Have you ever heard of « silent heats » in the bitch ? Or « false heats » ? Or « ghost heats » ? All these terms are synonyms. They describe a condition that, despite far from being uncommon in breeding bitches, still raises lots of questions in the dog breeder community. As you probably notice if you follow my blog, I always go by the say « An ounce of prevention is worth a pound of cure. » In this case, I believe the more you know about the disorder, the better then, since I often see questions about it on breeders’ forums. So here are 20 facts I think dog breeders need to know about « silent heats » in bitches.
#1 Let’s start with a definition : silent heats = heats that go totally unnoticed by the owner of the bitch. Which simply means there are no visible clinical signs that the bitch is actually in season. No blood loss, no vulvar swelling, no behavioural modification… Nothing.
#2 Ok, there are no external signs, but obviously, something is happening – why would we call them silent heats then ? There is indeed an ovarian activity. Follicles grow on the surface of the ovaries, ovulation occur… It’s like a normal cycle except that there is no external sign telling you about it.
#3 Sometimes I am told that this is a concern for breeders with only females. Because if you also have males around, « they will tell you something is happening ». Right ? Unfortunately, not so much… When dealing with silent heats, it is not uncommon that males that are around won’t notice a thing… My two cents here: do not rely too much on them then, you might sometimes be disappointed !
#4 So when to suspect silent heats then ? In canine reproduction this is something we will ALWAYS consider when the bitch is 2 months + due for her season.
#5 That is something we veterinarians refer to as « prolonged anoestrus » (=prolonged absence of visible heats).
#6 Don’t get me wrong however : prolonged anoestrus does not always mean silent heats. There are other potential causes to consider in the differential diagnosis. Especially, ovarian cyst(s).
#7 Something important to remember here : ovarian cysts do not always mean shortened period between heats. They have to be considered each time variations of the interestrus interval is observed.
#8 Rule of thumb : always record the dates your breeding bitch was in heats and always calculate the interval in-between. It should show a regular pattern.
#9 Regular does not mean they should cycle like a clock. Many factors influence onset of the season of the bitch, some of them on which we certainly have little knowledge and no control. A more or less 2 month period variation is usually tolerated when focusing on the interestrus interval.
DR. EMMANUEL FONTAINE 
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