\[ \boxed { {\frac {\rm d}{{\rm d}x}}y \left ( x \right ) ={\frac {-4\,xy \left ( x \right ) -{x}^{3}-2\,a{x}^{2}-4\,x+8}{8\,y \left ( x \right ) +2\,{x}^{2}+4\,ax+8}}=0} \]
Mathematica: cpu = 0.027003 (sec), leaf count = 45 \[ \left \{\left \{y(x)\to \frac {1}{4} \left (-2 a x-x^2-4\right )-\frac {2 \left (W\left (-e^{-\frac {a^2 x}{4}+c_1-1}\right )+1\right )}{a}\right \}\right \} \]
Maple: cpu = 0.078 (sec), leaf count = 50 \[ \left \{ y \left ( x \right ) =-{\frac {1}{4\,a} \left ( 2\,{a}^{2}x+a{x} ^{2}+8\,{\it lambertW} \left ( -1/2\,{{\rm e}^{-1/4\,{a}^{2}x}}{{\rm e} ^{-a/2}}{{\rm e}^{-1}}{{\rm e}^{1/4\,{\it \_C1}\,{a}^{2}}} \right ) +4 \,a+8 \right ) } \right \} \]