A method for collecting and analyzing a sample of a fluid from the oral cavity of a mammal, said method comprising: placing a device suitable for collecting said sample of said fluid in said oral cavity of said mammal, said device comprising: a mouthpiece comprising a chamber defined by front and rear inner walls and a base inner wall of said mouthpiece, said base wall extending between said front and rear inner walls; wherein said mouthpiece is suitable for directing a liquid onto a plurality of surfaces of said oral cavity, said front and rear inner walls (116, 118) of said chamber comprise a plurality of openings (132, 134), said mouthpiece further comprising, 1) a first manifold for containing a first portion of said liquid and providing said first portion to said chamber through said openings of said front inner wall, 2) a second manifold for containing a second portion of said liquid and providing said second portion to said chamber through said openings of said rear inner wall, 3) a first port for conveying said first portion of liquid to and from said first manifold, 4) a second port for conveying said second portion of liquid to and from said second manifold, 5) means for providing an effective seal of said mouthpiece within said oral cavity; and 6) means for collecting said fluid sample from said oral cavity, collecting said fluid sample from said oral cavity; and conducting an analysis of said fluid sample. a mouthpiece comprising a chamber defined by front and rear inner walls and a base inner wall of said mouthpiece, said base wall extending between said front and rear inner walls; wherein said mouthpiece is suitable for directing a liquid onto a plurality of surfaces of said oral cavity, said front and rear inner walls (116, 118) of said chamber comprise a plurality of openings (132, 134), said mouthpiece further comprising, 1) a first manifold for containing a first portion of said liquid and providing said first portion to said chamber through said openings of said front inner wall, 2) a second manifold for containing a second portion of said liquid and providing said second portion to said chamber through said openings of said rear inner wall, 3) a first port for conveying said first portion of liquid to and from said first manifold, 4) a second port for conveying said second portion of liquid to and from said second manifold, 5) means for providing an effective seal of said mouthpiece within said oral cavity; and 6) means for collecting said fluid sample from said oral cavity, 1) a first manifold for containing a first portion of said liquid and providing said first portion to said chamber through said openings of said front inner wall, 2) a second manifold for containing a second portion of said liquid and providing said second portion to said chamber through said openings of said rear inner wall, 3) a first port for conveying said first portion of liquid to and from said first manifold, 4) a second port for conveying said second portion of liquid to and from said second manifold, 5) means for providing an effective seal of said mouthpiece within said oral cavity; and 6) means for collecting said fluid sample from said oral cavity, collecting said fluid sample from said oral cavity; and conducting an analysis of said fluid sample.