Growth charts for small sample sizes using unsupervised clustering: Application to canine early growth

Abstract

Breed-specific growth curves (GCs) are needed for neonatal puppies, but breed-specific data may be insufficient. We investigated an unsupervised clustering methodology for modeling GCs by augmenting breed-specific data with data from breeds having similar growth profiles. Puppy breeds were grouped by median growth profiles (bodyweights between birth and Day 20) using hierarchical clustering on principal components. Median bodyweights for breeds in a cluster were centered to that cluster’s median and used to model cluster GCs by Generalized Additive Models for Location, Shape and Scale. These were centered back to breed growth profiles to produce cluster-scale breed GCs. The accuracy of breed-scale GCs modeled with breed-specific data only and cluster-scale breed GCs were compared when modeled from diminishing sample sizes. A complete dataset of Labrador Retriever bodyweights (birth to Day 20) was split into training (410 puppies) and test (460 puppies) datasets. Cluster-scale breed and breed-scale GCs were modelled from defined sample sizes from the training dataset. Quality criteria were the percentages of observed data in the test dataset outside the target growth centiles of simulations. Accuracy of cluster-scale breed GCs remained consistently high down to sampling sizes of three. They slightly overestimated breed variability, but centile curves were smooth and consistent with breed-scale GCs modeled from the complete Labrador Retriever dataset. At sampling sizes ≤ 20, the quality of breed-scale GCs reduced notably. In conclusion, GCs for neonatal puppies generated using a breed-cluster hybrid methodology can be more satisfactory than GCs at purely the breed level when sample sizes are small.

Neonatal–Maternal Bodyweight Ratio at Birth: An Indicator for First-Week Survival Prognosis in Canine Newborns

“…Reference values for NBW referring to the size of different breeds were evaluated, too, but it was demonstrated that NBW varies among breeds of the same size [20]. Ideally, data regarding NBW should be breed-specific to account for the large heterogeneity in weight among dog breeds (from less than 2 kg to over 100 kg in adults), but there are almost 400 breeds of dogs, and for less common breeds, only small sample sizes are available [21]. It is certain that veterinary practitioners are in need of a tool to evaluate NBW, which should be easy to use, and applicable to every canine neonate, regardless of size, breed and litter.…”