The effect of hormones on hip laxity

[BullyLady]

Sooo.... in an effort not to hijack....

When I heard of this phenomenon in another thread I became very interested. I don't run in dog breeding circles but I do run in dog medical circles and I hadn't ever heard of this before, so I did a little research.

Here is what PennHIP has to say about it:

Since the 1960’s it has been believed that increased estrogen levels during the female heat cycle will affect hip joint conformation by making them appear falsely lax (looser).


In 1997, researchers at the University of Pennsylvania decided to test this theory and followed 9 bitches through an entire cycle. During the study vaginal cytology, behavioral signs and physical exam findings were used to identify the different stages of the cycle. Blood samples were obtained during each estrus-phase, from which hormone concentrations were measured, specifically oestradiol-17β and progesterone. Hip x-rays were taken using the OFA view (hip-extended view) and the PennHIP radiographs during each phase of the heat cycle.


Results showed that even though the hormone levels fluctuated (as expected) the PennHIP DI (hip laxity) and the OFA-type scores did not change significantly.

In Short: The rise in hormone levels during the female heat cycle does not affect hip laxity as measured by PennHIP. However, hormones released during the birthing process (relaxin) and during lactation (prolactin) however, can increase hip laxity and hip evaluation at this time is therefore not recommended. PennHIP recommends waiting 8 weeks post lactation or 16 weeks post welping, before a PennHIP evaluation.

http://www.pennhip.org/OwnerBreederInfo ... fault.aspx

I'm not really interested in "well I heard" or "my vet once said...." but I wondered if anyone could provide references saying that estrus does affect hip laxity. I would be very interested to see it.

And Dr. Blabs, care to peruse VIN and let us know what the veterinary community at large has to say on the issue?

[Malli]

I'm interested in this...

What does this mean for male dogs...

[katiek0417]

Sooo.... in an effort not to hijack....

When I heard of this phenomenon in another thread I became very interested. I don't run in dog breeding circles but I do run in dog medical circles and I hadn't ever heard of this before, so I did a little research.

Here is what PennHIP has to say about it:

Since the 1960’s it has been believed that increased estrogen levels during the female heat cycle will affect hip joint conformation by making them appear falsely lax (looser).


In 1997, researchers at the University of Pennsylvania decided to test this theory and followed 9 bitches through an entire cycle. During the study vaginal cytology, behavioral signs and physical exam findings were used to identify the different stages of the cycle. Blood samples were obtained during each estrus-phase, from which hormone concentrations were measured, specifically oestradiol-17β and progesterone. Hip x-rays were taken using the OFA view (hip-extended view) and the PennHIP radiographs during each phase of the heat cycle.


Results showed that even though the hormone levels fluctuated (as expected) the PennHIP DI (hip laxity) and the OFA-type scores did not change significantly.

In Short: The rise in hormone levels during the female heat cycle does not affect hip laxity as measured by PennHIP. However, hormones released during the birthing process (relaxin) and during lactation (prolactin) however, can increase hip laxity and hip evaluation at this time is therefore not recommended. PennHIP recommends waiting 8 weeks post lactation or 16 weeks post welping, before a PennHIP evaluation.

http://www.pennhip.org/OwnerBreederInfo ... fault.aspx

I'm not really interested in "well I heard" or "my vet once said...." but I wondered if anyone could provide references saying that estrus does affect hip laxity. I would be very interested to see it.

And Dr. Blabs, care to peruse VIN and let us know what the veterinary community at large has to say on the issue?

I don't have a specific scientific reference, but OFA has this on their website:

Can I have my female radiographed while she is in season, pregnant, or nursing?
Some female dogs exhibit additional subluxation when radiographed during these times. The OFA recommends radiographing three to four weeks before or after the heat cycle, and three to four weeks after weaning a litter of puppies.

http://www.offa.org/faq.html#22

My guess would be that b/c OFA has been considered the "standard" for so long, that people go by what they say...not necessarily right...but likely...

[BritneyP]

I have read that info on the PennHip site and I found it very interesting. I'm definitely a firm believer in solid research and fact-based claims, so this is super interesting to me. I will probably never use OFA again, simply because of all of their other objectivity issues, etc.

[blabsforbullies]

And Dr. Blabs, care to peruse VIN and let us know what the veterinary community at large has to say on the issue?

I have to say, clinically, I have to agree with what Penn Hip stated. My boss just went through Penn Hip certification, so I can see if she has any concrete proof, as well. I will jump on VIN in the near future and see what I can dig up.

[blabsforbullies]

OK... just did a quick VIN search... here is what a board certified reproduction specialist says:

"OFA reps do not believe a bitch has ever not passed OFA who truly had normal hips, due only to relaxin (a hormone produced while females are in heat and pregnant). Relaxin probably would have a higher effect on making already loose hips, looser.

I do not hesitate to OFA the hips of a bitch at c-section time, if she has not been previously radiographed. The PennHIP studies also showed that hormonal changes in the bitch had minimal effects on hip laxiety."

And here is another post with a scientific article mentioned:


"Yippee, this has been looked at scientifically! Check out:

Hassinger KA et al. Effect of the oestrus cycle on coxofemoral joint laxity. Vet Comp Orthop Traumatology 1997: 10(2), 69-74.

This group did both OFA views and PennHIP laxity testing in nine bitches throughout various phases of their estrous cycles. What they found was that there was no significant difference (or even a trend) in hip laxity between estrus and the other phases of the cycle. The upshot is that you can take OFA radiographs at any point in the estrus cycle without affecting their validity.

OFA used to recommend not doing OFA rads during estrus, so this may be why this is such a hard behavior to extinguish."