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The 6-year-old Golden Retriever, Daisy, lay quietly on the table, her trusting eyes meeting ours as our gaze remained fixed on the ultrasound screen. We hoped to see embryos appearing, but to our great despair, there was… nothing. Daisy had been inseminated three weeks prior with frozen semen from the 80s. In the dog breeding world, and especially for her breed, this semen was a genetic treasure. We had meticulously followed every step, using ultrasounds to ensure her uterus was in perfect condition before breeding, while monitoring her ovaries and progesterone levels to pinpoint the precise moment of ovulation. Daisy’s journey became our own, but we were now facing harsh reality. Daisy didn’t conceive; the dream had faded. The weight of our shared hope settled into a heavy silence, filled with unspoken questions about what we could have done differently.
I often think about this story, as well as the many similar stories I’ve experienced at the veterinary clinic.
Despite our almost standardized approach to optimizing fertility in these complex cases (such as frozen semen insemination or cases with a history of infertility), we sometimes face failure. We stare at the ultrasound screen, searching for a hidden embryo that should be there, somewhere… but there’s nothing to be seen.
This is incredibly frustrating for both the clients and the veterinarian – believe me.
So, I always consider how we could do things differently and improve our approaches. And this week, I stumbled upon this:
“Determination of the Normal Reference Interval for Anti-Müllerian Hormone (AMH) in Bitches and Use of AMH as a Potential Predictor of Litter Size.”
You can check the full article here.
As I read through it, I couldn’t help but think… perhaps this is something we could add to our current approach for a better prognosis?
Want to find out how? Well, friends, keep reading!
AMH: Fertility Hormone Explained
AMH stands for Anti-Müllerian Hormone.
It is secreted by the testes and ovaries in mammals. We use it in canine reproduction, typically when we want to confirm if a male or female dog has indeed been spayed or neutered if there is any doubt remaining.
It can confirm the presence of an ovarian remnant or an intra-abdominal testis in cryptorchid dogs.
However, this is not why this test is interesting in a fertility case like this.
In humans, the production of AMH is reflective of the ovarian reserve, meaning the number of eggs that are technically available in the ovaries.
The canine world was long left wondering whether this hormone held the same significance in bitches.
This is what they actually explore in the paper I mentioned earlier.
The study’s aims were to establish a normal reference interval for AMH in breeding bitches using a canine-specific assay and to investigate possible correlations between AMH concentrations and reproductive performance.
The researchers observed that age had a significant effect on AMH concentrations. For each additional year, AMH concentrations fell by 0.5 ng/ml.
The study also found a positive correlation between litter size and AMH concentration, suggesting that AMH could indeed be used as a tool to predict litter size in bitches or at least give an idea of the breeding potential for a given bitch.
This opens the door to a new era of canine breeding, adding a new tool for selecting breeding females.
The AMH level of the bitch could be seen as a reliable marker at the beginning of a breeding cycle.
Perhaps most poignantly, the study highlighted the importance of breeding bitches when they are young, under 4 years of age, to maximize reproductive performance.
AMH Testing: Optimizing Canine Fertility
With the newfound knowledge of AMH’s role in canine reproduction, I couldn’t help but feel excited about the possibilities that lay ahead.
AMH testing in dogs involves measuring hormone levels in a blood sample, which is then analyzed using a canine-specific ELISA assay. This is not an in-house veterinary test, but today, most veterinary laboratories offer canine AMH testing.
We talk about the impact of age on AMH levels, but what is also interesting is that one variation factor is actually the size of the bitch. It is the opposite of what one might think! Indeed, the smaller the bitch, the higher the AMH levels typically.
The study came up with reference values based on this finding, which I think is great.
Because a test is only as good as its interpretation, this study gives us some insights on how to properly interpret those results.
On top of that, the stage of the cycle of the bitch will also influence AMH levels. In this study, they measured it during estrus.
Therefore, to accurately compare a result to the reference ranges they defined, the sample should always be drawn during estrus.
AMH testing provides a more comprehensive understanding of a bitch’s overall ovarian reserve and potential fecundity. It can allow us to optimize breeding potential by identifying bitches with higher AMH levels, which should translate to larger litter sizes.
Additionally, AMH testing can help us minimize breeding-related risks by guiding the selection of younger bitches with more favorable reproductive prospects.
You can see why I find this quite amazing! I am sure researchers will continue to explore the applications of AMH testing in canine breeding programs.
However, I think it already offers us some very interesting insights for those complex cases we talked about earlier. I cannot help but feel a renewed sense of optimism for the future.
AMH Testing: Benefits & Limitations in Dog Breeding
The discovery of AMH and its role in predicting litter sizes and fecundity could be a game-changer, but as usual, there is still much to learn.
It is not a panacea; it is an additional tool we can leverage in our veterinary clinics to optimize fertility results.
By itself, it cannot do much, but combined with progesterone tests and genital ultrasounds, I can clearly see the benefits. We could use it as an additional marker right from the get-go to immediately give a better fertility prognosis.
By identifying older bitches with declining AMH levels, we could focus our efforts on younger bitches with more favorable prospects, maximizing reproductive successes.
Of course, there are still some limitations. AMH levels vary depending on many factors, and we still need to better understand how to integrate those into our clinical settings.
On top of that, the ovarian reserve is just one aspect of fertility. Ovarian and uterine disorders, which are far from uncommon in canines, should also always be investigated in those complex fertility cases. And timing of ovulation using progesterone assays remains crucial obviously (after all, 50-80% of infertility cases in canines are linked to mistimed breeding).
AMH testing is not without its limitations, and we need to be cautious about relying solely on this marker. But the good news is that research is advancing.
I had a look at another paper fresh off the press:
“Monitoring of canine pregnancy by considering Anti-Mullerian hormone, C-reactive protein, progesterone and complete blood count in pregnant and non-pregnant dog”Monitoring of canine pregnancy by considering Anti-Mullerian hormone, C-reactive protein, progesterone and complete blood count in pregnant and non-pregnant dog.”
(Actually, this is the first one I was reading that directed me to the AMH one I mentioned).
And you can see that there are other markers they were investigating.
It feels to me like in the future, we will see the development of more accurate and precise testing methods, or the discovery of additional hormonal markers that could further enhance our breeding management practices.
AMH testing is a start, but there is more to come. I am sure of it!
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