Cytology in Dogs
Cytology is the examination and study of blood or tissue cells under a microscope. Cytology can be used to detect inflammation, infection, bacteria, fungi, parasites and cancer.
Cytology involves examination of a tissue or fluid sample. Often cytology is used to identify a lump or mass noted on physical examination. Certain skin diseases or hair loss situations – such as mange mite infection – can be diagnosed using cytology. Cytology is usually done when abnormal fluid is detected in a body cavity. Cytology may follow an abdominal ultrasound examination or surgical procedure that reveals abnormal organ tissue. Cytology of vaginal fluid can be used to guide breeding in females.
There is no real contraindication to performing this test. Negative results can exclude the presence of certain diseases. For example, a skin tumor might be malignant or benign. If the cytology shows the mass to be a simple fatty tumor, it may be left alone and followed. In contrast, identification of a dangerous skin cancer, such as a mast cell tumor, would indicate the need for surgical removal of the mass. As with all tests, a cytologic examination is neither 100 percent sensitive nor specific. Should a cytology exam be negative or inconclusive, your veterinarian may recommend a full tissue biopsy sample be obtained and submitted for analysis.
What Does Cytology Reveal?
Cytology can identify the presence of inflammation, infection, cancer, parasites, bacteria and fungi (molds and yeast). Following cytology, additional diagnostic tests, procedures, or medications may be recommended.
How Is Cytology Done?
Cytology testing involves obtaining a sample of suspicious material. The material can be obtained by pressing a microscope slide against the tissue, by gently scraping the area with a scalpel blade, or by inserting a needle or sterile Q-tip into the tissue to obtain fluid or tissue.
Once obtained, the material is spread thinly over a microscope slide and allowed to dry. Fluid samples may be placed in a centrifuge first to concentrate the cells before they are transferred to the slide. The sample is then dyed with special biological stains to ease identification of the cells. The sample is once again allowed to dry. Once the dye has dried, the slide is ready for microscopic evaluation.
Some veterinarians are sufficiently experienced to evaluate cytology specimens. Most veterinarians submit the cytology specimen to a diagnostic laboratory for evaluation by a veterinary pathologist. Even if your veterinarian provides you a presumptive diagnosis based on his/her evaluation of the slide, the final diagnosis is typically made after the pathologist reviews the sample.
The cytology test generally takes 20 to 30 minutes to perform if done in the veterinarian's office. If the sample is submitted to a laboratory, results may not be available for 2 to 3 days.
Is Cytology Painful?
In obtaining a sample with a needle, some pain may be involved, but very small needles typically are used. As with humans, the pain perceived from a needle stick varies among individual pets, but it should not be any more painful than an injection or a blood sample.
Is Sedation or Anesthesia Needed for Cytology?
Sedation or anesthesia is not typically needed, but might be necessary depending on how the cytology sample is collected. Those samples obtained from skin scrapings or aspirations typically do not require sedation. Obviously, a sample obtained during a surgical procedure will require anesthesia for the surgery.