Unsoundness and Blemishes of Horses: Head, Body, Respiratory Tract, and Stable Vices (E0921)


February 12, 2016 - Author: Melvin Bradley

For a discussion of unsoundnesses and blemishes of the feet and legs, see Extension Bulletin E-920, “Unsoundness and Blemishes of Horses: Feet and Legs.”

Any defect that affects serviceability is considered an unsoundness. A defect that detracts from appearance but does not impair serviceability is considered a blemish.



Blindness seriously affects the usefulness of a horse. It is usually characterized by cloudiness of the cornea or complete change of color to white. Pale blue watery eyes may indicate periodic ophthalmia (moon blindness), which is due in part to a B-vitamin deficiency. Watery eyes may appear in vitamin A deficiency. These conditions are not common to horses on pasture.

Poll evil (Figure 1).


Poll evil is an acquired unsoundness resulting from a bruise or persistent irritation in the region of the poll. Its cause is Brucella abortus, the same organism that causes Bang’s in cattle. Early symptoms are swelling, and the animal may become “touchy” about the head and ears when being bridled. Severe inflammation, eruption, and bad scars may result in neglected cases.

Parrot mouth (Figure 2).


Parrot mouth is a rather common hereditary defect where the lower jaw is too short and the upper and lower incisor teeth do not meet properly.

Monkey mouth.

Monkey mouth, or undershot jaw, is the opposite and is less common than parrot mouth. Both conditions may interfere with grazing.


Fistula (Figure 3).


Fistula is an inflammation of the withers affecting this region in much the same way as poll evil affects the poll. It may be present on one or both sides of the withers. It should be treated early otherwise the disease can linger on, resulting in severe infection and occasionally a “crestfallen” condition of the neck immediately in front of the withers.

Sweeney (Figure 4).


Sweeney is an atrophy or decrease in size of a muscle or group of muscles. It is most common to the shoulder muscles extending from the withers downward about two-thirds of the distance to the point of the shoulder. Sweeney is not very common to light horses. It may be associated with lameness from another source in the same limb.

Knocked-down hip.

 A fracture of the external angle of the hip bone (ilium) results in a lowering of the point the hip. It can be identified best by standing directly behind the horse. Hurrying through narrow doors, crowding in trailers, falling, and injury from other causes may be responsible. Usefulness is seldom impaired, but appearance is greatly affected.


Scars may appear on any part of the body. Attention is usually directed to them because of the presence of white hairs. Working stock horses with scars are not discriminated against very much, but gaited and parade horses are seriously faulted.

Hernias (Figure 5).


Hernia may appear on any portion of the abdomen, but are more common near the umbilicus. They are seldom serious enough to cause an unsoundness, although some are.

Respiration (Wind).

Any permanent abnormality in the respiration process is a serious unsoundness.

Roaring (Whistling).

A paralysis or partial paralysis of the nerves that control the muscles of the vocal cords may result in a roaring or whistling sound when air is inhaled into the lungs. The condition is seldom apparent when the horse is at rest, but becomes obvious upon exertion. Roaring may be limited to one nostril, and can be determined by plugging each nostril alternately.


Heaving is caused by a loss of elasticity of the lungs, resulting from a breakdown of the walls of a portion of the air cells. The condition is characterized by an apparent extra contraction of the flank muscles during expiration. The expiration process can be seen, and often heard, to proceed normally to about two-thirds of completion where it is stopped. The flank and lower rib muscles contract briefly, then expiration continues to completion. Dusty hay and/or atmosphere, severe exertion of horses out of condition, and respiratory infections are common causes of the disease.

Stable Vices That Affect Usefulness

Vices are habits acquired by some horses that are subjected to long periods of idleness. Hard work and freedom from close confinement are distinct preventives. Correct or prevent early, before the habits become confirmed, if you expect a high degree of success.

Wind sucking, cribbing, weaving, and stall walking horses are hard to keep in condition; and the latter two types are often fatigued when needed.

Wind Sucking (Figure 6).


A wind sucking horse identifies an object on which he can press his upper front teeth while pulling backward and sucking air into the stomach, usually accompanied by a prolonged grunting sound. The habit is practiced while eating, thus causing loss of food. Confirmed windsuckers will identify an object in pasture on which to suck wind, and will practice the habit when tied with bridle or halter as the opportunity is presented.

Cribbing (Crib Biting).

Crib-biting horses grasp an object (feed box edge or manger) between their teeth and apply pressure, gradually gnawing the object away if it is not metal. Wind sucking and crib biting are usually associated, although a horse may practice one without the other. Crib biting wears away the teeth to a point of decreased efficiency when grazing. Both habits may be partially prevented and sometimes stopped by a wide strap fitted sufficiently close about the throat to compress the larynx when pressure is borne on the front teeth. Normal swallowing is not impaired. Use care in placing the strap. It should be loose enough to prevent choking and tight enough to be effective.


Weaving is a rhythmical shifting of the weight from one front foot to the other. It is not a common vice, but when carried to extremes renders a horse almost useless. Its cause is obscure but its occurrence is correlated with enforced idleness in confined quarters. Some horsemen condemn vertical bars that can be seen through and others consider chain halter shanks that rattle when moved, as predisposing causes.

Stall Walking.

Stall walking is uncommon, but reduces condition and induces fatigue.


Occasionally horses will learn to destroy partitions or doors in stalls by kicking. Some kick only feeding time, thus giving vent to their impatience. Usually they do not kick outside the stall. Padding the stall has been known to stop some kickers.


Stallions often acquire the habit of nipping at the attendant for want of something to do. Gentle horses can be encouraged to nip when too much pressure is applied in grooming or during cinching the saddle girth. Many show horses learn to bite in self-defense when agitated by pokes from well-wishers as they rest in their stalls on the show circuit. Removing the cause will usually correct the condition.

Tail Rubbing.

Tail rubbing starts by agitation from parasites and continues from habit. Parasite control and tail boards prevent it.

Halter Pulling.

Halter pulling develops when a horse attains confidence that he is stronger than the rigging that secures him. Young horses in training will not gain such confidence when secured by strong halter equipment tied to stationary objects. Bridles should not be used in tying young horses.

The habit may be broken in early stages by a slip noose about the flank, with the rope shank passing between the forelegs, through the halter ring, and by being fastened securely. Pain experienced from hard pulling backward is usually given consideration before tightening a halter shank afterward. A second rather successful method is to pass the halter rope through a tie ring in the stall and fasten it to a hobble placed on a fore pastern.

Examining Horses for Soundness

It is not easy to make an accurate diagnosis of a horse’s soundness. Sometimes professional assistance is needed, and whenever possible the horse should be taken on a trial basis for use under conditions to which he will be subjected, under new ownership. Some guarantees of soundness are useful. Most horsemen can increase their competence in identifying unsoundnesses and blemishes by practice and use of a system of inspection. Whenever possible examine the horse in his stall under natural conditions the manner of tying—he may be a haler puller. If metal covers the manger of feed box, cribbing should be suspected. Look for signs of a strap around the throat latch. Note the arrangement of bedding. If he paws, it will be pile up near the back feet. Slight lameness may be detected by movement of bedding caused from pointing. Signs of kicking may be noted. Move the horse about and observe signs of slight founder, stiffness, crampiness, and stable attitude.

Lead the horse from the stall and observe the eyes closely for normal dilation and color. Test eyesight further by leading him over obstacles, such as bales of hay, immediately after coming out of the stall into brighter light. Back the horse and observe hock action for stringhalt and crampiness. Stiff shoulders and/or stiff limbs are indicated by a stilted, sluggish stride.

Examine for lameness in motion. Lameness in a front limb is indicated by a nod of the head when weight is placed on the sound limb. The croup drops when weight is shifted from a lame hind limb to a sound one. Splint lameness usually gets worse with exercise, whereas spavin lameness may improve. The horse should be examined when cool, when warmed up, and cooled off again, at both the walk and trot.

Soundness of wind should be checked under conditions of hard work. Be alert for roaring and heaves or the appearance of a discharge from the nose. Cocked ankles may appear after sharp exercise, and weak fetlocks and knees may tremble.

Make a general examination with the horse at rest. He should not point or shift his weight from one fore limb to the other. Stand directly in front of the horse and observe the eyes for signs of cloudiness, position of the ears for alertness, and the face for scars or indentations indicating diseased teeth. Pay particular attention to the knees, cannons, and hoof heads for irregularities. Mover to the side at an oblique angle and note strength of back and coupling, signs of body scars, and shape and cleanness of hocks, cannons, fetlocks, and hoof heads. Look for capped hocks, elbows, and leg set from side view. “Chin” the horse at the withers for an estimation of height. Stand behind the horse and observe symmetry of hips, thighs, gaskins, and hocks, and position of the feet. Move to the opposite side and the oblique angle previously described for final visual inspection before handling any part of the horse.

Determine age according to Extension Bulletin E-978.

The wall of a good hoof is composed of dense horn of uniform color without any signs of cracks in it or rings around it. The slant of the toe should be about 45 degrees and should correspond with that of the pastern. The heels should be deep and reasonably wide. Pick up each foot and look at the bearing surface. The frog should be full and elastic and help bear weight. The bars should be large and straight. The sole should be arched and should not appear flat as in “dropped sole.” Check for “hard heels” or sidebones, ringbone, corns, contracted feet, and thrush. If the horse is shod, check for wear on the shoe from contraction and expansion of healthy heels.

Examine the hocks (with care, for safety) for swellings, spavins, puffs, curbs, or other irregularities, by feeling when necessary.

A thorough examination combined with a week’s trial will identify almost any unsoundness or blemish.

Many horses serve man faithfully for a lifetime without developing unsoundness, vice, or bad manners. Such service can come to horse owners only through patience, knowledge, and attention to details of the needs of the animal.


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