Largest gathering of people dressed as dogs

According to Official Guinness Records,

The largest gathering of people dressed as dogs is 439 and was achieved by NFU Mutual (UK), in Stratford-Upon-Avon, UK, on 20 April 2016. The attempt was performed to raise money for "Guide Dogs For The Blind".

For a complete list of 2016 records, please visit 2016 Guinness Records in United Kingdom.

Other United Kingdom records that might interest you:

• Fastest marathon dressed as a fairy (female)
• Longest French knitting
• Fastest marathon in a martial arts suit (male)
• Most Laurence Olivier awards won by an actress
• Most Laurence Olivier awards won by an individual