Introduction
Cytologic evaluation of the female and male reproductive systems is more commonly performed in dogs than cats. Typically, vaginal cytology and semen samples are analyzed in healthy animals for breeding purposes.
Cytology of other reproductive organs is more likely to occur if disease is suspected. With the exception of the prostate and penis, surgical removal of the diseased reproductive organ is almost always the treatment of choice. In these cases, analysis of impression smears from the surgically excised tissue can be very beneficial in reaching a quick, definitive diagnosis.Female reproductive system
Cytology of the vulva and vagina
Introduction
In the dog, vaginal cytology is frequently used to optimize timing for breeding and improve pregnancy rates (England, 1992). Collection of vaginal cytology can be performed daily beginning 3–5 days after a bloody vaginal discharge is detected. When vaginal cytology is indicative of estrus, dogs are encouraged to mate within 48 hours. A recent study of the reliability of vaginal cytology results indicated some inaccuracy, even when an experienced person evaluated the samples. In this study, 4 people reviewed 32 vaginal cytology samples; their cytologic interpretations correlated with histologic changes in the uterus in 20–40% of proestrus, 25–50% of estrus, 60–100% of early diestrus, 33–67% of late diestrus, and 0–100% of anestrus samples (Moxon et al., 2010). For this reason, it is common to correlate vaginal cytology results with plasma progesterone concentration (expected to be 5 ng/ml at ovulation). Collection of vaginal cytology is not critical when breeding cats because ovulation is often induced by mating in this species. However, vaginal cytology may be important to perform in previously spayed dogs and cats with suspected ovarian remnants. The method of collection and cytologic appearance of vaginal samples are similar at each stage of the estrous cycle in dogs and cats.