It is known that the dental health of dogs or other domestic animals is often deficient owing to the impossibility of achieving an effective brushing of their teeth with suitable dental products in a way comparable to that in humans.
A number of therapeutic proteinaceous animal chews have been described in the prior art to address this problem. The therapeutic effect from these prior art compositions or devices comes primarily from the physical act of chewing an object to provide an abrasive effect on the teeth prior to swallowing the compositions. The act of regularly chewing an object (such as rawhide) sufficiently rigid to allow for an oral residence time of greater than thirty seconds or so has been shown to result in reduced tartar accumulation compared to a quickly consumable object, such as a biscuit (Lags, et al J. Am. Veterinary Medical Ass, 197, pp 213-219 (1990)).
Simone et al. U.S. Pat. No. 5,296,209, reported on an attempt to clean an animal's teeth through providing a foodstuff with a texture that allows for the animals tooth, during the act of chewing, to penetrate relatively deep into the food particle before it breaks apart into smaller particles. By doing so, the tooth surface is mechanically abraded by the food particle for a longer period of time than would be possible with a hard, readily breakable food particle. The disadvantage to this approach to companion animal dental hygiene is that only physical accumulation such as tartar, and perhaps some plaque structure, are removed. There is little offered in the way of a truly therapeutic or preventative effect.
These animal chews may in certain instances contain therapeutic compositions in addition to the chew itself. Compositions that have been incorporated into the animal chew may be identified as belonging to one of two categories. The first category is that of enzymatic compositions exemplified by Montgomery U.S. Pat. No. 5,310,541. Enzymatic compositions have been found to have limited antimicrobial effect. The second category is that of non-enzymatic compositions associated with the animal chews.
For example, Stacey, U.S. Pat. No. 5,296,217, described the use of a hexametaphosphate salt added to a consumable animal treat or foodstuff in order to prevent tartar accumulation in domestic animals. Not only is the residence time of the salt too short to have a significant therapeutic effect in the oral cavity of the animal, but furthermore, the hexametaphosphate is not antimicrobial. In Spanier et al., U.S. Pat. Nos 5,114,704 and 5,011,679, a rawhide carrier coated with an inorganic pyrophosphate compound was described for purposes of preventing tartar accumulation in dogs. Pyrophosphate is a calcium chelator that limits the accumulation of tartar and reduces the tartar build-up that has occurred. However, this composition lacks antimicrobial properties.
There are a number of cationic antimicrobial agents that have been utilized in toothpastes for human dental care. These agents strongly associate with protein and are not readily released from proteinaceous substrates.
There is an unmet need for an animal chew that has effective antimicrobial properties in the oral cavity of an animal.