Treating dogs poisoned by rodenticides - Animal Health

With cooler evenings and shorter days signaling the coming of fall, mice will be seeking shelter for the coming winter. This is also the time of year that veterinarians see an increase in the number of dogs with exposure to mice and rat poison.

Rodenticide toxicity is common in areas where poisons are used to control mice and rats. The most common type of rodenticide used is Warfarin or warfarin-like products.

Warfarin, also known as coumadin, is an anticoagulant, meaning it interferes with the body’s ability to clot blood.

Read Also

Producers face the reality of shifting grain price expectations

Significant price shifts have occurred in various grains as compared to what was expected at the beginning of the calendar year. Crop insurance prices can be used as a base for the changes.

The clotting of blood is a continual occurrence in the body. It is a necessary and complex process involving the vasculature, white blood cells called platelets and proteins.

Warfarin acts by inhibiting the enzyme that regenerates active vitamin K. Several clotting factors require vitamin K to function effectively. The three clotting pathways called intrinsic, extrinsic and common are typically affected by anticoagulant toxicity. Warfarin may be absorbed from the gastrointestinal tract, by inhalation, and to a much lesser extent, through the skin.

It is used in and around homes, agricultural buildings and commercial sites for rodent control, and is also used to treat people with blood hypercoagulation problems. Rodents do not tend to become bait shy and continue to consume it until its anti-clotting properties have caused death, usually by internal bleeding. Generally rodents will eat the toxin over a few days, but large single doses can also be fatal.

There are several kinds of anticoagulant rodenticides, each with its own level of duration. While warfarin lasts only for about one week, other products such as brodifacoum are potent and can last four to six weeks.

When the specific rodenticide is unknown, affected animals are usually treated with vitamin K for a duration that assumes they have encountered a potent, long-acting toxin. Blood clotting tests can also show whether an animal has the ability to clot its blood normally.

There is usually a delay of two to five days after ingestion before clinical effects are observed. The poisoned animal may be found dead with no signs of illness. This is usually due to bleeding in vital areas such as the lungs. Symptoms may include depression, lethargy, pale coloration, weakness, bruising or bleeding.

In cases of acute ingestion, vomitting may be induced and the animal may be given activated charcoal, which helps prevent further toxin absorption. Vitamin K1 is the specific antidote for anticoagulant toxicity and is usually given first as an injection under the skin and then orally until the toxin is cleared from the body. Since vitamin K1 can take up to 24 hours to correct clotting defects, transfusion with either whole blood or plasma to immediately provide clotting factors is necessary if the animal is suffering from a life-threatening hemorrhage.

If a dog has access to a poison, so may a child. Keep poisons out of reach of children and non-target animals. If you suspect your animal may have been poisoned, transport it to your veterinarian and bring the suspected poison if possible. Tamper resistant bait stations should be used wherever possible.

Daryl Meger is a veterinarian and outdoors enthusiast in a mixed animal practice in Westlock, Alta.