_Cause._ There are a variety of causes. Scientific investigation has led to the discovery of specific organisms responsible for various forms of diarrhea. It would be well for poultry rearers to study the results of such work, but, for the purposes of this book, it will be sufficient to state that the causal organism may be bacterial, mycotic, or protozoan. The owner of poultry will not usually be able himself to determine what type of diarrhea the fowls are suffering from, but as a rule the treatment will have to be the same. Advice will have to be sought from an expert when dangerous epidemics are feared. _Treatment._ The most energetic measures of disinfection must be undertaken. (See page 10.) 1. Isolate sick fowls. 2. Disinfect soil of run thoroughly. 3. Clean and disinfect coops. 4. In bad cases, remove the rest of the flock from the infested run. 5. Give sick fowls Epsom salts, or castor oil; feed fowls on soft food. 6. If the diarrhea is not checked, give 6 to 12 drops of chlorodyne. DIPHTHERIA OR DIPHTHERITIC ROUP _A dangerous disease, and infected birds should be killed at once_ _Symptoms._ A cold, accompanied by whitish and yellowish patches on the back of the throat and in the mouth. These patches apparently form a false membrane and cannot be torn off without causing bleeding. The disease is sometimes known as canker. [Illustration: FIG. 11.—DIPHTHERITIC ROUP _b_, lower beak; _t_, tongue; _m_, false membrane. (After Harrison and Streit.)] _Cause._ This disease is often clearly a later stage of roup. It is difficult to say where one ends and the other begins. It has been claimed that the organism is the same as that which causes diphtheria in human beings, but the weight of evidence is against this conclusion. _Treatment._ Diphtheria is extremely infectious. It is best to kill the first cases at once. If the bird is of particular value, it may be isolated and the patches on the throat swabbed with 50% hydrogen peroxide or 5% creolin, with a small bit of cotton wool wound around a stick. If great care is exercised, 20% carbolic acid or 20% creolin may be painted on the patches, but neither should be allowed to touch the normal skin. Burn the swabs. Treat accompanying roupy symptoms as recommended under roup. The term canker is also applied to certain spots or growths that occur on the throat. These are not in any way associated with diphtheritic roup, or any dangerous, contagious disease, and are due to injury or to an unhealthy condition of the mucous membrane. DROPSY _Not a common disease_ _Symptoms._ Distention of abdomen. _Cause._ Collection of liquid in abdominal cavity.