The Shrew You Find...
For an injured shrew, as for any other animal, the way to help it is to get it to a rehabilitation person or to a vet as quickly as possible. The speed is very important.
In some cases, when shrews seem to have starved, but are still alive, it is sometimes possible to revive them by giving them a few drops of concentrated glucose solution (a.k.a. dextrose, 'grape sugar', 'blood sugar', --C6H12O6) or a strong solution of sugar water.
If it is neccesary to keep a shrew for a short period of time (even in the range of a couple of hours) it is important to immediately supply them with some food and water. The food can be meal worms, any other small insects, spiders or earth worms, or if nothing else available: cat food or ground meat.
Housing: temporarily (only!) a large bucket will do. Put in some soil, leaves, moss, cover with pieces of bark. Dry nest should be provided: some cotton wool in a small flowerpot (turned upside down) or a small carton with a hole in it. The nest should be kept dry, whereas the soil should be moist (not wet), which will also provide sufficient air humidity. Keep the container and shrew as quiet as possible until delivered to medical help. Do not attempt to doctor it yourself.
If it was caught by a dog or cat it could have fractures and internal injuries. If a cat had it, even with no sign of injury, most small animals can be infected with Pasteurella from inhalation. This usually causes pneumonia, which must be treated with antibiotics or it's likely to be fatal.
A rehabilitator is equipped and trained to carry out the veterinary treatments recommended and to release the animal when it is ready to return to its' home.
Shrews as Pets?
The idea of an unusual wild pet is appealing. The reality has many hidden problems. Wild animals do not relate to humans in the way of a cat or dog. Any "tameness" is only a thin layer over their innate reactions. The wild pet who bites someone has often just earned a death sentence. Particularly where children and visitors are involved.
For a wild animal, their diet may be comprised of many unusual ingredients that don't store well. Difficult to provide if you don't have a zoos' kitchen! Also, it's not easy to find someone to provide care in your absence for such an animal. The long term dietary needs for wildlife are often not well understood - what keeps an animal alive for a few days may, over time, cause a variety of crippling results. One of the most common being loss of bone density leading to multiple fractures. Not a favor to give. Also, even a balanced diet made up of unfamiliar food items may not be eaten, or only certain items eaten, so it becomes unbalanced in fact.
Hedgehogs, flying squirrels, and even poor single prarie dogs, (which live in large extended social communities normally), are sold to people who know nothing about them by stores who also know nothing about them. The result usually is an animal who suffers all the way to its' death. If a wildlife in your care needs medical attention, finding a veterinarian who can address the problem is difficult.
Wildlife is not a part of the normal training, and what works for a domestic pet may harm the wild one. It is easy to produce in a captive wildling, conditions for which there is no effective treatment. A shrew is the product of a long evolution that fits it to occupy a particular job on earth. Sharing our lives is not a pleasure for them. Even the best captive care gives a life of endless boredom. Another way of saying endless misery. Children have not lived long enough to know these things so it is up to us to explain and to set an example of how we should deal with those smaller and weaker. The lesson is to treat other lives with respect. Mice taught me that the tiniest animal is a whole curious friendly universe. We just have to be still and listen.
The shrew you find? Let him go back to the life he was leading.
Don't keep a wild life only to become a sad memory!
M. D. Smith
Literature on small mammal borne diseases:
Childs, J.E., J.N. Mills and G.E. Glass. 1995. Rodent-borne hemorrhagic fever viruses: a special risk for mammalogists? Journal of Mammalogy 76(3): 664-680.