Reproductive Function Tests
Ovulation detection for timing of mating in female dogs
Since ovulation may occur at varying times after the onset of vulval bleeding, progesterone measurement can be used to determine the optimum time for mating. For most bitches, blood sampling for progesterone measurement should begin around 7 days after the onset of vulval swelling and bleeding. Bitches are then re-tested every 2–3 days until ovulation occurs.
Samples should be collected in a plain serum tube. Gel tubes should be avoided where possible or if used, the serum should be separated and removed from the gel tube as soon as possible.
Tests for detection of ovarian remnant in the bitch
A. When the bitch is showing signs of oestrus there are several tests which can detect ovarian tissue:
- Vaginal smear – cytological changes in vaginal epithelium can be used to identify ovarian activity
- Measurement of oestrogen – increases in late anoestrus, pro-oestrus and early oestrus but then declines
- Measurement of progesterone – increases in late oestrus and remains high in dioestrus (i.e., for 60 days post ovulation).
B. When there are no signs of oestrus:
Anti-Mullerian Hormone (AMH) is useful for detection of ovarian remnant in bitches > 6 months of age, after they have reached sexual maturity. AMH levels remain constant throughout the cycle although they may fall transiently around ovulation. Animals that have been neutered will have undetectable levels of AMH. A positive AMH test indicates the presence of ovarian tissue, but a negative result does not fully exclude the presence of ovarian remnant, especially if the sample is taken around the time of ovulation. If a low result is found when there are signs of oestrus, measurement of progesterone is recommended.
Please note this test is not sensitive for detecting ovarian remnant in bitches < 6 months old.
Detection of ovarian tissue in female cats
AMH combined with progesterone is recommended to identify ovarian remnant and distinguish between spayed and ovarian intact queens after they have reached the age of sexual maturity. Cats are generally considered to be induced ovulators but some queens can ovulate spontaneously, and this can result in falsely negative AMH results. Around ovulation the AMH falls and progesterone increases. Because it can be difficult to know at the time of sample collection if an ovarian remnant’s primary secretory product is AMH or progesterone, it is prudent to evaluate both hormones at the same time.
Tests for detection of testicular tissue in cats and dogs
Anti-Mullerian Hormone is a reliable test for detecting the presence of testicular tissue in both cats and dogs, including cryptorchid males, and young males prior to puberty. AMH levels should be very low (undetectable) in correctly castrated animals.