Treatment
Once animals have stabilized, or in animals presenting
before clinical signs have developed (e.g. within 1 h of ingestion),
decontamination should be performed. Induction of
emesis using apomorphine (0.08 mg/kg i.m. or s.c.) or hydrogen
peroxide should be initiated; in animals that have been
sedated due to seizures, gastric lavage may be considered.
Activated charcoal (1–4 g/kg, p.o.) should be administered;
because of the enterohepatic recirculation of methylxanthines,
repeated doses should be administered every 3 h for
up to 72 h in symptomatic animals (control vomiting with
metoclopramide, 0.2–0.4 mg/kg, s.c. or i.m.). Erythromycin
and corticosteroids should be avoided because they interfere
with excretion of methylxanthines. For ventricular-origin
tachyarrythmias lidocaine is applicated (1–2 mg/kg i.v.
until effect, followed by 25–80 mg/kg/min infusion rate to
effect to maintain). However, lidocaine cannot be used in
cats. If lidocaine fails, metoprolol injection is preferred over
propranolol, since metoprolol does not slow renal excretion
of methylxanthines as propranolol can. Suggested starting
dose for injectable form of either metoprolol or propranolol