Development of Yorkshire Terrier Dentition

Abstract

The development of dentition in dogs has been associated with several problems including tooth over-crowding, missing permanent dentition, and persistent deciduous teeth (PDT). Information on dentition development in different breeds is lacking. This study of 61 Yorkshire terriers aimed to determine the (i) average age at deciduous tooth exfoliation, (ii) average age at permanent tooth eruption, (iii) PDT incidence, and influencing factors such as body weight. The ages of exfoliation of deciduous teeth and eruption of permanent dentition were influenced by body weight and tooth type. These dentition changes tended to occur later in dogs ≤ 3 kg versus dogs > 5 kg. Generally, incisors were exfoliated first, followed by premolars and then canines. At a body weight of 4.5 kg, the middle of the data range, the estimated age at loss of deciduous teeth (with 95% confidence intervals) was 21.9 (21.1, 22.9) weeks for incisors, 26.1 (24.9, 27.4) weeks for canines, and 23.9 (22.9, 24.9) weeks for premolar. The estimated age at eruption of permanent dentition was 22.3 (21.6, 23.0) weeks for incisors, 23.8 (23.0, 24.6) weeks for canines, 24.7 (24.0, 25.5) weeks for premolars, and 26.4 (25.5, 27.3) for molar teeth. However, this sequence was disrupted in dogs ≤ 3 kg. Yorkshire terriers had a high incidence of PDT. At a body weight of 4.5 kg, the estimated proportion of PDT was: incisors 0.86% (0.32, 2.31), canines 15.62% (7.62, 29.37) and premolars 3.57% (1.62, 7.66). Canines constituted the most frequently retained tooth type, with 89.1% retained in dogs ≤ 3 kg compared to 12.0% in dogs > 5 kg. This information will enable veterinarians to provide personalised advice regarding the oral care requirements for Yorkshire terriers and highlights the need to regularly monitor this breed between the ages of two and seven months, during the active phases of tooth development.

Keywords: Yorkshire terrier; body weight; dentition development; dog; persistent deciduous teeth.

Figure 1

Smoothed average age representation of deciduous tooth loss (mouth average) according to body weight at 28 weeks of age. Coloured dots represent individual litters and the shaded area represents 95% confidence intervals.

Figure 2

Estimated average age of deciduous tooth loss for incisors (red), canines (black), and premolar (blue) teeth across a range of body weights seen in the cohort. Dotted lines represent pointwise 95% confidence intervals.

Figure 3

Smoothed average age at eruption of permanent dentition according to body weight. Coloured dots represent individual litters and the shaded area represents built-in 95% confidence intervals.

Figure 4

Average age at eruption of permanent dentition for each of the different tooth types (incisor, canine, premolar, and molar). The bars indicate 95% confidence intervals.

Figure 5

Estimated average age at eruption of permanent dentition for incisors (red), canines (black), premolars (blue), and molars (green) teeth across a range of body weights. The dotted lines represent 95% confidence intervals.

Figure 6

Smoothed mean proportion of PDT according to body weight. Coloured dots represent individual litters and the shaded area represents 95% confidence intervals.

Figure 7

Estimated mean proportion of PDT by body weight and tooth type: incisor (red), canine (black), and premolar (blue). Dotted lines represent 95% confidence intervals.