In Massachusetts the disease 

 seems to be frequent in growing and 

 mature chickens and has not as yet 

 been identified in chick flocks. The 

 predominating symptoms were res- 

 piratory rales (wheezing), nasal dis- 

 charge, decreased feed consumption, 

 loss in body weight, and a decline 

 of 10 to 40 percent in egg produc- 

 tion. The severity and persistence 

 of these symptoms varied markedly. 

 The resumption of normal egg 

 production was very slow, and some- 

 times did not return to normal. 

 Sexual maturity was delayed some- 

 what in birds affected before they 

 had begun to lay. Later, the 

 initial production rate was low for 

 a prolonged period. Egg quality in 

 affected birds was usually normal, 

 but sometimes changed slightly in 

 color and texture. In some in- 

 stances fertility was affected, es- 

 pecially if the breeding males were 

 infected. Sometimes hatchability 

 and survival of the chicks were 

 lowered, and feed consumption de- 

 clined 10 to 20 percent. Climatic 

 conditions seemed to influence the 

 severity of the symptoms. 



Spread of Disease Not General 



The disease may appear on the 

 same premises from year to year. 



^ # "%». #**' 





Sometimes the disease did not ap- 

 pear to spread to the mature birds 

 that had been on the premises for 

 one or more years, but was common 

 in birds that had been exposed to 

 either Newcastle disease or infec- 

 tious bronchitis vaccines. In many 

 cases the infection spread slowly 

 and appeared to be confined to cer- 

 tain pens of birds in the flock. Few 

 deaths, however, among mature 

 chickens seemed to be caused di- 

 rectly by the disease. In growing 

 birds, four weeks or older, mortality 

 as high as 35 percent has been ob- 

 served. 



In several flocks of chickens and 

 turkeys on the same premises, infec- 

 tious sinusitis was diagnosed in the 

 turkeys, and chronic respiratory 

 disease in the chickens. Since the 

 agents causing chronic respiratory 

 disease and infectious sinusitis have 

 many characteristics in common, 

 further investigation is necessary to 

 determine whether both diseases are 

 caused by the same agent. 



During the past year the disease 

 has been identified in approximately 

 70 flocks. A critical study of the 

 birds from these flocks revealed 

 that 90 percent manifested respir- 

 atory symptoms. Tracheal rales 

 were observed most frequently. On 

 post-mortem, most birds revealed a 

 tracheitis (infection of the wind- 

 pipe) and an aerosacculitis (infec- 

 tion of the air sacs) manifested, 

 usually, by thick, opaque air sac 

 membranes, which might be coated 

 with a yellowish creamy exudate 

 (discharge). 



More recently, the chronic respir- 

 atory disease agent has been identi- 



Fig. 2. Distended sinuses, parMy closed eye- 

 lids, and nasal discharge add up to chronic 

 respiratory disease and one sick poult. 



Photo by Robert L. Coffin. 



