LC-MS/MS Method Detects Rat Poison in Cats

As rat poison that thins the blood (anticoagulant rodenticide [AR]) is one of the toxins vets and investigators look for when a cat is suspected of being poisoned, researchers set out to build and test a standardized liquid chromatography-tandem mass spectrometry- quadrupole ion trap (LC-MS/MS-QTRAP) for detecting and measuring eight different types of rat poison in cats' stomach contents at the same time, and to see how well this method works for real-world veterinary forensic cases. A paper based on this research was published in the journal Veterinary Medicine & Science.¹

What Are Anticoagulant Rodenticides (ARs), and Why Are They Dangerous to Pets Like Cats?

ARs are commonly used to keep rat and mouse populations down on farms and in cities. They work by blocking the body's ability to use vitamin K, which is needed to make key blood-clotting proteins. Without these proteins, blood can't clot properly, leading to internal bleeding,and eventually death.^2,3

Rat poisons are grouped into two types, "first-generation" and "second-generation," based on how strong they are, how long they stay in the body, and how they behave once ingested. First-generation poisons (like warfarin, chlorophacinone, coumatetralyl, and diphacinone) are relatively mild and don't stick around in the body very long, so an animal usually must eat them multiple times before it's enough to be deadly. Second-generation poisons (like bromadiolone, brodifacoum, flocoumafen, and difethialone) are much stronger and stay in the body far longer;sometimes a single dose can be fatal. Because these second-generation poisons linger in the body for so long, they build up over time and can end up poisoning animals that were never the intended target, including pets, if those animals eat a poisoned rodent. Their tendency to stick around in the environment also raises concerns about long-term harm to pets and wildlife alike.^4,5

When an animal is poisoned by these blood-thinning rat poisons, the main symptoms are all related to bleeding. This can show up as pale gums, large bruise-like areas under the skin, bleeding in the lungs or gut, and serious internal bleeding.⁶

“Because exposure is often unwitnessed and clinical signs may be delayed,” write the authors of the paper,¹ “diagnosis in cats can be challenging.”

How Was the Detection Method Built and Tested?

Sample preparation for this research was automated to keep results consistent no matter who ran the test. To make sure the poison IDs were accurate (and to avoid false alarms from similar-looking compounds), the team double-checked each result using two different detection techniques, multiple reaction monitoring (MRM) and enhanced product ion (EPI) spectra. This method was then used on 747 real cat poisoning cases sent in for investigation between January 2020 and August 2025, where stomach tissue or contents were available to test.¹

What Did Applying the Detection Method to Real Cat Poisoning Cases Reveal?

Rat poison turned up in about 2.5% of cases (19 out of 747). The most common type was coumatetralyl, followed by flocoumafen and bromadiolone. Interestingly, flocoumafen showed up even though it is not an officially approved rat poison ingredient in Korea, which the researchers consider a sign that testing should cast a wide net rather than looking for just a few known culprits.¹

“The standardized LC-MS/MS-QTRAP method,” write the authors of the paper,¹ “enabled reliable detection and quantification of ARs in gastric matrices from cats. This approach provides useful forensic evidence of recent AR exposure in suspected poisoning cases and may support improved toxicovigilance for registered and unregistered rodenticides.”

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References

1. Chae, H.; Byun, J. W.; Yim, S. J. et al. Forensic LC-MS/MS Monitoring of Anticoagulant Rodenticide Poisoning in Cats Over a Half-Decade. Vet Med Sci. 2026, 12 (5), e71209. DOI: 10.1002/vms3.71209
2. Berny, P. J.; Buronfosse, T.; Lorgue, G. Anticoagulant Poisoning in Animals: A Simple New High-Performance Thin-layer Chromatographic (HPTLC) Method for the Simultaneous Determination of Eight Anticoagulant Rodenticides in Liver Samples. J Anal Toxicol. 1995, 19 (7), 576-580. DOI: 10.1093/jat/19.7.576
3. Mount, M. E. Diagnosis and Therapy of Anticoagulant Rodenticide Intoxications. Vet Clin North Am Small Anim Pract. 1988, 18 (1), 115-130. DOI: 10.1016/s0195-5616(88)50012-8
4. Sánchez-Barbudo, I. S.; Camarero, P. R.; Mateo, R. Primary and Secondary Poisoning by Anticoagulant Rodenticides of Non-target Animals in Spain. Sci Total Environ. 2012, 420, 280-288. DOI: 10.1016/j.scitotenv.2012.01.028
5. Vandenbroucke, V.; Bousquet-Melou, A.; De Backer, P. et al. Pharmacokinetics of Eight Anticoagulant Rodenticides in Mice after Single Oral Administration. J Vet Pharmacol Ther. 2008, 31 (5), 437-445. DOI: 10.1111/j.1365-2885.2008.00979.x
6. Griggs, A. N.; Allbaugh, R. A.; Tofflemire, K. L. et al. Anticoagulant Rodenticide Toxicity in Six Dogs Presenting for Ocular Disease. Vet Ophthalmol. 2016, 19 (1), 73-80. DOI: 10.1111/vop.12267