Part 54

BONES: DISEASES AND ACCIDENTS.

By V. T. ATKINSON, V. S.

Some knowledge of the skeleton is advisable to facilitate the study of diseases of bones and the accidental injuries to which they are exposed. The skeleton of the adult ox is made up of the following number of bones:

Spinal column 45 Head 28 Chest 27 Shoulder 2-- 1 on each side. Arm 2-- 1 on each side. Forearm 4-- 2 on each side. Forefoot 40--20 on each side. Pelvis 2-- 1 on each side. Thigh 2-- 1 on each side. Leg 6-- 3 on each side. Hind foot 38--19 on each side. ---- Total 196

Without attempting to burden the reader with the technical names and a scientific classification of each, it appears desirable to describe some of the characteristics of forms in general and of a few classes into which they may be divided, leaving the special study of individual bones to the illustrations of the skeleton (Pl. XXV), which will serve better than a great deal of writing to fix in the mind of the reader the location, relation, and function of each one. In early fetal life the place of bone is supplied by temporary cartilage, which gradually changes to bone. For convenience of study, bones may be said to be composed of a form of dense connective tissue impregnated with lime salts and to contain two elementary constituents--the organic or animal and the inorganic or earthy. In young animals the former predominates; with increasing years the relative proportions of the two change, so that when advanced age is reached the proportion of inorganic far exceeds the organic. The gradual change with advancing years from organic to inorganic has the effect of rendering the bone harder and more brittle, and though it is stronger, the reparative process is slower when injury does occur.

The bones are nourished in two ways: First, from the outside through their covering, called the periosteum--the thin, strong membrane that covers every part of the bone except the articular surface of the joints; and, second, from within through the minute branches of blood vessels which pass into the bones through holes (foramina) on their surface and are distributed in the soft structure (medulla) of the inside. The structure of the bone is divided into two parts--the compact or hard material of the outside, which gives strength and is more abundant in the shafts of long bones, and the cancellated, softer tissue of the inside, which affords accommodation to the blood vessels necessary for the nourishment of that part of the structure.

In shape, bones are divided into three classes--long, flat, and short. The long bones are the ribs and those mostly found in the limbs; the flat bones are found in the head, the shoulder, and the pelvis; the short bones in the spinal column and in the lower portions of the limbs.

With this little introduction, which seems almost indispensable, we will proceed at once to the consideration of diseases of bones, for they undergo disease processes like any other living tissue.

OSTEITIS.

Inflammation of the compact structure of bones (osteitis) may be either acute or chronic, and may involve the whole extent of the bone affected or may be confined to only a portion of it. This inflammation results from injury, such as concussion, laceration, or a crushing bruise; also from specific influences, as in actinomycosis (lumpy jaw) or cases of foul foot. The latter affection frequently involves the bones, and for this reason the pastern is the most frequent seat of osteitis. There is dull pain on pressure and a painful swelling of bone when pus is present. Suppuration may involve the overlying soft tissues, causing an abscess, which may finally break through the skin. The inflammatory condition sometimes assumes an ulcerated form (caries) or from interrupted nutrition of the part deprived of the blood necessary to its nourishment may cause death of a large section of bone (necrosis); this dead fragment (sequestrum), becoming separated from the main portion of bone, acts as a foreign body.

Treatment.--This consists in resting the affected part and in giving vent at the earliest possible moment to whatever pus may be present. Free drainage should then be maintained. Apply dressings of lactic acid or inject with 5 per cent zinc-chlorid solution and pack with tampons of cotton soaked in antiseptic solutions. A laxative to keep the bowels moving freely is the only internal treatment necessary.

PERIOSTITIS.

This disease is an inflammation of the external covering of bone (periosteum) and is usually produced by wounds, pressure, or crushing the part. The periosteum is well supplied with sensitive nerve endings and when inflamed is very sensitive to pressure and may cause lameness. This condition is often difficult to determine, and even an acute observer may fail to locate the point of its existence. There are three forms of periostitis--aseptic, purulent, and fibrous.

ASEPTIC PERIOSTITIS when it becomes chronic causes such a bony enlargement (exostosis) as is seen in the callous formation following the fracture of a bone. The formation of such a tumor or enlargement on the surface of a bone is liable to occur in any part of the bone covered with periosteum, and when found near a joint involving two or more bones it is liable to result in their union (anchylosis).

Treatment.--Applications of cold water to check the inflammatory processes is indicated for the first few days in aseptic periostitis, followed by hot fomentations to hurry resorption of fluids. Massage should then be given with camphor ointment, mercurial ointment, soap liniment, or Lugol's solution. In the chronic form point firing or a biniodid-of-mercury blister will be found beneficial.

PURULENT PERIOSTITIS follows wounds which reach the periosteum and become infected, as observed in compound fractures, or it may result from advancing purulent conditions in neighboring structures, as in foul foot. It may also occur in the course of an infectious disease, when small abscesses are formed under the periosteum (subperiosteal abscess). It may lead to necrosis of the bone or a fistulous tract from the bone to the surface. There is usually much pain and fever, and the odor from the wound is offensive.

Treatment.--In this form of periostitis the periosteum should be freely incised, followed either by continuous irrigation or frequent injection of the wound with antiseptic solutions.

FIBROUS PERIOSTITIS.--This form of the disease consists in the thickening of the outer layer of the periosteum from the inflammation reaching it from neighboring structures. This newly formed fibrous tissue may become ossified or may transmit the inflammation to the deeper bony structures. It is frequently seen in cases in which there has been an intense inflammation of the skin close to an underlying bone.

Treatment.--The treatment should be the same as that recommended for aseptic periostitis.

OSTEOMYELITIS.

This term refers to an inflammation of the bone marrow, which is most commonly seen following the bacterial infection of a compound fracture and usually results in pus formation. The bone is melted away and pus escapes from the bone under the periosteum, involving the soft tissues. It is principally confined to the long bones and seldom affects more than one.

Treatment.--The bone should be opened for the purpose of curetting out the diseased portion of the marrow cavity and removing all the necrotic pieces of bone. This should be undertaken only by a competent veterinarian. The after-treatment consists in tamponing the wound with pledgets of iodoform gauze or a mixture of iodoform 1 part and glycerin 4 parts. The wound in the soft tissue should be kept open until the cavity in the bone has filled with granulation tissue.

RICKETS.

This disease, also called "rachitis," is an inflammatory affection of young, growing bones, and mostly involves the ribs and long bones of the legs. It consists in a failure of the organism to deposit lime salts in bone, and for this reason the bones do not ossify so rapidly as they should. The cartilaginous ends of the bones grow rapidly, but ossification does not keep pace with it. The bones become long and their ends bend at the joints, the legs become crooked, and the joints are large and irregular. All the bones affected with this disease are thicker than normal, and the gait of the animal is stiff and painful. A row of bony enlargements may be found where the ribs articulate with the cartilages connecting them with the breastbone and is called the "beaded line." A catarrhal condition of the digestive tract is usually observed. The disease may result from an inherited weakness of constitution, poor hygienic surroundings, or improper diet. Calves and foals are less frequently affected with rickets than dogs and pigs.

Treatment.--The affected animal should have nourishing feed containing a proper quantity of lime salts. Outdoor exercise and plenty of fresh air are indispensable. Limewater should be given once daily for drinking purposes and ground bone meal mixed with the food. Phosphorus, one-fortieth of a grain, and calcium phosphate, 1 dram, given twice daily to a 2-month-old calf, and proportionally increased for older animals, has proved efficacious in this disease. In some cases the long bones of the limbs are too weak at birth to support the weight of the animal, and temporary splints, carefully padded and wrapped on with some soft bandages, become necessary.

OSTEOMALACIA (CREEPS).

This is a condition of bone brittleness or softening of bone found usually in adult life. It consists in the decalcification of mature bone, with the advancing diminution of the compact portion of bone by absorption. The periosteum strips very easily from the bone. This disease is seen in milch cows during the period of heavy lactation or in the later stages of pregnancy, and the greater the yield of milk the more rapid the progress of the disease. Heifers with their first calves are frequently affected, as these animals require a considerable quantity of mineral salts for their own growth and for the nourishment of their offspring.

Symptoms.--In marked cases there is a gradual emaciation and symptoms of gastrointestinal catarrh, with depraved appetite, the animal eating manure, decayed wood, dirt, leather, etc. Muscular weakness is prominent, together with muscle tremors, which simulate chills, but are not accompanied with any rise of temperature. The animal has a stiff, laborious gait; there is pain and swelling of the joints, and constant shifting of the weight from one leg to another. The restricted movements of the joints are frequently accompanied with a crackling sound, which has caused the name of "creeps" to be applied to the disease. The coat is dull and rough and the skin dry and hidebound. The animal is subject to frequent sprains or fracture of bones without apparent cause, as in lying down or turning around, and when such fractures occur they are difficult to unite. The bones principally involved are the upper bones of the legs, the haunch bone, and the middle bones of the spinal column. The disease in this country is confined to localized areas in the Southwest, known as the "alkali districts," and in the old dairy sections of New York State. The cause of this affection is the insufficiency of lime salts in the food, also to feeding hay of low, damp pastures, kitchen slops, and potatoes, or to overstocking lands. It occurs on old, worn-out soil poor in lime salts, and has also been observed to follow a dry season.