Blood smears and bone marrow

Every week we have several practical classes. These are the classes where we have hands on contact with animals, or are looking at microscope slides, or handling and assessing preserved tissues, etc. This year we have mostly had pathology practical classes. We spend a few hours in a cold room wearing our labcoats and gloves and handling tissues. Some of the tissues/organs we have been looking at are: digestive tracts (rumens, stomachs, esophagus), livers, kidneys, hearts, lungs (they have all been preserved). We look for signs of diseases, different presentations, abscesses, parasites, cancer, infection, inflammation, abnormalities…the list goes on! Usually the classes are long and overwhelming with information!

This week we did something a bit different than handling cold preserved organs. In the first half of prac we did some hematology work. Did you know that red blood cells are also called erythrocytes? We practiced blood smears; this is a common diagnostic test done in clinics. A blood smear lets you examine which cells are present, if they look normal, if there is too many cells or too few. This can give a veterinarian a lot of valuable information on a case!

My blood smears; practice makes perfect!

My blood smears; practice makes perfect!

We also checked packed cell volume (PCVs) of different animal bloods. PCV tells you the percentage of red blood cells in a sample (the other 2 parts of blood are plasma and a buffy coat (white blood cells and platelets). If there is not enough blood cells seen on a PCV, the animal might be anemic. We also spent some time looking at cells under the microscope to see if we could identify all the different types.

In the second half of prac class we got to practice bone marrow sampling. Did you know that red blood cells are made in the bone marrow and then move out of the bones into the blood? The bone marrow is sampled to check for signs of infection, disease, or other problems. We learned the correct way to use a bone marrow needle and the specific locations on the body that the needle need to be placed. The needle needs to be inserted through the skin and into the center of a bone in order to suck up bone marrow. After a few tries (on deceased animals) I was starting to get the hang of it!

This was a really fun and practical afternoon of practicing some clinical skills. I wanted to share with everyone so you could have a bit more of an understanding of what I do in uni!


A bone marrow aspiration needle. Image from: