Work performed by King et al. in the 1940's and 1950's, as well as recent studies by our group, have shown that the domestic ferret is a suitable model for the study of calculus formation, offering several advantages over the rodent and dog models in current use. We have demonstrated that mineral supplementation of a moist diet accelerates calculus accumulation, and that twice-daily application of a regular dentifrice slows the initial rate of calculus formation, but permits significant accumulation by the eighth week. The present study compared calculus accumulation in female ferrets receiving mineral-supplemented cat food and a twice-daily application of either Regular Crest toothpaste (Crest), Anti-tartar Crest (Crest-AT), or Anti-tartar Colgate Gold toothpaste (Colg-AT). Animals received an ultrasonic prophylaxis, then were fed once daily for eight weeks with moist canned cat food supplemented with sucrose and mineral salts, and were scored for area and extent of calculus accumulation at four and eight weeks after prophylaxis. The data show that the groups treated with the anti-calculus dentifrices produced significantly less calculus than the group treated with regular dentifrice; the Colg-AT group also exhibited lower scores than did the Crest-AT group, especially at four weeks. These results, similar to those seen in human studies, demonstrate that the ferret is a suitable model for the study of anti-calculus dentifrices.