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          Microscopic Exams

          by Dr. Becky Marks

The microscope is a marvelous invention. In the 1700s our ancestors discovered how to magnify an image using very simple principles. Two lenses and a light source could open up a new world of tiny structures.Today the light microscope is still a vital piece of equipment in any lab.  In order to identify cell tissue changes the microscope must be used. In the veterinary lab samples include blood, urine, feces, ear wax and tissues.

The blood exam is a very important procedure. Much information can be derived from blood analysis but the blood smear is critical.  One drop of blood is smeared and stained for information. The health of the red blood cells, white blood cells and platelets can determine if the animal is fighting new infection versus old infection. The cells may give indicators of stress, cancer, parasites and anemia. An organism called Mycoplasma in cats is only identified in a sample that is immediately examined. The organism is transmitted by fleas and attaches to the red blood cells causing red blood cell death. Without the microscope there is no diagnosis.

Urine samples contain a plethora of insights. In the animals world many problems occur in the urinary system. The contents of the is examined in two ways. The chemical analysis is a screening for pH, infection, sugar etc. The actual exam of the urine is done before and after centrifuging. The exam checks for white and red blood cells, slough of cells from the kidneys and  abnormal cells (CANCER). The exam also picks up crystals which are precursors to bladder stones. Many cats have crystals which a like pieces of sand. OUCH! The sand is passed and is likened to urinating glass. Without knowing what type of crystals exist the therapy can not be chosen.

The stool sample of your pet may seem like a big waste. However, in the veterinary hospital the sample is goal mine. A small amount of the sample is directly examined under the scope for bacteria sizes, shaped and numbers. The centrifuged sample is examined for large parasite eggs such as hookworm, whipworm and roundworm. Many parasites are zoonotic (can give people disease) and without the microscope you would never know they exist. In Oregon examples of parasites include Giardia, Toxoplasmosis and fluke eggs (Salmon poisoning). A high level or bacteria can be an indicator that your dog is eating garbage or cat feces even though all looks normal to you.

If your dog has itchy ears the Veterinarian will get a “juicy sample” on a Q-tip. Ear samples are examined microscopically  for yeast, bacteria and mites. There is no other way to identify the ear problems.

Finally, cells from tissue(skin, tumors, organ) can be examined for the normal versus abnormal. The in-house lab can often determine if the lump you have been worried about is a fatty tumor or a serious tumor. Each type of tumor has a unique cell(s) type and the appearance of the cells can be determined to be normal or abnormal. For example a lymph node biopsy may yield lymph cells that are reacting to infection . Some  lymph cells may simple be larger in size but if there are changes in the cell cytoplasm and nuclei the diagnosis can change from infection to cancer. Only the human eye has discern these changes.  In all of these examples the human eyes are tools in the diagnostic process.

After hundreds of years the microscope remains a very important tool in everyday practice.  Thanks to our ancestors we have advanced in the world of microscopy.  The trained eye,  the microscope and a tiny exam give big information.