Rodenticides

Question 1

Sources

Answer 1

Fumigation= extremely toxic, phosphates are used (Aluminium-P, Zinc-P): garlic smell (attractive to rodents).
In the stomach juice reacts with water => extremely toxic gas (= Phosphin: PO3) -> pulmonary edema, lethal.
Bait: anticoagulant rodenticides, powdered corn cob (= extremely hygroscopic -> suck out water => biokilling, no chemicals)

Question 2

Anticoagulant Rodenticides

Answer 2

Sweet clover (coumarin) -> coumaroid = food additive (non toxic)
BUT if u let it transform to Dicoumarol -> v toxic
Warfarin (synthetics)

1st Generation: Warfarin (resistance develops, short T1/2)
2nd Generation: Brodifacoum, Bromadiolone, Difenacoum (lower LD50, long T1/2, resistance is v rare!)

Question 3

Anticoagulant Rodenticides- Sources

Answer 3

Poisoned bait (vanilla smell -> attractive to dogs, cats)
Malicious -> clinical signs appear after 3 day (time to treat)
Rodent corpse

Question 4

Anticoagulant Rodenticides- Toxicity

Answer 4

Single dose: 50-100 mg/kg (rats), 50 mg/kg (dog), 25-50 mg/kg (cats)
Repeated uptake (warfarin much more effective)- Repeated dose:
1 mg/kg (rats), 5 mg/kg (dog), 1 mg/kg (cats)

PO LD50: Brodifacoum: 0.2-0.4 mg/kg (v danerous)&
Bromadiolone: 11-15 mg/kg (25< in cats) => they need to induce huge amounts.

Question 5

Anticoagulant Rodenticides- Toxicokinetics

Answer 5

Absorption: quick in the GI, 2% from skin (lipophilic). Repeated uptake -> accumulation in liver (Brodifacoum). Alb binding -> long half-life.
Metabolism, Excretion: long T1/2 (EH circul). Avg duration:
Give vit.K for 2w (Warfarin), 3w (Bromadiolon), 4w (Brodifacoum)

Question 6

Anticoagulant Rodenticides- Mechanism of action

Answer 6

Inhibits blood coagulation factors activation (inhibits Vit.K epoxy reductase)
=> damage of capillary endothel (spontaneous bleeding) -> bleedings & haematomas, hypovolaemia (shock -> death).
Prolonged effect: elevated PT (within 24h -> excellent parameter to check), incr clotting t (4-6 days), endothelial damage

Question 7

Anticoagulant Rodenticides- Clinical signs

Answer 7

Acute: usually 3-6 days, can be delayed
=> severe anaemia, incr coagulation time, pre-hepatic icterus (Hb destruction due to bleeding in the abdomen), bilateral bleedings, abortion
Death: due to hypovolaemic shock

Question 8

Diagnosis

Answer 8

Anamnesis, progressive blood clotting problems
X-ray (blood in the thoracic cavity -> white), US, FNA, clotting parameters
Lab results: increased bleeding time, clotting, PTT (primary), APTT, PIVKA (proteins induced by vit.K antagonism, but v expensive)
NO change in thrombocyte count

Question 9

Treatment

Answer 9

1st hour: give activated charcoal -> prevents its absorption
Induce emesis (<4h), blood transfusion 15-20 ml/kg
Vit.K SC/PO 3-5 mg/kg (SA), 0.5-1 mg/kg (LA), never IV => allergy, anaphylaxis.
5 weeks protocol: 3-5 mg/kg for 14 days, then 1-2 mg/kg for 7 days and last 1-2 mg/kg every other day for 14 days

Symptomatic therapy: vit.C (capillary membr stabilization, treat spontaneous bleedings), Ca (enhances blood coagulation).
Etamsylat (capillary stability & coagulation)
Give moist food (dry -> hurt the pharynx)