Report on Feather Diseases - Part II

In Part I, I described the 8 most significant conditions which accounted for two-thirds of the cases of feather disease examined. The second and final part of the report will deal with the remaining 29 diseases and consequently less common problems. These are shown in Table 2.

Preen Gland Tumours, Cysts and Abscesses

In these conditions, the preen gland is enlarged and distorted in shape. As a result the small feathers over the gland become raised and the tail feathers tend to fall out and not regrow. Two affected birds were received as atypical "tail-less wonders". Cysts and abscesses can be drained but tend to recur, and surgical removal is the best treatment for these conditions. Preen gland disease is not associated with any particular feather type.

Multifeathers

In this condition the bird grows long contour feathers, which consist of a series of normal looking feathers joined end to end by a very thin piece of feather shaft. A very few cases were seen in the birds with psittacine beak and feather disease. It is not known if this was as a result of the infection. Such birds are listed under psittacine beak and feather disease in Table 1 printed in Part I. They are not included in the cases of multi-feathers. In two additional cases the birds were related, and the fancier's records indicated that there was an inherited tendency to this condition. This could not be detected in the majority of cases because the records kept were not good enough. Birds tend to be affected for life, but one was seen in which normal feathers were eventually produced. There was no correlation with any feather type.

Longitudinal Splits and Narrow Areas in the Shaft

In some birds, there was a tendency for the shaft of some feathers to split along their lengths. Only a few feathers were affected on any individual bird. The large wing and tail feathers were most affected. Microscopic examination did not show any sign of weakness in the feathers. Other birds showed narrow areas in the shaft, and the feathers tended to snap off at this point. The causes of these conditions were not established, although some type of dietary deficiency seems likely in individual pernickety birds. Those affected birds which we were able to follow over time, grew normal feathers at the next moult. There was no association with any feather type.

The number of cases of the remaining diseases was too small to establish whether they were with any particular plumage type or not. Only with larger numbers of budgerigars would this be possible.

Distorted or Horny Feathers

This is a mixed group, with feathers with kinks in them, twisted and spiral feathers and short, hard, thick feathers, looking more like a small horn than a feather, the latter usually growing from swollen follicles. Usually only one or two feathers on a bird, were affected. These were believed to be due to individual diseased-feather follicles, but this could not be proven. Even in those cases which were followed for some time the birds never grew normal feathers to replace the abnormal ones.

Inflammation Adjacent to Follicles, Distorted Inflamed Follicles and Dermatitis

These were all bacterial infections of segments of the skin and were usually associated with feather loss in the affected area. The usual common cause was staphylococci and the conditions were usually cured with antibacterial washes and antibiotics. However, the feathers may not regrow and those which do may be may be malformed.

Loss of Follicles

Affected birds had bald areas and detailed examination of these showed that the follicles which should have been there were absent. The cause of this was not established, but it is likely that the follicles had been diseased some time in the past, and both the disease and the follicles had disappeared by the time the birds were examined.

Polyfollicles

In this disease two, or sometimes more, feathers grow from a single follicle. This results in deformed feathers being produced; in some cases the condition appears to be irritant and the affected area may be bald, due to the bird plucking itself. The skin is usually thickened in the affected areas. The condition was seen both in contour feathers and the tail feathers and can develop at any age. The cause is unknown and there is no known cure. The disease appears to be much more common in Australia than in the UK.

Excessively Long After-Feathers

The contour feathers of budgerigars consist of two main parts. The main feather which is seen on the body and a small so-called after-feather which consists of downy barbs which keep the bird warm. Three birds were seen in which the after-feathers were excessively long and protruded between the normal, front, part of the feather, so that the birds appeared to be covered with downy feathers. One bird looked more normal, but the contour feathers looked as if they had been pushed away from the body. This bird also had excessively long after-feathers. It is probable that this condition may be inherited but too few affected birds were seen to prove this.

Pearls of Shaft Material in the Wall or Lumen of the Shaft/Abnormal Airspaces in the Shaft

These were only seen at the microscopic level when examining abnormally-shaped feathers which had fractured. The cause is unknown, and it is not clear whether they were the cause or the result the abnormal feather shape. Unfortunately, in none of these cases was it possible to examine the follicles with the microscope. At least one of the affected birds grew normal feathers at the next moult.

Inactive or Undersized Follicles

These were found in birds with bald areas. Microscopic examination showed that there were normal follicles but with no feathers forming in them, as well as excessively small and also inactive follicles. No cause for this condition was found. The disease tended to persist with the bald areas remaining.

Loss of Feathers of Unknown Cause

These were also birds with bald areas, but with normal skin and follicles. This was different from the previous condition in that, normal feathers were regrowing from the follicles. This may be an abnormal type of moult although the possibility that the feather loss was due to fighting cannot be excluded.

Feathers on Shanks and Toes, Feathers Growing at Odd Angles, Friable Feathers, Congenital Absence of One Wing and the Silky Mutation

This is a group of congenital abnormalities. In the first one, the birds grow numbers of feathers on the normally bald shanks and toes. This does not appear to cause the bird any distress. In chickens, this is a genetic inherited condition and, in certain breeds, a desirable trait. The feathers growing at odd angles were like displaced crests on the neck of the two birds which were siblings. This suggests that inheritance may have played a part. A bird was sent in, in which all the feathers were very short or missing. This was because the feathers were fragile and when the bird was handled, more of the feathers would break or fall out. Another bird was submitted with a history of loss of the large wing feathers from one wing. When it was examined the wing was totally missing and had been since hatching. The silky mutation (sometimes known as "straw-feathered" birds) is one condition in which the barbs on the feathers are short and the barbules do not form. This produces slender feathers, the barbs of which do not lock together. This has been reported in a number of bird species, but it does not appear to be inherited. None of these oddities is curable.

Abscess, Trichomoniasis, Lipoma. Hernia and Epidermal Cyst

It seems to be a feature of the budgerigar that, if there is a medium or large swelling below the skin, the feathers are lost from the area of the swelling. One case of each of the above conditions was seen, each with associated feather loss. Provided that the underlying swellings are cured the feathers usually regrow.

Vitamin A deficiency

This bird had patchy feather-loss together with signs elsewhere in the body suggesting a vitamin A deficiency. Dosing the bird with this vitamin cured the condition and the feathers regrew.

Polyomavirus infection

Polyomavirus is one cause of French moult (I think there may well be other causes). For reasons explained above, this single case, representing 0.5% of the feather diseases seen, should not be taken as an indication of the prevalence of this in exhibition budgerigars.

Table 2 - Minor Feather Diseases found in a Survey of 198 affected Budgerigars. Data from another survey of all types of psittacines are included for comparison purposes (Schmidt 1987)

Condition	No of Cases	% of Cases	Schmidt Data %
Preen gland tumours, cysts or abscesses	9	4.5
Multifeathers	9	4.5
Longitudinal splits	8	4.0
Distorted or horny feathers	7	3.5
Inflammation adjacent to follicles	7	3.5
Loss of follicles	7	3.5
Polyfollicles	5	2.5
Excessively long after-feathers	4	2.0
Distorted, inflamed follicles	4	2.0
Narrow areas in shaft	4	2.0
Pearls of shaft material in wall or lumen of shaft	4	2.0
Inactive or undersized follicles	4	2.0	10.3
Loss of feathers of unknown cause	3	1.5
Dermatitis	2	1.0	9.4
Feathers on shanks	2	1.0
Feathers growing at odd angles	2	1.0
Abnormal airspaces in shaft	1	0.5
Abscess	1	0.5
Friable feathers	1	0.5	9.4
Pink feathers	1	0.5
Trichomonas	1	0.5
Vitamin A deficiency	1	0.5
Lipoma	1	0.5
Ringworm	1	0.5	1.4
Hernia	1	0.5	9.4
Epidermal cyst	1	0.5
Congenital absence of one wing	1	0.5
Polyoma virus infection	1	0.5
Silky mutation	1	0.5

Ringworm

A single bird was seen with a patch of feather loss on one side of its body associated with a thick, grey, flaky skin. This proved to be a case of ringworm due to infection with a Trichopyhton fungus. The disease should have been curable but the owner did not want the treatment carried out.

Pink Feathers

Some feathers were submitted which had a marked pink suffusion. The owner said that two of his Albino budgerigars were gradually turning pink. No further details could be obtained.

Conclusions

1. Table 3 presents a summary of the results of the most common conditions which accounted for two-thirds of the cases. From this it will be seen that buff feathering was a predisposing cause of one-third of all the feather diseases investigated. It is suggested that the budgerigar fancy should discourage the breeding of buff birds for this reason. It should be mentioned that buff birds also have breeding problems as shown by some of the previous research done here.
2. In addition to buff feathering, other genetic and probable genetic faults were found in 17% of the birds submitted. It is suggested that their faults may well have been exacerbated by breeding for exhibition characteristics. The reduction or elimination of genetic faults is in the hands of the fancy.
3. If a budgerigar develops one type of feather abnormality, others are likely to follow. This means that in treatable conditions two or more lines of treatment may well have to be used.
4. Of the 37 conditions listed 19 were potentially curable, either medically or surgically.
5. Fanciers need to take precautions to avoid the introduction of psittacine beak and feather disease into their studs. It is suggested that all new birds should be tested for this infection while in quarantine before they are introduced into the stud proper. If they test positive they should either be returned to where they came from or destroyed.
6. "Tail-less wonders" have several causes including pulpitis, mites, feather cysts on the tail and preen gland disease. Other diseases which may do this, but which were not seen in the present work are polyomavirus infection in adults, the early stages of some cases of psittacine beak and feather disease, and injury to the tail.
7. Feather diseases have many causes and if they are a problem in a stud only detailed examination will establish the nature of the condition and indicate a cure if one is available.

Table 3 - Summary of the eight most common feather diseases. These accounted for 199 of the 293 conditions seen in 198 birds (68%)

Condition	Cause	Treatment?	Associated feather type
Psittacine beak and feather disease	Viral infection	None	None
Pulpitis	Viruses and bacteria	40% success	Buff
Feather mites	Mites	Yes	None
Feather cysts	Buff feathers probably genetic	Surgery only	Buff
Stress marks and related conditions	Illness,diet,stress	Yes if basic problem treated	None
Feather dusters	Genetic	None	Buff

Original text copyright 1996, Dr John R Baker

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