Can I just use one tube for larger dogs and split it for two smaller dogs?
No, never self-dose any flea and tick product. This is very dangerous! It is not possible to ensure you are applying the same amount of active ingredients to both pets. Applying an insufficient amount of the active ingredients can result in lowered effectiveness. Applying too much of the active ingredients can, most importantly, result in an overdose to your dog and put their health at risk.