The Short Answer Is: It Depends on the Setting
Inside the home, a Whippet and a cat is one of the more workable sighthound pairings. Whippets are gentle, non-confrontational dogs, and a cat who is part of the household furniture, confident, and disinclined to run quickly gets filed by most Whippets as family rather than quarry. It is common to find the two sharing a sofa, sometimes with the cat firmly in charge of the arrangement.
The distinction that decides everything is movement. A sighthound's chase response is triggered visually, by something fleeing, and it operates faster than conscious training. A cat sprinting across a garden does not register to a Whippet as their housemate; it registers as the exact stimulus the breed was built, over generations, to pursue at full speed.
Introductions That Set the Pair Up Well
Start before the animals meet. Swap bedding so each learns the other's scent as background, feed them on opposite sides of a closed door, and let the cat keep escape routes and high perches the dog cannot reach. First meetings work best with the Whippet on a lead, tired from a walk, rewarded for calm glances away from the cat rather than fixed staring. That stare matters: a still, locked-on Whippet is not calm, and the session should end or gain distance at that point.
Barriers earn their keep in this phase: a baby gate or playpen gives the cat a genuinely dog-free zone to retreat to, and gives the Whippet a clear, consistent picture of which rooms are shared and which are not. Sessions stay short and boring on purpose. You are building the cat into the Whippet's picture of ordinary life, and ordinary is the goal. Over days and weeks, most households reach supervised freedom indoors, then unsupervised time for a proven pair. A nervous, flighty cat raises the difficulty considerably, and a household with a cat who bolts at every surprise should think carefully and introduce far more gradually.
Outdoor Rules That Never Relax
The garden is where good indoor relationships can still come undone. Keep early garden time leaded or on a long line, keep the boundary genuinely secure, and never assume a Whippet who adores the household cat will treat a neighbour's cat the same way; unfamiliar cats outdoors are quarry in a way the family cat, in context, is not.
Recall training helps with general responsiveness but should never be the plan for a chase already launched. Management, not obedience, is the safety system: supervision, secure fencing, and a lead anywhere the pair might meet running wildlife or unfamiliar animals. If a chase does happen, note what triggered it and tighten the management around that setting rather than blaming the dog for being exactly what it is.
Keeping Everyone in the Household on the Same Plan
Mixed-pet introductions fail most often on inconsistency: one person allows sofa cuddles, another leaves the pair alone too soon, a sitter never hears about the long-line rule. For the first stretch, the steps, limits and progress notes need to reach every person involved, every time.
That coordination is simpler through KinsLe Messenger, where every conversation about your Whippet, from family updates to a sitter's questions about the cat, stays in one per-pet communications hub that everyone involved can check.