An indirect haemagglutination test for the sero-diagnosis of C ovis infection in sheep.

An indirect haemagglutination (IHA) test for the diagnosis of caseous lymphadenitis in sheep is described; the test uses purified Corynebacterium ovis toxin to sensitise formalinised sheep erythrocytes treated with bis-diazobenzidine. Animals with titres of 1/16 and above were considered positive to the test. Examination of sera from proven cases of caseous lymphadenitis by the IHA test and anti-haemolysin-inhibition (AHI) tests showed that the IHA test was more sensitive than the AHI test.