DISEASE IN HAND-REARED GROUSE 439 



tide of the outbreak. Unfortunately, in the cases observed to date, the treatment was by ne- 

 cessity given to all the birds and no control group was left untreated as a check on the normal 

 course of the disease. In view of information desired in the selective breeding program, it 

 was considered inadvisable to risk loss of part of the exposed group if they could be saved 

 by the treatment. Similar therapy has been reported to be of value in treating blackhead in 

 turkeys''^. 



It should be reiterated that blackhead is no large problem when birds are kept on wire 

 and good sanitation is practised. Its devastating effects will soon be apparent if attempts are 

 made to maintain grouse in pens on the ground. 



Tuberculosis (Caused by Mycobacterium avium) 



Cause. A bacterial organism, Mycobacterium avium, is the causative agent of avian tu- 

 berculosis, which was recognized as a disease of chickens as early as 1868 and was reported 

 from pheasants and ducks in 1872. The disease has been reported from many species of birds 

 including sparrows, crows, hawks and owls. Among captive birds, the gallinaceous and pigeon 

 groups seem to be the most susceptible. 



Nature of the Disease. Tuberculosis in birds is a contagious disease which pursues a 

 chronic course. It is characterized by the production of nodular lesions, known as tubercles. 

 These are grayish yellow or white and of firm consistency, varying in size from that of a 

 |)in point to over an inch in diameter, the larger ones being more irregular in shape. The 

 organs most frequently affected are the intestines, liver and spleen, which may become con- 

 siderably enlarged as a result of the infection. Other organs which are often involved are the 

 lungs and bone marrow. 



Development of the disease takes place slowly over a number of months. In some cases, 

 a couple of years may elapse before death ensues. It is therefore almost always found in 

 older birds. As the malady progresses, the birds generally suffer a loss of weight and ap- 

 petite. 



Tuberculosis has occurred very rarely and only in isolated cases among the captive grouse 

 at the Research Center. Less than one case a year has been observed and all the affected birds 

 were over two years old. 



Dissemination. The presence of the tubercle bacilli in the feces of infected birds is prob- 

 ably the most important factor in the sjiread of the disease. Earthworms and fly larvae which 

 have fed on the carcasses of dead tuberculous ])oullry, have been suggested as disseminating 

 agents, but exposure to these vectors is not likely to occur in modern grouse rearing. 



Control. Ingestion of the organisms by other birds is effectively eliminated in grouse 

 propagation by keeping the birds on wire. 



Aspergillosis (Caused by Aspergillus fumigaius) 



Cause. A mold or fungus organism is the causative agent of the condition known as asper- 

 gillosis, pulmonary mycosis or brooder pneumonia. The mold and its spores occur in moldy 

 grain, straw or other plant material and are inhaled by birds which contact these products. 



Nature of the Disease. The spores which are taken in by exposed birds find their way to 

 the lungs and air sacs where they germinate and give rise to mold colonies varying in size 

 from those which are barely visible to the naked eye to some over one quarter of an inch in 



A Service Bulletin No. 30. Larro Milling Co.. pp 1-5 (undated). 



