Mouth sores in horses: causes, symptoms and prevention

Mouth sores in horses are injuries to the mucous membrane, bars, tongue or corners of the mouth, and most often occur through the interaction between the bit, the hand and the horse’s mouth anatomy. There are many possible causes – an incorrectly shaped bit, sharp hooks on the molars, an unsteady hand, or, in rarer cases, viruses and infections. The first thing you should do is give the mouth a break from the bit, have a dentist or veterinarian check the teeth, and make sure the bit is actually shaped to fit your horse’s mouth.

The most important points:

• Sores most often occur from pressure or rubbing against the tongue, bars, corners of the mouth or palate.
• Even a mild bit can cause sores if the shape does not suit the mouth anatomy.
• Common signs include blood at the corner of the mouth, resistance to the bit and head tossing.
• The first step is rest from the bit and a dental check.
• Correct anatomical fit is the most important preventive measure.

What can cause mouth sores?

Mouth sores are almost always caused by one of three things: the equipment, the teeth, or an external cause such as a virus. The most common reason is that the shape of the bit and the horse’s mouth anatomy do not match, causing pressure to be placed where it should not be.

Bits that do not fit the shape of the mouth. It is a common myth that only harsh bits or heavy hands cause sores. Even a mild and well-intended bit can create rubbing if it is too thick for a low palate, has a port that presses against sharp bars, or a center piece that pinches a large tongue. The tongue is a muscle, while the bars consist of bone with a thin layer of skin, making the bars more delicate and more prone to sores.

Sharp hooks on the molars. When the teeth are not floated regularly, sharp edges can form and rub against the inside of the cheek or the tongue as soon as the bit is in the mouth. These sores are often located further back and are rarely visible until a dentist looks inside.

Hand and contact. An uneven or unsteady hand combined with a bit that lacks a soft landing creates pressure on the corners of the mouth and the bars. This is often where traces of blood at the corner of the mouth come from.

Viruses and infections. In rare cases, blisters and sores can be caused by viruses. If the sores look unusual, are found in several places at the same time, or if the horse seems generally lethargic – contact a veterinarian.

How do you know if the horse has pain in its mouth?

You can tell that a horse has pain in its mouth through changes in the bit contact, behavior when bridling, and visible signs in and around the mouth. Often, the riding will tell you something first, before you actually find the sore.

Common signs of mouth sores:

• The horse may toss its head or pull away from the hand.
• The horse may chew unusually much on the bit or open its mouth.
• The horse may be difficult to bridle and turn its head away.
• The horse may drop feed or chew unevenly.
• The horse may show blood or pink-tinged foam at the corner of the mouth after riding.
• The horse overreacts to rein aids that previously caused no problem.

Also check the mouth yourself when the horse is relaxed. Gently lift the lip, look at the corner of the mouth, and check towards the bars and tongue. Red marks, small sores or rubs are very clear warning signs.

What should you do about mouth sores?

The first thing you should do is give the mouth a break from the bit until the sores have healed, while also finding out what caused them. Continuing to ride with the same equipment on a sore mouth means the problem will come back.

Rest from the bit. Riding bitless during the healing period relieves the mouth.

Book a dental check. Have a dentist check for sharp hooks and other problems that may have contributed. Also ask the dentist to describe the shape of your horse’s mouth.

Contact a veterinarian if the sores are deep, bleed a lot, are found in several places, or if the horse is lethargic and does not want to eat.

Review the bit. Once the mouth has healed, evaluate whether the bit actually fits the shape of your horse’s mouth, or whether it is time to change to a shape that gives freedom where the horse is sensitive.

NOTE! Do not go back to the same bit unless you know it actually fits. Otherwise, there is a high risk that the sores will return.

At Fager, we work with small details that make a big difference, because all horses are different and need different shapes. We are here to guide you to the best option for you and your horse.

Prevent sores: the bit should fit the shape of the horse’s mouth

The best protection against mouth sores is a bit that is shaped according to your horse’s specific mouth anatomy. All riders know how important it is to have a saddle that fits the shape of the horse’s back – the same principle applies to the bit, except the mouth is even more sensitive.

All horses have different shapes and sizes and need different types of bits. The choice of bit cannot only be based on the feel you want from the bit; it must also be based on the shape of the horse’s mouth in order to minimize discomfort and injuries.