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Anticoagulant Poisoning in Dogs

Anticoagulant Rodenticide Poisoning in Dogs

Anticoagulant rodenticides serve the purpose of hindering blood clotting, which is vital for preventing hemorrhaging. These substances are frequently found in rat and mouse poisons, constituting one of the primary sources of accidental poisoning in dogs. Upon ingestion, anticoagulants impede the synthesis of vitamin K, a crucial element in blood clotting, leading to spontaneous and uncontrollable bleeding.

Typically, dogs with mild anticoagulant poisoning won’t exhibit signs of toxicity for several days. However, as the poison takes effect, dogs may display weakness and paleness due to blood loss. External bleeding could manifest as nosebleeds, bloody vomit, or bleeding from the rectum. Additionally, dogs may suffer from internal bleeding, which may go unnoticed, such as bleeding into the chest or abdomen, posing a fatal threat if not promptly diagnosed.

Symptoms and Types

Below are some prevalent symptoms associated with anticoagulant poisoning:

  • Weakness, instability, wobbliness
  • Nosebleeds
  • Vomiting blood
  • Blood in stools
  • Rectal bleeding
  • Bruising and hematomas beneath the skin
  • Excessive bleeding in the gums (hemorrhages)
  • Abdominal swelling (ascites) caused by blood accumulation
  • Breathing difficulties due to blood in the lungs, characterized by rattling or crackling sounds


The primary cause of anticoagulant poisoning stems from the consumption of rodent poison. If you suspect your dog has been exposed to rat or mouse poison and is displaying symptoms mentioned earlier, it’s imperative to promptly seek veterinary attention to prevent the deterioration of your pet’s health.

It’s important to note that outdoor dogs, or those frequently outside, are particularly vulnerable to rodent poisoning. The poison might be present in a neighbor’s yard, a discarded trash bag, or within alleyways. Dogs that engage in chasing and capturing rodents also face risks of such poisoning. Even in areas where rats or mice aren’t prevalent, rodent poison might be used for other common suburban pests like raccoons, opossums, or squirrels.

Various anticoagulant chemicals found in rodent poisons or household products include:

  • Warfarin
  • Hydroxycoumadin
  • Brodifacoum
  • Bromadiolone
  • Pindone
  • Diphacinone
  • Diphenadione
  • Chlorohacinone

The first category of anticoagulants operates as cumulative poisons, featuring warfarin and hydroxycoumadin as primary components. These poisons necessitate multiple feedings over several days to exterminate a rodent.

The second category of anticoagulants is significantly more lethal, capable of killing rodents with a single dose. These potent anticoagulant poisons include indanedione class products such as pindone, diphacinone, diphenadione, and chlorohacinone, all of which exhibit extreme toxicity. Rodenticides containing bromadiolone and brodifacoum, for instance, are 50 to 200 times more poisonous than those containing warfarin and hydroxycoumadin.

Another cause of anticoagulant poisoning in dogs is the inadvertent ingestion of medication. Heparin, a common drug for managing blood clotting in humans, can pose a toxic threat to animals. Often, dogs may ingest medications they come across, whether because the drugs are accessible or due to an unlocked drug cabinet.


During the diagnosis process, your veterinarian will conduct a comprehensive physical examination of your dog, considering the history of symptoms and potential incidents that could have led to the condition. Providing a detailed account of your dog’s health and recent activities is crucial. The diagnostic procedures will encompass a complete blood profile, including a chemical blood profile, a full blood count, and a urinalysis. Moreover, the veterinarian will assess the clotting time of the dog’s blood to gauge the severity of the poisoning.

If you possess a sample of the poison, it’s essential to bring it to the veterinarian’s office for examination. Additionally, providing samples of your dog’s vomit and/or stool can aid in the diagnostic process.


If your dog is experiencing spontaneous bleeding due to anticoagulants, the treatment plan will involve administering fresh whole blood or frozen plasma, adjusted according to the rate and volume of blood loss. Vitamin K, essential for normal blood clotting, serves as the antidote and will be delivered through subcutaneous injections, with repeated doses as required—either through injection or orally—until the blood clotting time returns to normal.

Avoid inducing vomiting unless instructed to do so by your veterinarian. Certain poisons may cause more harm if brought back up through the esophagus than they did when ingested.

Living and Management

After ingesting a mild cumulative form of anticoagulant, your dog may recuperate within a week. However, if it was exposed to the lethal single-dose anticoagulant, recovery may extend up to a month.


To prevent anticoagulant poisoning, ensure that all poisons are inaccessible to your pets. Store chemicals, drugs, and medications, particularly blood thinners, out of your dog’s reach, preferably inside a secure cabinet.

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