This article is from the Dogs Agility FAQ, by J L Gauntt with numerous contributions by others.
Dogs must be at least 6 (UKC) or 12 (AKC) months of age to participate
in trials held under domestic rule variations and at least eighteen
months of age to compete in trials held under international rules
(USDAA, AAC, and NADAC).
Although agility training is best started with a young adult dog, some
agility training can be appropriate for young puppies; this includes
tunnel work, jumps lower than elbow height, and basic control
training. Contact equipment work (i.e. A-frames, Dog Walks, and
See-saws) should be delayed and/or kept very low until the puppy has
developed the necessary physical coordination to negotiate a plank
suspended above the ground.
Serious jumping and weaving work should be put off entirely until the
puppy is much older. Because of the long term negative impact of
jumping and flexing on immature, growing bones, owners are advised to
research their breed thoroughly and only begin intensive agility
training of this type when the dog is past the age at which the
'growth plates' are known to typically close for that breed. A very
imprecise guideline for growth plate closure in mixed breed dogs would
be 9 - 12 months for dogs under 50 pounds and 10-14 months for dogs
over 50 pounds.
Most dogs are able to participate and do well in agility until they
reach 8-10 years of age. Owners should then gradually scale back their
training and competing to obstacle heights and classes more
appropriate to their 'veterans' if they wish to continue at that