Changes in the Dentition of Small Dogs up to 4 Months of Age

Simple Summary National and EU legislation impose age restrictions for the rabies vaccination which is required in the export of dogs. This makes it important to know whether a particular dog is older than three months or not. In veterinary practice, age estimation is mostly based on dentition, although there is no standardized method described in the literature for determining the age of dogs under four months old and we found considerable variation in the references. We observed and recorded the changes in cranial shape and dentition of two Yorkshire Terriers born by caesarean section on 2 March 2018 up to four months of age. At the age of three months, both individuals showed the same characteristics of a wide gap between the upper maxillary incisors (i2 and i3) and the lower maxillary incisor and canine (i3 and c). It is common practice in EU member states to permit the entry of dogs vaccinated against rabies at the age of at least 3 months. In the absence of easily applicable comparative data, subjective disputes emerge around age. The aim of our study was to observe the development of dog teeth. During birth, an abnormally lying Yorkshire Terrier fetus was stuck in the birth canal, which led to a caesarean section, hence, the exact date of birth was known. For the next 4 months, two puppies were examined weekly, and they showed the same development. The dogs were born without teeth. At the age of 4.5 weeks, the canines I appeared, together with the adjacent incisors (i3), and the second incisor (i2) also erupted at the age of 6 weeks. A week later, a first incisor (i1) also appeared. From the age of 2.5 months, the distance between the teeth was increasing, especially on the upper dental arch. At 3.5 months of age, only the bottom front incisors (i1) had not grown in a row, and the significant distance between the top incisors, comparable to the width of the tooth, was striking. Since only two dogs of one breed were involved in this case study, the observations cannot be generalized.