Form follows function, both on the presence of breasts and the number of.
Specifically, the number of breasts is generally proportional to the size of their average litter. So unless you seriously expect a female anthro to birth half a dozen babies at once, one pair is probably enough to go around. Otherwise, honestly, most of the mammaries would be sitting there unused.
Another overlooked point is that if you want to ply to the animal qualities of the anthro, many female animals don't even lactate until they give birth, ergo a non-nursing female (and especially a virgin) probably won't have visible breasts to begin with. (If you really need the visual aid, a well-coiffed "ruff" of thick fur around the chest comes in handy here.)
For example.