If you need to get to dose 1/4 units, you can do this two ways:
1. Eyeball the amount. Look closely at the syringe and ensure that the plunger is halfway between the 1/2 unit marked lines.
2. Fill the syringe to 1 unit with water. Slowly depress the plunger and count the number of drops of water that come out of the needle. For example, say that 4 drops come out of the needle for the 1 unit. That means that a 1/2 unit is 2 drops and a 1/4 unit is 1 drop. So if normally you need to give 0.75 units of insulin to your cat, you would fill your syringe to 1 unit and then push out 1 drop before injecting the remaining insulin into your cat.
I hope this helps!
Liz