Once you have decided to acquire a small animal, such as a hamster, gerbil or parakeet as a pet, it is important to choose one that is healthy, and hopefully friendly.
Before Purchasing any Animal
Be sure to find out what kind of care it needs, and whether you are capable of providing it. Please.
Choosing a Healthy Pet
First thing, examine the store and the cages. They should be clean, and fresh food and water should be available. If they are not, then it is likely that the animals have been receiving poor care, and are likely to die soon after you get them home. If there are any dead animals in the cage, you should definitely take your business elsewhere.
You should also look at the number of animals housed in each cage, as overcrowding increases the chance of animals having caught something. There should not be more than one hamster or gerbil for every two and one half gallons of cage volume, or more than five mice in the same size space. In a medium size bird cage, there should not be more than ten parakeets or finches, and hedgehogs, chinchillas, and rabbits should have at least a 20-gallon tank to themselves.
What to Look for
When actually selecting a pet, examine them carefully. There should be no runny orifices (nose, eyes, under tail), the animal should appear alert and energetic, and should not be overly thin. In the case of most small mammals too thin is when the bones of the spine and pelvis are clearly visible. For furry animals such as teddy bear hamsters, feel along their back with a finger, and if the bones seem sharp, the animal is probably underweight.
If purchasing a bird, the same applies except for the size (birds are supposed to be skinny under those feathers). However, with birds there are other signs of bad health. Listless sitting with feathers puffed is one. Extremely ratty and ungroomed feathers is another - do not confuse this with moulting.
If you are interested in a reptile, it should not be too thin, have smooth and even scales, and also it should be examined for mites. Mites are very small and typically take up residence under a reptiles scales, causing a small distortion in the scale pattern. They are treatable, and rarely fatal, although they can contaminate an entire tank or terrarium.
It is also wise to not only examine the animal you are considering purchasing, but the others in the cage as well. If there is a sick animal sharing the cage it is possible that your animal may have caught the disease but not yet be showing any symptoms yet.
Choosing a Friendly Pet
With any small mammal or bird, you want one that is not terrified of you, or unreasonably prone to biting or pecking.
For Small Animals
When approaching the cage, look for the ones who seem curious about your approach, or who do not immediately run and hide. Further, concentrate on those who do not panic when the cage lid is removed. Try picking one up, holding it a centimetre above the cage floor in case it jumps. If it seems unconcerned about being in your hand, and has not bitten you yet, you probably have a winner.
Try approaching the cage slowly, and take note of which birds do not join in the panicky fluttering. Then try moving a hand slowly around the outside of the cage, watching for the birds that eye your hand cautiously instead of flapping away. If possible, get the store attendant to let you put your hand into the cage, and then slowly approach your candidate. If the bird merely sidles away when your hand approaches it will probably be easily tamed. (None of this will work for finches, they just don't have the brainpower for it. If you put your hand into a finch cage and hold still for a minute or two they will simply start landing on it.) Finally, watch when the attendant removes the bird from the cage. If it draws blood attempting to escape then maybe it is not the best candidate.
Look for one that does not panic when approached, or attack. Iguanas particularly can be very nasty. They can whip with their tails, raising welts, and can also bite quite badly. Snakes that strike at hands are also a bit too aggressive. Smaller lizards, such as chameleons, skinks, and geckos are not very prone to taming, and if vicious are generally too small to do any damage.
When you make your decision, be sure to get all of the necessary supplies to keep your pet healthy too.
And if you go into a store and the conditions are bad, and the animals are unhealthy, perhaps a complaint to the management might help improve things.