Ovarian Remnant Syndrome Dog Pet
Ovarian Remnant Syndrome Female Pet Becoming into Heat
Whether the patient is a dog or a cat, ovarian remnant syndrome is suspected when a spayed female pet appears to be coming into heat, something that should be impossible after spaying. A spayed female has had both her ovaries removed, and she should not cycle and should not display behaviors typical of heat.
If she is, it’s necessary to search for an estrogen source. Often this means a piece of ovarian tissue is left inside. If so, the only treatment is surgical removal of the extra offending tissue, so we want to be sure there is no other explanation before committing to this relatively invasive solution.
The Girl Dog in Heat
The female dog comes into heat every 6-8 months on the average. During this time, the most prominent feature is the vaginal discharge, which begins bloody and switches to a more golden straw color. The girl dog in heat will attract males and will most likely flirt playfully with them. This period of hormonal activity lasts about 3 weeks and culminates in a false pregnancy (or potentially a real one if she has been bred) that lasts roughly a couple of months after.
The Girl Cat in Heat
The female cat in heat does not have an apparent vaginal discharge. For her, the signs of heat are more behavioral. She becomes restless and is loudly vocal. She may urinate in the house in an attempt to notify local tomcats of her state. She is often unusually affectionate and has a tendency to stick her rear in the air and even tread her feet when she is petted over her back.
The female cat cycles seasonally when the days are longer, and tends to stop cycling when the days begin to get shorter. She is in heat for 5 days or so and then out of heat for a couple of weeks, then back in, then back out over and over until she is either bred or the seasons change. If she is bred, she will ovulate and go into a false pregnancy (or a real one if the breeding was successful). In any case, it is her behavior that is the clue that her hormones are active.
Signs of heat (also referred to as estrus) imply estrogen in the pet’s system. The first step is to confirm that there genuinely are estrogens in her system.
Testing for Hormones
You might expect a blood test to be necessary to look for estrogen or progesterone, but in fact, the best test is a vaginal smear test. Using a cotton swab, the veterinarian harvests some cells from the vaginal wall and looks at them under the microscope. If the female is in heat at the time of the test, the cells will have a characteristic appearance called cornification. This means there are estrogens in her body.
Testing for estradiol, one of the estrogen hormones, can be done but it is not as accurate as the vaginal smear test. If the spayed female has high estrogen levels during the time she appears to be in heat, this would be considered a positive test. The problem is that low levels can still be in the bloodstream even if there is an ovarian remnant, so low levels are hard to interpret.
Another approach is to give her a shot of GnRH (gonadotropin releasing hormone) while she appears NOT to be in heat. If she responds to the injection by producing progesterone two weeks later - detectable with a blood test - this would be consistent with an ovarian remnant.
The vaginal smear costs a fraction of the amount of blood testing and can generally be done in a matter of minutes in the doctor’s office so these types of blood tests are rarely performed.
Status LH and Spay Check Testing
There is an in-house test kit for luteinizing hormone (LH) that can determine if a female cat or dog has been spayed or not, provided she is not experiencing a heat at the time of the test. This test could be performed to assist in diagnosis but would have to be done during a time without symptoms of heat. A low LH level is compatible with the presence of estrogen and presumably ovarian tissue.
The newer spay check test for anti-mullerian hormone is reportedly more reliable but requires that at least 2-3 months have passed since the original spay surgery for accuracy.
Your veterinarian may suggest more than one type of test to be sure there is little room for ambiguity. After it is clear that estrogens are definitely present, the next question to address is: where did they come from?
Estrogen Crèmes for Human Use
Topical estrogen-containing crèmes have numerous human uses. These crèmes invariably end up on the user’s hands or arms where a loving pet can lick them. A female pet exposed to a hormone crème in this way can easily manifest signs of heat but will not show a hormone cycle in any predictable way. Generally, people are aware that hormone crèmes are in use at home and can be more careful about avoiding exposure to pets. Crèmes may be applied using gloves, which can be discarded away from the pet; hands can be washed carefully, etc.
Did Something go Wrong with the Original Surgery?
You would think that if there is a remnant of ovarian tissue in the spayed pet’s abdomen, the surgeon must have left it behind. This is not necessarily so. It appears that some females possess accessory ovarian tissue separate from the main ovary and this tissue becomes active only after the main ovaries are removed. Further, if an ovary contacts the abdominal wall, cells appear able to adhere and get blood vessels, effectively creating a new, albeit small, ovary. In many cases the original spay surgery was performed months or even years before. These secondary bits of ovary are growing during this time and do not show themselves until they have achieved sufficient hormone producing power. Once it has been determined that there is an ovarian remnant, it can be removed surgically.
It is worth mentioning that adrenal tumors can produce hormones. These can be difficult if not impossible to remove but exploratory surgery should at least identify them over an ovarian remnant. In the situation of this type of tumor, signs of heat are constant; they do not cycle as with ovarian tissue.
The ovarian tissue will be most prominent or visible just following the active heat period. This is the time after ovulation when the ovary is normally ripe with large progesterone-secreting structures called corpora lutea, and this is the best time for surgical exploration. If errant ovarian tissue is found, it can be removed generally without difficulty. It is not unheard of, however, for the ovarian remnant or remnants to be impossible to find. If that is the case with your pet, Discuss with your veterinarian whether referral to a surgical specialist would be best for you and your pet.
What if it isn’t Heat?
Female dogs can have a bloody vaginal discharge for reasons other than heat. It is possible the owner is seeing bloody urine, for example, and the medical work up will need to shift to address the different causes of this problem. Alternatively, a transmissible venereal tumor or vaginal injury might lead to bleeding.
As for a female cat, she may simply have behavioral issues to address.
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