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31 August 1998
The Ministry of Agriculture and Forestry says dog owners need to be aware of the risks to their pets from a range of poisons commonly used to control pests.
Dr Marjorie Orr of MAF Quality Management’s Animal Welfare Services Group said although the risks to dogs from use of 1080 are quite widely known, the risks associated with other common poisons may not be appreciated to the same extent.
Dr Orr said poison operators must be licensed to use 1080, phosphorus and cyanide, and they must make every effort to keep accidental deaths to a minimum. This includes publishing in the Public Notices column of local newspapers the intention to lay poison and posting notices around the area to be poisoned giving the dates of the operation and the poison used. Animal owners must heed these warnings to prevent accidental deaths of dogs and livestock.
There is no restriction on the use of anticoagulant poisons and no requirement to display notices. Since there is no way of knowing if anticoagulant has been laid on private land without asking the owner, it is best to exercise dogs only in areas known to be safe.
The following briefly describes the effects of poisoning by 1080, anticoagulants, phosphorus and cyanide, the treatment available if any, and the importance of heeding warnings during and after poisoning operations:
1080 kills most species relatively quickly and with little evidence of distress, but in dogs it causes frenzied behaviour with signs of great agitation such as howling and trembling before the onset of fits then death. There is no effective treatment.
Anticoagulant poisons like Talon, Storm or Warfarin are in common use in and around homes and farmsteads, and may be used in ground poisoning operations with no requirement for notices to be displayed. Anyone who uses anticoagulant poisons against rodents, possums and rabbits should make every effort to ensure that other animals do not get access to the baits, and that dogs are not able to scavenge poisoned carcases.
Anticoagulants cause death through internal bleeding and there may be signs such as reddened areas under the surface of the gums, nose bleeds or lameness as a result of bleeding into the joints, and the dog becomes anaemic and weak. Fortunately, unlike the other poisons in common use, there is an antidote. Early cases of poisoning can sometimes be treated successfully with vitamin K. Treatment by a veterinarian must be started very soon after the poison has been eaten, and it is protracted and expensive.
Death from phosphorus poisoning may follow minutes or days of illness with diarrhoea, vomiting and signs of intense abdominal pain. There is no effective treatment and no attempt should be made to cause vomiting as this only adds to the animal’s distress.
Cyanide poisons on the other hand cause death within minutes of animal contact and tiny amounts can be fatal. The advantage of cyanide in pest control is that little persists in the carcase, so the risk of dogs being poisoned as a result of scavenging is low.
If it is known that 1080 or anticoagulant poison has been eaten, making the dog vomit right away might save its life. This means taking the dog to a vet immediately or giving it an emetic capsule (available from some pest control agencies), but if this is not possible there are various last resort methods of inducing vomiting. These include drenching with a supersaturated solution of household salt in warm water or making the dog swallow a crystal of washing soda (sodium carbonate) coated in butter.
For weeks or months after poisoning operations using 1080, there is a very real risk to dogs, not just from ingestion of bait, but also from scavenging poisoned carcases. Dogs must not be allowed access to poisoned land until it is likely that all poisoned carcases have completely decomposed. Usually this takes at least 10 weeks if more than 10 cm rain has fallen, and much longer in dry or freezing weather which tends to preserve the carcases. There are similar risks of accidental phosphorus and anticoagulant poisoning in dogs as a result of scavenging. Muzzling and keeping dogs under observation, and feeding them before going near poisoned areas can help reduce the risk.
Most Regional Councils have information leaflets on poisoning operations, and information about specific operations can be obtained from the approved operator involved. Muzzles can be purchased at various outlets including veterinary clinics, and the open wire types which allow dogs to pant are best.
For more information contact:
Dr Marjorie Orr, Animal Welfare Veterinarian
MAF Quality Management, Invermay Animal Health & Food Quality Laboratory
Private Bag 50034, Mosgiel
Phone (03) 489 3809; A/H (03) 489 7920
Fax (03) 489 7988