There are numerous causes of vomiting in cats. Some examples include parasites (especially roundworms), furballs, motion sickness, side effects of drugs, chronic renal disease, gastric ulcers (Helicobacter felis), pancreatitis, and overeating.
Motion sickness is a common condition in cats, showing symptoms of salivation (ptyalism) and other signs of nausea/discomfort often leading to productive vomiting.
Maropitant administered 1, 2 or 10 hours before transportation reduced the incidence of motion induced emesis by approximately 80% compared with placebo treatment.
Maropitant is well tolerated in the cat as demonstrated in acute toleration studies and during a 15 day safety study. Subcutaneous administrations of maropitant at up to 5.0 mg/kg produced no abnormalities in behaviour, appetite or level of consciousness. Physical examination revealed no evidence of neurological or cardiovascular abnormalities. Repeated administration of maropitant at a daily dose of 0.5 mg/kg for four consecutive days did not reveal any adverse clinical signs.
Although substance P was identified in the 1930s from extracts of brain and intestine, it wasn't until the early 1990s that its role in emesis became appreciated. Substance P is a member of the tachykinin family of peptides which also include neurokinin A and neurokinin B. Tachykinin receptors include tachykinin NK-1 receptor, tachykinin NK-2 receptor and tachykinin NK-3 receptor. Substance P is the most potent tachykinin at the NK-1 receptor whereas neurokinin A exhibits highest affinity for the tachykinin NK-2 receptor and neurokinin B has the greatest affinity at the tachykinin NK-3 receptor.
Multiple lines of evidence indicate that substance P plays an important role in eliciting emesis. Substance P is found in high concentrations in areas of the brain stem involved in emesis including the nucleus solitarius, the area postrema and the dorsal motor nucleus of the vagus. Microinjection of substance P into the brain stem elicits an immediate emetic response.
Resiniferatoxin, a naturally occurring analgesic compound that depletes substance P, was found to have broad spectrum anti-emetic effects in the ferret. These data suggested that an NK-1 receptor antagonist might have anti-emetic properties. It is now well recognised that NK-1 receptor antagonists, including Maropitant, can be used to inhibit emesis produced by a wide variety of emetic stimuli, in contrast to the more limited efficacy observed with other commercially available anti-emetics such as 5-HT3 receptor antagonists.
Recommended dosages in cats is 1 mg/kg IV, SQ or orally once daily.
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