Anaesthetic didn't work-so worried :(

[EvenBetter]

My 12 month old Sheltie Springer cross girl was left in today to get spayed (attempt number two-last time she was having a phantom pregnancy so couldn't be done)

The vet phoned to say she couldn't spay her today because the anaesthetic didn't work on her. Technically she was unconscious, but her heart was racing and her breathing was fast and shallow, so she didn't want to perform the surgery with her like that. Apparantly it's the most commonly used type of anaesthetic but occasionally it doesn't work-usually on collies. So we have to take her back next week to try again with the other type of anaesthetic.

Now I'm freaking out, waiting to collect her, worried sick that there's something wrong with her heart or something, and of course panicking big time about next week.

Has this happened to anyone else? Any vets here?!

I would suggest finding exactly what combination of pre-meds and anaesthetics were used.
There so anaesthetics I have not used, but I have never encountered this so it maybe one of the ones I have not used.

It was Acepromazine, doctor google tells me that some collie/herding breeds and their mixes can have a genetic mutation that causes this drug to not work on them. But will the other anasthetic work?! Will she die if they try?!

I presume your vet is talking about the mutated MDR1 gene which can be present in various pastoral breeds and their crosses.

If she does have the mutated version of the gene (you can have her DNA tested to find out if she's affected, a carrier or clear) then theres a list of medications that shouldn't be used at all and others that should only be used under very close veterinary supervision.

There's some information about the MDR1 mutation and which drugs to avoid/be careful with here and here.

I would get her checked over with pre anaesthetic bloods etc. Your vet sounds trustworthy so go with what they say. Never had this when i was a vet nurse but this may be new anaesthetic. Collies do react badly to ivomectin (usually used for flea and mange treatment) and related drugs.

If it is a specific drug reaction then other anaesthesia prob be fine. If you are at all worried ask vet to explain details and if in doubt second opinion.

Acepromazine is a premed so if this is all she had then she ain't had anaesthetic. Normally it is combined with another drug like methadone, buprenorphine or some others.
I always use it a very low doses in combination with other drugs and all the evidence that is more effective with reduced side effect.
There are several different combinations that don't use acepromazine that are totally different drug classes tat should give viable options.

Castilian that is really interesting and I think you may have just explained some of my collies weirdness!

The vet just said she'd seen collies not go under with it when she asked us what breed mixture the puppy is, then I googled (I know, do not google anything health related!!) drug name+herding dog and got more scared.

The vet is lovely, we chose her despite being a bit of an arduous drive away because she was recommended as someone who genuinely likes animals, unlike our usual vet.
Poor sausage is here whining, woozy and with a shaved belly and legs.
Thank you for all your expertise! Feel slightly less anxious now.