Rat Bait Poisoning (Anticoagulant Toxicosis) in Dogs

Anticoagulant poisoning is an emergency. Anticoagulant rodenticides interfere with normal blood clotting and lead to internal bleeding, which can be fatal. Prompt veterinary care is required for a dog that has ingested poison or shows symptoms like bloody saliva, moist cough, rapid breathing, pale gums, and weakness.

It is important to note that the effects of anticoagulant poisoning are delayed. Symptoms of internal bleeding usually appear 3-7 days following ingestion, but this varies, especially if a dog consumes multiple smaller doses over a period of time. If a pet parent has reason to suspect their dog could have ingested rat poison, urgent veterinary care is required even if the dog appears well.

Treatment initiated as quickly as possible after ingestion is more likely to lead to a good outcome. The prognosis worsens once signs of abnormal bleeding develop.

Less common symptoms can develop depending on the extent and site of the internal bleeding.

Dogs are exposed to anticoagulants when they eat rodenticide baits, or rodents or other animals that have ingested the poison.
Dogs become poisoned when they ingest a toxic dose of the anticoagulant.

Anticoagulant poisons inhibit an enzyme vital for Vitamin K1 recycling in the body. Vitamin K1 is essential for production of blood-clotting factors by the liver. When the circulating supply of Vitamin K1 is exhausted after consumption of an anticoagulant poison, uncontrolled internal bleeding starts to occur. Symptoms may be subtle and include moist cough, rapid breathing, tarry stools, and bloody gums. If a lethal dose is consumed, the dog bleeds to death, usually internally. The effects of the poison are not immediate and develop over several days.

If ingestion is known, a diagnosis is suggested. A diagnosis of anticoagulant poisoning is confirmed using blood work to examine clotting times.

The effects of the poison are detectable by blood analysis 2 to 5 days following ingestion. Signs of bleeding typically develop 3 to 7 days following ingestion.

Treatments for recent ingestion of anticoagulant poison include inducing vomiting and administration of activated charcoal to decontaminate the GI tract and prevent absorption into the bloodstream. There is no safe way to induce vomiting at home.

The antidote to anticoagulant poison is oral Vitamin K1.

Vitamin K1 therapy must be continued for the full course even if the dog appears well. Scheduled blood tests are required to confirm the poison is no longer in the dog’s system before discontinuing Vitamin K1 therapy. Anticoagulant poisoning must be treated by a veterinarian; over-the-counter vitamin supplements may not be suitable and doses must be prescribed. Restriction of activity is recommended during the treatment period to reduce the likelihood of internal bleeding.

The prognosis for dogs treated before bleeding occurs is good. The effect of anticoagulant poisons can be avoided and reversed by administering the antidote, Vitamin K1.

Without prompt treatment, poisoned dogs develop internal bleeding which requires IV fluids, blood transfusion, and oxygen therapy. The prognosis varies depending on the poison dose, length of time before treatment, and the extent of damage to affected organ systems.

Poisoning is not contagious between animals. Only ingestion of another poisoned animal by the dog causes secondary poisoning (relay toxicosis). As with any form of poisoning, anticoagulant poisoning can be prevented by eliminating exposure to the toxin. Alternate methods of pest control are available, and keeping dogs under supervision on leash in outdoor public places will minimize the likelihood of exposure to toxins.

Anticoagulant poisons are commonly available in retail stores for pest control. Toxic doses are small enough that it is easy for a dog to consume a potentially lethal dose of bait. Relay, or secondary, toxicosis that results when a dog is exposed by eating poisoned animals, is less common. Rodenticide toxicoses of all types (not just anticoagulants) are usually one of the top ten calls to pet poison hotlines each year. Dogs that roam outdoors or live in areas where rodents are common and rodenticide is commonly used (e.g., farms) are at higher risk for exposure. Rarely, a dog may be poisoned maliciously.

In the US and Canada, second-generation anticoagulant poisons are banned from residential/domestic use. Commercial and agricultural pest control may still use second-generation anticoagulant poison. The risk of secondary poisoning from the dog ingesting a rodent poisoned with first-generation anticoagulant is less than for more potent second-generation poisons.

Typical treatments include:

• Inducing vomiting
• Activated charcoal
• Vitamin K1 therapy
• IV fluids
• Blood transfusion
• Oxygen therapy