HAMILTON & DISTRICT BUDGERIGAR SOCIETY INC.

TUMOURS & CYSTS & SIMILAR STRUCTURES


A "tumor" simply means a swelling, and the use of the term is usually confined to swellings which are not directly caused by inflammation. The term "neoplasm", has a roughly parallel meaning. It literally signifies a new growth, except that while it is initially developing it may not be recognizable as a swelling or tumor. The cells of a true neoplasm grow and multiply without the customary controls exerted by the body. The cells closely resemble the healthy cells from which they arise, but they are not arranged in any orderly fashion as they multiply and so far as is known they serve no useful function. Tumors are occasionally found in most avian species, but neoplasm's in budgerigars form a high proportion of that species' diseases, in which indeed they appear to be more common than in any other vertebrate animal. Tumors can affect any area or tissue of the body, including the blood, but a high proportion of tumors exist in, or just beneath the skin and produce a noticeable swelling. As time passes, more and more types are described and identified in cage birds, most bearing a close similarity in structure to those reported in man, mammals and especially poultry.

For horn like growths on the cere see hypertrophy of the cere.

Types of Neoplasm's:
Tumor pathologists or oncologists as they are known, have classified the diverse list of non-inflammatory tumors in several ways. Most tumors can be separated into those which are benign and relatively harmless and those which are malignant. Benign tumors are usually firm, enclosed in a fibrous coat, and fail to spread out of that capsule. Malignant tumors are generally softer, not encapsulated and tend to spread to other organs; they invade tissues by the easiest routes, such as between tissue masses and via the blood or lymph vessels, producing secondary tumors or so-called metastases. It is these malignant tumors which give rise to the disease known as cancer. Oncologists classify tumors much further than this, however, depending on the origin of the cells from which they derive. It has been found that neoplasm's correspond to almost every type of cell recognized in the body, but some come from cells occurring only at certain stages in embryonic development.

Benign tumors are usually named by adding "-oma" to the name of the tissue of origin. For example, a fibroma is a tumor of fibrous or connective tissue; a lipoma is a tumor of fat or adipose tissue; an adenoma is derived from glandular tissue, and an osteoma is a bone tumor. There are, however, some exceptions to this rule. If the tumors are malignant and resemble tissues which in the embryo were derived from so-called mesodermal tissues they are known as sarcomas, those derived from ectodermal tissues being known as carcinomas. Thus a malignant tumor of fibrous or connective tissue is called a fibrosarcoma and a malignant, gland cell tumor is known as an adeno-carcinoma. Various odd terms such as papilloma are used for benign skin tumors or warts, this being an old name based on a fanciful likeness to a "little nipple". These names may sound a little confusing, but they are a neat way of describing the various neoplasm's.

Only a pathologist can pronounce the last word on the true nature of a growth, although a good guess can be made as to its type, from observing site, color, consistency and speed of growth. A benign growth, if situated in a vital organ like the brain or the liver, can be as lethal as a malignant tumor owing to the vital space it fills and the mechanical pressure it exerts on surrounding tissues. A tumor is not always a distinct sphere of tissue. Rapid growth in some neoplasm's causes rupture of the capsule and exposure of the contents. Many tumors are multiple. They can start in several places at once, but sometimes fibrous tissue cuts a tumor into groups or clusters. Others, mainly the malignant types, allow groups of one or more cells to break off which are carried to different parts of the body by blood vessels or lymph and start growing wherever they are deposited. These metastases liberate chemicals into the system which rapidly lead to death. Birds, other than poultry, do not appear to be greatly afflicted by such metastasizing growths.

Normal Growths:
A number of structures are present on certain birds. These have functional or ornamental purposes. Some are present in one sex only and clearly play a part in courtship. The fleshy comb and wattles of poultry and the snood of turkeys both have a breeding and heat-regulating function. Some characteristics like the colors of the beak play a part in stimulating the response of nestlings to imminent food as soon as the parent appears near. The cere of the budgerigar, the cere or wattle of the pigeon, the preen gland of numerous birds and the crest of the cardinal and cockatoo are all examples of specialized normal growths. Some of these structures, for example the various feather variations and the distensible crop of the pouter pigeon, are man-made since they have been produced by selective breeding. Occasionally, as the result of breeding for an unusual type of feathering--the crested canaries for example-man has implanted in these birds the unwanted tendency to develop hereditary "lumps", which are feather cysts known as "hypopteronosis cystica". The great majority of curious projections from the head and elsewhere in various breeds of canaries and pigeons are normal. Non-domesticated birds also show a wide range of feather variation. Although normal structures, these are by no means immune from disease, becoming injured or infected in the ordinary way and sometimes affected by neoplastic growths: seasonal variations in size and color may also occur.

Pathological growths, Subcutaneous & other superficial skin growths:
Some of the swellings found on the surface layers of birds are hard, hemispherical masses which make the skin bulge. They are painless and when the skin over them is cut, are seen to be lying free beneath the skin, apparently growing out of the underlying muscle, bone or other tissue. A deeper incision may reveal yellowish, cheesy contents which represent dead tissue. Lesions of this kind may be of several different origins. Some are abscesses which are relatively uncommon in birds, except for the chronic or so-called "cold" abscesses. The vast majority of such cheesy masses are devoid of any pathogenic bacteria. In racing pigeons, they are quite common in the breast and shoulder region; the contents are usually more fibrous and greasy than in other species, and sometimes contain a meshwork of fungal hyphae, usually Aspergillus. In such cases the swellings generally involve the interclavicular or subscapular parts of the airsac system. Sometimes a scar indicates where the exhausted bird has crash-landed into a wire or branch.

Pigeons, canaries and other species, especially budgerigars, sometimes develop skin swellings caused by fat tumors or lipomas. Usual sites are over the wings near the elbow or carpal joints, in the thigh and less commonly on the neck and head. On the breast of budgerigars in particular, excessive fat deposits can sometimes assume tumor proportions. Skin lipomas are very prone to internal degeneration: the center dies and may liquefy or become solid and granular, developing a greyish-pink or creamy coloration, which has little or no odour when opened. Some of these growths do not remain in the underlying tissues like a dome (the so-called sessile tumors), but separate and hang suspended in a fold of skin attached to the breast by small blood vessels, when they are known as pendulous or pedunculated tumors.

Sessile growths near joints are generally tumors of fibrous tissue or bone and are liable to be malignant. Fibromas can generally be removed by a veterinarian provided they are not too closely attached to muscle, bone or joints. Unfortunately it is seldom possible to be sure from external appearances whether such closely anchored masses are malignant or benign. Sarcomas and fibrosarcomas (malignant tumors) are almost as common as fibromas. Osteosarcomas, although less common than these, have been found affecting most bones of the limbs, the spinal column and also the skull. Perhaps the commonest bones involved are the femur, tibia, humerus, radius and ulna, especially near the joints. When malignant tumors are suspected by a veterinarian, the only hope of saving the bird's life is amputation of the limb well above the growth. This would only be justified in a valuable bird needed for breeding, there being no evidence that such malignant tumors are hereditary. If a part only of any tumor is removed, especially a malignant one, it tends to speed the growth and spread of the remainder. True skin tumors of birds papillomas), epitheliomas and carcinomas--are not common. Papillomas or warts seldom occur as frequently as they do in man and domesticated animals. A few sites which are prone to damage, such as the preen gland, the cere, the eyelids and the corners of the mouth, seem to develop a higher proportion of these tumors and related malignancies than other parts of the body.

Bizarre growths around the head are sometimes met with in budgerigars and less frequently in other birds. From their appearance they somewhat resemble horns. In about half the cases, some evidence of knemidocoptic mange or "scaly face" is present, suggesting that the disease is basically an inflammatory response. In others not even pathogenic bacteria can be found. These horns generally grow out from the fleshy parts near the corners of the mouth, the eyelids and other parts of the face or mask as it is known in budgerigars. They are small knobs or pillar-shaped objects, beige or orange colored, with a rough surface and are composed of a core of living tissue, well supplied with blood vessels, which is covered by scales of keratin and sebaceous material. They bleed profusely if incised, but can be pinched off, using ophthalmic-sized artery forceps. A little antibiotic dusting powder should be applied and an antiparasitic dressing may be necessary when Knemidocoptes mite infestation is suspected.

A number of non-neoplastic swellings may be confused with tumors. Near the joints, particularly those of the feet and to a lesser extent, the hock and tarsus (tarso-metatarsal region), shiny, creamy-yellow subcutaneous nodules which cause swelling, loss of joint movement and severe pain are generally signs of gout. Less frequently, the wing joints and cervical vertebrae are involved. Budgerigars are more frequently affected than other species. Hard fibrous nodules on the soles of the feet, containing material like pus, sometimes covered with a strawberry-like swelling which has a tendency to bleed easily, usually represent infected corns. This type of lesion is called "bumble foot". It can be crippling, and prevent the bird from gripping its perch properly, as well as causing lameness. Soft, fluctuating swellings anywhere on the body may be hematomas or blood blisters, cysts, or merely edematous areas. If they crackle on pressure, are translucent or give a soft hollow sound when lightly tapped, they probably contain air or gas and are emphysematous swellings. Painful swellings of the limbs are liable to be fractures, or tumors of the bone-destroying type. Feather cysts or so-called "lumps" in canaries, which are more correctly known as hypopteronosis cystica are hereditary.

Swellings affecting the deeper layer of muscle & bone:
In all species of vertebrates muscle is among those tissues least affected by tumors: cage birds are no exception. Tumors of other neighbouring tissues may spread between muscles or even infiltrate occasionally into muscle tissue itself, if malignant; but this is uncommon. Tumors of all three types of muscle--skeletal, smooth, and heart muscle---are extremely rare. Bone is much more commonly affected than muscle, both by tumors and affections of similar gross appearance. The benign slow-growing osteoma is rare, but chronic inflammatory bone thickenings are relatively common, and include periostitis, arthritis, gout, and certain other lesions of doubtful identity. Partially healed fractures can easily be confused with malignant bone tumors such as osteosarcomas. In such cases the affected limb is often swollen, hot and very painful; it is usually drawn up into an abnormal position. Manipulation will often show abnormal movement of the bone within the swelling. This is because the neoplastic cells invading the bone have caused it to fracture. This mostly occurs in long bones, such as the tibio-tarsus and tarso-metatarsus. When the bony orbit of the eye or the spine is affected, a somewhat tender, hard or rubbery swelling is all that is obvious in the early stages. The faster the growth, the softer the swelling, because the most active tumor cells are incapable of depositing bone or calcium. Although not common, osteosarcomas are among the most unpleasant tumors of birds, being those most likely to metastasize. The connective tissue is a common site of tumors. Fibrous, "fibro-fatty", and fibro sarcomatous tumors can occur anywhere in the body. Their consistency is the best guide to malignancy. A soft mass with little or no capsule is likely to be a cancerous or sarcomatous type. Tumors of blood vessels rather than blood cells have rarely been reported.

Swellings of the Head, Brain & Spinal Cord:
In these areas, swellings are usually neoplastic in origin and the head, with its specialized, highly active parts, is quite a common site for tumors. Irritation of long duration such as is produced by a chronic infestation of the cere by Knemidocoptic mites or a deformed beak which hinders feeding, seem to favor the formation of malignant growths. Cancer, that is carcinomas and sarcomas and of the beak, cere, forehead, eyelids and ear canal have been found both associated and unassociated with such irritations. Surgery is usually impossible, although cautery is successful in a few cases. Only a veterinarian, of course, should contemplate such drastic and potentially dangerous treatment. The mainly benign fatty and fibrous growths have already been dealt with. Tumors of the brain and spinal cord are comparatively rare. Those confirmed on post-mortem examination in budgerigars usually affect the pituitary gland in the base of the brain. Clinical signs as the result of brain tumors vary enormously. With some tumors as the growth enlarges, the optic nerve may be compressed and result in blindness. General pressure on brain tissue results in abnormal behavior, such as circling, staggering, inco-ordination of limbs and head, and metabolic disturbances. Local involvement of the area that controls feeding results in death within a few hours or a day or so, as the result of starvation. Diagnosis of the site, size and nature of brain growths on the basis of clinical signs is an unrewarding and virtually impossible exercise.

Swellings of the Internal Organs:
The diagnosis of a thoracic or abdominal neoplasm is often little more than an inspired guess. Circumstantial evidence may be present in abundance, but only in quite a small proportion of cases can a swelling be felt in that limited area of the abdomen not enclosed by the bony skeleton. Internal tumors cause illness in several ways:
1. By invading and destroying a vital organ, such as the liver or kidneys.
2. By liberating poisonous waste products into the tissue fluid and bloodstream.
3. By so enlarging and filling the limited space of the body cavity that neighbouring organs are squeezed and restricted in their action. Finally, they can no longer function adequately to support life.

The first two methods apply mainly to malignant tumors and the third to benign growths. Organs which commonly become neoplastic are the testicles, ovaries, kidney, liver, spleen, thyroid gland, and lung; roughly in that order of frequency. Other organs are occasionally affected. Of those mentioned, all except the lung usually contain tumors composed of one or other of their own tissues, the lung being a frequent site of secondary tumors or metastases. More than one type of tumor can be present at the same time, the first to develop apparently having no suppressive effect on the development of another type in the same or another organ. Because of their position, when any abdominal organs are affected by benign growths, the clinical signs produced as the result of pressure on adjacent organs are similar and indistinguishable from one another. The organs most sensitive to pressure are the lungs, heart and associated great vessels, and the gut. Pressure on the sciatic nerves caused by kidney tumors gives rise to leg paralysis. Clinical signs denoting neoplasia of the internal organs include panting, gasping, tiring quickly, fainting attacks, fits of the epileptic type leading to inco-ordination and other nervous symptoms, constipation, diarrhea, straining as if attempting to pass an egg, marked loss of weight, exhaustion and loss of consciousness. Swellings in the posterior part of the abdomen cause abdominal distension which may even lead to rupture of the muscle layers of the abdominal wall.

Diffuse and malignant tumors invading the liver or kidney generally produce a wasting illness, with diarrhea and watery, yellowish-white droppings and other evidence of indigestion which appear long before the abdomen shows enlargement. Testicular and ovarian tumors, if they do not produce abnormal sexual behavior patterns usually manifest clinical signs as the result of pressure on nearby organs, as well as abdominal swelling. They generally behave as benign growths and are among the few which are palpable through the abdominal wall with gentle, intermittent probing of the fingers. Sometimes these tumors can be removed by a veterinarian under suitable anesthesia. Thyroid enlargements are not usually neoplastic but rather an overgrowth of the gland in an attempt to overcome the lack of such substances as iodine. Neoplastic growth, with or without excessive thyroxine production, is, like carcinoma of the thyroid gland, uncommon, although cases have been reported in budgerigars, parrots and pigeons. A description of clinical signs associated with thyroid enlargement is given elsewhere.

Leucosis:
Leucosis is an abnormal multiplication of the cells which give rise to various types of white blood cells. All types of white cells, or rather their primitive formation stages, can multiply abnormally to form neoplastic tissue and give rise to forms of leucosis known as lymphatic, myeloid and erythroleucosis according to the types of cells mainly involved. In spite of the excessive multiplication of blood elements in this way, only a small proportion of the circulating blood cells is altered, and so the term leukemia or excess white cells in the blood is seldom appropriate. In poultry, lymphatic leucosis involving the nerves, liver and some other organs has a high incidence, and has been shown to be caused by a virus with an incubation period of several weeks or months. In cage and aviary birds it is not yet certain whether leucosis occurs in the same forms in which it is seen in poultry, but pathologists have found similar diseases, especially in budgerigars and less frequently in a few other species.

Clinical signs of leucosis include great loss of weight resulting in emaciation and death. Some birds show anaemia, and grey or yellowish diarrhea often occurs when the disease is advanced. Appetite and activity are reduced, and handling or frightening the bird greatly increases its distress. When the bird is suffering from the nervous form of leucosis known as neurolymphomatosis or Marek's disease, partial paralysis of one or both legs occurs, or sometimes one or both wings. The leg weaknesses so commonly seen in caged birds, however, are much more likely to be due to other causes, there being many diseases which can produce similar clinical signs. Except when more than one or two birds become affected in a single season, it is unlikely that the disease will be diagnosed except on post-mortem examination. There is usually no treatment. Euthanasia is the only course when leucosis is suspected. It is inadvisable to continue to breed from stock which has bred affected birds. Birds which have been in contact with those affected or with parents of the diseased stock are liable to be infected as a virus is probably responsible for the disease.

Cysts:
A cyst is a bag-like structure within a capsule of connective tissue and occasionally muscle. It is generally lined with a layer of secreting cells. Cysts normally contain fluid produced by this lining. Sometimes the contents are solid after water has been extracted from the secretion. Some authorities include under this heading hematomas,, pockets of air in the tissues, and in fact all abnormal cavities. True cysts can form almost anywhere in the body, but are particularly common in tissues containing gland cells, such as mucous and serous membranes, the liver, oviduct, kidney and the thyroid gland. Skin and subcutaneous cysts are fairly uncommon in cage birds, although the feather cysts of canaries are an exception. Degenerating fatty tumors with fluid centers, sometimes seen in budgerigars, can easily be mistaken for cysts. Experience helps to distinguish them, but only microscopic examination can reveal the true nature of these fluid-filled masses.

Cysts in the body cavity are even more difficult to diagnose than tumors. Most are found at necropsy or during an exploratory operation of the abdomen under anesthesia. Cysts are not malignant, but sometimes they can cause severe illness and death as the result of their size. Cysts of the thyroid gland, sometimes encountered in budgerigars, are very well supplied with blood vessels and are easily ruptured if the bird is roughly handled. This can lead to death in a few minutes as the result of internal hemorrhage. Cysts or dilations of the oviduct are met with quite frequently in budgerigars and occasionally in other species and may simulate abdominal tumors or egg-binding. Peritonitis may ensue if retained egg material accumulates in these pockets of the wall of the oviduct. Painstaking removal of the entire oviduct through a midline abdominal wound may have to be undertaken by a veterinarian if the bird is to survive.

Inflammatory Swellings:
The remaining processes which may be confused with the tumors and similar swellings already dealt with are almost entirely associated with injury or infection, and are therefore mainly inflammatory in nature. Sudden or acute inflammations are accompanied by the classical signs of swelling, heat, pain and usually reddening and impaired function of the part which is inflamed. Long-term or chronic inflammations on the other hand are seldom very painful, are cool to the touch, often of the same color or paler than the surrounding tissues, and although producing an obvious swelling do not usually interfere with the function of nearby organs, except sometimes mechanically, if near a joint or other mobile part of the body. Chronically infected areas may be of the cold or dormant type, which are symptomless apart from the swellings they produce. Others which are exposed to scratching, pressure or other factors causing continuous irritation, develop into so-called granulomas. These lesions caused by excessive production of repair or granulation tissue, contain scar-forming cells, numerous capillary blood vessels, and pockets of infection. The vitality of the area is so lowered by repeated minor injury and infection that complete healing becomes impossible. Common sites are the soles of the feet but also affected are the hocks, nostrils, third eyelid, angles of the beak, the fatty pad over the breastbone, the under side of the wing, the bastard wing, the tail and the preen gland. All these areas are prone to damage and most undergo repeated movement. Skin granulomas can be confused with tumors, the surface of which has undergone ulceration. This is often due to pecking or friction of some kind, almost invariably resulting in the destruction of the nerve endings and blood vessels in the skin. Necrosis or death of the over-lying skin inevitably follows' the loss of blood and nerve supply. Granulomas and ulcerating tumors can usually only be differentiated with certainty from one another by examination under a microscope. A special type of granulation tissue occurs in the remnants of the abdominal muscles, when these rupture after invasion by large quantities of fat or after enlargement of the abdominal contents by tumors or egg-binding. Granulomas in the abdomen are occasionally found to affect various organs, including the gut; in these sites they are potentially as dangerous as malignant tumors. Unlike true tumors, granulomas are sometimes associated with a degree of peritonitis.

Haematomas or Blood Blisters:
Haematomas or blood blisters are really confined hemorrhages. When blood vessels are torn or otherwise damaged, and the blood cannot escape from the wound to the surface of the skin or into a large cavity such as the abdomen, it collects in spaces between layers of tissue where it is trapped and produces a local swelling. In view of the small amount of blood loss needed to kill a small bird, such lesions are best left alone in case the excitement caused by handling results in further hemorrhage. In confined spaces, back pressure of the blood slows down the hemorrhage and clotting soon occurs. Left alone, the blood clots in haematomas and contracts, squeezing out serum which is slowly absorbed back into the lymph and finally into the circulation. The clot is gradually replaced by granulation and finally scar tissue, leaving nothing but a tiny nodule to mark its position. Organs can be enlarged by an increased inflow of blood or a decreased outflow. This occurs normally in the wattles and other fleshy structures of some birds and is a seasonal and hormonal variation.

Sometimes swellings may reach the size of a tumor when there is obstruction to blood flow due to tumor pressure or rupture of tissues. Congestion or engorgement of tissues with blood hinders tissue fluid flowing back into the bloodstream and its build-up in the congested organ leads to oedema. Oedema or dropsy is really the accumulation of lymphatic or tissue fluid in the tissues between cells. In a mild form it accompanies almost all inflammatory conditions and many others as well. In mammals it is commonly associated with a failing heart as well as several debilitating diseases. Ascites or abdominal dropsy is caused by the accumulation of fluid in the peritoneal cavity, when tissue fluid produced in the abdominal organs fails to drain into the lymphatic system. It is usually produced as the result of damage to the liver and kidneys and also when abdominal tumors interfere with the blood circulation. Ascites occurs in birds and should be suspected when a large, soft, fluctuating abdominal swelling develops. Oedema of the limbs or extremities is probably most frequently seen in foot enlargements caused by identification rings on the legs which are too small, becoming tight and interfering with the circulation. Once the swelling of an injured leg fills the space within the ring, the circulation to that limb soon ceases and lymphatic vessels, veins, and even arteries may be progressively blocked off by the strangulating pressure. The thin walled veins become blocked first, but the arteries continue for a time to carry more blood into the foot, so that the limb below the ring swells greatly. This swelling, partly venous engorgement but mainly oedema, persists until the ring is removed or the foot dies. Such a swelling if squeezed for a few seconds and then released, shows an indentation for some seconds where pressed with the fingers it "pits" under pressure. This pitting and blanching of the squeezed area is a sure sign of oedema. Treatment of oedema is related to removal of the cause when possible. In the case of pressure from a leg-ring, the answer is obvious, often, however, no cause can be found. In tissues which have been dropsical (swollen with an excessive accumulation of fluid) for long periods of time permanent changes will result, such as the deposition of fibrous material, especially around blood and lymph vessels. Thickened swellings of this kind can never revert to a normal state.

Tumours and Lameness:
Tumours are a serious problem for which no effective cure has been found although birds that are supplemented with vitamins almost never develop such problems. When tumours appear on the breast of the Budgerigar, they probably are caused by keeping them a long time in a cage that is too small. They have too little exercise and their wing muscles degenerate. Tumours on the head look more like cancer tumours. If tumours occur, lance them with a needle sterilised by boiling or heating them red-hot under a flame. Squeeze out any dirt inside the swelling. Then sterilise the wound with mercurochrome. The bird survives this type of operation remarkably well. But the affected Budgerigar will tend to develop another tumour in a new location. Sometimes, it may also develop a fatty degeneration. Humanely dispose of such a bird because nothing will help it. The cause is a disturbance in glandular function. Ask your veterinarian for advice! Wartlike excema on the head near the eyes and under the beak, the well-known scaly face, can be cured by applying penicillin as a salve. Isolate the affected bird till the cure is complete. Dettol disinfectant can also be used.

Swellings on the feet often are caused by mosquitoes that suck the birds blood while they sleep. These swellings are easily cured by making a few vary small cuts using a properly disinfected razor blade. Treat the wounds with mercurochrome--not tincture of iodine because that stings too much. Then wrap the treated leg with a small adhesive bandage. You don't have to worry about removing the bandage later. The bird will remove it, or else it will just rub off naturally. This treatment prevents infection when the bird scratches around the cage floor with the sore leg. If you have any hesitations about doing this, it would be better to consult an experienced avian veterinarian. I recommend mercurochrome to prevent infection in all types of wounds, whether caused by accidental injury or by a fight. A bird that no longer can use its legs properly suffers from lameness. The cause is thought to be a sexual disturbance. The lameness worsens with time till finally the bird can no longer perch and starts lying on the floor, unable to so much as move its legs. For the rest, such a bird is completely healthy and even will continue to eat normally. Since lameness is incurable, it is kindest to humanely dispose of afflicted birds.



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E-Mail: berniehansen@sympatico.ca

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