I just finished a course on Elder Abuse and was shocked to find how prevalent it is. The causes are varied and, largely unstudied, but it is an area of concern for those of us working with and/or responsible for an elder.
Here is a short list of some common signs that may indicate abuse in your elder:
Fractures and breaks
Cuts, open wounds or punctures
Bruises and abrasions
Sprains or dislocations
Internal bleeding
Change in mood or behavior
Consider activity levels and the elder's particular situation when attempting to evaluate whether there is a concern for abuse.
If a caregiver is involved and doesn't want the elders to have visitors alone or indicates the elder is not available to visitors, this may be a potential indicator for abuse.
It should go without say, but it doesn't: If an elder reports being hit, slapped, pinched or hurt in anyway this is a potential indicator for abuse and should be investigated.
Caregiving can be stressful and often those providing this valuable service are overworked and underpaid, as the saying goes. They may have additional stressors they bring from home or pressures from employers that may fuel their frustration.
Develop a relationship with the caregiver and visit often and at varied times to be sure you are getting a complete picture or your elder's day.
For the second year in a row Jim has had to spend a 1/2 hour or so extricating snakes from the blueberry netting we keep in the shed! I felt terrible - he worked all day, mowed the lawn and then had to free this poor little guy (5 feet and a bit skinny) from the netting. 
