Hi Jenn,
What I can't speak to:
Use of the pred. I've no experience with steroids with any cat I've ever had.
Heart condition. Ditto. I am not sure why PZI would be easier on it, nor how any insulin would or wouldn't be.
My first question is what you mean specifically by "PZI". Are you talking about Prozinc (which is a human rDNA insulin designed specifically to use on cats), or are you talking about compounded PZI, which is bovine based? They aren't the same thing, and while they work in a similar fashion, they are not identical.
Prozinc has an advertised duration of 10-14 hours with a nadir between +5 to +7, typically.
Compounded PZI has a duration in the 8-10 hour range, with a nadir by +5, typically.
Bob was on compounded PZI purchased from "VPA", and I believe that VPA no longer produces it. My understanding is that PZI is available from multiple sources, and that BCP (in Houston TX) is supposed to be the best place to get it from.
An additional problem with compounded PZI is the reliability of the lab that makes it, and the question about whether or not one batch and the next batch are close to being the same quality. Dr. Peterson has a blog which addresses that specifically, and this is a good article to read if compounded PZI is what you'll be using:
http://endocrinevet.blogspot.com/2012/06/characteristics-of-commercially.html
You are familiar with Lantus TR from treating Mikey, and you are familiar with Lantus and Levemir with Tidus. I am familiar with neither, nor with Prozinc, so anything I "know", I've learned from FDMB.
Bob was not on any sort of a protocol with PZI. He was dosed for 10 weeks, on a sliding scale based solely on his preshot numbers. He started at 1u BID and went as high as 4u BID. That was all as directed by my vet. Once I came here and learned a lot, I started unilaterally reducing his dose, again using a sliding scale based on preshots, and in about a month, he was OTJ. Oh yeah, he also got all his shots IM, and not sub-Q. So Bob and I pretty much did nothing "by the books". That probably would have been different had I joined FDMB the day he was DX'd, but that's a moot point.
The biggest drawback that I see to PZI/Prozinc is the lack of a published easy-to-follow protocol. There is the TR protocol of Dr. Hodgkins, but nobody here uses it, and it's (IMO) more intense than the Lantus TR. So while there are members of this board that use Prozinc or PZI, and there's an ISG (which isn't as busy as it used to be), there isn't the wealth of knowledge and experience that exists with the L's. The people in PZI are all great, and all give good advice, but there's just not as many. And there's no rules to follow. Just a lot of personal experiences on what worked or didn't work for our kitties. But we can't definitively say that a spreadsheet indicates a specific increase or reduction is warranted.
PZI is what I call an "if/then" insulin. If you shoot X dose, then you get X results. If you shoot 2X, you'd expect more to happen. There isn't any depot, and very little carryover when it does happen. So when you adjust the dose, you don't see as much "NDW", and you can expect to see results that cycle (assuming the adjustment was big enough to really make a difference). It is much more flexible in terms of adjusting dose and in terms of "12 hours apart" than the L's are.
But..... there's still bouncing, there's still "where the heck did THAT number come from", there's still the ability to shape the curve using food and timing of meals (although not too many people take advantage of that in my opinion).
There are other forums, like DCC and DCH, where there are a higher percentage of cats on the "P" insulins, but I'm not familiar with them or the beans who belong to those boards.
I can only recall one PZI kitty who used to be on Lev and switched to PZI and went off the juice but there may be others. That would be Harley (of Rob and Harly). Many kitties have switched from a P to an L since I've been around. Some have gone OTJ, some have done really well, others not so much, but I don't think any of them are doing worse than they were.
I can't advise that you switch or don't switch to Prozinc or PZI. I'd like to understand more about why it might be easier on his heart, and also if the vet is aware of the issues raised by others concerning the pred and his heart condition.
And as far as the Acro thing goes. I know you are trying out other options before attempting the test for that. I don't know which insulin is "best" for dealing with that if you find out Tidus is an Acrocat. My sense is that Lev is the insulin of choice, but I really don't have an idea.
I don't know if that helps or not, but I hope so.
Carl
