A combination of history, examination findings, and diagnostic tests are used to diagnose the presence of ovarian tissue. The same strategy can be used to determine if a bitch is intact, spayed, or has an ovarian remnant (OR).
Luteinizing hormone (LH) is negative (<1 ng/mL) in intact bitches or those with ovarian remnant syndrome (ORS). In addition, LH is negative in bitches exposed to endogenous or exogenous estrogen.2 LH tests are not performed if the patient is currently showing signs of estrogen stimulation. A negative result in a nonestrogenized bitch is consistent with the presence of ovarian tissue.
Serum LH is positive (>1 ng/mL) in bitches without ovarian tissue unless the test has detected the LH surge for that cycle. The LH test can be used to screen for ovarian tissue if the bitch does not show evidence of estrogen stimulation at the time of evaluation. Two positive tests performed several days apart (to ensure the sample was not taken during the LH surge) provide conclusive evidence that ovarian tissue is not present. Major veterinary laboratories perform LH tests, and an LH test kit is also available (Witness LH, zoetis.com) for in-house use.
Progesterone concentrations are consistently <0.2 ng/mL in bitches without ovarian tissue and rise following ovulation in intact bitches or those with ORS. Documenting serum progesterone >5 ng/mL in a bitch with evidence of estrogen stimulation 3–4 weeks prior confirms the presence of ovarian tissue. In addition, progesterone concentrations <1 ng/mL alone do not rule out ORS, as the dog may be in between heat cycles (anestrus). Quantitative progesterone measurements are performed at major veterinary laboratories.