Microscopy is an Essential Technique in Veterinary General Practice.
Veterinarians, veterinary technicians, and veterinary assistants use microscopes to view blood and animal fecal samples or animal fluids. Our hospital most commonly uses microscopes to check fecal samples for parasites, diagnose skin conditions, take a closer look at urine samples (urinalysis), and other cytologies.
Reasons In-House Microscopy is Important
While our lab equipment is highly accurate, there is nothing more accurate than a well-trained human eye! We will often use various lab techniques to verify abnormal findings in bloodwork or urinalyses.
They play an important role in the diagnosis and treatment planning of conditions that require immediate attention. For example, the identification of a skin mass as a mast cell tumor will determine how much tissue beyond the mass should be taken off to ensure complete removal and to prevent it from spreading.
While we do have the ability to send samples off to our outside laboratory, the diagnosis of certain conditions like Demodex sp. mange mites is best determined by the examination of fresh hair plucks or skin scrapings as these samples do not travel well to an outside laboratory.
Interesting VetMed Facts:
The focus of early veterinary microscopy was the diagnosis of diseases that were public health risks.
Example: the causative agent of Anthrax
Most Common Reasons We Use the Microscope
A urinalysis is a routine test that reports the physical and chemical properties of urine. It is used mainly to assess the health of the kidneys and urinary system, but it can also reveal problems in other organ systems, and is important for diagnosing metabolic disease such as diabetes mellitus. It is a valuable test in both healthy and sick animals and should be included in any comprehensive evaluation of a pet's health. Our laboratory uses the Abaxis UA and SA analyzers but routinely will also view urine sediment manually. After using a centrifuge to spin down a urine sample, the sediment from the bottom is collected, sometimes stained, and viewed under a microscope where we look for any irregularities with:
Skin and Ears
One of the chief problems seen in a small animal clinic is ear infections that diagnostically will include a good ol’ swab and look-see under the microscope for bacteria and yeast. Small animal vets also diagnose a plethora of common skin problems under the microscope.
Small animal vets also diagnose a plethora of common skin problems under the microscope. Large animal vets rarely if ever do any type of ear swab (I don’t believe I ever have) since horses, cattle, sheep, and goats just don’t get yeasty ears like Labradors do, and our patients’ skin diseases don’t require “skin scrapes” quite as frequently. There is also the issue of convenience.
When your pet has a lump, we may perform a fine needle aspiration. We will use a needle to pull cells out of the lump to identify them. We can diagnose fatty lumps just by looking at the cells under the microscope, though we may send more complicated samples to the laboratory.
One of the most common uses of the microscope in both the small and large animal realms is the fecal float. A diagnostic tool that takes a small fecal sample, mixes it with a special solution and then sits the resultant “poo-slurry” in a tube with a microscope coverslip on top, the fecal flotation test determines the presence of gastrointestinal parasites eggs.
There are many methods for the fecal flotation test. Variations include how much fecal matter you need, what type of solution you use (choices include sugar water and zinc sulfate, which cause the fecal eggs to separate from the fecal matter and rise to the top of the tube), whether or not you centrifuge the sample, and how long you let the sample sit before examining it under the microscope. Each variation has its pros and cons, including time and expertise required, expense, and sensitivity.
Once you’ve got the coverslip ready and on the slide, it’s then time to venture into the microscopic world of parasite eggs. The identification of different types of parasite eggs takes time and training. Not only can different parasites have different looking eggs (although not always the case, as in a group of roundworms in horses, cattle, and small ruminants called strongyles), but also different species of animals carry different types of parasites.
Most common parasites/organisms found in fecal samples: