Revisiting basic spay practices for dogs (and are pain scores too blunt a tool to measure them by?)
Among our veterinary chattering classes there's been a lot of talk lately on the subject of the lowly "spay" in dogs. When should it happen? Which way is best? And what comprises best practices for pain control purposes?
All three are great questions that I'm heartened to see my profession doggedly tackling in academic and private practice settings alike.
When? This first issue is one we've addressed here in past posts, sometimes belaboring its points ad nauseum, so that if anything's clear, it's that the jury's still out on the ideal timing for dog spays. No longer is it necessarily considered ideal — from the standpoint of the individual animal's well being, that is — to sterilize at six months of age.
Which way? This is a point we've also discussed. It has to do with whether we remove the ovaries and the uterus when we spay (as is the traditional American way), or just the ovaries (as is more typical in Europe). Ovariohysterectomy versus ovariectomy, respectively, or OVH vs. OVE.
Turns out there's a raging debate here. Proponents of the OVH claim it's a more complete procedure and it's not any more stressful for dogs than the OVE. Detractors say it's more invasive, more painful, takes longer and doesn't help prevent any more reproductive diseases than the OVE. So why go the extra mile to take the whole shebang to task?
This latter point is kind of where I stand. Though I still spay cats by taking the whole thing out, it's truly because the procedure's duration and incision length are identical for both OVH and OVE.
For dogs (especially large dogs), however, the OVE wins out. It's a smaller incision and it takes less time. Hence, there's less pain (in my experience) and, theoretically, a lowered adverse anesthetic reaction rate due to the decreased time spent under anesthesia. Moreover, there's a lower risk of bleeding and of accidentally harming the nearby urinary structures. And a smaller incision means a reduced rate of suture site complications.
For me there's an additional bonus: Since I like to offer stomach "tacks" to my large breed spay patients (to prevent the twisting of a bloated stomach), the location of the OVH incision makes it easier to reach the stomach, too.
So what's not to like?
Apparently, plenty of American veterinarians aren't warming to the idea of a change from the OVH. Some have even taken issue with the question of reduced pain, which has been touted as the OVE's primary selling point. How much less painful can it really be for an experienced surgeon? Does it make a big difference, pain-wise, that extra bit of organ that's removed? Does the smaller incision size make a big difference?
In a study published in the most recent Journal of the American Veterinary Medical Association (JAVMA, not online yet, unfortunately), researchers compared the pain scores of dogs who underwent either the OVH or OVE procedure. A statistically nil differential was the finding.
In other words, dogs experienced identical degrees of pain, given identical pain control protocols. This tells you one of four things: (1) the spay is a relatively painless procedure; (2) our pain control protocols are excellent; (3) the OVH and the OVE are identically painful procedures; or (4) the use of a pain control scoring system, as currently approached in research and clinical settings, is a very blunt tool, indeed.
As you might've gleaned from the title of this post, I'm somewhat inclined to believe that number 4 is the likeliest reflection of reality. After all, I've already copped to my anecdotal experience with reduced pain in large breed OVE cases. Which brings me to a fifth possibility: Perhaps pain is reduced only in the case of more invasive spays (i.e., large breed dogs and/or older dogs) where the issue of analgesia is a more pressing concern.
So, too, did this pain-slash-spay finding grate on me: A statistically minimal difference in pain between spayed dogs who received nerve blocks at their incision sites (so called, "linea blocks") was reported in yet another JAVMA paper — at which point I wasn't the only one to cry "foul." A follow-up letter to the editor disputed the paper's findings on the basis of, among other possibilities, insufficient sensitivity in the pain scoring process.
Could it be that how we identify pain in animals is too insensitive a tool by which to gauge the pain differential between two similar veterinary procedures? Could it be that with our modern pain control methods it becomes even more so?
The questions raised by the evaluation of these procedures ultimately indicates more than just how we treat our spay cases. Indeed, I believe they speak in eloquent tones as to how it is that we identify pain in all animals, not just dogs.
Dr. Patty Khuly