HUMANE DESTRUCTION OF HORSES WITH A MIXTURE OF QUINALBARBITONE AND CINCHOCAINE

One hundred and-two horses requiring to be euthanased for a variety of reasons were killed by the intravenous injection of a mixture of quin albarbitone sodium (400 mg/ml) and cinchocaine hydrochloride (25 mg/ml ). The dose rates used were 1 ml/10, 15, 20 and 30 kg bodyweight, and the time of injection was varied between 5 and 25 seconds. The average time to collapse from the start of the injection was 34 seconds and t he average time to clinical death was 230 seconds. Slow injection (par ticularly of the low dose rates) and premedication with detomidine res ulted in a longer time to collapse (median 46 seconds). Premedication with xylazine and low dose rates of the mixture resulted in an unaccep table degree of muscular activity and agonal gasping and death was del ayed. Premedication with romifidine and butorphanol resulted in an app arent (but insignificant) reduction in the time to collapse and death but was also accompanied by significant agonal gasping. Without premed ication quinalbarbitone and cinchocaine resulted in a smooth and quiet collapse with the cessation of cardiac and respiratory functions with in three minutes in all cases, but the palpebral reflex of the horses was prolonged significantly beyond the time when all other reflex acti vity was lost. Occasional gasping and muscular tremors, particularly o f the upper forelimb, occurred particularly when lower dose rates and either very slow or very fast rates of injection were used. One horse which was premedicated with xylazine and received a very low dose at a slow rate showed unacceptably violent muscular activity. At no other time was the procedure regarded as violent or unacceptable. Inadverten t extravascular injection caused no apparent pain. A dose rate of 25 m l for ponies and 50 ml for horses is recommended, and the injection sh ould be administered intravenously over 10 to 15 seconds. The carcase of a horse killed in this way is not fit for human or animal consumpti on.