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POISONING · DOGS

Dog ate rat poison: clotting tests, signs and outlook

Most rat and mouse poisons stop the blood from clotting. A dog that eats them often looks perfectly well for several days, then starts to bleed inside. Clotting tests show the problem before the bleeding, which is why your vet may ask to test your dog even when it seems fine.

Written by the AI DiagAnimals editorial teamReviewed by the AI DiagAnimals TeamUpdated Our editorial policy

The essentials

Anticoagulant rat poisons block the recycling of vitamin K, which the liver needs to make working clotting factors. Bleeding usually starts 3 to 5 days after the dog eats the bait. The prothrombin time (PT) is the first clotting test to rise, and vets often check it 48 to 72 hours after the dog ate the bait. Vitamin K1, given by the vet, is the antidote. With treatment, most dogs survive. If your dog eats any rodent bait, call your vet or a pet poison center right away and bring the packaging.

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How rat poison works in dogs

Most rat poisons are anticoagulants. They block an enzyme that recycles vitamin K. Without it, the liver can no longer activate clotting factors II, VII, IX and X. As the working factors run out, significant bleeding starts after 3 to 5 days [1]. Second-generation products such as brodifacoum, bromadiolone and diphacinone last much longer in the body than the older ones [1].

These poisons are the most common cause of this kind of clotting problem, and they are reported most often in dogs [2]. Owners often do not see the dog eat the bait: in a German study of 52 poisoned dogs, the intake was witnessed in only 2 (4%) [6].

  • Not all rodent baits are anticoagulants. The three most common types are anticoagulants, bromethalin and cholecalciferol (vitamin D3). Owners often call any bait by a brand name, so the active ingredient on the label matters [9].
  • Cholecalciferol raises blood calcium sharply, with vomiting, loss of appetite and heavy drinking and urination [10]. See high calcium in dogs and cats.
  • Bromethalin affects the nervous system, with signs such as tremors or wobbliness. In a study of 192 dogs that ate it, 25 developed signs [11].

Signs and when they appear

Signs are often vague: tiredness, loss of appetite and pale gums [1]. In a study of 349 dogs, only 30% had signs when seen. Among dogs with signs, 86% were lethargic, 55% had trouble breathing and 44% had visible bleeding [4].

Bleeding can happen almost anywhere. In 62 dogs, the most common sites were the chest around the lungs (37%), the lungs themselves (24%), the abdomen (24%) and the skin (21%). More than half bled in more than one place [1]. Trouble breathing is common, and the chest was the most frequent bleeding site in the larger study [4, 5].

What the clotting tests and blood count show

Typical findings in dogs that are already bleeding. A dog tested soon after eating bait can have normal results.
TestWhat it often showsWhy
PT (prothrombin time)Prolonged, often the mostFactor VII has the shortest life of the vitamin K factors, so the PT rises first [2]
aPTTProlonged, often a little laterRises as the other factors run out; bleeding usually comes with both tests long [2]
Red cells (PCV, hematocrit)Anemia in 75–83% of dogsBleeding, often inside the body [5, 6]
PlateletsNormal or mildly to moderately lowUsed up by heavy bleeding; low in 24–61% across studies [2, 4, 5]
Total proteinLow in 57% in one studyA common finding in bleeding dogs [5]
FibrinogenUsually normalHelps tell it apart from DIC [2]

For the full blood count, see the CBC for dogs, anemia in dogs and low platelets in dogs.

Reading the PT line

The PT measures, in seconds, how long a blood sample takes to clot in the laboratory. In poisoned dogs it is often well above the interval: in one study every dog had a strongly altered PT at admission [6].

An annotated line from a lab report · Illustrative example
AbbreviationResultUnitLaboratory intervalFlag
PT Prothrombin time48s11–14H
  1. Abbreviation PT, sometimes OSPT (one-stage prothrombin time). It is read together with the aPTT.
  2. Result 48 seconds in this illustrative line: far above the interval, as is common in a dog bleeding from rat poison [6].
  3. Unit Seconds.
  4. Laboratory interval 11–14 s was the dog interval of one university hospital [12]; each laboratory and machine sets its own.
  5. Flag H: the blood clots too slowly. A long PT with a near-normal aPTT can mean early poisoning [2].

How the vet confirms it and follows up

  • PT 48 to 72 hours after the dog ate bait: in 151 dogs brought in within 6 hours and made to vomit, only 11 later had a prolonged PT, and none bled. Checking the PT at 48 to 72 hours before deciding on vitamin K appeared safe [3].
  • PIVKA test: detects inactive clotting proteins. With a 150-second cutoff it had over 90% sensitivity and over 98% specificity. Severe liver disease can give false positives; vitamin K1 already given, or testing within a few hours of eating, can give false negatives [8]. Most laboratories do not offer it [2].
  • Toxin screen: measuring the poison in blood or liver is the gold standard, but it is expensive [2].
  • Imaging: X-rays or ultrasound look for blood in the chest, abdomen or around the heart [1].
  • Other causes of internal bleeding: in dogs with severe clotting problems but a negative toxin screen, cancer was the most common diagnosis (31%) [7]. See hemangiosarcoma in dogs.

Vitamin K1 is the antidote and is given by your vet, often with plasma or a transfusion when the dog is bleeding [4]. In one hospital, clotting times were back within the interval within 24 hours of admission in all treated patients [12].

Outlook

The outlook is good when the poisoning is recognized and treated. Survival was 98.7% in dogs with a positive toxin screen in one study [7], 94% of dogs went home after a median of 3 days in another [6], and 86% of dogs that were already bleeding survived to discharge in a third [4]. An older study of 21 dogs, most of them bleeding, reported 83% survival [5].

Related articles

Hemangiosarcoma in dogs

Another cause of bleeding inside the body.

Read the article

All the foods and products to keep away, with the tests for each: toxic foods for dogs and cats.

Other poisonings explained: xylitol, antifreeze and grapes and raisins.

En français : mort aux rats et chien.

Questions to ask your veterinarian

  1. Which type of poison does this product contain, and does it change the tests?
  2. When should we check the PT, and is one test enough?
  3. Are the PT and aPTT both prolonged, and how far above the interval?
  4. Is there anemia or blood in the chest or abdomen?
  5. When should the clotting test be repeated after treatment ends?
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Frequently asked questions

Can a dog survive eating rat poison?

Yes, most do when treated. Studies report survival of 86% to 98.7% in dogs with anticoagulant rat poison, including dogs that were already bleeding [4, 7].

How long does rat poison take to kick in for a dog?

Anticoagulant baits act slowly. Clotting factors run out over several days, and significant bleeding usually starts 3 to 5 days after the dog eats the bait [1].

What to do if a dog accidentally eats rat poison?

Call your vet or a pet poison center right away, even if your dog seems fine, and bring the packaging. The active ingredient matters, because not all baits are anticoagulants [9]. Your vet may make the dog vomit and check the PT 48 to 72 hours later [3].

How do I know if my dog has been rat poisoned?

Signs are often vague: tiredness, pale gums, loss of appetite, trouble breathing, bruising or bleeding [1, 4]. A prolonged PT and aPTT on a blood test, with anemia, strongly suggest it [2, 5].

Why is the PT test used first?

Factor VII has the shortest life of the vitamin K clotting factors, so the PT becomes prolonged earlier than the aPTT [2].

Sources

  1. Stroope S et al. Retrospective Evaluation of Clinical Bleeding in Dogs With Anticoagulant Rodenticide Toxicity – A Multi-Center Evaluation of 62 Cases (2010–2020). Front Vet Sci. 2022;9:879179. doi.org/10.3389/fvets.2022.879179
  2. eClinPath, Cornell University College of Veterinary Medicine. Vitamin K. eclinpath.com/hemostasis/disorders/vitamin-k
  3. Pachtinger GE, Otto CM, Syring RS. Incidence of prolonged prothrombin time in dogs following gastrointestinal decontamination for acute anticoagulant rodenticide ingestion. J Vet Emerg Crit Care. 2008;18(3):285-291. doi.org/10.1111/j.1476-4431.2008.00313.x
  4. Paulin MV et al. Anticoagulant rodenticide toxicity in dogs: A retrospective study of 349 confirmed cases in Saskatchewan. Can Vet J. 2024;65(5):496-503. pubmed.ncbi.nlm.nih.gov/38694735
  5. Sheafor SE, Couto CG. Anticoagulant rodenticide toxicity in 21 dogs. J Am Anim Hosp Assoc. 1999;35(1):38-46. doi.org/10.5326/15473317-35-1-38
  6. Frommeyer A, Mischke R. Anticoagulant rodenticide poisoning in dogs: retrospective analysis of clinical and laboratory diagnostic data (in German). Tierarztl Prax Ausg K Kleintiere Heimtiere. 2024;52(1):5-16. doi.org/10.1055/a-2226-4348
  7. Waddell LS, Poppenga RH, Drobatz KJ. Anticoagulant rodenticide screening in dogs: 123 cases (1996–2003). J Am Vet Med Assoc. 2013;242(4):516-521. doi.org/10.2460/javma.242.4.516
  8. Mount ME, Kim BU, Kass PH. Use of a test for proteins induced by vitamin K absence or antagonism in diagnosis of anticoagulant poisoning in dogs: 325 cases (1987–1997). J Am Vet Med Assoc. 2003;222(2):194-198. doi.org/10.2460/javma.2003.222.194
  9. DeClementi C, Sobczak BR. Common Rodenticide Toxicoses in Small Animals. Vet Clin North Am Small Anim Pract. 2018;48(6):1027-1038. doi.org/10.1016/j.cvsm.2018.06.006
  10. Peterson ME, Fluegeman K. Cholecalciferol. Top Companion Anim Med. 2013;28(1):24-27. doi.org/10.1053/j.tcam.2013.03.006
  11. Scotti KM et al. Retrospective evaluation of the effects and outcome of bromethalin ingestion: 192 dogs (2010–2016). J Vet Emerg Crit Care. 2021;31(1):94-98. doi.org/10.1111/vec.13026
  12. Dartencet C et al. Intravenous Administration of Vitamin K1 in Dogs and Cats Presented for Anticoagulant Rodenticide Poisoning: A Retrospective Study of 58 Cases. J Vet Emerg Crit Care. 2026;36(3):365-371. doi.org/10.1111/vec.70120

Laboratory methods and reference intervals vary. This article explains; it does not diagnose. For a decision about your pet, use the original report and talk to your veterinarian. Our editorial policy.

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