How Using a Microscope Is Like Having a Veterinary Superpower

It is fascinating what details about pets’ health can be revealed under microscopic views.

A microscope can help a veterinarian pinpoint why a cat is having trouble urinating. By: tambako

If you think the microscope has little place in day-to-day life, think again.

I love microscopes. To me, using a microscope is like having a superpower — it opens up whole new worlds.

For example, looking down a microscope can help diagnose the cause of itching in a pet and make the difference between management and cure.


Let’s Look at Microscopes

My favorite equipment in the consult room is a microscope because it answers so many questions — and quickly. It can even save a pet’s life by identifying a life-threatening blood disorder without having to wait for lab results to come back.

So let’s look at why using a microscope is my superpower as a veterinarian and helps solve cases.

Skin Symptoms

Why is your pet itchy? Collect some dandruff and hair on a piece of sticky tape, and what do we see under the microscope?

  • Mites: Cheyletiella, yeah! A diagnosis.
  • Fungi wrapped around hair shafts: Yeah! Ringworm, a diagnosis.
  • Broken hair shafts: Hmm, this cat is over-grooming.
  • Lice eggs: Whoa, didn’t expect that.
  • Dandruff: I guess his skin is really dry.
  • Flea dirt: I suspected as much, but it’s good to have proof.

A skin scrape can also give useful answers for dogs with itchy skin or bald patches. By gently abrading the skin with a scalpel blade and placing the debris on a microscope slide, we can identify mites such as demodex living deep within the skin.

Lumps and Bumps

If there’s anything more stressful than finding a lump on your pet, it’s waiting days for biopsy results to come back. However, when you know what to look for, a microscope can speed things up.

I’m a great fan of the fine needle aspirate, which is when you pop a needle into a lump and suck back to obtain a sample of cells to place on a microscope slide. It has pros (no anesthetic needed) and cons (the sample is tiny and not always representative of the whole lump), but in some cases it gives an instant answer.

It’s a great way to quickly identify:

  • Lipomas: Fatty lumps
  • Mast cell tumors: serious cancer that needs wide excision
  • Eosinophilic lesions: Not a cancer at all, but an allergic reaction
  • Sarcomas: Another potentially worrying cancer

Sometimes this puts minds at rest. Other times, it flags that urgent action is needed. Either way, you know better what you’re dealing with and can act accordingly.

A blood smear under a microscope can tell you if your dog is anemic. By: eddietruman

Fresh Blood Smears

A weak cat or dog who suddenly collapses is anemic…but why?

Looking at a fresh blood smear under the microscope provides an instant answer. For example, many years ago, after hours I saw a collapsed Labrador whose gums were as white as a sheet. The lab was shut and a diagnosis wouldn’t wait until the morning, so I fell back on the trusty microscope.

A quick look at a blood smear showed not only confirmation that the dog was severely anemic with few red blood cells but also that those present had a shape and size that suggested they’d been attacked by the body’s immune system. Intravenous steroids and a blood transfusion later, and the dog was on the road to recovery.

Golden Wonder: Urine

I may be a little weird (or need to get out more), but I love looking at urine under the microscope. It gives the clinician so much valuable information, especially for cats who have trouble peeing.

Spin down a urine sample and look at the sediment. What do you see?

  • Red blood cells: A sign of inflammation.
  • White cells: The number and type tell you if the cat is fighting an infection or has inflammation.
  • Bacteria: The smoking gun when it comes to infection.
  • Crystals: My favorite! Crystals chafe the lining of the bladder — a bit like rubbing it with sandpaper. But more to the point, different crystals grow in different conditions, and finding them gives the clinician a means of changing things such as diet to make those conditions less favorable for crystal growth.
  • Renal casts: Evidence of kidney damage.

The Secret World of Cytology

Cytology is the study of the structure of cells, and looking at samples of cells under the microscope can tell you things such as whether a female dog is coming into heat or a skin sore is caused by cancer or an allergic reaction.

It’s not leaping tall buildings in a single bound, but as far as superpowers go, using a microscope is wonderful because it helps me diagnose pets’ health problems so I can get them the treatment they need.


This pet health content was written by a veterinarian, Dr. Pippa Elliott, BVMS, MRCVS. It was last reviewed Oct. 11, 2018.


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