Comparison of growth patterns in healthy dogs and dogs in abnormal body condition using growth standards

Abstract

In dogs, optimal growth is critical for future health and wellbeing. Recently, a series of evidence-based growth standards, based on bodyweight, were developed for male and female dogs across 5 different size categories. The aim of the current study was to compare growth curves depicted by the standards with patterns of growth in dogs that were either healthy, had abnormal body condition, or had various diseases with the potential to affect growth. The data came from 2 research colonies in Europe (France and UK), and a large corporate network of primary care veterinary hospitals across the USA. Age and bodyweight data were used to model growth in healthy dogs, in dogs that became overweight or underweight by 3 years of age, and in dogs with diseases associated with altered growth. Centile line crossing during the growth phase was uncommon in healthy dogs, with <5% of dogs crossing >2 centile lines. In contrast, centile line crossing was more frequent in dogs with abnormal growth patterns or abnormal body condition. Dogs that developed obesity by 3 years grew faster than the growth standards predicted, and 68% crossed ≥2 centile lines in an upwards direction. Dogs with conditions associated with accelerated growth also grew faster than expected, and 54% crossed ≥2 centile lines. In contrast dogs that became underweight by 3 years gained weight slower than expected, and 49% crossed ≥2 centile lines in a downwards direction. These results suggest that the growth standards are useful for monitoring healthy growth in dogs. Prospective studies are now required to confirm these findings and to determine whether early intervention can prevent the development of diseases.

Fig 1. Flow diagram illustrating the data cleaning process.

This cleaning process was used for datasets used in the creation of the predicted median growth trajectories. Data are expressed as either thousands (10³) or millions (10⁶) as appropriate.

Fig 2. Examples of individual growth trajectories from healthy dogs plotted onto the growth curves.

The red open circles represent separate weight measurements for the same dog, whilst the solid blue lines represent the growth curves for the respective breed size category. (a) The growth curve of a male Yorkshire terrier which closely followed the centile lines. (b and c) Growth curves of a female Miniature Schnauzer (b) and a female Cocker Spaniel (c) whose growth pattern followed the centile lines relatively well. (d) Growth curve of a male Labrador retriever whose pattern of growth showed some differences from the centile lines, as indicated by some centile line crossing.

Fig 3. Examples of individual growth trajectories from dogs on restricted and supplemental feeding diets.

The red open circles represent weights, whilst the solid blue lines represent the growth centiles for the respective breed size category. (a) A female Labrador Retriever on a restricted diet crossing centile lines on a downwards trajectory. (b) Growth curves from a female Labrador Retriever on a supplemental diet crossing multiple centile lines and (c) a male Labrador Retriever on a supplemental diet crossing centile lines on an upwards trajectory. (d) Growth curve from a female Labrador Retriever on a supplemental diet showing no centile line crossing.

Fig 4. Median weight by age (on the centile scale) for the WALTHAM Research Colony dataset in 5 size classes.

On each graph, the median for the validation dataset is depicted by the solid line, whilst the growth standard centiles are indicated by dotted horizontal lines.

Fig 5. Median weight curves by age (on the centile scale) for obese, overweight and underweight dogs from the Body Condition Veterinary Records dataset in 5 size classes.

The trajectories for obese, overweight and underweight dogs are depicted by solid light green, tawny, and light blue lines, respectively, whilst the growth standard centiles are indicated by dotted horizontal lines. For obese and overweight dogs the centiles cross upwards, while for underweight dogs they cross downwards.

Fig 6. Median weight curves (on the centile scale) for diseases associated with retarded growth in 5 size classes.

Diseases are persistent right aortic arch/vascular ring anomaly (blue), megaoesophagus (pink), portosystemic shunt (yellow), hepatic encephalopathy (brown), dwarfism (green) and 'osteodystrophy, nutritional' (grey).

Fig 7. Median weight curves (on the centile scale) for diseases associated with accelerated growth in 5 size classes.

Diseases are OCD (red), ‘anconeal & coronoid process’ (blue), ‘hip dysplasia, medical’ (green), ‘hip dysplasia, surgical’ (black) and hypertrophic osteodystrophy (purple).