Vaginal Cytology in Dogs: Timing the Heat and Breeding

Vaginal cytology in dogs is a simple lab test in which cells from the vaginal wall are spread on a glass slide, stained and studied under a microscope. The cells change shape as the heat cycle moves forward, so the test helps a vet judge the stage a female dog has reached. It is usually read together with a progesterone blood test.

How is the sample taken?

Cytology means looking at cells. For this test, the vet or a trained technician passes a soft, moistened swab a short way into the vagina and rolls it gently across a glass slide. Most dogs accept it calmly, and it takes only a moment. The slide is dried and stained before it is read under the microscope.

Tell your vet when you first noticed swelling or bleeding, and mention if she has had litters before. Those notes help the vet decide how often to repeat the smear.

What do the cells show through the heat cycle?

A heat cycle has four stages, and the smear looks different in each one.

• Pro-oestrus, the lead-up. Males are interested, but she does not yet accept them. The smear usually shows small round cells, red blood cells and white blood cells.
• Oestrus, when she accepts the male. The cells become large, flat and angular. Vets call them cornified cells. The white cells usually fade from the background.
• Dioestrus, the stage that follows. Small round cells return together with white cells, and the change can look sudden.
• Anoestrus, the long rest between cycles. The smear usually has few cells.

The shape of the cells follows the effect of the hormone oestrogen on the vaginal lining. That is why a smear gives a picture of how far the heat has moved, even though the dog cannot tell you.

Why do vets pair it with progesterone?

The smear shows the oestrogen effect, but it cannot name the moment of ovulation, when eggs leave the ovary. Progesterone is a hormone that begins to rise around that time. A Canine Progesterone (cProgesterone) measures it in a blood sample, and vets often repeat it through the heat while they follow the smear. The lab also lists a general Progesterone, Serum test, and your vet will say which one fits your dog.

Discharge and behaviour vary from one dog to another, so they are only rough guides to the right time for mating. Please do not compare the numbers on your report with charts you find online. A registered veterinarian reads the hormone value, the smear and the dog's behaviour together.

What can a vaginal smear not tell you?

A smear is a snapshot of one moment, so it has clear limits. On its own it cannot show:

• whether the dog is pregnant
• the exact day of ovulation
• whether the womb is healthy or infected
• whether the mating will succeed

If a female dog becomes dull, drinks more than usual or has pus-like discharge after a heat, see a registered veterinarian promptly. A vaginal smear is not the test for that problem, and waiting can be risky.

Which other checks go with a breeding plan?

A Complete Blood Count (CBC) gives a general picture of her health before a pregnancy, including whether she is anaemic or fighting an infection. Many owners also want her screened for brucellosis, an infection that can cause lost litters and poor fertility in dogs.

The Dog Breeding Check Pack typically groups a canine brucellosis rapid test, RT-PCR for Brucella canis, canine progesterone, vaginal cytology and a blood count. The exact list is confirmed when you book. Brucellosis can pass to people, so wash your hands after touching a dog's discharge or birth material, wear gloves, and speak to a doctor if you feel unwell.

Read next

Before you plan a litter, Canine Brucellosis Rapid Test: Screening Dogs Before Breeding explains how the rapid screening test is used and what a positive result means for the vet. If a dog ever needs blood from a donor, Blood Typing and Cross-Matching Before a Transfusion shows how the match is checked.

Testing in Bhopal

Your vet will usually do the swabbing for a vaginal smear. For blood tests such as progesterone, the lab at C-200, C Sector, Shahpura collects samples free anywhere in Bhopal, and other districts can send blood by courier, bus parcel or through their vet. Call or WhatsApp +91 88175 01118 to plan the visit, and the lab confirms the method, sample needs and reporting time when you book.