A spate of dog deaths has been linked to the powerful weed killer paraquat widely used in Hong Kong. Now, under pressure from experts and dog lovers, officials are considering following the example of the mainland and other places and restricting or banning use of the herbicide, report Simon Parry and Hazel Knowles.

Gisela Cheung vividly remembers the trauma of seeing the pet dog who had been her devoted companion for six years die slowly and agonisingly from what she believes was a fatal dose of the weed killer paraquat.

A friend had been looking after GoGo while Gisela was away from the home on Lamma on a short trip. While out walking on a leash one day, she picked up a morsel of tainted food left in the grass. From that moment, her fate was sealed.

"When I got back, I watched her getting weaker and weaker," said Gisela. "She couldn't drink, and was obviously getting weaker, and the panting was getting worse and worse.

"When we went to the vet, they at first suspected some kind of dehydration. She was put on a drip. She stayed there for five days and then she was suddenly gone during the night. She died in the end of respiratory failure."

GoGo was one of around 10 dogs poisoned on Lamma last autumn. Most of the poisonings took place in the same area and vets and dog owners suspect they were deliberate killings using the potent herbicide paraquat - a chemical widely used and easily available in Hong Kong even though it is banned or restricted in many places overseas.

Those dog deaths have been followed by similar poisonings in Big Wave Bay where four more pets were killed last month. Toxicology tests are currently being conducted to see if paraquat was involved.

More dogs, meanwhile, have been poisoned on Lamma - where one dog owner who had two pets killed last year lost a third dog in early October. In each case, food laced with paraquat is suspected to have been used.

Lamma vet Hans de Vries said the pet owner was "devastated" to have lost a third pet to what appeared to be another case of deliberate poisoning. For veterinary staff too, the ordeal of watching a dog die slowly knowing nothing can be done to prevent its death, is clearly a harrowing experience.

"(Paraquat) is a hit and run poison - it sets off a chain reaction," said de Vries. "It is very unpleasant. There is not much you can do. You can only try to alleviate the suffering, and every day you keep them on the drip is one more day of suffering.

"They practically choke to death. It gets more and more difficult for oxygen to penetrate into the blood stream. They are breathing faster but there is still no oxygen getting in. It must be horrible. You can see it in their eyes because they look panicky and scared. They don't know what is happening."

Whoever was responsible for the poisonings must know the chances of being caught are exceptionally slim, de Vries said. "It must be so easy," he said. "You walk around with a plastic bag with laced bait and you just drop it somewhere when there's no one around.

"Even if a police officer stopped you, they must have a warrant to check your bag, and even if you showed it to them, there is no law against walking around with green meat."

It is not only pets that are potentially at risk, according to de Vries. "In some of the cases, the laced meat has been dropped close to a kindergarten," he said. "That is horrific - I don't have enough adjectives to describe it."

What made the crime even harder to trace was that paraquat rarely showed up in toxicology tests done after an animal's death. "You have to test them for poison within 24 hours," said de Vries. "After that it is out of their system. So police might say there is no poison in the blood or body and you can only have a clinical diagnosis."

Nevertheless, there is little doubt in the mind of de Vries and others that paraquat is behind the poisonings. "We can only guess at the motive," he said. "Maybe it is someone who doesn't like dogs or doesn't like the mess they leave. The suspicion is that some people know who is doing this but they are not talking.

"My opinion is that paraquat should definitely be restricted. It should be restricted to farmers, and people should have to give their ID card details when they buy it."

Elizabeth Huang, chairwoman of the Lamma Animal Welfare Centre, said she believed the actions of a minority of irresponsible dog owners may have led to the poisoning of random, innocent pets on the island.

"Some dogs have been making a nuisance of themselves," she said. "Irresponsible owners just let their dogs roam free and they make a mess everywhere and run across people's vegetables, ruining their produce.

"We have put up posters asking people to be responsible but it has fallen on deaf ears. People just aren't listening. The situation is rather disappointing but of course nothing deserves this kind of reaction."

Huang said she supported a ban on the use of paraquat in Hong Kong. "There are things that people can use in place of paraquat that are a lot less dangerous," she said. "Even from a human point of view, paraquat should be banned because it could affect people who use it and it could even kill them."

Vet Chris Dixon, who runs an animal hospital in Tin Hau, treated two dogs poisoned last month in Big Wave Bay. The animals, a nine-year-old shih tzu cross breed and a one-year-old labradoodle, both died with symptoms he says are textbook paraquat poisoning symptoms.

"We are waiting for toxicology tests but we suspect they were poisoned," Dixon said. "The first dog's throat was burnt on the inside which happens with this weed killer.

"All the symptoms are those associated with poisoning by paraquat which is easily available in Hong Kong. It's a cruel poison which causes a horrible death for wildlife. That is why it has been banned in Europe.

"This is not the poison used by the Bowen Road dog poisoner. That's an organic phosphate. The real problem with this poison is that it is irreversible. There is no antidote. It is a very unpleasant death because it causes respiratory failure.

"Once it's been eaten, that's it. They (a poisoned animal) start off feeling tired and then they start with vomiting and diarrhoea. The liver starts to deteriorate, the kidney function deteriorates, and then the animal suffocates because it causes fibrosis of the lungs.

"Death can take a few hours if it's a big dose, a few days if it's a moderate dose, and a few weeks if it's a small dose."

Dixon said long term studies had also shown health risks to agricultural workers using this weed killer, which was one of the reasons it had already been banned in other countries. Restrictions on its use have also been announced this year on the mainland, where ironically most of the world's paraquat is produced.

"It should be banned in Hong Kong," he said. "We don't have any large scale agriculture taking place. There is no reason for it to be here. Hong Kong is not a farming place. It is one of those poisons where there are alternatives available which do the same job of killing weeds."

The Hong Kong government is currently reviewing the Pesticides Ordinance and may ultimately ban or restrict paraquat - most commonly sold under the trade name Gramoxone. But horticulturalist Paul Melsom says officials have been far too slow to act.

Melsom, who has campaigned for years for an urgent update of the Pesticides Ordinance, said: "This is one of the most important bills for health and safety and should go through as soon as possible but the government has been sitting on it for years. The last time anything major was done was in the 1990s.

"For something so serious, it is scandalous. It is totally irresponsible for the health and safety of children and the public and obviously animals. The sad thing is that everyone is oblivious to the dangers of these chemicals and the long-term accumulation, and that is the most worrying thing."

Melsom argued: "The government should be held to account. "It's frightening to think that they are so far behind many of the best recognized international pesticide safety standards for instance in the UK."

The biggest danger was unregulated spraying of chemicals like paraquat in the New Territories which he said was done in public with no warning, Melsom said. "The foliage just goes brown," he said. "The newly sprayed chemical is very active and is then there for anybody including children playing to absorb on their hands or skin and also for dogs who may stray off the path to get it on their noses or paws.

"Basically you should compare it to other laws that are now enacted like the smoking law where any person smoking or carrying a lighted cigarette in a designated no-smoking area will be liable to a fixed penalty of HK$1,500.

"There are some ridiculous laws compared to the situation with pesticides where there is no monitoring of anybody spraying dangerous pesticides at all, let alone any kind of enforcement. It is all just guidelines. That's what I find so worrying and utterly irresponsible."

A spokeswoman for Agriculture, Fisheries and Conservation Department (AFCD) said in a statement that more than 30 cases of suspected dog poisonings had been referred to the department by police from 2009 to 2011 but no traces of paraquat were found in any of the cases.

No traces of paraquat were found either in tests on dogs involved in last year's killings on Lamma, the statement said. The cases in Big Wave Bay last month were still being investigated by police.

The statement went on: "Paraquat is registered under the Pesticides Ordinance with additional registration conditions requiring that paraquat products in Hong Kong must be sold with an emetic (vomiting agent), stinking agent and colorant to prevent accidental intake," the statement said.

"In September 2012, the AFCD further tightened up the registration conditions which stipulated that the quantity levels of the emetic agent and warning colorant of all paraquat products must be included."

Responding to questions about developments on the mainland, the statement added: "The AFCD has been closely monitoring the global developments on the regulation of paraquat, including information recently announced by the mainland with regard to the restrictions of the production and use of paraquat products in the future.

"The AFCD is in the process of reviewing the registration of paraquat and gathering information to facilitate the evaluation process that would help decide whether the registration of this herbicide should be cancelled.

"If the registration of this herbicide is cancelled, further use of paraquat will be subject to regulation under a permit system and only individuals who are properly trained will be allowed to gain access and apply this herbicide."

While the government ponders what to do, Gisela Cheung is taking no chances as she goes on walks with her new pet, a rescue dog she took in to replace GoGo. "I'm really careful when I take him for walks," she said. "I keep him on a leash all the time and never let him out of my sight."

(HK Edition 11/08/2012 page4)