Out-of-Distribution Prediction: Dog Weight Regression

A veterinarian builds a regression model to predict the weight of golden retriever puppies over their first 3 years of life. The model is trained on weight measurements from 2,000 golden retrievers, sampled every 3 months. A patient comes in with a 1-year-old poodle. The vet wants to use the model to predict the poodle's weight. Is this likely to produce an accurate prediction? Why or why not?