Why this is an emergency

Anticoagulant rodenticides or rat bait interferes with normal blood clotting and can cause life-threatening internal bleeding. Pets may appear completely well for several days after ingestion, so treatment should not be delayed while waiting for signs to develop.

Not all rat baits are the same

Rodenticides contain different active ingredients and require different treatments. Anticoagulant products include brodifacoum, bromadiolone, difenacoum, diphacinone and warfarin. Please bring the packet, label or a photograph of the product whenever possible.

Some rodenticides contain cholecalciferol (vitamin D3) rather than an anticoagulant. Cholecalciferol causes dangerously high calcium levels and kidney injury and is treated very differently; vitamin K1 is not an antidote for these products. Other rodenticides may also cause neurological or metabolic toxicity.

How do anticoagulant rodenticides cause bleeding?

The liver requires active vitamin K to produce several clotting factors. Anticoagulant rodenticides prevent vitamin K from being recycled. Existing clotting factors are gradually used up, after which the body can no longer form stable blood clots. Clinical bleeding commonly develops two to five days after exposure, although timing varies with the product and dose.

What signs might I see?

• Weakness, tiredness, reluctance to exercise or collapse
• Pale gums, rapid breathing or difficulty breathing
• Coughing, abdominal swelling or discomfort
• Bruising, soft swellings or bleeding from the nose or mouth
• Blood in the urine, vomit or faeces, or black tarry stools
• Lameness or painful swollen joints caused by bleeding
• Neurological signs if bleeding occurs around the brain or spinal cord

External bleeding may be absent even when severe bleeding is occurring internally.

What should I do after a known or suspected ingestion?

Contact a veterinarian immediately, even if your pet appears normal. Do not induce vomiting or give vitamin K, food, milk or other home treatments unless specifically instructed. Early veterinary decontamination may prevent poisoning.

If ingestion was recent and your pet is well enough, your veterinarian may induce vomiting and may administer activated charcoal. The safest plan depends on the active ingredient, amount ingested, time since exposure and your pet’s clinical condition.

How is anticoagulant rodenticide toxicosis diagnosed?

Your veterinarian will assess the exposure history, physical examination and blood test results. Testing may include:

• Prothrombin time (PT) and activated partial thromboplastin time (aPTT) to assess clotting
• Packed cell volume or complete blood count to assess blood loss and anaemia
• Blood typing and cross-matching if transfusion may be required
• Chest or abdominal imaging to look for internal bleeding when clinically appropriate

Clotting tests can remain normal soon after ingestion. If preventive vitamin K1 is not started, a PT is commonly checked approximately 48 hours after exposure. The timing and need for testing are determined by the treating veterinarian.

How is it treated?

Recent or witnessed ingestion: treatment is aimed at preventing absorption. Your veterinarian may induce vomiting and may give activated charcoal, depending on the product, dose and time since ingestion.

Clinical coagulopathy or active bleeding: these patients require urgent clotting tests, blood tests and imaging to identify the location and severity of haemorrhage.

Treatment may include:

Vitamin K1 (phytomenadione) is the specific antidote. For animals with clinically important bleeding or marked coagulopathy, rapid correction is essential. At Pet Emergency, a mixed-micelle vitamin K1 product (Konakion) may be administered as a carefully controlled intravenous infusion with close monitoring. Once stable, patients are transitioned to oral vitamin K1, usually given with a fatty meal to improve absorption.

Plasma transfusion: Fresh frozen plasma provides functional clotting factors immediately and may be used for severe or ongoing bleeding, particularly while vitamin K1 is taking effect.

Packed red blood cell transfusion: Packed red blood cells may be required when blood loss has caused clinically significant anaemia or reduced oxygen delivery. Some patients may need both plasma and red blood cells.

Supportive and emergency care: Oxygen, intravenous access, careful fluid therapy, pain relief, monitoring and drainage of blood from the chest or abdomen may be required depending on the site and severity of bleeding.

How long is vitamin K1 required?

Long-acting anticoagulant rodenticides can remain in the body for weeks. Oral vitamin K1 is commonly continued for approximately four weeks, although the exact duration depends on the product and the individual patient. It is important not to miss doses or stop treatment early.

A PT is usually checked 48 to 72 hours after the final vitamin K1 dose. Testing while your pet is still receiving vitamin K1 cannot confirm that the rodenticide has cleared. If the PT is prolonged after treatment stops, vitamin K1 must be restarted and continued for longer.

What is the outlook?

The prognosis is usually excellent when exposure is recognised early and treatment is started before significant bleeding occurs. The outlook is more guarded in animals with severe internal bleeding, respiratory compromise, neurological bleeding or delayed presentation, but many recover with intensive treatment and appropriate transfusion support.

Care at home

• Give vitamin K1 exactly as prescribed and with food as directed.
• Restrict strenuous activity and avoid rough play while clotting remains abnormal.
• Do not give aspirin, NSAIDs or other medications unless approved by your veterinarian.
• Store rodenticides securely and prevent access to poisoned rodents or bait stations.
• Attend the scheduled post-treatment PT test, even if your pet appears completely well.

 

Return for urgent veterinary assessment if your pet becomes weak, pale, breathless, painful or unusually quiet; develops bruising, swelling or any visible bleeding; passes blood or black stools; collapses; or you are concerned for any reason.