Equine obesity is an epidemic across the industry that negatively impacts the horse’s well-being. With an increasing number of horses being obese, many owners may not even realize that there is a problem as we are becoming conditioned to seeing horses that we feel are at a ‘healthy’ weight, when in fact they aren’t. Multiple studies have evaluated the prevalence of equine obesity in various populations and many concluded that about 50% of the observed populations were overweight.

It can be easy to turn a blind eye to equine obesity; however, it is a serious welfare concern. Implementing dietary and management changes is critical when weight loss is required. An important responsibility that the horse owner has is to recognize when their horse is not maintaining a healthy body condition score. Regularly body condition scoring your horse can assist you in determining when changes need to be made. Depending on the horse and the type of work they are required to do, their ideal body condition may vary, but should be in the range of 4-6 on the 9-point Henneke scale. If a horse has a body condition of 7 or greater, action must be taken to support weight loss.

Research has estimated that wearing a grazing muzzle reduces intake by about 30-80% depending on the length of pasture and how many hours it is worn for.

How They Work

Grazing muzzles are a slow-feeding tool that are an effective option for the management of easy keepers. They work by reducing the amount of forage a horse gets per bite they take of pasture, therefore reducing their pasture intake. Research has estimated that wearing a grazing muzzle reduces intake by about 30-80% depending on the length of pasture and how many hours it is worn for.

However, there are a multitude of considerations to make prior to formulating a weight control plan that incorporates a grazing muzzle. These include the number of hours they should wear it, the length of pasture, and the species of grass they are grazing, as well as how these management tools may impact their behaviour and welfare.

The Research

As these tools gain popularity, more research is being published on their efficacy and how they impact equine behaviour. A study published in 2016 (Longland et al.) investigated weight gain when ponies were housed on pasture 24/7. The grazing muzzle group wore the muzzles for 10 hours per day and had free grazing for the remainder of the day. The authors concluded that muzzle use for 10 hours generally reduced the rate of weight gain; however, they noted that it was unknown if muzzling for 9-12 hours per day reduced the overall daily intake, or if the animal will compensate with increased intake during the hours in which they do not wear a muzzle.

A more recent study published in 2020 (Davis et al.) evaluated the effects of grazing muzzles on dry matter intake, as well as behaviour and physiological stress. Three treatment groups were used: no muzzle; a muzzle worn for 10 hours per day; and worn for 24 hours per day. This study concluded that the horses that wore a grazing muzzle for 10 hours per day did compensate with additional pasture intake during the other 14 hours.

Therefore, the 2020 study recommended that for adequate weight control while the animal had access to pasture, muzzling for 24 hours was the most effective as they were the only treatment group that lost weight. In fact, the horses that were in the other two groups both gained weight.

The time spent wearing the muzzle did not influence the horse’s willingness to accept it and did not increase behaviours associated with frustration.

Whenever we implement new management tactics for our horses, understanding how it may impact their behaviour and physiological stress is an important consideration. In the previously mentioned study, the researchers scored the horse’s willingness to accept the muzzle application, tracked salivary cortisol levels and heart rate as well as variability and recorded their behaviour via one-hour video in the morning and afternoon twice weekly. Their conclusion was that the time spent wearing the muzzle did not influence the horse’s willingness to accept it and did not increase behaviours associated with frustration. Additionally, the salivary cortisol did not differ between the treatment groups.

Overall, the 2020 study demonstrated that when implementing grazing muzzles, the horse must wear it for 24 hours to effectively prevent weight gain. Additionally, the authors were able to illustrate that wearing the muzzle did not induce physiological stress based on the parameters they measured, but that the time budget of the horses was altered as the unmuzzled horses spent the most time walking and the muzzled horses spent the most time grazing.

Safety & Welfare

With equine management, safety and welfare should always be a top consideration. When implementing a grazing muzzle for your horse, there are some key steps to follow:

1) Attach to a breakaway halter.
There are a variety of muzzle options on the market – some which attach to a halter and others which incorporate a halter – and choosing the best option for your horse may include some trial and error. However, either the muzzle or the halter MUST be breakaway to ensure they do not get caught on anything and cause injury to the horse.

2) Introduce the muzzle slowly over a 7-14 day period.
It is important to implement an adaptation period before a horse can wear one for an extended period of time. Introducing it when you start allowing them time on pasture is a great starting point. That way, as the number of hours of pasture time increases slowly, so does their time spent wearing their muzzle.

3) Observe them while both eating and drinking.
Prior to leaving your horse wearing a muzzle, you must ensure that you have observed them both eating and drinking successfully.

4) Remove the muzzle at minimum once per day.
Similar to our blanketed horses, rubs and inadequate fit can occur with grazing muzzles. They should be removed at minimum once per day to allow for inspection. In the study that had the horses wearing their muzzles for 24 hours per day on pasture, they did spend 30 minutes without the muzzle to eat their ration balancer.

Deciding What is Best for Your Horse

Every horse is unique, and the muzzle that works best for one horse may not be the ideal choice for another. When choosing one for your horse, take time to browse the available options prior to purchasing. Ensure that you read the reviews, and even reach out to the company if you have additional questions. These tools are an investment that can cost well over $100, so you want to ensure it will be a good match for your horse.

Once you have decided on a muzzle, designing an optimal plan for them wearing it can be difficult. The number of hours they should wear it for will directly relate to their pasture access. For example, if your horse spends the daytime on a dry lot with their hay ration and only has pasture access overnight, then they will only wear it when pasture is available. However, if they have continual pasture access, wearing a muzzle for 24 hours is the better choice based on the most recent research as long as they can be monitored adequately.

Grazing muzzles are a practical management tool for promoting weight loss and preventing further weight gain that have been gaining popularity. If you have any further questions about implementing a grazing muzzle for your horse, please reach out to a qualified equine nutritionist.