Tongue talk
It’s just a tongue, right? Wrong. This highly specialised organ filled with an astounding number of muscles plays a leading role in keeping your horse alive — and injuries are common, says
Our equine anatomy series continues with the horse’s extraordinary but sensitive tongue
AHORSE’S TONGUE IS made up of more than a dozen individual muscles. These muscles receive their nerve supply from a dedicated nerve, the hypoglossal, which arises directly from the brain. Some of the extrinsic muscles anchor the organ to the lower jawbones and the hyoid apparatus (voice box), while other intrinsic muscles begin and end entirely within the tongue. In fact, the tongue is one of the very few places in the body where the horse has control of muscles that are not directly attached to bones. The tongue is not uniform in shape. Progressing back from its tapered spatulashaped apex (end), it becomes wider and thicker with a central swelling of muscle (the lingus) at the level of the first cheek teeth. The frenulum is where the attachment of the tongue to the underlying tissue begins and it is this rooted part of the tongue that plays a vital role in chewing and swallowing. Papillae, specialised protuberances that cover the entire upper surface of the tongue, help to guide food into position. The food is then pressed up against the ridged roof of the mouth. This serves to force the food over onto the chewing surfaces of the teeth where it is ground and passed across the tongue, again in a spiral that moves it gradually towards the rear of the oral cavity. Here, the now thoroughly pulped food encounters the lingus, which pushes it back for swallowing. The tongue also helps to keep the teeth clean, as the horse shifts his tongue around in the mouth to dislodge bits of food.
Injuries happen
The tongue is easily injured, and certainly this happens more frequently than most people realise. The signs to look out for are: Reluctance to eat (especially rougher food) Increased salivation (drooling) Dropping of feed or hay Swollen cheeks (or the tongue itself) Bad breath Even though there may be profuse bleeding on account of the excellent blood supply, unless the lingual artery itself is cut — which can lead to major haemorrhage — the blood is often swallowed rather than spat out and so the signs are missed. With horses frequently carrying on as normal with a damaged tongue, even quite severe injuries may go undetected and are only picked up when the mouth is being examined for other purposes, such as a dental check-up. By far and away the most common cause of injury to the tongue is by the bit, for instance harsh use of a bit or the horse pulling back when tied up using the reins. A horse can accidentally bite his tongue
“As well as being a key tool in the horse’s ability to eat, the tongue is extremely sensitive in detecting pain, heat, pressure and taste”
if he falls or suffers a blow or kick that causes the teeth to close on the tongue. A horse may lacerate his tongue on a sharp object while browsing and more superficial (but often very sore) cuts can occur when the tongue rubs against a sharp tooth. This can trigger chronic ulceration and pain, particularly if the bit is holding the tongue down against the sharp edge.
Recovery chances
A cut tongue can be difficult to suture (stitch) and the wound often breaks down. The tongue can’t be immobilised by bandaging and the constant movement, combined with bathing in saliva, can break down the stitches. Fortunately, because of the tongue’s fantastic blood supply, most wounds will heal well so it is almost always worthwhile for your vet to attempt a surgical repair, even if this can be difficult with space being at a premium in the horse’s long, narrow mouth. The pain of tongue wounds may affect the horse’s ability to eat, so while healing it’s best to switch to soft foods that are easy to chew and swallow. Wet down the hay and feed, or switch to hay cubes or a softer forage. It’s also a good idea to avoid riding with a bit until the injury heals. Even injuries that heal well can leave a prominent scar and this can affect how a horse responds to the bit, especially if the injury is in the bit path. Sometimes the injury causes nerve damage and this can have long-lasting repercussions, making a horse head shy and/or influencing how he responds to the bit.
Losing the tongue
Horses often cope well even if a portion of the tongue is lost. In most cases they are still able to eat and work normally, providing the missing part is in front of the frenulum. This is the part that attaches the tongue to the floor of the mouth and is an area that comprises around 20% of the entire organ. However, since the tongue holds the bit
“Horses are terrific nibblers and adept at picking up only the choicest pieces while leaving less undesirable bits behind”
in place and prevents it from moving around in the mouth, losing part of the tongue may or may not affect the horse’s performance at a certain discipline. For example, it could be career ending for a dressage horse, but not for a horse who performs in a bitless bridle.
Tongue ties
Tongue tying is a standard procedure in the racing industry and horses appear to tolerate it very well. It involves the tongue being pulled forwards and then tied close to its base around the lower jaw with a nylon strap, the free part of the strap then being moved out of the side of the mouth. The purpose is to decrease the likelihood of a breathing disorder while the horse is performing by stabilising the position of the upper airway structures. It’s of particular use in horses that suffer from a condition called Dorsal Displacement of the Soft Palate (DDSP), where the soft palate shifts in an upwards direction so that its end rests above the epiglottis (cartilage located at the base of the tongue), where it then obstructs air flow. Some say tongue tying also makes racing safer by ensuring the horse doesn’t flip his tongue above the bit, thereby ensuring the rider can maintain control. However, the practice has led to significant welfare debates since misuse of the ties can easily cut the tongue or cause nerve injuries. Sometimes, when off the track, thoroughbreds loll their tongues as a result of partial paralysis. Perhaps not surprisingly, the use of tongue ties is restricted in some countries and banned altogether in Switzerland.
“Horses often cope well even if a portion of the tongue is lost. They are still able to eat and work normally”