Elyse Bangerter
Biology 1615
Breed and Sex Differences in Growth Curves for Two Breeds of Dog Guides
Introduction
Scientists wanted to do research on which two breeds of dogs (Labrador retrievers
and German Shepards) had the best mature growth and weight curves.They wanted to
find which of the two breeds will fall within the mature weight between the ranges of 18
to 32 kilograms (kg).
The scientists did studies on both male and female Labradors (labs) and
German Shepards, and weighed around 880 dogs and made 10,484 observations.
They needed to test so many dogs to make sure that they were getting an adequate
reading on the experiments.
Scientists also did studies on the dams, sires and their litters to see if the
breed would make a difference in the growth rate. They wanted to see if a German
Shepard would make a better canadite or if a Labrador would be better for this
experiment.
The scientists wanted to find the right range of growth rate for the Seeing Eye
dogs. The Labradors and Shepards needed to be the right weight because heavier dogs
would be too difficult to handle.
Scientists needed to find out the right breed to use and the correct weight
and growth rate of each dog. They did this by conducting experiments on both breeds,
male and female to determine which would be better for the blind to use. The researchers
needed this information on both types of dogs so future generations would know which
breed would be better to use.
Researchers needed to test the dogs to find if it would make a difference if
the dog was a male or female. This is why they tested both sexes instead of just one sex
to see if it would make an alteration to their study.
Their hypothesis was that male German Shepards would be the best breed
of dog for the Seeing Eye. They had the most percentage in the range for what the right
weight of a Seeing Eye dog should be. Labs and females had a better percentage to have a
greater weight not within the range.
Materials and Methods
They used several different experiments in this research project. They weighed
the dogs several times whenever they went into the clinic from when they were born until
they reached the mature age. They determined if the sex of the dog mattered and they
found that the males were more likely to reach their mature weight. The last experiment
they tried was taking the dogs away from the Seeing Eye and their caretakers for a while
to see if they would gain weight or lose it.
They used a calculation called the Gompertz function to determine each
individual dog’s growth rate or curve.The Gompertz function equation looks like this, Wt
= Wmax exp(-e{-(t-c)/b}). The Wt stands for weight at time, Wmax is the mature body
weight, b would be the duration of growth proportion, C is the age when the dogs were
inflected and t is the time during the days.
Results
The scientisits found that the mature weight they wanted the dogs to be at
was between 18 to 32kg. They also found that males were more likely able to reach the
required mature weight and growth.
They were surprised that breeding didn’t have to do much with one of the
experiments. When they tested the dams and sires together it didn’t matter if they were a
Labrador or a Shepard.
Discussion
The results meant that the scientists were able to look for an appropriate growth
and weight range for the next generation of Seeing Eye dogs. “The construction of
growth curves for male and female German shepherd dogs and Labrador retrievers at the
Seeing Eye provides information about the average mature weight and the average
growth term for the dogs in this population. These findings may be used to aid in
development of a selection protocol to increase the probability that dogs will attain
mature weight within the range of 18 to 32kg.” This means the growth curve for the
seeingeye dogs offers evidence for the mature weight that ranges between 18 to 32
kilograms.
Works cited
Breed and sex differences in growth curves for two breeds of dog guides,
S. K. Helmink, R. D. Shanks, and E. A. Leighton