I prefer an injection rather than drops in the water or food, as it is easier to ensure the correct dosage. However, this will mean you have to visit the surgery for 3 to 5 days for treatment. All Gerbils have a scent gland in the middle of their tummy. This is long, thin and yellow in colour. It is sometimes mistaken for a wound or tumour.
Gerbils mark their territory by rubbing their scent gland on it.
Male Gerbils kept with other males are particularly prone to scent gland tumours. Excessive marking of territory causes the tumour. It starts off just looking like a pimple. Sometimes it never develops beyond this stage. Sometimes it grows rapidly and starts to bleed.