Hamsters offered for sale should not be less than 5 weeks of age and males and females should be kept in separate cages to avoid buying a pregnant female. If the seller cannot guarantee the sex of any hamster then it is best to look elsewhere.
First check that the cage is clean and not overcrowded, that any droppings in the cage look firm and not runny, and that the hamsters have access to food and water.
Next look at all the hamsters in the cage to see that they all look healthy and are lively when awake as if one hamster appears ill there is a chance that others in the cage may also be ill or are at risk of becoming ill as some illnesses may not display symptoms for a few days after infection. Look out for sneezing, excessive scratching, dirty coats or lethargy as any of these could indicate health problems.
If there is no cause for concern after an initial inspection of the cage and hamsters, then ask to hold any hamster that you are thinking of choosing and go through the checklist below.
Take your time over choosing a hamster and ensuring that it is healthy and has a good temperament. Don't be rushed by the seller into making a decision.