Green’s Dictionary of Slang

1. (US shortorder) a sausage, a ‘hot dog’.

1911

E.B. Morris Senior 10: Meade. Buckwheat cakes, for mine. Thompson. Sausage. Mike (calling off) Make it a round of buck. One order of Fido.

2. (US prison) a trusty.

1933		Ersine Und. and Prison Sl.
1949		Monteleone Criminal Sl. (rev. edn).

3. see barking dogs n. (1)