In this paper, I undertake a reading of the ‘Canis’ story appearing in manuscript M of the Old French Roman de Dolopathos, with an eye to how passages present only in this version and the specific resources of the Old French language draw attention to the internal tensions of chivalric animal domestication. ‘Canis’ points to the contradictory or even suicidal consequences of an ideology that cannot properly account for the status of its animals: from an illusory subjective ground, a knight asserts murderous control over the same animal companions through whom he is constituted and derives his authority. When the knight’s greyhound emerges as an ethical subject in his absence, an unanswered question latent in the practice of domestication reaches a breaking point: are animals in knightly possession to be understood mainly as objects to be retained and discarded, or as living beings capable of independent ethical action? To account better for the uncanny status of a chivellier who murders his cheval, I draw both from the nascent field of critical animal studies and from the psychoanalytic theory of Alenka Zupančič.