Medicine Section

RODENTICIDES

1. What are they?
• The three main types of rodenticides
1. Products containing anticoagulants (warfarin,brodifacoum, diphacinone [also called diphenadione]),
2. Products containing bromethalin, and
3. Products containing cholecalciferol
2. What happens if ingested?
• Anticoagulant rodenticides
• Most common
• Ingestion can block vitamin K-dependent clotting factor synthesis by inhibiting the 2,3-epoxide reductase enzyme, which results in a coagulopathy three to five days after ingestion (possibly sooner in immature animals).
• Bromethalin-containing rodenticide
• Signs ranges from tremors and seizures (convulsant syndrome) to weakness and paralysis (paralytic syndrome) due to vacuolization and severe spongiosis of the white matter within the CNS and cerebral edema
• Convulsant syndrome usually occurs at doses of 2.3 mg/kg and higher.
• Ingesting lower doses causes paralytic syndrome
• Cholecalciferol-containing rodenticides
• Can cause acute renal failure and tissue mineralization due to increase in dogs' serum calcium and phosphorus concentrations
3. How to treat?
• Aticoagulant rodenticides
• Induce emesis and administer activated charcoal with a cathartic as soon as possible. Do not induce emesis in symptomatic animals (e.g. bleeding or seizing animals).
• Vitamin K1 orally for 14 to 30 days, depending on the specific active ingredient.
• Evaluate the one-stage prothrombin time at 48 hours after the last dose of vitamin K1. or alternatively monitor the prothrombin time at 48 and 72 hours after ingestion, and if elevated, initiate vitamin K1 therapy.
• If coagulopathy develops animals require whole blood or plasma transfusion and oxygen and in these animals prognosis is guarded and depends on the bleeding site.
• Bromethalin-containing rodenticide
• No specific treatment
• Aggressive decontamination is critical
• Prognosis is guarded when clinical signs are exhibited
• Resolve cerebral edema and seizures are treated by administering corticosteroids, furosemide, mannitol, and diazepam.
• The cerebral edema is intramyelinic, it does not respond well to standard therapy.
• Mannitol, corticosteroids, and furosemide may temporarily lower cerebrospinal fluid pressure
• If treatment are discontinued the clinical signs recurs
• Cholecalciferol-containing rodenticide
• Serum calcium and phosphorus concentrations and the renal function parameters are to be monitored for 72 to 96 hours.
• Perform saline diuresis, and administer corticosteroids, furosemide, or phosphate-binding agents.
• Salmon calcitonin or pamidronate may also be needed.
• Pamidronate, a bisphosphonate used in people to treat hypercalcemia of malignancy, is a preferred agent in treating cholecalciferol toxicosis. It is expensive, a single dose of pamidronate is often sufficient to lower calcium concentrations