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Coccygeal Block

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Christy Michael, BVMS, demonstrates how to perform a coccygeal block on a cat, ideal pain management for cats suffering from a urethral obstruction.

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Christy Michael's picture
Christy Michael

BVMS

Enrolled: 08/2011

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Morgan VanFleet's picture

Absolutely love the local anesthesia videos. Fantastic explanation by Dr. Michael! Thank you!

Karen Harris's picture

Could you use a hanging drop technique here? What size and length of needle is preferred?

Christy Michael's picture

Karen, we keep it simple for these and just use a 25g 5/8" or 3/4" hypodermic needle for this procedure, whichever you stock. This procedure does not require a spinal needle and even the most rotund of felines has a little divot in the region of this injection that makes the small needle effective.

I will admit that I don't actively use the hanging drop technique but if you are accustomed to using it then you may find it useful. As with any block of this type you do want to have fluid in your needle to prevent any introduction of air. For me it is very easy to feel the needle passing through the ligament and when you let go of the needle you will see a huge difference between a needle seated subcutaneously versus one that has passed through the interarcuate ligament. My only concern with depending solely on the hanging drop technique is that I'm not certain how much the column will shift because I simply have not paid that much attention in the past!

Sheri Harmon's picture

How long does the anesthetic last? Could you use Bupivicaine?

Sheri Harmon's picture

One other question: could this be done in dogs? We do a lot of tail amputations at my shelter. I would guess a larger needle would be needed.

Christy Michael's picture

Sheri, lidocaine anesthetic will take effect within ~5 minutes and can be expected to last around an hour. I think that in theory you could use bupivicaine but given that it takes longer to take effect it could lead to significant delays in your procedure if you were to need to take a second "stab" at it! With bupivicaine's expected onset of anesthesia somewhere ~20-30 minutes, two tries would take an hour or more when your patient could really use some relief. Having said that, bupivicaine lasts a lot longer so if you were just using this to provide additional analgesia for a cat post urethral deobstruction, your patient could get up to 4-6 hours worth of anesthesia.

Christy Michael's picture

Sheri, I do not see any reason why this procedure could not be done in dogs. It's a quick & safe option for cats because their spinal cord usually ends ~S1 but since dogs usually end ~L6 there should not be any problems with using a similar procedure. I haven't done this myself so I can't vouch for how easy or hard it might be to find your landmarks or what length of needle might be needed and very likely this will vary from one patient to the next. I would be willing to give it a try since this form of anesthesia is so inexpensive!

Veronica Bingamon's picture

I just used the coccygeal block for a tail amputation! We were able to run the pt at 0.75 of Sevo!! I printed out the pdf after watching the video and it was a very utilitarian procedure to follow and perform. Thank you @Dove:)

Megan Brashear's picture

That's awesome Veronica! Thanks for sharing, we LOVE to hear how it goes when people try new techniques!

Lauren Brief's picture

Hi there, what dose of Lidocaine and Bupivicaine would you use for this block in cats? Also would you combine either of those drugs with morphine, as if it were an epidural?

Christy Michael's picture

Hi Lauren,

The coccygeal epidural published dose is 0.1-0.2 ml/kg of lidocaine. For most cats the dose ends up being around 0.5ml of 2% lidocaine which is a great volume to achieve your desired results without concern that the lidocaine administered will pass cranially too far and compromise pelvic limb function.

For bupivacaine the published epidural dose is 0.1 mg/kg but it is available in 0.25%, 0.5%, and 0.75% concentrations so the volume will vary depending on the concentration you stock from 0.7-2ml of bupivacaine for the average sized cat (5kg - often a very small blocked cat!). Ultimately those volumes could become too great causing side effects higher than intended. If you are faced with some of the larger blocked cats sheer volume could become a barrier to administration of bupivacaine in addition to the concerns I listed above for blocked cats.

I don't think that it is wrong to add morphine as long as you are both unblocking and placing an indwelling urinary catheter. I say this for a couple of reasons - one is that it can contribute to urinary retention so in the absence of an indwelling urinary catheter you could exacerbate the patient's problem. The second is that I would be worried that increasing the volume could cause your block to ascend further than intended and may subsequently affect pelvic limb function. Patients that are hospitalized with an indwelling urinary catheter can be more closely monitored if this does occur!

Thank you for the excellent questions :)
Christy