283 SUMMARY OF EVIDENCE ON PLEURO-PNEUMONIA. 



successfully inoculated were brought into contact with 

 diseased stock and took the disease ? 



8. Have you ever known a case where animals that had been 



successfully inoculated were brought into contact with 

 diseased stock and remained healthy ? 



9. Have you ever known of an animal successfully inoculated, 



and yet taking the disease more than six weeks or two 

 months thereafter ? 



10. In your experience have you found the fifty-six days' rule 



sufiiciently large for perfect protection? 



11. If relieved of your personal liability for the cost of the 



slaughter of a possibly healthy animal, would you be in 

 better position to prevent the spread of the disease with- 

 out wholesale slaughter ? 

 About one hundred veterinary inspectors answered the queries, 



and the following may be accepted as a fair description of the 



information supplied under each head. 



1. It is the almost unanimous opinion that the disease is pro- 

 pagated by the contact or herding together of diseased and 

 healthy animals; and the great majority believe that it cannot 

 be propagated in any other way. It is not necessary that a dis- 

 eased animal should come into actual contact with a healthy 

 one in order to communicate the disease. It is sufficient that 

 the animals should be so situated that the air that has been 

 exhaled by the diseased animal may be inhaled by the healthy 

 one. Close, badly-ventilated byres are frequently referred to as 

 favouring the spread of the disease. It is the common opinion 

 that the only certain way of propagating the disease is by 

 housing a diseased animal with healthy ones under the same 

 roof 



2. There is considerable difference of opinion regarding the 

 distance to which the infection may be carried from the body 

 of a diseased animal in the open air. Forty reply that the 

 animals must be herding together, and capable of coming into 

 actual contact ; fifteen consider that the infection may be carried 

 to some distance between ten and fifty yards ; twelve do not 

 regard animals as safe from infection unless they are separated 

 from the diseased animals by distances varying from 100 to 500 

 yards, and they regard these as the radius of an infected area 

 around the seat of an outbreak ; twelve are not content with so 

 small a radius, and recommend that the infected area should have 

 a radius varying from half a mile to four miles. No accurate 

 observations are recorded to prove the distance to which the 

 infection may be carried in the open air, but instances are given 

 in which diseased animals have been separated from healthy ones 

 by a distance of from 20 to 30 feet, such as the breadth of a road, 

 and there was no communication of the disease from the one herd 



