Split heat versus hypoluteoidism
For Veterinary doctors
It is good to have a chat with Veterinary doctors around the world on the issue of split heat and hypoluteoidism. This is because the writer recalled a question which was asked in a gynecology examination. The question is on introduction to Veterinary gynecology.
Question: A bitch was presented to you by a client who reports having observed the bitch on ‘heat’ but it was not bred and one month after the bitch was noticed to return to heat again.
i) Attempt a diagnosis? (1 mark)
ii) Explain the phenomenon with possible causes/reasons ?(4marks)
iii) What is the best treatment approach? (2 marks)
The writer has a problem with this question because even though it was mentioned that the bitch was seen on ‘heat’ no reason was given as to why the bitch was not bred. That is did the bitch fail to stand to be mounted (absence of standing heat) or the owner did not want to bred it for any reason which can be personal/no available stud with desired traits among others. This part of the question would have been gotten via doctor and client interaction.
It is known that most dog breeders use ‘heat’ to mean both proestrus and estrus phases of the sexual cycle in bitches unlike most other species. That is in the bitch, proestrus marks the beginning of the estrous cycle while the actually standing heat is seen on the estrus phase of the cycle. Split heat is said to occur when a bitch is seen on proestrus but fails to enter the estrus phase of the cycle. That is a situation in which a bitch moves from proestrus to diestrus without entering the estrus phase.
It is said that progesterone secretion (increase) and estrogen decrease starts 1-2 days before estrus. That is progesterone is important for estrus/standing heat in the bitch which is not same in most other species. Some people claim that split is associated to a situation in which ovulation does not occur. The writer thinks that since ovulation occurs about 4-7 days of estrus depending on breed. That is ovulation does not occur at the beginning of estrus so at least if anovulation is the only/main reason of split heat, then the bitch should be able to show/enter estrus even though ovulation fails to occur some days later in the estrus phase.
Split heat is said to be commonly observed in young bitches that are on heat for the first time and it is believed that it will, usually, correct on its own without any serious medical intervention. However, the writer read an article in which a lady claimed that her bitch showed signs of split heat and she sort for veterinary advise. After much interaction with different veterinary doctors, most of the doctors said it was a case of split heat but the case continued. The end of the story was that one of the Veterinary doctors later told her to check the bitch for infection. Then it was discovered that her bitch had infection which was responsible for the observed split heat. The infection was treated then the bitch went through its normal cycle without further complications. Her case seems to suggest that infections can also be responsible for split heat.
Progesterone is known to be important in the estrus phase so it can be said that an abnormal low levels of progesterone can prevent the estrus phase of the cycle. This is the situation in hypoluteoidism even though the term may suggest that ovulation had occurred and corpus luteum formed but of an abnormal size or secretes low progesterone. The main fact here is that there is low level of progesterone and it can cause reproductive abnormalities. Therefore, if the developing follicles fail to secrete sufficient amount of progesterone which is necessary for estrus/standing heat in the bitch then the bitch will not, under normal scientific theory, show estrus. This is because of hormonal interplay which can cause split heat and various factors can cause low levels of progesterone to be in circulation. Progesterone is also a hormone of pregnancy in that it is important to maintain pregnancy and in its absence or low levels pregnancy will not be maintained even if fertilization took place.
Therefore, in the case presented above (question) even if we assume that the bitch went through its normal cycle and ovulated. Is it not possible for the bitch to return to heat faster than expected if, for any reason, little or no progesterone was in the circulation as a result of hypoluteoidism?
Therefore, the writer would like to hear from veterinary doctors on what they think is the best diagnosis of the question above.