Here is an example of a basic fur shader for Unity

Shader "Custom/Fur" {
    Properties {
        _MainTex ("Fur Texture", 2D) = "white" {}
        _BumpMap ("Normal Map", 2D) = "bump" {}
        _FurLength ("Fur Length", Range(0, 1)) = 0.1
        _FurDensity ("Fur Density", Range(0, 1)) = 0.5
        _FurDirection ("Fur Direction", Vector) = (0, 1, 0)
        _FurColor ("Fur Color", Color) = (0.8, 0.8, 0.8, 1)
        _FurSpecular ("Fur Specular", Range(0, 1)) = 0.5
        _FurShininess ("Fur Shininess", Range(0, 1)) = 0.07
    }

    SubShader {
        Tags {"Queue"="Transparent"}
        LOD 200

        CGPROGRAM
        #pragma surface surf Lambert

        sampler2D _MainTex;
        sampler2D _BumpMap;
        float _FurLength;
        float _FurDensity;
        float3 _FurDirection;
        fixed4 _FurColor;
        float _FurSpecular;
        float _FurShininess;

        struct Input {
            float2 uv_MainTex;
            float2 uv_BumpMap;
            float3 viewDir;
        };

        void surf (Input IN, inout SurfaceOutput o) {
            fixed4 tex = tex2D (_MainTex, IN.uv_MainTex);
            fixed4 bump = tex2D (_BumpMap, IN.uv_BumpMap);
            float furAmount = dot(bump.rgb, _FurDirection) * _FurDensity;
            o.Albedo = tex.rgb * _FurColor.rgb;
            o.Alpha = tex.a * (1 - furAmount * _FurLength);
            o.Normal = UnpackNormal(tex2D(_BumpMap, IN.uv_BumpMap));
            o.Specular = _FurSpecular;
            o.Gloss = _FurShininess;
        }
        ENDCG
    }
    FallBack "Diffuse"
}