For non nationals wishing to purchase property in St. Lucia, the property must first be identified and then an application made for an Aliens’ Land Holding Licence.
Most towns and cities do have adequate veterinary surgeons, before travel it may be wise to locate the nearest to you. Currently pets can only be brought in from the UK.
Medical care is limited. There are two public hospitals and one private hospital in St. Lucia, and the standard of care they provide may be lower than you would expect in the UK.