The Approach to Diarrhea [chapter]

Anthony P. Carr
2007 Canine Internal Medicine Secrets  
Metoclopramide is a commonly used antiemetic drug. It can be given by intermittent subcutaneous injection (0.2-0.4 mg/kg every 6 hours, subcutaneously [SQ] or intramuscularly [IM]) or as a constant intravenous infusion (1-2 mg/kg/day). The latter mode of administration appears to be more efficacious. This medication predominantly affects the D 2 dopaminergic receptors in the CRTZ and gut. It also affects the 5-HT 3 serotonergic receptors in the CRTZ. Phenothiazine drugs such as chlorpromazine
more » ... .2-0.5 mg/kg every 8 hours SQ) or prochlorperazine (0.1-0.5 mg/kg every 8 hours SQ or IM) are broad spectrum antiemetics (they have activity at the a 2 -adrenergic, D 2 -dopaminergic, histaminergic, and cholinergic receptors). However, use can cause hypotension, so blood pressure should be monitored. Sedation is also usually quite pronounced with use of these agents. These medications are a good choice for dogs that fail to respond to metoclopramide. It is possible to use both agents concurrently. A limited number of medications are specific to the 5-HT 3 serotonergic receptors. Ondansetron (0.5-1.0 mg/kg every 12 to 24 hours, by mouth [PO]) can be helpful in some cases of vomiting associated with stimulation of the CRTZ. H 1 -histaminergic receptor antagonists include diphenhydramine (2-4 mg/kg every 8 hours PO) and dimenhydrinate (4-8 mg/kg every 8 hours PO). These can be used for the treatment of motion sickness or vestibular disease. Erythromycin at low dosages (0.5-1.0 mg/kg every 8 hours) can also act as an antiemetic by stimulation of the motilin receptors that increase GI motility and promote gastric emptying.
doi:10.1016/b978-1-56053-629-1.50038-8 fatcat:gf64fmml6rav5la7q36y26ernm