I tied one once with the tail hair from my dog, a golden retriever.
The hair was much too supple and did foul. Didn't try that again.
You could always stiffen it up with a glue spine as with a mushmouth style fly
The Mushmouth Series
The Mushmouth Series of flies were all designed to be non-fouling, quick-to-tie baitfish and squid imitations. The original version was made primarily of Angel Hair or Wing 'N Flash and since then innumerous variations have been created to match different baitfish with different materials. Any non-tapered synthetic or natural material can be used. Popular choices are Slinkyfibre, Unique Hair, Bozo Hair, PolyBear, Mega Mushy flash and natural yak hair. Tiers will find that each material has its own distinct purpose as their length and denier vary. As you might expect, longer and thicker fibers are best suited for big flies and shorter, finer fibers are best for smaller offerings.
The common element of all Mushmouth family members is a stiff, yet flexible spine of Super Hair and Softex or Soft Body Glue that extends past the hook bend. This Super Hair / Softex spine keeps the fly from fouling during the cast. It also helps the fly retain its profile when fished in fast current and protects it from becoming a one-fish wonder