Hi Myriam,
I will try to give some advice, but I have not used Canninsulin. Unfortunately, there are few people who are presently using it on this forum. I have helped others with general advice and I have asked some of the previous users of your insulin to come by and look at your thread.
There are two problems with Canninsulin. One is that it tends to hit fast and then jump right back up. It tends to be harsh and not long lasting. That seems to be what is happening right now with your reduced dose. The other issue is the recall and whether the inconsistency you see are due to its quality control issues.
We can try to help you with it, as is. I think there were some people who lived in your area who had suggestions about other insulins, but I don't know where you are with that.
So - you were definitely getting better numbers at 2.5. I think they were too low for comfort for a brand new diabetic. Your one unit and .5 didn't make much of an impact. Depending on whether you have recently changed the diet and whether you can be around to monitor, I would think it is safe to give more insulin. If you recently changed to wet lo carb, I would have been cautious and do 1 unit for awhile until you see the impact of the diet. (Oliver dived 100 points overnight when we changed.) I would also get some mid cycle numbers to see how it is working - it is possible that he is going very low mid cycle and then bouncing back up to the higher numbers.
I have to say I am a little nervous about the 1.5 you gave this morning. Is anyone around to monitor today? (If you are still giving dry food, this is not as much of a concern.) He will probably be fine because he didn't crash on the 2.5, but the diet change is the unknown factor - that is if you changed. If he has always been on wet lo carb, he should be fine.
This is a guessing game with a new diabetic and your best ammunition is that glucometer. If possible, it would be nice to hold the dose for several days to see what it does. But you do balance that with preshot numbers in the 400s.
I am sorry for my rambling, bu what I would do is increase the dose a little from the .5, with lots of monitoring. I would also get ketostix and test regularly for ketones:
ketones