands and inches. It is to be noted that the pre-trial medications were given to help treat equine Cushing’s disease and are not anti-inflammatory. This has been converted to meters. Each Prascend® tablet contained 1 mg of pergolide mesylate.
Table 1. Biometrics of trial horses
| Horse number | Height HH*/ m | Body mass Kg | Age years | Workload | Pre-trial medication | Daily dosage Turmeric g |
| 1 | 11.2 – 1.15 | 252 | 22 | Full | None | 0 |
| 2 | 10.2 – 1.05 | 211 | 25 | Reduced | ½ 1mg Prascend tablet | 0 |
| 3 | 13.2 – 1.35 | 359 | 22 | Full | None | 0 |
| 4 | 12.3 – 1.28 | 247 | 36 | Retired | 1 ½ 1mg Prascend tablet | 12.35 |
| 5 | 14.2 – 1.45 | 423 | 30 | Retired | None | 21.15 |
| 6 | 14.3 – 1.48 | 372 | 26 | Reduced | None | 18.6 |
| *Hands high height, hands and inches, converted to m, where one HH equals 10 cm | ||||||
Table 2. shows the circumference of the fetlock joint pre- and post-trial in control and test horses. Control horses one, two, three showed either no change in fetlock circumference or an increase in inflammation of +0.5mm as measured by the study technique. In contrast horses, four to six show a reduction in inflammatory circumference of -2.5 to -5.0 mm. Figure 3. Shows the change in fetlock circumference after ten days.
Table 2. Circumference of front, offside* fetlock joints in control and test horses, pre and post treatment with 3.19% curcumin content turmeric powder over 10 days
| Horse number | Initial circumference mm | End circumference mm | Change in circumference mm |
| 1 – control** | 210.5 | 211.0 | + 0.5 |
| 2 – control | 189.5 | 190.0 | + 0.5 |
| 3 – control | 242.0 | 242.0 | 0.0 |
| 4 – test *** | 215.0 | 212.5 | – 2.5 |
| 5 – test | 253.5 | 248.5 | – 5.0 |
| 6 – test | 245.0 | 242.5 | – 2.5 |
| *Offside is a common equine referring to horses’ right side **Control horses did not receive turmeric as a dietary supplement |
|||
| ***Test horses received 0.05g/kg body mass turmeric for ten days | |||
In addition to quantitative measurement as shown in Table 2. Table 3. shows the subjective assessment of control and test horses. For independent employees working with each animal on a daily basis, no noticeable change in inflammation of the fetlock was observed for control animals. Neither was any significant change seen in their mood and mobility. For test horses, visual assessment rated inflammation as decreased and each horse more physically active and with a happier disposition.
Table 3. Visual and behavioural assessment of control and test horse, post treatment with 3.19% curcumin content turmeric powder over 10 days
| Horse number | Visual assessment | Behavioural assessment |
| 1 – control | No noticeable change | No significant change |
| 2 – control | No noticeable change | No significant change |
| 3 – control | No noticeable change | No significant change |
| 4 – test | Decreased inflammation | More active & better mood |
| 5 – test | Decreased inflammation | More active & better mood |
| 6 – test | Decreased inflammation | More active & better mood |
Figure 3.
Discussion
Turmeric has been used since antiquity as a food ingredient and medicine (Gupta et al., 2013). However, its therapeutic use in treatment of inflammation in animals has been a relatively recent event, with most studies focusing on in vitro rather than in vivo investigations. It is a good candidate molecule for the treatment of acute inflammatory disease involving excessive free radical production (Derochette et al., 2013) and inhibits inflammatory prostaglandins (Clutterbuck et al., 2009). This study set out to determine if there were any quantitative and qualitative effects of 0.05g/kg body mass turmeric given to horses with fetlock inflammation over ten days. Figure 2. shows that six horses of different breeds were recruited to the study out of a potential population of thirty horses at the yard. Whilst this sample is low, it would be unethical to induce fetlock inflammation in other horses to increase the sample size. Other horses could have been recruited from different yards to increase the sample size. However, variables such as basal diet, exercise regime and environmental conditions could not be replicated and controlled for at each yard because of differences in diet and methods of care. Table 1. shows that two horses, one control group and one test, received Prascend®. Although it may have affected the results of the trial, it would have been unethical to remove the treatment by Prascend®. It could be argued that differences in pre-trial treatment with Prascend®, as well as horse workload, could introduce some bias to the results. Nevertheless, these differences arose because of the need to randomly assign trial horses to either control or test groups. Table 1. also shows that each horse had a different body mass and therefore a different daily dose of turmeric so as to give an equivalent dose of 0.05g/kg body mass turmeric. The turmeric chosen for this study contained a high content (3.19%) of the active ingredient curcumin, with the supplier recommending oral administration with linseed oil and ground black pepper. Curcumin has poor bioavailability but co-administration with piperine, the active ingredient in black pepper, increases bioavailability up to 2000% (Shoba et al., 1998). Curcumin is lipophilic and thus linseed oil was primarily used to aid formulation of the turmeric powder into the feed stock. Nevertheless, the method did not control for administration of linseed oil in test horses. It could be considered that linseed oil improves fatty acid serum profiles in horses and may therefore add to the anti-inflammatory effect (Patoux & Istasse, 2016). This should be controlled for in future studies. Table 2. and Figure 3. show that two out of three control horses displayed negligible increases in fetlock inflammation over ten days and thus it should be control horses did not improve in condition. In contrast, test horses receiving turmeric showed up to 5mm reduction in fetlock circumference, indicating reduced inflammation. The quantitative measurement of reduction in inflammation can be compared with qualitative assessments as shown in Table. 3. Test horses showed an improved visual reduction in inflammation, were more active and had a better mood. These results strongly suggest that administration of 0.05g/kg body mass turmeric reduces inflammation and improves mobility and mood in horses with fetlock inflammation. If the null hypothesis were true no improvement would be expected, as measured both quantitatively and qualitatively by our techniques. However, the sample size is too small to carry out significance testing of the results, for reasons discussed above. Future studies should focus on recruiting greater numbers of horses from different yards to lend greater statistical weight to the results, whilst controlling for variables between different yards. Further studies could compare and contrast turmeric with curcumin alone to investigate if there were any differences in efficacy in addition to trialling different dosages to find the optimum. It might be the case that curcumin alone is more potent as an anti-inflammatory, or that the other phenolic compounds in turmeric may synergise with curcumin to enhance its anti-inflammatory effects. Nonetheless, considering the potential for adverse side effects following treatment with most NSAIDs, dietary turmeric would seem to offer an effective, low cost and well tolerated alternative.
Conclusion
Both quantitative and qualitative results of this study strongly suggest that 0.05g/kg body mass dietary turmeric containing 3.19% curcumin, is an effective and easily administered phytopharmaceutical which reduces inflammation and improves mobility and mood in horses with fetlock joint inflammation.
Acknowledgements
The author gratefully acknowledges the help in study design and animal assessment given by Mrs Jennifer Best, Stable Manager of Old Barn Stables, Chessington and staff of the Priory veterinary practice, Banstead as well as the help of the professional stable employees in the continuation of this investigation throughout the study period. The written consent of the owners was gained before the start of the trial. The assistance of Mr Adam Lee (BSc) in the formatting and reviewing of this manuscript is acknowledged with gratitude.
Surbiton High School, Surbiton Crescent, Kingston upon Thames KT1 2JT
Contents
Figure 1. Chemical structure of curcumin………………………………………………….4
Equine subjects…………………………………………………………………………5
Test materials………………………………………………………………………….5
Study design…………………………………………………………………………5-6
Figure 2. Profile of test horses……………………………………………………………….6
Table 1. Biometrics of trial horses…………………………………………………………..7
Table 2. Circumference of front, offside fetlock joints in control
and test horses, pre and post-treatment with 3.19% curcumin content
turmeric powder over ten days……………………………………………………………….8
Figure 3. Change in circumference of front, offside fetlock joints
in control and test horses, pre and post-treatment with 3.19%
curcumin content turmeric powder over ten days………………………………………….9
Table 3. Visual and behavioural assessment of control and test
horses, post treatment with 3.19% curcumin content turmeric power
over ten days………………………………………………………………………….…………9
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