Q: Our cat seems to have a silent purr. We have never heard him make any purring noises, but we have felt a vibration in his throat when he is content. Is this common?
A: It is likely that your feline is purring, but at such a low volume that you cannot hear it. If you can feel that a vibration is occurring, you should not worry unduly, although it may be worthwhile discussing it with your vet. Have them check your cat's throat in case there is an underlying medical problem that is causing a sore throat and loss of volume. However, it is likely to just be a quirk that is particular to your cat.
Scott Miller, vet