\[ \boxed { 2\, \left ( {\frac {{\rm d}^{2}}{{\rm d}{x}^{2}}}y \left ( x \right ) \right ) y \left ( x \right ) - \left ( {\frac {\rm d}{{\rm d}x}}y \left ( x \right ) \right ) ^{2}+b-4\, \left ( {x}^{2}+a \right ) \left ( y \left ( x \right ) \right ) ^{2}-8\,x \left ( y \left ( x \right ) \right ) ^{3}-3\, \left ( y \left ( x \right ) \right ) ^{4}=0} \]
Mathematica: cpu = 1.182650 (sec), leaf count = 48 \[ \text {DSolve}\left [-4 \left (a+x^2\right ) y(x)^2+b+2 y(x) y''(x)-y'(x)^2-3 y(x)^4-8 x y(x)^3=0,y(x),x\right ] \]
Maple: cpu = 1.779 (sec), leaf count = 0 \[ \text {could not solve} \]