Some are ill-treated through the ignorance of their owners, some are mistreated through cruelty, and others are simply ignored and forgotten about.
In New Zealand, donkeys come under the umbrella of the International League of the Horse, and since figures have been collected more than 80 donkeys have been rescued.
But in Britain more than 7300 donkeys have so far been rescued by The Donkey Sanctuary, the fifth largest animal charity in the UK. The Sanctuary owns 10 farms covering 1600 acres throughout the UK, and its headquarters in Devon is home to about 600 donkeys, most of whom need to be close to veterinary care.
Slade House Farm, in Sidmouth, Devon, is also a place where visitors can visit, stroll around the fields where the donkeys graze, or take a planned walk. There is no admission fee.
Farmers have found that having a donkey among a herd of stroppy bulls settles the bovines down. Donkeys tend to "rule the roost" when they run with young bulls.
Donkeys also make kind and gentle pets for children - and adults -- and have been many a horse rider's first mount.
Many children have had their first experience of farm animals while taking a donkey ride on seaside visits in England.
But in many countries donkeys are simply used as a work tool, and are often seen toting loads far heavier than themselves.
The Sanctuary was the brainchild of administrator Dr Elizabeth Svendsen. Its main aim to give every donkey admitted to the Sanctuary the right of life, and the best possible treatment. It is 25 years since the Donkey Sanctuary became a registered charity, "although my first donkey, Naughty Face, arrived much earlier - in 1969," Dr Svendsen says.
Back then, she says, the cost of keeping a donkey was 2.50 pounds a week. By mid-1973, she had taken 38 donkeys into care, and was struggling to cope with a full-time job and four children.
The Donkey Sanctuary must seem like heaven for donkeys - in winter each donkey has a choice of being in a large, airy barn - complete with infra-red lights - or venturing out into the exercise yards.
And if any of the residents becomes ill - or arrive in poor shape - the team at the Sanctuary's veterinary hospital is probably the world's most experienced in donkey care.
Until a few years ago, Dr Svendsen says, most vets treated donkeys as they would a small horse: "but we have learned that the donkey differs in many ways."
The Sanctuary compiled a publication, 'The Professional Handbook of the Donkey', which includes information from donkey specialists world-wide. The book is distributed to veterinary universities and practices. It also sells a video on basic donkey care.
The International Donkey Protection Trust (IDPT) was founded in 1976 by Dr Svendsen. It is making progress in overseas countries, where about 57 million donkeys and mules are working animals. Dr Svendsen estimates at least 50 million of them could be in need of help.
The IDPT has just built a clinic in Ethiopia, and its opening is planned for October. One of the worst problems in the country are saddle sores, and donkeys dropping from exhaustion at the markets.
The Sanctuary has released a book 'The Story of Dusty, the Little Ethiopian Donkey', which has been distributed to schools in many parts of Ethiopia. It is proving a success in its education of both children and adults, who before had little idea of a donkey's needs. Every copy bought means a free copy goes to Ethiopia, where more than 5000 have already gone. The IDPT also helps fund the donkey clinic programme of Kenya's SPCA.
A project is also under way in India.
Mexico is a success story, with a third mobile unit being set up in the state of Tlaxcala, in conjunction with the International League for the Protection of Horses.
'The Story of Joe, the Donkey who Flew to Jamaica' is being sold to aid education of children in Jamaica and the Turks and Caicos Islands. It sells for 7 pounds.
Each week up to 150 children with special needs - be it a learning disability, behaviour problems, or a sensory impairment - attend one of the Sanctuary's four centres to learn riding skills, and to have some fun on horseback.
The Elizabeth Svendsen Trust for Children and Donkeys aims to bring pleasure and enjoyment into the lives of children by riding. The children are encouraged to groom and look after their charges themselves.
During summer mobile units take donkeys out to schools and hospitals to see children who cannot travel.