CHAPTER XXVIII. 
DISEASES, PARASITES, AND ENEMIES. 
In every flock of poultry, regardless of size, an outbreak of 
disease is always possible. In some cases this is due to environ- 
ment or management for which the poultryman is directly respon- 
sible; in others, disease may break out in a flock well cared for. 
Every poultryman, therefore, should familiarize himself with the 
structure and functions of the bird’s body, so that the first 
symptoms of disease will be perceived, and proper steps taken 
to check its spread. Perfect health depends upon a full under- 
standing of environment and feeding, which have been elsewhere 
outlined, with a knowledge of the laws of sanitation and preven- 
tion of disease. 
Treating Diseased Poultry.—With the average fowl or average 
flock it is a well-established principle that it does not pay to treat 
diseased birds unless they are of exceptionally high value and the 
disease is not infectious. The reasons are as follows: 
Birds which have ever been affected with the common diseases 
and are supposedly cured are a constant menace to the flock. If 
allowed to mingle with the others, their identity may be mistaken, 
and they may be put in the breeding pen, to perpetuate through 
their offspring a weakened constitution and tendency to similar 
diseases in succeeding generations. 
The value of the individual bird and its production are so 
small, in comparison with the time which must be devoted io 
treatment and the cost of medicine, that it is rarely a profitable 
expenditure of time unless a bird be very valuable. 
Diseases that are infectious or highly contagious should never 
be treated with the idea of subsequently using or selling the affected 
birds. The custom should be to kill all that are diseased, and at 
once to begin thorough disinfection and keep it up for an indefinite 
period. 
When to Treat Poultry—It is both practicable and profitable 
to treat sick poultry under any of the following circumstances: 
1. When only one or a few fowls need treatment which is simple, 
easy of administration, and absolutely certain in its effects. 
2. When, as in the case of certain common and simple infec- 
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