What are anticoagulant rodenticides?
Anticoagulant rodenticides are poisons used to kill mice, rats, and other rodents by preventing blood clotting. They are commonly found in hard bait blocks, soft baits (firm clay consistency), and pellets, but may also be in powder, grain/meal, and liquid formulations.
Several active ingredients may be used in anticoagulant rodenticides, including chlorophacinone, brodifacoum, bromadiolone, difenacoum, difethialone, diphacinone, and warfarin. The active ingredient and bait formulation depend on the product's intended place of use and federal regulations.
What is anticoagulant rodenticide poisoning?
Anticoagulant rodenticide poisoning occurs when a dog ingests a rodenticide containing an active ingredient that prevents blood clotting. The dog usually ingests the poison when it is placed, without a protective bait station, in and around buildings, which allows dogs and other non-target animals to easily access the poison.
Secondary (relay) poisoning can also occur, in which an animal is poisoned after it eats a rodent killed by rodenticide. However, secondary poisoning is rare because a dog would need to eat many rodents that died from the poison.
How does poisoning occur?
Anticoagulant rodenticides cause excessive bleeding by interfering with vitamin K1, which is needed for the body to make certain clotting factors that allow blood to clot and help control bleeding. Anticoagulant rodenticides decrease vitamin K1 to levels that are too low to produce the needed clotting factors, resulting in uncontrolled bleeding.
What are the clinical signs of anticoagulant rodenticide poisoning?
Initially, dogs do not show signs of anticoagulant poisoning. After ingesting this type of bait, it takes one to two days for clotting factors in the body to be used up. Next, it takes three to seven days before signs of poisoning occur due to blood loss. Bleeding is not always obvious as it often occurs inside the abdomen, chest, lungs, joints, and gastrointestinal tract. In some cases, bleeding may be visible from the mouth, nose, or ears.
Signs of internal bleeding in dogs may include:
- Weakness/depression
- Increased respiratory rate
- Difficulty breathing
- Coughing (which may produce blood)
- Pale gums
- Lack of appetite
- Distended abdomen
- Vomiting
- Bloody or dark tarry stools
- Swelling or pain in the joints
- Bruising
If bleeding occurs in the brain or spinal cord, dogs may have neurologic signs. If bleeding is not recognized and treated, death may occur. If you suspect your pet has ingested an anticoagulant rodenticide, it is important to immediately contact your veterinarian or Pet Poison Helpline, a 24/7 pet poison center, at 1-800-213-6680, to determine the risk of poisoning to your pet.
How is anticoagulant rodenticide poisoning diagnosed?
Most cases of poisoning are diagnosed in pets with signs of bleeding and a known or suspected exposure to anticoagulant rodenticides. Bloodwork is often performed to assess for abnormalities. Radiographs (X-rays) and ultrasound may be used to check for blood in the chest or abdomen.
How is anticoagulant rodenticide poisoning treated?
Early decontamination and treatment decrease the risk of serious poisoning. If your dog ingested an anticoagulant rodenticide within a few hours of treatment, the veterinarian may induce vomiting. Once vomiting is controlled, your veterinarian may administer medical-grade activated charcoal. Activated charcoal should only be given by a veterinarian and never given at home, as dogs may inhale (aspirate) it into the lungs, causing life-threatening changes in the blood sodium level.
The antidote to anticoagulant rodenticide is vitamin K1, a prescription medication given to increase vitamin K1 levels in the body and prevent bleeding. Your dog may need to be hospitalized, depending on the time since ingestion and the clinical signs present. Dogs that develop more serious signs may require intensive therapy, as they have an increased risk of death.
What care will my dog require after treatment?
When anticoagulant rodenticide poisoning occurs, vitamin K1 supplementation must be continued for several weeks. Approximately 48 hours after discontinuing vitamin K1, your veterinarian should evaluate blood clotting times to ensure no further supplementation is needed. During the early stages of recovery at home, limited activity is recommended to prevent injuries that could cause bleeding. Once vitamin K1 supplementation can be discontinued, the dog can return to regular activities.
Pet Poison Helpline, a pet poison control center based out of Minneapolis, MN, is available 24/7 for pet owners and veterinary professionals that require assistance treating a potentially poisoned pet. The staff provides treatment advice for poisoning cases of all species, including dogs, cats, birds, small mammals, large animals, and exotic species. As the most cost-effective option for animal poison control care, Pet Poison Helpline’s per-incident fee includes follow-up consultations for the duration of the poison case. Pet Poison Helpline is available in North America by calling 800-213-6680. Additional information can be found online at www.petpoisonhelpline.com.