Ten C.ovis strains isolated from different localities in Egypt were tested for toxin production by three different methods. Measuring of the potency of the prepared toxin was applied by determination of mini mal reacting dose (MRD/ml) in rabbit skin sensitivity test.
The results indicated the recovery of 8 toxinogenic strains from the local strains examined while 2 were non-toxinogenic. The modified method produced higher level of C.ovis toxin which varied from 20-640 mini mal reacting dose/ml.
The modified method for preparation of the toxin was carried out by inoculating the examined strains on veal infusion agar and icubated for 24 hours at 37°C. Then the resultant growth was transferred to the mo dified digest medium and incubated for 7 days.