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TDK conference 2021

Examining the presence of Demodex mites in healthy dogs and fetuses
Balogh Sára - year 5
University of Veterinary Medicine Budapest, Department of Pathology
Supervisors: Dr. Míra Mándoki, Dr. Alexandra Juhász


The Demodex mite is a commensalistic microorganism that is found on healthy dogs. The disease called demodicosis is caused by the overgrowth of this mite, which is triggered by an immunosuppressive effect on the host’s body. Demodicosis is a well studied disease, but our knowledge about the Demodex mite is incomplete. The goal of our study was to fill some of these gaps and answer some questions like how the Demodex mite spreads from the dam to the puppies, its detection and whether the mite is normally present on the skin.

We examined fetuses, newborns and adult dogs in our research. In the case of fetuses and newborns we studied the internal organs and the outer ear canal to prove the possibility of transplacental infection with the Demodex mite. We carried out the examination by dissolving the organs and the outer ear in a 10% NaOH solution, then we used a light microscope for detection. In the case of adult dogs, we used different sampling methods in different regions of the body. After sampling we examined the trichograms in their native forms and we dyed the smears with a mixture of Oil Red O and Sudan Red III oil-based dyes. For detection we used a light microscope.

With the aforementioned methods we could not detect Demodex mites or their eggs in the fetuses and in the newborns. The trichogram taken with cold wax and the sample taken with the superglue method were both negative for Demodex mites in adult dogs. From the scrapings taken from the adult dogs’ outer ear canal we could detect adult Demodex mites on multiple occasions.

Our results highlight the difficulty of detecting the Demodex mite which resides in low numbers in the healthy dog. Because the fetuses used in our study were deep-frozen prior to the experiments the negative results should be treated with reservations, thus we recommend repeating the experiment using fresh samples to ensure the authenticity of the results. According to the results of the adult dog examinations it seems that the area of predilection for the occurrence of the Demodex mite is the outer ear canal. These examinations also show that the trichogram and the superglue method have a low sensitivity for the Demodex mite, because using these methods mites could not be detected in dogs that were found to be infected.

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