Hello, I'm Dr. Deb and will do my best to help you today.
I'm sorry that Spike has been diagnosed with lymphoma. Cerenia is an excellent drug for many reasons but it can be difficult to administer to a cat.
Zoftran, as you know, can also be given to felines and may be just as effective as Cerenia for some patients.
There's quite a huge dosage range for cats--0.5 to 4.5 mg at one time. I tend to split the difference for my patients and start with 2 mg initially.
If the concentration of the drug you have is 4 mg/2 cc's, then his dose would be 1 cc at one time.
This drug doesn't have to be diluted and can be given SQ twice a day.
Just double check that the expiration date hasn't passed. It won't be harmful to administer if it has but the drug is less likely to be effective.
Most cats tolerate this drug very well which I assume will be the case with Spike since he's been given it before...(at least my assumption is that it was dispensed for him originally).
I hope this helps. Deb