Boyle's plans feature the use of live animals, including 12 horses, 3 cows, 2 goats, 10 chickens, 10 ducks, 9 geese, 70 sheep and 3 sheep.
"It is not true to say the 'Olympics opening is cruel to animals'," said director of London 2012 ceremonies, live sites and education Bill Morris in a letter to Metro.
"The RSPCA is providing independent animal welfare advice to the London 2012 ceremonies team throughout the process of working with animals for the ceremony.
"Not only has their been consultation with the animal suppliers, the RSPCA has also provided expert advice on every aspect of care in accordance with welfare needs."
He added that the animals would be visited by the RSPCA's performing animals consultants in their usual accommodation, the on-site accommodation, during rehearsals and the 'Isles of Wonder' ceremony itself.
"The welfare of the animals is of the utmost importance to our team, which is why we're working with the RSPCA to ensure their welfare needs are met," he concluded.