Here is an update on what we have found so far, which of course would never have been possible without the help of all our participants and their lovely dogs! We carried out an initial study into different ways of measuring puppy nostrils to determine whether they were open or closed, with the aim of finding a reliable numerical indicator of the degree of nostril opening.
First of all, we looked at example photographs to test out different methods of measurement. An ideal method of measurement would be one that showed a pattern that agreed with the grades of nostril opening given using the grading system that is currently used. We also wanted any measurements to be straightforward to take, so that different people could take the measurement and get the same number.
The most useful measurement was found to be the ratio width of the alar fold divided by half the nose width. Another useful measurement was the ratio nostril area divided by half the nose area. (The reason for dividing by the nose width or area is simply to adjust for the different nose sizes on the photographs, which can obviously depend on the size of the dog and how zoomed in the photograph is.)
First of all, we looked at example photographs to test out different methods of measurement. An ideal method of measurement would be one that showed a pattern that agreed with the grades of nostril opening given using the grading system that is currently used. We also wanted any measurements to be straightforward to take, so that different people could take the measurement and get the same number.
The most useful measurement was found to be the ratio width of the alar fold divided by half the nose width. Another useful measurement was the ratio nostril area divided by half the nose area. (The reason for dividing by the nose width or area is simply to adjust for the different nose sizes on the photographs, which can obviously depend on the size of the dog and how zoomed in the photograph is.)
The next step was to take measurements from the photographs that had been sent in to us and calculate the ratios for each one. Each photograph was given a grade of nostril opening using the existing grading system. We were looking for a good correlation relating the grade of nostril opening to each of the ratios. Spearman’s rank correlation coefficients were calculated, which gives a number between -1 and 1 known as the R-value. The closer the R-value is to -1 or to 1, the stronger the correlation between the grade of nostril opening assigned to the photographs, and the numerical measurements that were made.
The results indicated a strong negative correlation between the grade of nostril opening and the nostril area divided by half the nose area, with an R value of -0.794.
There was a very strong positive correlation between the grade of nostril opening and the alar fold divided by half the nose width, with an R value of 0.904.
So looking at the R values, the alar fold width divided by half the nose width appears to be a slightly better indicator of the degree of nostril opening, though this could possibly just be because there is less interference from shadows in the photographs.
The next step will be to involve more puppies and carry out a larger study using these measurements, to try and determine the age at which it becomes apparent whether puppies have closed or open nostrils.
The results indicated a strong negative correlation between the grade of nostril opening and the nostril area divided by half the nose area, with an R value of -0.794.
There was a very strong positive correlation between the grade of nostril opening and the alar fold divided by half the nose width, with an R value of 0.904.
So looking at the R values, the alar fold width divided by half the nose width appears to be a slightly better indicator of the degree of nostril opening, though this could possibly just be because there is less interference from shadows in the photographs.
The next step will be to involve more puppies and carry out a larger study using these measurements, to try and determine the age at which it becomes apparent whether puppies have closed or open nostrils.