Dolphins killed by ‘heroin’ overdose. By Gary Jones. express.co.uk.  May 6, 2012Two dolphins who suffered ‘drawn out and painful’ deaths at a zoo after it hosted a weekend rave were probably killed by a heroin substitute, a leaked toxicology report has claimed. The animals died within five days of each other in November of last year after bosses had rented land near their training pool to organisers of a weekend rave party for thousands of clubbers. Prosecutors said at the time that they believed that antibiotics given by zoo vets were to blame for the deaths of the two dolphins at the ‘Connyland’ zoo in Lipperswil, Switzerland, and they were considering negligence charges.

But now another toxicology report has been leaked to Swiss media that was carried out at the time by the forensics institute in St Gallen – which found the heroin substitute Buprenorphin was present in the animals urine. Leading marine biologist and dolphin expert Cornelis van Elk said: "Opiates are extremely dangerous for underwater mammals and would never be used in any legitimate treatment. 
"The reason is that dolphins are conscious breathers which means they actively decide when to come to the surface to breathe, for which they need to be awake. 
"Even when sleeping – there is part of the brain that automatically controls the breathing instinct in the same way as it does for people when asleep. 
"Drugging them with opiates could well cause this part of the brain to switch off with fatal consequences." It was originally suggested by keepers that rave-goers could have caused the death by feeding the dolphins illegal recreational drugs but prosecutors had rejected this, blaming the zoo’s vets