HAMILTON & DISTRICT BUDGERIGAR SOCIETY INC.


THE MUSCULO-SKELETON SYSTEM,


Fractures & Dislocations:
See Fractures & Breaks for more info.
Bone is a brittle material. In birds it is more porcelain-like than in mammals and the areas of porous or spongy bone form a much smaller part of the skeleton. In small flying birds, many bones are little thicker than egg shells but they have internal reinforcing struts. Avian bones are therefore very prone to fracture. When a bird collides in flight with a solid object, it frequently fractures the skull, limb bones, or spinal column. Most fractures are quite easy to locate, although fractures of the skull are difficult to diagnose and liable to be made far worse by the probing of inexperienced fingers. Shock, cranial hemorrhage and concussion may be just as severe in the absence of a cranial fracture, as they are when one is present. Dislocations are much less common than fractures and generally produce obvious deformities. They can be-rectified by gentle pressure and manipulation of the dislocated joint. Quite often the bones will click back into place quite readily. Dislocations with fractures near the joints are more difficult to diagnose and to treat, and an x-ray may be necessary to establish accurately the nature of the damage.

Periostitis:
Bone is produced mainly by the thin sheet of cells or periosteum which covers its surface. When this covering is injured it tends to separate from the bone beneath, because of the presence of hemorrhage or oedema. New bone then develops in the fluid-filled cavity and forms a hard lump, which may be felt through the skin if the cavity is large. If the wound becomes infected, and especially if a major blood vessel is cut and the vitality of the tissues greatly lowered, periostitis may result. When the invading bacteria are of low virulence, nodular masses of bone will be deposited. If more virulent bacteria are involved, they may cause the periosteum to be underrun with pus, so that large areas are stripped away from the bone. This can be a very painful condition. Sometimes infection may spread through the existing bone into the marrow cavity and cause osteomyelitis, or disperse outwards between the muscles and tendons causing myositis and tendonitis. If the joints become infected, arthritis and synovitis result and lead to severe lameness. Treatment involves the use of anesthesia by a veterinarian, and the scraping out of diseased and necrotic tissue. The wound must be packed with antibiotics or other drugs as indicated, to assist the healing process. Administration of antibiotics by injection or by mouth for several days, however, is also necessary. Most birds nevertheless will remain chronically ill for a while or may die. Luckily periostitis and its associated lesions are not commonly seen in birds.

Osteomyelitis:
Inflammation of the bone marrow is almost invariably caused by infectious agents such as bacteria. Most of these gain entrance through dirty wounds, associated with severe tissue bruising which impairs the blood supply. It is most likely to occur when broken ends of bone project from a wound, as happens in compound fractures. In a few cases infection may reach the bone marrow via the bloodstream. It is quite amazing, however, that even in such injuries osteomyelitis is relatively rare. When infection does become established, pockets of pus may form and become surrounded by granulation tissue. This may allow the fracture to heal to a certain extent, although in some areas no bone formation occurs. In other areas it becomes excessive and grossly irregular in distribution. Although the skin and muscle layers over such bone will heal in a week or so, the limb never returns to full use and sooner or later pus is likely to work its way through a weak area of the bone. The pus may then spread between the granulating replacement tissue, and up or down the affected limb between the sheets of connective tissue which bind the muscles and tendons. Eventually it emerges through a hole or sinus to the external surface of the skin. Such a sinus is likely to ooze pus mixed with blood and serum either continuously or intermittently until the bird is satisfactorily cured or dies. Various distortions of the limb result from lesions of this kind.

There may be thickening of the bones and wastage of muscles due to disuse as the result of pain. As the result of adhesions caused by infection, the muscles and tendons may become incapable of functioning and this immobility can lead to crippling deformity. When such an advanced stage is reached treatment is not likely to be of much avail, because the fibrous sealing-off of the diseased tissues will prevent antibiotics reaching the area via the bloodstream and combating the infection. In any case the bacteria will probably be resistant to all available antibiotics by this late stage. Similarly, the long tortuous sinus tract cannot be adequately cleansed and packed with suspensions of antibiotic in sufficient quantities to reach inside the bone itself. Injections of chymotrypsin (in a form suitable for local and intramuscular use) help to digest and liquefy dead tissue and aid access to the infected area by antibiotics. Hydrogen peroxide ("20 volume" solution) can be used with beneficial effect in larger birds to flush out the sinuses. Surgery is the last resort, amputation of the affected limb well above the suspected highest point of infection being the only treatment which is likely to succeed. Clearly this procedure is the province of a veterinarian.

Arthritis:
Inflammation of joints or arthritis can arise in several ways. Mechanical injuries are probably the most common cause, although a popular unproven belief is that arthritis may arise from standing or sitting in cold or damp places. Infection is often introduced through puncture wounds or scratches of the skin in the region of a joint. Joint infection which is borne by the blood may also arise in birds with a septicaemia. Traumatic lesions or localized infections will often resolve quite quickly, especially if the bird rests the affected joint. Such lesions are characterized by swelling, as the result of congestion and oedema, associated with varying degrees of lameness or other disability, depending upon the joint affected. The swollen joint feels warm as the result of the increased blood flow to the area. Severely infected joints are most painful in the early stages, when there is an increase in the amount of synovial fluid or "joint oil". Pressure from the excess fluid confined by the joint capsule is responsible for much of the pain.

As the early acute stage passes, the excess synovial fluid is slowly absorbed, providing that the infection has been overcome by the defence mechanisms of the body. When pus bas been produced this is gradually reduced by organizing granulation tissue which eventually forms a scar, immobilizing the articular surfaces of the joint. Although this chronic stage is less painful, it usually restricts joint movement. Eventually, actual bone may be deposited in or around the joint, causing osteoarthritis and ankylosis, or immobility of the joint. This is rather more painful, especially when the joint can be moved a little and the spiky deposits of bone press on the soft tissue. The cartilage's covering the joint surfaces may be eroded irregularly and produce clicking, scraping and creaking sensations when the joint is manipulated. When there is arthritis of the leg joints, or several toes, the bird usually shuffles about on its hocks, and then the under surfaces become covered with infected corns or thickened pads of skin or scales. Arthritis involving the wing usually results in it being held away from the body in a dropped position because this is less painful than when the wing is held normally. Arthritis involving the vertebrae of the spine (spondylitis) is quite common in the sacral, lumbar, posterior and thoracic regions, but only occasionally affects the neck. It often results in consecutive vertebrae becoming fused into a solid single piece of bone with large irregular masses underneath the vertebrae. This state is referred to as spondylosis. It occurs most commonly in older budgerigars and senile parrots. No real clue as to its cause has been found in birds, although increasing age or mineral and vitamin imbalance may be contributory factors.

Spondylosis does not respond to any form of treatment. Acute septic arthritis of the limbs caused by bacteria such as Staphylococci is best treated with broad-spectrum antibiotics in the acute stages, given either in medicated seed, drinking water, by dropper, or preferably by subcutaneous injection for five to 10 days according to the response. In the chronic stage after infection has been controlled, treatment consists of lessening the pain and freeing the fibrous tissue which is restricting movement of the joint. This can be done by the use of various salicylates (aspirin), the cortisone group of drugs such as hydrocortisone, as well as other drugs only available to veterinarians. Such drugs may also be used in conjunction with anabolic steroids.

Defects of Bone Development & Maintenance:

Rachitits:
Weak bones (rachitis) is a disease of young growing animals. Young birds of prey, reared by hand on a purely meat diet, soon develop this disease; but all young birds are susceptible, especially long-legged species, which grow rapidly and need large amounts of calcium and phosphorus. A high level of vitamin D3 is also needed at this stage. This is available in fresh food and can even be formed in the skin of the bird itself, provided adequate sunlight is available to stimulate its manufacture. Absorbable calcium and phosphorus, in the ratio of between 1.5:1 and 3:1, are essential. Adequate intake of vitamin D3 is also essential for the absorption of calcium and phosphorus. Small amounts of magnesium and other trace elements are also required. Even if all these minerals are present in adequate amounts and balanced, bone formation may be impaired by illness. If the appetite falls or diarrhea results from a change of diet or a chill, these raw materials are not used in sufficient quantities, or they are lost by excretion in diarrhea. Additionally, an adequate output of parathyroid and other hormones is necessary to regulate blood levels of minerals and their rate of deposition in developing bone.

A bird with weak bones, a large head, ungainly feet and knobby joints is more prone to fractures of the wing and lower limb bones. X-ray examination shows a shortening of many bones of the skeleton, and the long bones with thin external surfaces. The ends of these long bones, called epiphyses, which articulate together, show spreading or "mushrooming", with thick irregular layers of cartilage instead of the usual thin line separating epiphyses from the shafts of the bones. In behavior, the bird is subdued, walks and moves its wings reluctantly, rests on its hocks and is reluctant to perch. It eats little, has loose droppings, and appears to be waiting for death. The latter will soon occur if the bird remains untreated, especially as such specimens have little resistance to disease. Vitamin D3 is essential in the treatment of rickets, either by injection or by mouth. A varied, fresh and interesting diet should be provided, together with warm, dry and if possible sunny quarters. Calcium lactate or gluconate tablets can be ground to a powder and mixed with fruit or gentles, according to the feeding habits of the affected bird. Calcium gluconate (with or without magnesium or phosphorus) in a 20 per cent or 40 per cent solution, as used for injecting cattle with "milk fever" can be used at a dilution of one part to 10 or 20 in the drinking water. It can also be injected in 10-20 per cent solution under the skin of the neck. A general vitamin and mineral tonic in the drinking water is also recommended.

Ostelmalacia:
Osteomalacia is the name for weak bones in the adult bird. It is sometimes associated with diseases, injury or tumors of the parathyroid gland and occasionally occurs in old parrots. Most frequently it is a result of prolonged egg laying when the bird is receiving inadequate amounts of calcium. Signs of the disease are often inapparent until some trivial accident results in a fractured limb, because the shafts of the bone have become thin and fragile. The deeper, spongy type of bone in the vertebrae for example, becomes softer than usual. When bone or osseous tissue releases its calcium salts it leaves behind pre-bone or osteoid tissue. Fortunately this process--which occurs in the laying bird--is reversible once the young are fledged, providing the diet is satisfactory. Treatment consists of removing the cock to stop breeding and if possible to foster any young onto another hen. Close attention must be paid to the diet and intake of calcium, phosphorus and vitamin D3. Fortunately parathyroid lesions are rare, as they are generally untreatable.

Osteofibrosis:
Osteofibrosis is the replacement of bone with fibrous tissue. This can happen in small areas as the result of local inflammatory reactions or it may be generalized. It may be associated with liver dysfunction and kidney disease, the latter resulting in failure to discard urates which build up in the tissues, causing gout. Another important effect is the loss of calcium by excretion and the retention of phosphorus Since calcium is not conserved by the kidney, more of it is mobilized from the bone in order to maintain adequate blood levels, without which severe nervous signs would result. In the process, an excess of phosphorus accumulates in the body tissues and bone becomes replaced by fibrous or scar tissue. There is consequently a softening of all layers of bone, which is most noticeable in the pelvis and limbs and the facial bones supporting the beak. The advanced and clinically apparent disease is seldom recognized, however, but the signs of renal disease may be, and it is this which is responsible for death. There is little hope of cure or even of easing the clinical signs for any length of time. A simple bacterial infection is seldom responsible for the renal disease and usually the cause cannot be found.

Other osteodystrophies are poorly understood in birds. A skeletal abnormality which is characterized by thin walled and soft long bones, which buckle or fracture without external violence of any sort, is sometimes seen in parrots, macaws and other large psittacines. It is probably a dietary deficiency of a similar kind to osteomalacia. It is referred to as osteoporosis (porous bone) because calcium salts are sparsely scattered throughout the osteoid tissues, leaving un-mineralized spaces containing soft tissue. A skeletal deformity associated with disturbances in estrogen production is known as hyperostosis.

Diseases of Ligaments & Tendens
Ligaments and tendons are seldom affected by disease, although occasionally they do become cut or torn. They are composed of parallel bundles of cords of fibrous and sometimes elastic tissue, which contain few cells and have very little blood supply. When damaged, the healing process produces a less springy scar substance which is composed of criss-crossing fibres that are not as strong as the original tissue. Such areas are the weak link in the ligament or tendon and are prone to further rupture which results in the formation of bigger and bigger scars. In small birds, the joints are so small that it is almost impossible to diagnose these tears unless a whole group of tendons or ligaments is torn. Treatment consists of immobilizing the limb by the application of sticking plaster or, for birds over 200 grams in weight, a gypsona plaster. The limb should be restrained for 1 to 3 weeks until the repair is achieved and the swelling has largely disappeared. As tendons are liable to pull apart at the level of the tear, healing is often slow and incomplete. Where an entire group of tendons is cut through on one face of a limb, the joint supplied by those tendons is liable to drop. When the gastrocnemius tendon of the hock is cut, the bird drops onto its hocks and loses all power of extending the leg. Surgical repair of tendons is difficult, especially in birds weighing less than 200 grams. Surgery is hampered by the fact that immediately above the hock joint the limb consists of little more than skin, bone, tendons, blood vessels and nerves. A slight error with the scalpel can therefore result in a necrotic or a paralyzed foot if the blood or nerve supply is damaged. The original injury may produce similar results, so a delay of one to three days between accident and operation is preferable to be as sure as possible about the vitality of the lower part of the limb.

Perosis or slipped tendon is a disease of poultry produced mainly by a deficiency of manganese, but other elements may be involved. In turkeys the disease is sometimes called "spraddle legs" or "hock disease". In captive, mainly seed-eating birds, such as budgerigars, canaries, Java sparrows and probably other species, a similar clinical disease occurs, but no conclusive evidence of dietary deficiency has yet been found in these species. Perosis is first noticed soon after youngsters leave the parents. The hocks become broadened; they bow outwards or inwards and appear to be mechanically weak, the bird soon becoming content to rest on its breast and hocks. Corns, in the form of thickened pads of skin, develop at these pressure points. The large gastrocnemius tendon which extends to the under surface of the toes normally runs over the back of the hock in a deep bony groove, but in perosis the broadening of the bones comprising the hock results in the groove becoming shallower and incomplete. The tendon therefore easily slips out of the groove and forward onto the inside of the hock, so that the toes of the foot, instead of tightening when the bird sinks down on its perch, stay loose and flaccid and are unable to grip. The clinical signs superficially resemble some forms of arthritis of the hock. An arthritic joint, however, tends to be a cylindrical or spindle-shaped swelling and the tendon cannot be displaced with the fingers as in perosis. The lesions of perosis are irreversible in the advanced stages and cannot be cured by feeding the minerals or vitamins which prevent the disease.

Bursitis and Synovitis:
Bursae--which are specialized synovial membranes surrounding and lubricating tendons and ligaments where they pass over bony prominences--are prone to mechanical damage. This may occur, for example, when a cage bird is released into an aviary to which it is unaccustomed, and gets a direct injury by colliding with obstructions. It may also occur as the result of a blow or peck, or by being trapped in a cage door or the wire netting, etc. Depending upon the degree, direction and nature of the injury, inflammation of muscles, tendons, ligaments, synovial membranes, or even of nerves, bone and cartilage may result. After a period of rest these tissues usually repair themselves, and unless the damage is very severe, normal functioning is soon re-established. A torn tendon or ligament, however, may so alter the action of muscles around a joint, that the resulting abnormal wear produced in the joint, causes a painful condition. Muscles may then no longer function correctly and cause deformity of the affected limb, resulting in so- called "rheumatism" or "cage paralysis". The damaged limb should be immobilized in a comfortable semi-flexed position using an adhesive, plaster support with or without stiffening splints. After two to three weeks, assisted by the application of skilful dressings, nature will usually have repaired the damage.

Diseases of The Skeletal Muscles:
Apart from simple injuries, such as cuts and sprains and infected wounds, skeletal muscles suffer little from specific disease. Certain deficiencies such as vitamin E, sometimes in l conjunction with methionine, are thought to produce muscle dystrophy. This is manifested by muscle weakness and in severe cases leads to wasting of the affected muscles, particularly the most powerful ones such. as those of the thigh and the pectoral muscles. Birds do not suffer from rheumatism as far as it is known. The various types of lameness and impairment of muscles seen in birds are usually caused by temporary or permanent loss of nerve function to the affected limb and may be due to a variety of causes. When loss of nerve supply is complete, and in other circumstances when there is disuse of muscles for some weeks, the muscles become flabby and smaller, eventually being replaced by fibrous tissue. This decrease in muscle size is called atrophy. In the absence of a nerve supply an atrophied muscle cannot regain its normal size. Atrophy from other causes is, however, usually reversible if the cause is removed.



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Hamilton & District Budgerigar Society Inc.