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Anticoagulant Rodenticide Toxicosis 69

Client Education SUGGESTED READING AUTHOR: Silvia Funes Sebastián, DVM, MS, DACVIM
• Increased food palatability and food options Agnew W, et al: Pharmacological appetite stimulation: EDITOR: Leah A. Cohn, DVM, PhD, DACVIM
VetBooks.ir • Inspect the entry site for feeding tubes daily Surg 16:749-756, 2014. Diseases and Disorders
• Identify weight loss and signs of nausea or
rational choices in the inappetent cat. J Fel Med
pain
for inflammation or excessive discharge. Keep
the tube as clean as possible.

Anticoagulant Rodenticide Toxicosis Client Education
Sheet

BASIC INFORMATION than first-generation anticoagulants,
GEOGRAPHY AND SEASONALITY resulting in more persistent effects.
Definition Poisoning is more common in fall and winter • Indanediones
Anticoagulant rodenticides are designed to kill months but possible any time of year. ○ Indanedione products (pindone, chloro-
rats, mice, and other rodents by internal bleed- Clinical Presentation phacinone, difethialone) list 1,3 indane-
ing. Toxicosis in small animals generally dione in active ingredients.
manifests 4-7 days after consuming the bait HISTORY, CHIEF COMPLAINT ○ Chlorophacinone and difethialone are con-
and is characterized by generalized hemorrhage, • Often, there is no history of exposure. sidered second-generation anticoagulants.
pale mucous membranes, hematomas, anorexia, • History or evidence of exposure (e.g., colored • Many generics and trade names. Some
lethargy, swollen joints, melena/hematochezia, bait appearing in stool) several days before companies market products with the same
dyspnea, weakness, or sudden death. Antico- onset of signs trade name but different active ingredients.
agulant toxicosis ranks among the more • Initial clinical signs are often vague. In the United States, second-generation
commonly reported poisonings in dogs but is ○ Lethargy, exercise intolerance, anorexia, anticoagulants and loose pellets are being
uncommon in cats. dyspnea, coughing, lameness, swollen removed from the market.
joints • Concentrations of active ingredients range
Synonyms • Sudden death with no reported clinical signs from 0.0025% (difethialone) to 0.005%
Because formulations for rodenticides can is possible. (most others), whereas warfarin-containing
change, always attempt to identify the active baits often have concentrations of 0.025%.
ingredient by packaging or U.S. Environmental PHYSICAL EXAM FINDINGS Mechanism of toxicosis:
Protection Agency (EPA) registration number. • Pale mucous membranes • Anticoagulants block activation of vitamin
• Tachycardia, dyspnea, harsh lung K–dependent clotting factors by inhibiting
Agent Name Selected Trade Names sounds vitamin K 1 epoxide reductase, which results
Warfarin Anchor Rat and Mouse Bait, ○ Pulmonary hemorrhage in inability of vitamin K to be recycled to
Cat-in-a-Bag ○ Hemorrhagic pleural effusion its active form.
Pindone Purina Rat Kill Soluble, Eaton’s ○ Mediastinal hemorrhage ○ Affected clotting factors include II, VII,
AC Formula 50 ○ Airway hematoma: upper respiratory IX, and X, altering the extrinsic, intrinsic,
Diphacinone Assassin Rodenticide Bait, sounds and common pathways.
Exterminator’s Choice ○ Hypovolemic shock Factor VII has the shortest half-life;
Difethialone D-Cease, Generations, D-Con • Weakness, exercise intolerance ■ therefore, the extrinsic pathway is
Rat and Mouse Bait • Subcutaneous masses (subcutaneous or affected first in anticoagulant rodenti-
Brodifacoum D-Con Mouse Prufe II, Havoc, intradermal hematomas) cide toxicosis, and prothrombin time
Jaguar, Final Blox • Oozing or bleeding at venipuncture sites or (PT) is elevated before activated partial
Bromadiolone Boot Hill, Hawk, Just One Bite
wounds thromboplastin time (aPTT).
• Lameness, swollen joints ■ The resulting vitamin K 1 deficiency is
Epidemiology • Epistaxis responsible for coagulopathy and is the
SPECIES, AGE, SEX • Exophthalmos (retrobulbar hemorrhage) basis for treatment with vitamin K 1.
All are susceptible; young and elderly animals • Petechiae, ecchymoses ○ Coagulation factors already present
are more sensitive. • Frank bleeding from the mouth, rectum degrade naturally and are used up
(rare); melena slowly. Therefore, clinical signs are not
RISK FACTORS • Paralysis or seizures if bleeding into spinal expected for 4-7 days after ingestion.
• Underlying hepatic disease can enhance toxic canal or brain
effects. DIAGNOSIS
• A high-fat diet enhances anticoagulant Etiology and Pathophysiology
absorption. Source: Diagnostic Overview
• Prolonged treatment with sulfonamides can • First-generation warfarin anticoagulants Anticoagulant rodenticide toxicosis is possible
enhance toxicity by reducing the synthesis ○ Warfarin products list 4-hydroxycoumarin in patients presenting with vague, nonspecific
of vitamin K 1. in active ingredients. signs such as lethargy or dyspnea. Suspicion
• Secondary (relay) toxicosis may occur in dogs • Second-generation anticoagulants increases with history of exposure, evidence of
or cats that eat poisoned rodents (e.g., barn ○ Brodifacoum, bromadiolone, diphacinone, internal or external hemorrhage, or failure of
cats). difenacoum blood to clot at venipuncture sites. Confirma-
• Transfer across placenta and into milk is ○ Second-generation anticoagulants are tion is achieved with a combination of active
thought to occur. generally more toxic and longer acting bleeding, markedly increased PT, and lack

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