Hello,
No worries.
Since you are using Herptivite, it has Beta carotene in it, which you are very unlikely to overdose on.
Beta carotene is the precursor to vitamin A & has to be converted in their body. So, they will covert the amount of Beta carotene over to Vitamin A when they need it which will control how much they get. The rest will get excreted. Beta carotene is natural, so it will not build up in toxic levels in their body like synthetic vitamin A will.
Feeding carrots certainly wont overdose them on vitamin A because carrots contain carotene & carotenoids which have to be converted in the liver, to vitamin A. So, feeding some carrots are not going to cause harm.
These natural supplements which do not contain straight synthetic vitamin A will not store in the body since they are water soluble. Instead they will be excreted out of the body.
Now, supplementing them with supplements that contain synthetic vitamin A can & will, over time, cause toxicity. They are fat soluble which simply means they are stored in fat cells & do not readily excrete from the body.
If you are using Herptivite 2 times per week, that will be fine. He should not have any toxicities from that supplement.
I hope this helps.
Tracie