The ARs are some of the most common toxicants that are ingested by dogs.1 They result in life-threatening coagulopathy by antagonizing vitamin K epoxide reductase in the liver.2 This enzyme is required to reduce vitamin K epoxide back to active vitamin K. Without appropriate recycling of vitamin K, factors II, VII, IX, and X and the anticoagulant proteins C and S are unable to be carboxylated, a necessary step for them to become active factors.2 As plasma levels of these factors are depleted, coagulopathy will develop unless vitamin K is supplemented.
Anticoagulant rodenticide screening is a valuable tool for confirming the diagnosis of AR intoxication in cases where ingestion was not witnessed. It is exceptionally valuable in cases in which owners are adamant that there has been no possible exposure to these toxicants. The clinical signs of AR are vague and usually consist of lethargy, anorexia, dyspnea, hemoptysis, tachycardia, poor pulses, pale mucous membranes, and collapse secondary to bleeding.3–10 Thoracic auscultation may reveal dull lung sounds if there is a pleural effusion and dull heart sounds if pericardial effusion is present.11 These signs are consistent with bleeding from any cause of coagulopathy. When patients are initially examined with severe coagulopathies, the differential diagnoses that should be considered include AR intoxication, DIC secondary to neoplasia or other disease processes including angiostrongylosis, heat stroke, sepsis or systemic inflammatory response syndrome, hemophilia or other hereditary coagulation disorders, liver failure, or severe autoimmune disease such as immune-mediated thrombocytopenia.2,12–14 Anticoagulant rodenticide intoxication is generally regarded as having the best prognosis of these disease processes, making correct diagnosis and treatment essential.
The purpose of the study reported here was to evaluate the use of AR screening in dogs, determine the frequency of positive results, identify any correlation between prolongation of PT and aPTT and concentration and type of AR, and evaluate the prognostic value of both positive and negative results for AR screening. The final diagnoses and prognosis for dogs with negative results for AR screenings were also evaluated.
Activated partial thromboplastim time
Disseminated intravascular coagulation
Fresh frozen plasma
Limits of quantification
Parts per billion
Total solids concentration
SepPack C-18, Waters Corp, Milford, Mass.
Stata, version3 8.0 for Windows, Stata Corp, College Station, Tex.
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