This article investigates Shakespeare's use of animal dreams -- dreams of or by animals -- in A Midsummer Night's Dream. It argues that the Ovidian model of human-animal transformation, in which animal states and animal imagery describe, amplify, or symbolise aspects of human character, is fundamental to understanding Shakespeare's use of animal dreams in this play. The article further contends that Shakespeare in A Midsummer Night's Dream successfully adapted Ovidian animal symbolism for early modern culture by filtering it through religious and demonological references. The article falls into four parts. Firstly, it investigates the representation of animals, dreams, and animal dreams in classical culture and particularly in Ovid's Metamorphoses. The article then goes on to investigate Hermia's dream of a serpent in A Midsummer Night's Dream, combining close reading with examinations of early modern dream books and with cultural historical insights into the representation of serpents in Christian iconography. Then, the article proceeds to a discussion of Bottom's oneiric transformation into an ass, drawing on classical source texts, demonological treatises, and early modern animal symbolism. The article concludes with a (re-) consideration of the dramatic functions of Shakespeare's Ovidian animal dreams in the context of the moral and aesthetic imperatives of Renaissance culture.