Hay dunking describes an abnormal equine feeding behaviour in which horses dunk their hay in water before chewing and swallowing it.

This can be a messy habit and many horse owners want to know why it happens and how to stop it. While there is little research into why horses dunk their hay, several theories attempt to explain the behaviour.

Anecdotal reports suggest some horses dunk their hay before eating it simply because they prefer it when it is dampened or because it helps them chew. [1]

It is also thought that underlying health issues can promote the behaviour, including gastrointestinal discomfort, allergies to dust, and dental issues.

If you are concerned that your horse’s hay dunking habit is a serious issue, consult with your veterinarian to determine if she requires treatment for any health problems.

If your horse simply prefers moistened hay, you may want to consider soaking your forage prior to feeding. Placing one water source near the hay and another one further away can also ensure your horse always has access to clean water.

Strategies to reduce the mess caused by hay dunking include placing a rubber mat in your horse’s feeding area and feeding hay from a hay net.

What is Hay Dunking?

Hay dunking describes the equine behaviour of taking hay into the mouth and subsequently dunking it in a nearby water source before chewing and swallowing it.

Horses that engage in hay dunking typically dip the hay in water located close to their feed. However, some anecdotal reports describe horses dragging their hay to a water source to be able to engage in the behaviour.

Hay dunking is most noticeable when horses are fed in a stall or small area. The prevalence of hay dunking in horses is unknown.

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Advantages of Hay Dunking

Hay dunking is not necessarily a negative behaviour. A key physiological benefit of dunking hay in water is increased hydration.

Horses in the wild or on pasture consume large amounts of water as moisture in grass and other plants. In comparison, horses that are domesticated often consume a diet consisting primarily of dry hay.

Dunking hay in water before chewing and swallowing may help to increase water intake, reducing the risk of digestive issues such as choking and impaction colic.

In addition, adding moisture to the hay may make it easier for the horse to chew, swallow, and digest, leading to improved nutrient absorption.

Disadvantages of Hay Dunking

Hay dunking can be a messy habit. If hay is dropped in and left in a horse’s water source for an extended period, it can ferment and accumulate mould or bacteria. [13]

Horses that dunk their hay typically need their water sources cleaned more often, especially in warm temperatures. Water troughs or buckets can turn slimy quickly as microorganisms propagate.

Hay dunking may indicate a medical problem related to gastrointestinal, dental, or respiratory health. Horses that are uncomfortable may dunk their hay to try to feel better.

For some horses, the behaviour is a learned habit and does not indicate any underlying health problem. However, it is important to rule out pain and illness as possible causes of this behaviour before you assume your horse is doing it for no reason.

Causes of Hay Dunking

Although the exact causes of hay dunking are unknown, potential causes for this behaviour may include respiratory irritation, dental issues, gastric ulcers, or behavioural issues.

1) Respiratory Irritation

All horses are obligate nasal breathers, meaning they can only breathe through their nostrils and not their mouths.

Nasal irritation due to exposure to inhaled allergens is a possible reason that horses might dunk their hay in water before eating it. Dunking the hay before eating it reduces the amount of dust that is inhaled. [14]

Horses can be allergic to a wide range of allergens in the barn, hay, or feed. Dust, molds, and bacteria are known to cause allergic reactions in horses.