Fixation on Histology

Histologists Must Love Dogs


DogFor most dog owners, the quality of the food, toys, chews, and treats their canine best friends put in their mouths is of the utmost importance. A regular dog owner may just read the label, and trust it, but a histotech, curious by nature, is bound to dig deeper. The Journal of Histotechnology has published several articles in the last few years, including one in this most recent issue, discussing the histology of what our dogs consume.

Microscopic Examination of Dog Chews: Correlation of Histological Findings to Product Labeling, by Adam W. Stern and Laurie A. Martin

This new study, published online in the June issue of JOH, uses histology to study whether or not dog chews labeled as rawhide-free, really live up to their product labels. For those of us non-dog people out there, raw-hide chews are those things dogs chew on that most of the time are shaped like bones. They’re made from the inner layer of horse or cow hides. Dogs love to chew on them, but they have the potential to obstruct the digestive tract if the dog eats large pieces of it. There are alternatively chews that advertise as raw-hide free, and position themselves as a more natural alternative. The studies authors purchased samples of both rawhide and rawhide free chews, soaked them in deionized water to soften them, and fixed the slices in 10% neutral-buffered formalin for 24 hours. They were then processed, and embedded in paraffin. The samples were examined by light microscopy using hematoxylin and eosin and Masson’s trichrome stains. The majority of the products findings were consistent with the labeling, however two products labeled as rawhide free, showed similar histologic appearance to dermis and other products labeled as rawhide. Check out the full process, conclusions, and staining online in the Journal of Histotechnology article! JOH is free to access for NSH members!

Histologists Must Love Dogs

Histologic Examination of Canned Beef Dog Food: What Does it Really Contain? By Brigid E. Prayson, William R. Poulson & Richard A. Prayson

Stern’s 2020 dog chew research builds upon this older JOH article from 2016, which uses histology to study cans of beef dog food, assessing the beef content, as well as identifying other types of tissue present. This study took samples from beef dog food cans, which were formalin-fixed, paraffin-embedded, sectioned at 4 microns, and stained with hematoxylin and eosin. To locate “beef content” they looked for skeletal muscle. Using an overlay grid system, they were able to estimate beef content for each sample, which ranged from .2% to 13.6%, with the median being 1.3%. In addition to their meat they found other types of tissue including connective tissue, blood vessels, bone, cartilage, lung, peripheral nerve, skin, adipose tissue, and rarely other solid organs such as kidney and pancreas. Despite the differences between the brands in meat content, there was no correlation found between percentage of beef and unit price for the food. Check out the full article online in the JOH archives here.