15/09/2025
Rat Bait Poisoning in Dogs
There are two types of rat bait poisons (rodenticides) in NZ
• An anticoagulant which interferes with blood clotting.
• A type of vitamin D (cholecalciferol) which interferes with the calcium and phosphorus levels in the blood.
Both types can poison dogs as well as rodents.
Anticoagulant rat bait decreases the production of some clotting factors by interfering with vitamin K levels in the liver. Think of this like a supermarket shelf that is not able to be restocked. Once the clotting factors on hand are used they are not replaced and then the dog bleeds.
The two common scenarios for this type of rat bait are:
1. Dogs are seen to eat the bait and the owner takes them to the vet straight away where they are made to vomit and may have a blood test to check clotting factors a few days later.
2. Dogs eat rat bait in sufficient quantities to cause a problem without the owner knowing. Two to five days later the dog starts to bleed, usually into the body so it is often not obvious until they are getting weak, their gums are pale or clinical signs are caused by the bleeding. For example coughing if the bleeding is into the lungs. The other important point is there is a lag. Rat bait doesn’t cause these signs straight away. Dogs that develop clinical signs need to see a vet ASAP for blood testing including clotting factors, hospitalisation, often blood transfusions and vitamin K supplementation for a number of weeks.
The outcome is good with scenario one and usually good with scenario two if the dog is brought to the vet in time.
The other type of rat bait is a type of vitamin D (cholecalciferol) in excessive quantities. This throws the calcium and phosphorus levels in the blood out of kilter and these dogs can develop severe kidney failure as well as having other organs affected. Clinical signs include loss of appetite, vomiting, increased drinking and weakness. These dogs need hospitalisation and intensive treatment. Unfortunately, some of these dogs do not survive especially if owners did not realise they had eaten the rat bait and treatment was not started until the clinical signs had developed and considerable damage had been done.
In summary, rat bait is a risk to dogs. If using rat poison, the anticoagulant type is a better option. Rat and mouse traps which don’t rely on poisons, such as the Good Nature traps, are a better choice for dog owners.