Calculating Growth / by Michael Johns

Figure 1. Noosa's predicted growth (blue line) as a function of her age. Polynomial equation derived from actual weight measurements (orange points) from 6 different vet visits throughout her development. 

The most popular question we get from people who meet our dog Noosa for the first time is, "She's huge for a puppy! How big will she get?". Since Noosa's is a mix of many different breeds, specifically Maremma, Saint Bernard, Newfoundland, Great Pyrenees, and Bernese Mountain Dog (see family photos below), we can't just look at examples of other dogs to gauge her final adult size. There's no doubt she'll be big, but just how remains a bit of a mystery? One way to estimate this is to use a model based on her observed weights to predict how much she might weigh in the future. A simple approach is to fit the observed values with a polynomial equation (Fig. 1), which doesn't perform well for ages less than 20 days old (negative weights), but fits the rest of the data pretty well. Another method would be to use more complex equations with additional terms, such as Von Bertalanffy model or some other growth equation. Either way, based on a simple polynomial fit, it looks like she will likely max out at just over 80 pounds; which is what we would expect based on her parental recipe. 

The mom

The dad (right)