23/01/2023
Really useful advice for using muzzles
Fat Ponies, Swards and Muzzles
Do you know that in SOME circumstances the use of grazing muzzles has been reported to:
· INCREASE body weight;
· INCREASE frustration;
· CAUSE tooth damage;
· INCREASE rates of laminitis!
Here I will help you understand those circumstances so you can avoid them.
USEFUL DEFINITIONS:
Sward: an area covered in grass.
Sward height: height of the blades of grass in the sward.
WHAT WE KNOW FROM SCIENCE ABOUT USE OF MUZZLES
Muzzles are a relatively popular method around the world for aiming to control weight in “good doers” (Cameron et al., 2021). However, the use of them stimulates strong polarized opinions with the for and against camps in existence (Cameron et al., 2021 and Jaqueth et al., 2018). Let’s look at some facts to help inform you when making decisions for weight management in 2023…
· Full time use of muzzles (24 h/d) can REDUCE body weight (Davis et al., 2020).
· Part time use of muzzles (10h/d) can INCREASE in body weight (Davis et al., 2020).
· Full time use of muzzles (24 h/d) can REDUCE heart rate when compared to part time or unmuzzled horses (Davis et al., 2020).
· Part time use of grazing muzzles may INCREASE rates of laminitis (Pollar et al., 2019).
· Grazing muzzles can DECREASE the amount of forage consumed (Glunk et al., 2011 and 2014).
· Grazing muzzled horses on pasture which has grass length greater than 10cms or less than 3cms (sward height) causes frustration and potentially may be responsible for some of the cases of teeth damage observed in muzzled horses (Longland et al., 2016).
LET’S ADDRESS THE ELEPHANT IN THE ROOM
The higher rates of laminitis and greater body weight gain in part-time muzzled horses are important observations and might be considered surprising. However, muzzling horses part time will teach the horse that there are periods of non-muzzling. If that horse has access to good pasture during periods of non-muzzling it will gorge (phenomenon called “compensatory eating”). This will allow the horse to gain weight despite part time muzzling and therefore increase the risk of laminitis.
If you are only able to part time muzzle your horse for practical (e.g. yard rules), or emotional (you end up feeling guilty and taking the muzzle off), or other reasons, and your horse has access to pasture the rest of the time, it is probably better to consider a different weight management option.
SO, WHAT IS THE BEST SCENARIO FOR USE OF MUZZLES?
Sward height is another CRITICAL parameter you must consider when deciding whether or not to muzzle your horse. If you have paddocks with a sward length of between 3-10cms, then the use of a muzzle for 24h/d is likely to reduce/maintain body weight, without causing frustration or allowing gorging. It is also the scenario under which it is unlikely that the muzzle will lead to tooth damage as the grass passes easily through grazing muzzle holes. If you have paddocks with only long or extremely short grass this is not the scenario to use a muzzle under as you are likely to increase frustration and potentially cause tooth damage with the horse trying extremely hard to access the grass swards that do not enter easily the muzzle.
TAKE HOME ADVICE FOR CONSIDERING USING GRAZING MUZZLES
The most effective and safe use of grazing muzzles is if they are worn 24/hr/day on pastures with sward height between 3-10cms. If worn part time, the horse must not have access to good pasture for the times it is un-muzzled. The critical consideration for preventing frustration and teeth damage is sward height.
Cameron A, Harris P, Longland A, Horseman S, Hockenhull J. (2021) UK Horse Carers' Experiences of Restricting Grazing When Aiming to Prevent Health Issues in Their Horses. J Equine Vet Sci. 2021 Sep;104:103685. doi: 10.1016/j.jevs.2021.103685. Epub 2021 Jun 13. PMID: 34417001.
Davis K.M., Iwaniuk M.E., Dennis R.L., Harris P.A., Burk A.O. (2020) Effects of grazing muzzles on behavior, voluntary exercise, and physiological stress of miniature horses housed in a herd. Applied Animal Behaviour Science. 232. https://doi.org/10.1016/j.applanim.2020.105108.
Glunk E.C., Sheaffer C.C., Hathaway M.R., Martinson K.L. (2014) Interaction of Grazing Muzzle Use and Grass Species on Forage Intake of Horses. Journal of Equine Veterinary Science, 34 (7), 930-933, https://doi.org/10.1016/j.jevs.2014.04.004.
Jaqueth AL, Iwaniuk ME, Burk AO. Characterization of the Prevalence and Management of Over-Conditioned Ponies and Horses in Maryland. J Equine Vet Sci. 2018 Sep;68:26-32. doi: 10.1016/j.jevs.2018.02.007. Epub 2018 Feb 28. PMID: 31256884.
Longland A.C., Barfoot C., Harris P.A (2016) Effects of Grazing Muzzles on Intakes of Dry Matter and Water-Soluble Carbohydrates by Ponies Grazing Spring, Summer, and Autumn Swards, as well as Autumn Swards of Different Heights. Journal of Equine Veterinary Science, 40, 26-33, https://doi.org/10.1016/j.jevs.2015.09.009.
Longland A.C., Barfoot C., Harris P.A. (2011) The effect of wearing a grazing muzzle vs not wearing a grazing muzzle on pasture dry matter intake by ponies. Journal of Equine Veterinary Science, 31 (5–6), 282-283, https://doi.org/10.1016/j.jevs.2011.03.105.
Pollard D, Wylie CE, Verheyen KLP, Newton JR. Identification of modifiable factors associated with owner-reported equine laminitis in Britain using a web-based cohort study approach. BMC Vet Res. 2019 Feb 12;15(1):59. doi: 10.1186/s12917-019-1798-8. PMID: 30755193; PMCID: PMC6373032.