can be given in low doses (0.02-0.05 mg/kg i.m.) but should not be used in the presence
of cardiovascular disease such as endocardiosis and congestive heart failure, as
it can cause rapid hypotension. Acepromazine should also be avoided in dogs prone to seizures,
and it is contraindicated in the presence of renal impairment. Intravenous administration
can cause profound hypotension and it should only be used by this route with great
care. The author has witnessed a geriatric dog collapsing and dying immediately following
the intravenous administration of acepromazine.
Xylazine and medetomidine should only be used with extreme
care in geriatric canine and feline patients because they can cause deep and prolonged
sedation with bradycardia and severe cardiovascular depression. Vomiting often follows
their administration and this could result in aspiration in old animals with impaired
laryngeal reflexes. Caution is needed when using these substances in the presence
of pulmonary disease.
In dogs neuroleptanalgesics have the advantage that the
narcotic component can be reversed by an antagonist. However they have proeffects
on the cardiovascular and respiratory systems causing tachycardia or bradycardia,
hypertension or hypotension, depressed respiration and cyanosis. After reversal some
dogs relapse into a sedated state that may last for up to 36 hours.
These agents are contraindicated in the presence of impaired
hepatic or renal function, should only be used at reduced dose rates (50% that recommended
for adults) and with great care in elderly patients. When using narcotic analgesics
or neuroleptanalgesics dogs should be premeditated with anticholinergics to avoid secondary