There are 2 13-letter words that start with 'dog'.
| doggishnesses | dogmatization | 
Note: These 2 13-letter words that start with 'dog' are found from the USA & Canada version of the tournament Scrabble word list.
Also see words start with dogg, dogm, doge, dogn, dogs, dogf, dogt, dogl, dogb, dogc, dogw, dogh, dogd, dogi, dogr, dogv, dogy.
4-letter words start with 'dog' (3)