Plaque and/or tarter is build up on the teeth of a dog or cat. Plaque can be referring to either the teeth or the arteries; however, in either case, it can be a serious problem in pets. When dogs or cats develop plaque on their teeth, it can lead to periodontal disease, abscesses, tooth loss and even heart disease. When plaque builds up in the arteries, there is limited space for blood to flow. This can cause serious and even fatal problems in dogs including heart attacks and strokes.