Hogs peed all over farmer's best friend (8)

I believe the answer is:

sheepdog

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'farmer's best friend' is the definition.
I can't judge whether this definition defines the answer.

'hogs peed all over' is the wordplay.
'all over' indicates an anagram.
'hogs'+'peed'='hogspeed'
'hogspeed' is an anagram of 'SHEEPDOG'.

Can you help me to learn more?

(Other definitions for sheepdog that I've seen before include "Canine trained to control flock" , "could it be Old English?" , "Collie, for example" , "Shaggy-haired canine" , "Collie, perhaps" .)

I've seen this clue in The Independent.

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