Ear Cytology For Dogs And Cats

Cytology is a technique used in many aspects of veterinary and human medical practice.

“Cyto” comes from the Greek kytos, meaning “cell.” Logos is Greek for “science.” So, cytology is the science (or study) of cells. More specifically in everyday use cytology is used to study cells placed on a microscope slide from a body source.

Today we are only concerned with cytology of canine and feline ears.

Most commonly ear cytology in veterinary practice is used to determine the cause of inflammatory processes, usually infection and/or allergy-related. Cytology can also help us find cancerous cells growing in the ear canal(s).

Cytology starts with taking a specimen from the ear, obtained with a cotton swab. Separate swabs are used for opposite ears, as the same process is not always active in both ears at the same time. Gentleness is indicated in obtaining the offending material, not only to prevent exacerbating pain for the patient, but to prevent artifacts, as well. Rough handling of delicate blood and skin cells might prevent us from identifying important factors in a dog or cat’s ear problem.

Convention guides us to place the specimen from the left ear on the left side of a frosted-end microscope slide, the right ear’s sample on the right (see photo).

The frosted end allows patient identification as well as the "up" side of a microscope slide.
The frosted end allows patient identification as well as the “up” side of a microscope slide.

Again, a gentle technique is important, so the swab rolls the material onto the slide instead of dragging it.

Just as “Coke” is a generic term for soft drinks and “Kleenex” has become a standardized term for tissues, Diff Quik is a term clinicians use to describe any brand of a combination of three staining materials that are variants of the Romanovsky type. Simply looking at the microscope slide unstained, even at high magnification, would not tell us much because individual structures’ characteristics couldn’t be identified.

Diff Quik stains consist of a fixative (for stabilizing cell structures), an eosinophilic (red) stain and a basophilic (blue) stain.

Many, many other types of stains may be used to evaluate various kinds of cytologies. Diff Quik is simply the most common in clinical use.

If the material from an ear is particularly moist, the slide might be air-dried, hair-dryer dried or placed atop a source of gentle heat. One colleague uses a coffee-mug warmer.

The slide is then immersed into each color in the order listed above. Standard timing is ten seconds or “dips” in each color, but specimens suspected to be difficult to “fix” may be left in station one longer. If a doctor or technician is especially interested in the eosinophilic- or basophilic-staining structures he will leave the slide in the appropriate station longer.

Excess stain is then rinsed from the slide with tap water and the slide is dried by the method preferred by the operator.

Next comes evaluation under the microscope. To facilitate easy focusing the microscopist starts with a very low power objective called scanning. When the field is clear he switches to “high-dry,” which has the next step in higher magnification. He may use either or both of these to choose the field he wants to evaluate more closely, based on the patient’s and/or infective cells he sees. Finally the highest magnification is used, oil immersion.

Oil immersion is so-named because a special synthetic oil is introduced between the microscope objective and the stained slide. The oil displaces the tiny bit of air between the two that would otherwise distort the operator’s view.

Common infectious organisms in pets’ ears include bacteria and yeast. Bacteria may be of a round shape, cocci, or a rod shape bacilli. Yeast are usually of the genus Malasezzia, with the most common organism being Malasezzia pachydermatis.

Now, when your pet’s doctor performs cytology on your pet’s ears, you will know that a lot of technique and training go into both the preparation and the evaluation of the slide.


  1. My cat was taken to a vet by a friend who had him in her care since the 2018 fires claimed he”d been seen once and eardrops we’re given and gone Second appt , cat still shaking head , Vet did a Cytology test ( charged me )$70 which should been conducted at the first exam , if so , why would the 2nd Cytology test be reguired ?

    • I’m not completely clear that there WAS a cytology on the first visit, since you said, “should [have] been conducted.” If cytology were performed on the first visit it should be a line item on the receipt. Regardless, when a patient’s problem isn’t resolving, it’s not unusual to repeat laboratory testing to find out why. Good example: A few years ago a friend brought his dog in for itchy ears. We performed cytology and there were quite a few yeast on the slide. No bacteria were visible. About a week later he called and said, “FooFoo’s ears aren’t getting better, and there is a bad odor.” We made him another appointment and discovered pus draining from the left ear. Cytology showed extensive bacilli infection. FooFoo went from yeast infection to bacterial infection. The most likely explanation was that the yeast had been there for a while (she’s a swimmer) and that the rods were just starting to grow, thus, their numbers were too low to appear on the first cytology. We dispensed an appropriate medication to kill both bacteria and yeast and FooFoo resolved without any complications. Thanks for reading, Dr. Randolph.

  2. Took my doc a poo to a vet for ear itching issues. She did a exam, got a sample of material from ears using a q tip and did a cytology test in a shirt amount if time. I wanted to be conservative. She prescribed ear wash and gentisole drops for ten days. No written results just verbal? Sound rught?

  3. My 9 year chocolate lab, has fowl breath, I brushed his teeth and the smell was a lot less, I asked my vet to examine his teeth, and my Vet, said no worries, there a typical 9 Year lab mouth and there normal with no concerns, he also has a bacteria cocci ear infection and I’m cleaning it every day with the vets cleaner and drops, but it’s not getting better, it’s been over a month….. should I get a 2nd opinion…… the Vet said he is completely healthy and is just immuno compromised and wrote a low dose steroid and suggested it for the lifetime of the lab…… but I researched more diet changes and and trying a holistic approach with no grain, raw fruits and veggies and Merricks grain free cans, am I doing the right thing or should I just listen to the veg and keep him on steroids forever and should I pursue getting his teeth cleaned or listen to the vets observation when my gut tells me different…… My lab, has always been the picture of perfect health, lean and clean, but now all of a sudden after he got all his vaccines….. it’s like he’s super sick and we can’t get a grip on it….. he was also excessively drooling and eye gunk too….. Please help me with your honest thoughts

    • You might not be ready for a second opinion, but a reevaluation is definitely in order. Ask your current veterinarian to have another look, because only incurable ear conditions should last so long. You might also be cleaning too often, but ask your veterinarian for guidance. I usually have pet owners clean weekly, or, at the most, twice weekly during treatment. More often might wash the medicine out of the ears. However, if you have lost confidence in this doctor, it might be time to seek another doctor’s advice.

  4. Should my vet have documentation of the results of the ear cytology test they claim to have performed? I paid $50 for the test and was not given a report.

    • I am not an attorney, so I can’t speak from a legal viewpoint. Also, practices are regulated differently in each state. In our practice, we keep cytology results in the medical record. If we happened to have not issued an examination report form in a case, a copy of the medical record could still be issued to share the results with the client. Hope this helps, and thanks for reading, Dr. Randolph.

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