Animal Growth

The target animal grows to twice its normal size and eight times its normal weight. This alteration changes the animal's size category to the next largest, grants it a +8 size bonus to Strength and a +4 size bonus to Constitution (and thus an extra 2 hit points per HD), and imposes a –2 size penalty to Dexterity. The creature's existing natural armor bonus to AC increases by 2. The size change also affects the animal's modifier to AC, attack rolls, and its base damage. The animal's space and reach change as appropriate to the new size, but its speed does not change. Multiple magical effects that increase size don't stack.