Os Comensais da Morte não precisam dos encantos dos Patronos.
De esta entrevista com JK Rowling:
Samantha: Was snape the only death eater who could produce a full patronus
J.K. Rowling: Yes, because a Patronus is used against things that the Death Eaters generally generate, or fight alongside. They would not need Patronuses.
Cite para apoiar a afirmação acima, do Senhor V falando com seus Comensais da Morte em Cálice de Fogo recentemente lembrado:
Voldemort moved on, and stopped, staring at the space - large enough for two people - that separated Malfoy and the next man.
'The Lestranges should stand here,' said Voldemort quietly. 'But they are entombed in Azkaban. They were faithful. They went to Azkaban rather than renounce me…When Azkaban is broken open, the Lestranges will be honored beyond their dreams. The dementors will join us…they are our natural allies… we will recall the banished giants…I shall have all my devoted servants returned to me, and an army of creatures whom all fear…'