_Diagnosis._--The diagnosis of infectious abortion is made from the changes occurring in the fetal membranes and in the expelled fetus. This, however, is substantiated with certainty only by microscopic demonstration of the germ of abortion. The fact that repeated abortions are observed in a herd is also evidence of the presence of the disease. In consideration, however, of the fact that animals may be affected with the disease and disseminate the germs, even though they carry the fetus to full time, a diagnosis in such instances is only possible by laboratory methods. For this purpose the agglutination and also the complement-fixation tests are being used with splendid results, and by the aid of these biological tests it is possible to determine all infected animals in a herd. The tests are carried out with the serum from animals to be examined, only a teaspoonful of serum being necessary for the execution of both of these tests. It, however, has to be confined to laboratories which are properly equipped for such work. _Treatment and prevention._--It may be said in general that treatment is without avail and all efforts should be directed toward prevention. Various medicinal agents, such as carbolic acid administered subcutaneously and methylene blue fed in large quantities, have been recommended, but have failed to stand the tests of scientific investigation and practical use. Serums and vaccines have also been prepared and sold as cures and preventives, but the work is still considered in the experimental stage. Bacterial vaccines are at present extensively used in the control of this disease, and while numerous reports indicate beneficial results from their administration, in other instances total failures have been recorded. It appears that the experiments in this line have not progressed sufficiently to justify definite conclusions. The spread of the disease can be controlled to a great degree by the practice of sanitary measures directed toward the disinfection of premises and the isolation of animals at time of calving and aborting. For methods of disinfection of premises see page 363. Make frequent observations of the animals of affected herds for symptoms of aborting, such as swelling of vulva or udder enlargement, and upon the discovery of an animal showing these symptoms place her immediately in a stall which is somewhat remote from healthy stock as a means of confining the products of abortion as much as possible should the act occur. If an animal aborts unexpectedly she should be removed to separate quarters and given proper attention as promptly as possible. The fetus, afterbirth, provided it has been expelled, and all litter that has been contaminated with them and uterine discharges should be gathered up and destroyed either by burning or burying. Clean and thoroughly disinfect the floor, gutters, and manger in the vicinity of the aborting animal.