When any horse is castrated or destroyed under section 8, the market-value of such horse immediately before it became affected with dourine shall be ascertained; and the State Government shall pay as compensation to the owner thereof—
(a) in the case of a mare which has been destroyed, or of an entire horse which has died in consequence of castration, such market-value, and,
(b) in the case of an entire horse which survives castration, half the amount by which such value has been diminished owing to infection with dourine and castration.