ľ�ϸ���Ӱ��

Experts from the Faculty of Veterinary Medicine have developed a new method to estimate the age of puppies based on their teeth. Hundreds of dog owners participated in this study, which was commissioned by the Ministry of Agriculture, Fisheries, Food Security, and Nature (LVVN). The new insights can be used by veterinarians for health guidance, such as planning vaccinations. The State Secretary has informed the House of Representatives about the results.

Approximately 50,000 dogs are imported into the Netherlands each year, a large portion of which are puppies. The legal age at which a puppy may cross the Dutch border is 15 weeks (105 days). Unfortunately, veterinarians and enforcement officers regularly encounter fraudulent practices involving passports and underage imported puppies.

Welfare and Risk of Zoonoses 

Separating puppies from their mother too early leads to welfare issues and increases the risk of zoonoses, such as rabies. Dogs can be vaccinated against rabies from 12 weeks old and are protected after 15 weeks. 

Until now, there was a lack of objective criteria to practically and reliably estimate a puppy’s age. The research now shows that the replacement pattern of the milk incisors can be used for this purpose. It is important to consider the breed of the dog, as the size of the dog affects the start age and duration of teething.

Citizen Science

The study was carried out by the Expertise Center for Genetic Veterinary Medicine, the Department of Veterinary Dentistry, and the Department of Statistics. Participants were recruited for this citizen-science project via social media, veterinary clinics, chip professionals from the Dutch Kennel Club, and various breed and breeding associations. Owners of puppies at least 10 weeks old with a known and reliable birth date could participate. Puppies from abroad were excluded from the study.

Owners sent a photo of their puppy’s teeth on two fixed days a week starting at 10 weeks old, continuing until all the milk incisors had been replaced. A total of 980 puppies started the study. The participating puppies were born between 21 May 2020 and 31 December 2022. For 227 owners, it was not possible to take a photo of their puppy’s teeth, leading to discontinuation. Additionally, the adult weight of 8 dogs could not be estimated, so their data was excluded from the analyses. 

Lead researcher Hille Fieten: “It’s fantastic how committed the owners were to this study. We are very grateful to them. With the data on the replacement of milk incisors, we can now give a validated estimate of a puppy's age. We've developed a flowchart for this.”

Valuable Tool

According to the State Secretary, the report serves as a valuable reference database for age determination by veterinarians. However, the method is not suitable as a formal enforcement tool by the Dutch Food and Consumer Product Safety Authority (NVWA), as many puppies only begin teething after the age of 15 weeks. This is the age at which a puppy may be imported from another EU member state or a country outside the EU with a low rabies risk. 

To determine the age of a puppy that has not yet started teething, the puppy would need to be monitored until teething begins. “Due to the capacity this would require, it is not feasible for the NVWA to implement this in practice,” stated the State Secretary. “However, the NVWA can use this report to support a notification to the country of origin, when puppies are confiscated following a violation, to demonstrate that the animal was too young.”