Page 177 - Cote clinical veterinary advisor dogs and cats 4th

70 Anticoagulant Rodenticide Toxicosis

of other explanations for bleeding. Absolute • Vascular volume support if bleeding has • Supportive care (as needed)
confirmation may include analysis of stomach caused hypovolemia (blood transfusions, ○ Intravenous fluids
VetBooks.ir for the presence of anticoagulants, but this is • Respiratory support (airway hematoma, ○ Thermoregulation
○ Oxygen supplementation
intravenous [IV] crystalloids/colloids)
contents, feces, blood/serum, liver, or kidney
○ Cage rest
rarely performed or necessary in clinical cases.
mediastinal hemorrhage, pleural effusion,
pulmonary hemorrhage)
Differential Diagnosis • Vitamin K 1 is antidotal, plus plasma Chronic Treatment
Toxicologic: transfusion (active clotting factors) if severe • Vitamin K 1 treatment may be required for
• Accidental ingestion of warfarin-based anti- signs. many weeks in cases involving large amounts
coagulant human medications (rare), toxins • Early decontamination (induction of vomit- of ingested bait and/or ingestion of long-
causing severe hepatic necrosis (xylitol [dogs], ing, activated charcoal administration); not acting anticoagulants.
blue-green algae, sago palm, aflatoxin) indicated if signs are apparent as exposure • Physical activity modifications
Spontaneous, nontoxicologic: would have been days earlier ○ Confine animals and limit exercise while
• Bleeding disorders due to liver disease, • If ingestion was recent (<24 hours), no monitoring PT or PIVKA after recent
hemophilia, thrombocytopenia, disseminated clinical signs should be apparent and decon- ingestions or during vitamin K 1 therapy,
intravascular coagulation tamination of the patient is appropriate. even if animal “feels normal.”
• Differentiation is often straightforward based ○ Cage rest is essential for animals exhibiting
on signalment, history, physical examination, Acute General Treatment coagulopathy.
and routine laboratory tests. Decontamination of the patient (p. 1087) and
monitoring of patients without overt clinical Nutrition/Diet
Initial Database signs: Administer vitamin K 1 with high-fat food (e.g.,
• CBC • Induction of vomiting (p. 1188), followed canned dog/cat food, peanut butter, cheese) to
○ Regenerative anemia may be present due by administration of activated charcoal enhance vitamin absorption.
to bleeding. (1-2 g/kg) and a cathartic (use labeled doses
○ Mild to moderate thrombocytopenia may for commercial products) Drug Interactions
occur (50,000-150,000/mL). • Monitor PT, aPTT, or PIVKA at baseline, Anticoagulants are highly protein bound.
• Serum chemistry panel (no specific changes 48 hours, and 72 hours. If the 72-hour PT/ Concurrent use of highly protein-bound drugs
expected) PIVKA is normal, no additional treatment such as corticosteroids or nonsteroidal antiin-
• Coagulation panel is needed. flammatory drugs may increase anticoagulant
○ PT and aPTT increase before hemorrhage • Because coagulopathy develops over several toxicity.
occurs, and elevation persists during days, an injection of vitamin K 1 on the day
clinical signs. of bait ingestion is NOT necessary. Possible Complications
PT increases first and is more sensitive • If PT or PIVKA increases, start vitamin K 1 • Retrobulbar hemorrhage: temporary
■
than aPTT for anticoagulant rodenti- 1.5-2.5 mg/kg PO q 12h or 3-5 mg/kg q blindness
cide toxicosis. 24h. • Permanent neurologic dysfunction if bleed-
○ Proteins induced by vitamin K 1 absence ○ The injectable formulation of vitamin K 1 ing occurs in the central nervous system
or antagonism (PIVKA) will be elevated. may be used orally for very small animals (CNS)
Test not as widely available (e.g., nursing puppies or kittens).
■
○ Increased PT or PIVKA value three or ○ Continue treatment for 14-30 days, Recommended Monitoring
more times higher than normal is sup- depending on the specific anticoagulant. Clinical signs, PT, hematocrit
portive of anticoagulant rodenticide ○ PT or PIVKA should be checked 48 hours
toxicosis. after the last dose of vitamin K 1 . PROGNOSIS & OUTCOME
○ Prior administration of vitamin K 1 can ■ If PT or PIVKA is elevated 48 hours
attenuate PT prolongation. after last dose (16-32 days after expo- • Excellent if animal is presented before clinical
○ No change expected if exposure was sure), resume vitamin K 1 treatment for signs develop. Most animals respond very
witnessed in preceding 24 hours; test still 1 more week, and then remeasure PT well to vitamin K 1 therapy.
done for baseline PT value. or PIVKA 48 hours after last dose. • Prognosis guarded to poor if animal bleeds
• Radiographs may reveal thoracic or abdomi- Some animals require vitamin K 1 into chest or CNS
nal effusions or pulmonary infiltrate. Tracheal treatment for 30-50 days.
narrowing or soft-tissue opacity may be ■ After the PT or PIVKA is normal at 48 PEARLS & CONSIDERATIONS
present due to airway hematoma. hours, discontinue vitamin K 1 therapy.
Treatment of hemorrhaging animals: Comments
Advanced or Confirmatory Testing • Decontamination of the patient is • New EPA regulations restrict sales of pelleted
• Results are generally not received in time to contraindicated. bait products and replace them with block
impact treatment but can be important in • Blood transfusions to replace lost red cell forms in a tamper-resistant station. Only
medicolegal cases. mass if indicated (p. 1169) chlorophacinone and diphacinone are available
• Stomach contents, blood, or serum may be • Frozen or fresh-frozen plasma transfusions for the consumer market. Agricultural and
analyzed for anticoagulants by a veterinary to provide clotting factors immediately professional use products may still contain
or other diagnostic laboratory. (p. 1169) second-generation anticoagulant rodenticides.
• Necropsy samples include serum, liver, and • Vitamin K 1 2.5 mg/kg PO q 8-12h ○ Many homes continue to have older
kidney. • With hemorrhagic pleural effusion causing packaging and pelleted baits available.
severe dyspnea, thoracocentesis may be • Brodifacoum is among the most toxic of the
TREATMENT necessary (p. 1164). Removed blood can be anticoagulants; the LD50 for dogs is
given back to the patient to increase oxygen 0.2-4 mg/kg.
Treatment Overview carrying capacity, but this blood has no ○ Animals can develop toxicosis after inges-
Patients showing overt signs due to toxicosis clotting factors, and those need to be replaced tion of one-tenth of the LD50.
may require treatment on several levels simulta- by whole blood or fresh/fresh-frozen plasma ○ Animals ingesting a dose > 0.02 mg/kg
neously, depending on abnormalities identified: transfusion. should be decontaminated and monitored.

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