This company had a stand at Paws in the Park last month and I bought the beef super chews and beef jerky, both of which have gone down well and the super chews lasted longer than most chews I give them. Ro and Caoimhe demolish most chews in a matter of minutes but those lasted for a good few hours which is almost unheard of, I'll definitely order more when we run out:
http://www.barfpetfoods.co.uk/dog-treats/chews.html I also order ostrich tendons, duck and turkey necks and venison ears, sinews and trachea from Zooplus as Tilly can also have these occasionally but they don't tend to last all that long. They get the occasional pizzle and 'normal' rawhide as well but again they don't last too long.
They love buffalo trachea which are about a foot long. They're quite rich so they only get them occasionally but they last for a good hour or so. They're hard to get hold of though, I had to order the last lot from the US.
Rodaidh has a couple of Nylabones which he absolutely loves; Tilly and Caoimhe would never look at them but Ro has always been a proper chewer, as in he likes to chew for its own sake rather than just on something edible, and even now at 6 years old he'll very often lie there having a good old go at one of the Nylabones. Because he can grip them between his paws and they're really hard he can really go for it and it seems to satisfy him more than edible chews - he also chews them to calm himself down if he gets wound up.
