Rodenticide Poisoning (Anticoagulant) in Cats

Summary

Anticoagulant poisons are commonly used for pest control of rodents. Cats occasionally consume toxic doses of these poisons and subsequently develop life-threatening internal bleeding. Anticoagulants interfere with the blood clotting process, so symptoms include abnormal bleeding, bruising, lethargy, coughing up blood, and pale gums.    The toxic dose for cats is small, so rodenticide ingestion is an emergency.

Some poison may be removed before it is absorbed if the cat is brought to a veterinarian to induce vomiting <4 hours after ingestion.  The antidote for anticoagulant toxicosis is oral administration of Vitamin K. Cats presented for treatment before the onset of symptoms have a good prognosis. The prognosis is poor when treatment is delayed until after the onset of clinical signs. Cats may succumb even when treated aggressively with blood transfusions and oxygen.

Risk Factors

Anticoagulant poisons are commonly used in rodent control, giving cats access to the toxin. Although cats are less likely to eat rodent bait than dogs, they may still find them appealing. The toxic dose is based on body weight, so smaller amounts of poison are dangerous to cats compared to what is required to harm a large dog. 

There is no way to safely induce vomiting at home for cats, so ingestion of any amount of rodent poison is an emergency requiring immediate veterinary care. The prognosis for rodent poison ingestion is fair with prompt treatment. If treatment is delayed until after the onset of symptoms associated with abnormal bleeding, the prognosis is poor.

Possible Causes

Cats gain access to anticoagulant poisons when they are placed in the environment for rodent control purposes. Rodenticides are formulated into baits that are appealing to eat and the pellets or blocks look and smell like kibble or a treat to a cat. Cats can also be exposed when they eat a rodent that died from rodenticide toxicity, although it is uncommon for a cat to ingest a dangerous dose of the poison in this manner.

Main Symptoms

Anticoagulant rodent poisons work by preventing the body from producing vitamin K. Vitamin K is a critical component of several proteins required for blood clotting. Without these proteins, even tiny leaks from blood vessels cannot be stopped. Symptoms of bleeding disorders include: 

Lethargy • Weakness • Nosebleeds (epistaxis) • Coughing, including coughing up blood • Pale gums

• Difficulty breathing (dyspnea) • Bloody saliva • Numerous red to dark brown spots on the gums or skin

• Rapid breathing (tachypnea) • Extensive bruising • Vomiting blood • Blood in the feces or urine

Detailed Characterization

At the time of poison ingestion, the blood contains an abundance of clotting proteins. Over a period of 24 hours to 3 days, these clotting proteins are used up by the body’s normal processes. It takes 3-7 days for symptoms to first appear. The severity of the symptoms is dependent upon the ingested dose relative to the cat’s body weight. Ingestion of anticoagulant rodenticides has the potential to be fatal.

Less common symptoms associated with anticoagulant toxicity include:

• Sudden collapse • Bleeding from the eyes, nose, or mouth

• Bloody appearance to the whites of the eyes

• Swelling of the joints with sudden lameness • Swelling of the abdomen

The severity of toxicity depends on the type of anticoagulant rodent poison used and the dose consumed. First generation products have a high toxic dose, meaning the cat must consume a large amount of rodenticide, or multiple smaller doses, to be affected. First generation products include:

• Warfarin • Pindone • Chlorphacinone • Diphacinone

Second generation rodenticides are more potent, and a single dose of a small amount of rodenticide is potentially fatal to a cat. These rodenticides include:

• Brodifacoum • Bromadiolone • Difethiolone • Difenacoum

Treatment of anticoagulant rodent poison ingestion takes up to a month, to allow time for the body to rebuild clotting proteins and remove the toxin. The biggest factors affecting the outcome are the type of poison consumed, the amount ingested, and how quickly the cat is presented for treatment.

Testing and Diagnosis

If the cat is known to have eaten rodent poison, no diagnostic tests are needed. Vomiting is induced if the cat arrives at the veterinarian within 4 hours of ingestion, in an effort to remove some of the poison from the stomach before it is absorbed. There are no safe methods to induce vomiting in cats at home. Cats that have ingested rodent poison require immediate veterinary care to induce vomiting. 

Cats without a history of exposure who present with symptoms of abnormal bleeding undergo routine diagnostics including a physical exam and bloodwork. Abnormal results on a blood clotting profile confirm the diagnosis.

Steps to Recovery

Cases of known anticoagulant ingestion presenting more than 4 hours after ingestion typically have baseline blood work performed and are started on oral Vitamin K therapy. Induction of vomiting is not indicated after 4 hours have elapsed from time of ingestion, as the poison is presumed to be fully absorbed by that time. The antidote for anticoagulant rodent poison is vitamin K, given daily over a period of up to 28 days. This treatment does not remove the toxin from the body, but counteracts its effects. During this treatment period, cats often show no symptoms, leading some owners to believe the medication is unnecessary. It is important to give vitamin K injections or pills for the entire recommended period. 

Repeated blood clotting tests are used to track treatment response, to ensure the cat is fully recovered before vitamin K treatment is stopped. 

Cats showing symptoms upon arrival to the vet often require additional treatments, including:

• IV fluids • Blood transfusions • Supplemental oxygen

Prevention

Rodenticide poisoning is prevented by using non-toxic methods of pest control. If using rodent bait is unavoidable, it should be placed in areas where pets cannot access it. All known toxic substances should be stored in sealed containers out of reach of children and animals. Outdoor cats may still be exposed to rodenticides when they are out exploring, which is an inherent risk of allowing cats to live an outdoor lifestyle.

Is Anticoagulant Poisoning Common in Cats?

All types of rodent poison toxicities are rare in cats.

Typical Treatment

• Vitamin K • Blood transfusions

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