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Chairdog - Heretics of Dune by roset03 on DeviantArt

McKie imagined the Bureau's Director of Discretion, a suave little Laclac sitting in that nicely tailored environment back at Central. Siker would be relaxed, fighting tendril withdrawn, his face split open, an elite chairdog ministering to his flesh, trained minions a button-push away. - 1970, page 67 of Whipping Star by Frank Herbert.
Unlike the Bene Gesserits who understood their places and required no ostentatious symbols of rank, Honored Matres demanded gaudy signs of status, like extravagant thrones or chairdogs, ornate capes in vivid colors. - 2006, page 30 of Hunters of Dune by Brian Herbert

In the Dune universe, the object and species known as chairdogs were first mentioned in Heretics of Dune.

Described in more detail in Whipping Star, these were bio-engineered dogs shaped into chairs. They were trained to massage the people who sat in them, similar to modern-day vibrating massage chairs, except without needing electricity or computerization.