The Breed Standard, Colour Descriptions, Guidance Notes, Specific Faults and Disqualifications is that of the Agouti except Belly to be ticked evenly all over, as per the body.
In addition, it should be noted that some of these cavies are born solid in colour and develop ticking later; so darkness on head & feet of u/5 exhibits should not be unduly penalised.
The evenly ticked belly of a Solid Agouti; bred by Penny Bell (Optimist Stud)
SOME HISTORY
The Solid Agouti is different from the standard Agouti cavy in that, rather than having a plain coloured belly panel to match the ticking colour, there is no belly panel – the ticking covers the entire body. They were unknown in the UK until recently, being first introduced into the UK by Dave Bumford, a breeder of Dalmations, who imported some in 1999 to put spots on the bellies of Agouti Dalmations.
Dave’s experiment in breeding spotty bellied Agouti Dalmations was successful but by then the Solid Agouti had attracted interest as a breed in its own right, and was taken up by other breeders, including myself.
Although it appears to be similar to the standard Agouti, it has a different ancestor in a wild cavy called Cavia rufescens, and the ones we see today are genetically about one-sixteenth wild agouti. They have been known in Europe and America for many years and indeed have been shown for about 40 years in America where they are known as “Solids”.
As well as having uniform ticking covering the whole cavy, the way the ticking develops is also different from the standard Agouti. Some Solid Agoutis are born with a full set of ticking like the standard Agouti, and these grow up to be too light, though such cavies are useful to lengthen the ticking if it is getting over short in your stud. The best Solid Agoutis are those born with some ticking and will grow most of the remainder over the first three months of life. They have short but distinct ticking. The third version look like dilutes, but you can tell at birth if the cavy is a true dilute or if it will eventually be an agouti. If you look just in front of the ears, you will find a small patch of ticking on the agouti, but none on the dilute. The ticking on these is the shortest, and can be so short as to be hard to see on the ungroomed cavy.
Solid Agoutis should not be bred to standard Agoutis, as this can give them the illusion of a belly band, the belly being lighter and longer tipped. The Solid Agouti tends to have dark (unticked) feet, dark eye circles and a dark head, though this last can often be improved by grooming. In America dark feet and faces are a minor fault, all over evenness of ticking being the primary goal. The Solid in general also has a very short coat, with not as many guard hairs to groom out as some other breeds. The type is similar to the standard Agouti.
The Solid Agouti received its Guide Standard in 2004 and was granted a Full Standard from the 1st January 2009 in the same colours as the standard Agouti.
A fine Silver Solid Agouti bred by Penny Bell (Optimist Stud)
The evenly ticked belly of a Solid Agouti; bred by Penny Bell (Optimist Stud)
A fine Silver Solid Agouti bred by Penny Bell (Optimist Stud) 
