Family crest?

[KGarrad]

From a guide to Heraldry:
it will be seen that besides the ordinary position of the dog, which is passant, it may be represented, sejant, rampant, salient, skipping, questing(i.e. pointing), courant, and in full cry.

Sejant means in a sitting position - the nearest a herald can capture "flatly refusing to move"?!
Could also use couchant - lying down.

These terms tend to be used for beasts (i.e. animals with 4 legs).
Birds have different terms.

[Viktoria]

What is the heraldic term for flatly refusing to move?

Pertinax

Now I thought he was Astyanax’s brother!
( seriously ,TGarrad andMike, thank you both).
Viktoria.

[cristeen]

Thanks for all the replies. The 'spotted talbot' description was from the Ebay listing and I agree it does seem to be a sort of hound. I hadn't noticed the raised foreleg is different on the button, well spotted Mike!
Having googled Firmin it appears the addresses on the button were in use from 1875 to 1904 so quite a long time frame. Carol, I will drop them an email when I get the chance. The family name is Newson, originally from the Chelsea area of London. I don't think any of them were wealthy enough during the aforementioned timeframe to have had servants with such livery buttons. I now wonder if the crest might actually have been linked to an employer of theirs??