UNSOUNDNESSES AND BLEMISHES
GENERAL DISCUSSION.--The value of a horse depends largely on the condition
of the limbs and their ability to do the work for which they are intended.
This fact is frequently overlooked by experienced horsemen, who give
attention to general conformation and action rather than to soundness of
limb.
Diseases affecting the limbs may be classed as _unsoundnesses_ and
_blemishes_. This classification is based on the degree to which the
disease interferes or may interfere with the work that the animal is called
on to perform. Unsoundnesses interfere with the use of the part or the use
of the animal for a certain work; blemishes do not. Such a basis for the
classification of diseases does not enable us to place certain diseased
conditions of the limbs in the unsound, or the blemish class at all times.
A curb may, if it produces lameness, be classed as an unsoundness. If it
does not cause the animal to go lame, and the enlargement on the posterior
border of the hock is small, it is classed as a blemish. A high splint may
place the animal in the unsound class, but usually a low splint is not
considered a serious blemish. This classification is based to a certain
extent on the relative economic importance of the disease, or the influence
that the disease may have on the value of the animal, as well as any
interference with the animal's ability to work.
RECOGNITION OF THE DISEASE.--The seat of the disease may be in a muscle,
tendon, bone or ligament. The general symptom manifested is lameness or
pain. The local symptoms are heat, pain, swelling and bony enlargements.
The degree of lameness and the character of the local lesions vary greatly
in the different cases. When the animal shows a slight lameness and there
is little evidence of any local symptom, it requires the services of a
skilled and experienced person to locate the diseased part. When the part
shows local lesions of disease and the lameness is characteristic,
diagnosis is not difficult.
THE EXAMINATION should be made while the animal is at rest; while standing
in the stall and on level ground; when moved at a walk, or a slow trot on
soft ground, or a hard roadway; and when moved out after resting a few
hours. While examining the animal under the different conditions mentioned,
the examiner must be careful and not pass over any part of a limb without
determining whether it is normal or not. He should note any abnormal
position that the animal may take while standing at rest. Every movement
should be watched closely, as the manner of favoring the part may
characterize the lameness. Negative symptoms of lameness in a part may at
times prove as valuable in forming a diagnosis as positive symptoms.
The resting of either of the front feet, when the horse is standing at
ease, indicates that there is some soreness in the rested limb. _Pointing_
or placing one or both feet well in front of the line of support, when the
animal is standing, usually indicates a diseased condition of the feet. It
is natural for a horse that is standing in a stall to rest the hindfeet
alternately. When the hindfoot is rested because of a soreness in some
portion of the limb, it may be flexed or extended, the weight rested on the
toe, and the foot flexed and bearing practically no weight. In serious
inflammation of the front feet, both feet may be placed well in front of
the normal position, and the hindfeet well under the body.
WHEN EXAMINING A HORSE, the blanket or harness should be removed. The horse
should have on an open bridle or halter, and the attendant should give it
as much freedom of the head as possible. The examiner should examine each
limb carefully and note any symptom of disease that may be present. The
attendant should walk the animal straight away from the person making the
examination, toward, and past him, so that the animal's movements can be
observed from both sides, from behind and in front. This examination should
be repeated with the horse at a slow trot.
The character of the lameness may enable us to locate the seat of the
disease. We must first determine in which limb the animal is lame. This
part of the diagnosis is not difficult. The pain suffered every time weight
is thrown on the diseased limb causes the horse to step quickly and shift
as much of the body weight as possible on the well foot. The foot of the
lame limb is jerked up rather quickly after weight is thrown on it. This
favoring of the part varies in the different diseases. When the foot of the
sound limb comes to the ground, more weight than common is placed on it. If
the seat of the lameness is in a front limb, there is a decided nodding or
movement of the head downward when the weight is placed on the well foot.
If both forefeet are diseased, the animal steps shorter and more quickly
than common. Lameness in a hind limb is characterized by more or less
dropping of the quarter of the well limb when weight is thrown on it, and
sometimes by a "hitch" or elevation of the quarter of the diseased limb
when it is carried forward.
Unless there are _local symptoms of disease_ present, it may be quite
difficult to locate the seat of lameness. Sometimes local symptoms are
misleading. After the lameness has been located in a certain limb, its
movement must be carefully noted in order to detect the part favored. If
the lameness is not characteristic enough to enable the examiner to locate
the seat of it, it is then necessary to put the animal through some
movement that may emphasize the soreness in the part. The animal may show a
certain reluctance to throw weight on the limb when turned to the right or
left. Moving the horse in a small circle with the lame limb on the outside
may cause the animal to use the muscles of the shoulder more freely, and
emphasize any soreness that may be present. If the lame limb is on the
inside, soreness anywhere in the foot may be increased, because of the
extra weight thrown on this portion of the limb. Moving the animal over a
hard driveway may increase the pain resulting from an inflammation of the
feet. Causing the animal to trot on soft ground, step over high objects,
flexing, extending, abducting and adducting the part may enable the
examiner to locate the exact group of shoulder or arm muscles involved by
the disease.
IN EXAMINING THE FEET it may be necessary to remove the shoes and practise
percussion and pressure over the region of the sole. In some forms of
lameness it may be necessary to destroy the sensation in the foot by
injecting cocaine along the course of the nerves that supply the foot
before arriving at a definite diagnosis.
QUESTIONS
1. Define the term unsoundness and give an example.
2. Define the term blemish and give an example.
3. Give the general method of examining a horse for soundness.