What is the appropriate treatment and management for a goat that has ingested diphacinone?

Treatment of Diphacinone Ingestion in Goats

Administer vitamin K1 (phytonadione) at 0.5-2.5 mg/kg subcutaneously or intramuscularly immediately upon suspected or confirmed diphacinone ingestion in goats, with treatment duration of at least 30 days due to the prolonged anticoagulant effects of this second-generation rodenticide. 1

Immediate Management

• Begin vitamin K1 therapy without waiting for laboratory confirmation if diphacinone exposure is suspected, as bleeding complications can be delayed for days to weeks after ingestion 2, 3
• Use the higher end of the dosing range (2.5 mg/kg) for second-generation rodenticides like diphacinone, as these agents have significantly longer half-lives and greater potency than warfarin 1, 3
• Administer subcutaneously or intramuscularly; if intravenous administration is unavoidable, dilute with 0.9% sodium chloride, 5% dextrose, or 5% dextrose and sodium chloride, and inject very slowly (not exceeding 1 mg per minute) 1

Monitoring and Laboratory Assessment

• Measure prothrombin time (PT) and other coagulation parameters 36-48 hours post-exposure to assess the degree of anticoagulation 3
• Monitor for clinical signs of bleeding including epistaxis, gingival bleeding, widespread bruising, hematomas, hematuria, gastrointestinal bleeding, and hemorrhage into internal organs 3
• Continue monitoring coagulation parameters throughout treatment, as the vitamin K-enzyme complex can remain inhibited for approximately 30 days with diphacinone 2

Treatment Duration and Regimens

• Administer vitamin K1 for a minimum of 30 days, divided into multiple daily doses (typically 2-3 times daily) 2
• Diphacinone-poisoned animals may require multiple 5-day vitamin K1 regimens (2-3 courses) to prevent recurrent bleeding, unlike warfarin which typically requires only one regimen 2
• Bleeding episodes can occur up to 2 weeks after initial treatment begins, necessitating extended therapy 2

Management of Active Hemorrhage

• If active bleeding occurs, administer whole blood or blood component therapy immediately while continuing vitamin K1 treatment concurrently 1
• Blood products address acute blood loss and shock but do not correct the underlying coagulopathy 1
• In cases of shock or excessive blood loss, whole blood component therapy is indicated as a life-saving measure 1

Critical Pitfalls to Avoid

• Do not discontinue vitamin K1 therapy prematurely: Diphacinone has an exceptionally long duration of action due to high lipid solubility, hepatic accumulation, and enterohepatic circulation, requiring treatment for weeks to months 3
• Do not rely on a single normal coagulation test to rule out toxicity, as clinical signs of bleeding may be delayed for days after exposure 3
• Avoid intramuscular injections of other medications during the coagulopathic period, as this can cause hematoma formation 3

Mechanism and Toxicity Considerations

• Diphacinone inhibits vitamin K1-2,3-epoxide reductase at multiple points in the vitamin K cycle, preventing synthesis of clotting factors II, VII, IX, and X 3
• The greater potency of diphacinone compared to warfarin is due to its higher affinity for the enzyme, ability to disrupt the vitamin K cycle at multiple sites, and unusually long biological half-life 3
• Even sublethal doses (434 mg/kg in avian models) can prolong clotting time at 48 hours post-exposure, with effects persisting before overt clinical signs appear 4

Species-Specific Considerations for Goats

• Goats are classified as livestock for which no licensed rabies vaccine exists, but this is irrelevant to diphacinone toxicity management 5
• The FDA-approved dosing range for livestock including goats is 0.5-2.5 mg/kg for both acute and non-acute hypoprothrombinemia 1
• Veterinary care should be retained throughout the treatment period to monitor response and adjust therapy as needed 5