72



A. E. Hamerton—Diseases of Aviary Birds



leprosy ; later, Klein changed his opinion, and agreed that the disease

was tuberculous. Cage birds of all kinds are susceptible to the avian

type of tubercle bacillus ; but, with the exception of cockatoos and

parrots, they are said to be resistant to the human and bovine strains.

The only mammal of economic importance that is commonly infected

with avian tubercle bacilli is the domestic pig, and it is possible that in

the very rare cases in which man has become infected with the avian

type of tubercle bacillus he has contracted it through the pig. Calves

are susceptible to the avian type of tubercle bacillus, but to a much less

degree. In the Zoological Gardens, a kangaroo was recently found

infected with avian tubercle bacilli in the pancreas, and Stanley Griffith

has reported a similar infection of the udder of a goat.


Although tuberculosis probably attacks every avian species living

in captivity or domestication, it seems to be extremely rare among wild

birds. The authenticated cases on record are so few that they may be

mentioned. Shattock and others described a case in a lapwing ( Vanellus

vanellus) which was captured in Scotland. The specimen is now in the

Museum of the College of Surgeons. Hammond Smith records a case

in a wild kestrel ( Falco tinnunculus). Cobbett found a case in

a Partridge ( Perdix perdix), and Hare, of the Royal Veterinary College,

quite recently described a case in a wild Blackbird (Turdus merula )

caught by a cat in a London garden.


In most birds affected with tuberculosis, the lesions are large and

conspicuous by advanced caseation. The liver, spleen, and intestines

are, in most cases, the organs most severely attacked. Sometimes the

disease may be confined to the respiratory system, in which case the

trachea, lungs, and air sacs may be affected. In these cases it is often

impossible to distinguish the lesion from mycosis, except by

microscopical examination, when the finding of tubercle bacilli is

decisive. I have never found mycotic lesions and tuberculous lesions

co-existing. In records of such double infections I can find no data

regarding microscopical examination, which in certain cases is the

only means of distinguishing between the two diseases. Tuberculosis

of the avian glands (thymus, or lymph glands of neck) is fairly common,

and in fact there is no internal avian tissue or structure, except that of

the nervous system, in which I have not found lesions of tuberculosis.



