BUREAU OF ANIMAL INDUSTRY. 139 



Maryland, Virginia, and West Virginia, numbering 51 cases, while 

 those from the District of Columbia numbered only 28 cases. Of the 

 79 suspected cases a positive diagnosis was made in 43. The positive 

 cases were 36 dogs, '2 cats, 4 cattle, and 1 hog. A considerable nimiber 

 of persons, as well as a number of animals, had been bitten by the 

 affected animals. 



EXAMINATION OF ARMY HORSES FROM OVERSEAS. 



In cooj^eration with the Quarantine Division, diagnostic laboratory 

 work was done on materials submitted from Army horses returned 

 from overseas service, to exclude animals affected with infectious 

 diseases. Samples of blood serum from all animals held in quarantine 

 were submitted to the complement-fixation test for glanders and 

 trypanosomiasis. All the animals were found to be free from 

 glanders infection, while one was found to be infected with trypano- 

 somiasis and was destroyed. Blood smears from all these animals 

 were also examined microscopically at regular intervals for evidence 

 of infection with piroplasmosis, but no evidence of this disease was 

 found. By means of the toxin-antitoxin test one animal was found 

 to be affected with ulcerative lymphangitis, a disease not known to 

 exist in this countrj", and Avas therefore destroyed. 



BLACKLEG VACCINE. 



During the last year the demand for vaccine for immunizing cattle 

 against blackleg did not equal the requirements of some previous 

 years, yet 1,757,805 doses were distributed to stock owners free of 

 charge. 



BIOLOGICAL PRODUCTS. 



Cooperating with the Division of Virus-Serum Control, which 

 conducts regulatory work of supervising the commercial production 

 of veterinary biological products, the Pathological Division has con- 

 tinued the testing of certain products and has carried on some re- 

 search work in the field. During the year 218 samples, representing 

 42 different kinds of serums, bacterins, vaccines, and germ-free fil- 

 trates, were submitted for examination, and 48 of them were found 

 to be unsatisfactory because of contaminations or lack of potency. 

 There were also submitted for examination 1,024 cultures of organ- 

 isms intended for use in the preparation of biological products, of 

 which 22G were found to be unsatisfactory because of contaminations 

 or atypical cultural characteristics. 



The complement-fixation test has been regularly used in the ex- 

 amination of hemorrhagic-septicemia cultures and bacterins. The 

 uniformly good results with so large a number of samples has proved 

 its reliability to be unquestionable. Because of the good results 

 obtained in this laboratory, several biological houses have adopted 

 this ]:)roccdure as a routine test for these organisms, and the good 

 effects are already evident in their products. 



Serums and similar therapeutic products are almost invariably 

 filtered through bacteria-retaining filters before transfer to final con- 

 tainers, and frequently this step is preceded by filtration through 

 kieselghur to remove coarse particles. As kieselghur and other 



