A 6-year old female spayed English Pointer presents for lethargy and weight gain. The owner notes that the dog is eating and drinking a normal amount, but the dog is still gaining weight. A physical exam reveals weak pelvic limbs, facial nerve paralysis, a symmetrically patchy haircoat, and seborrhea. Lab work reveals a normocytic, normochromic anemia with a PCV of 29% (35-57%), lipemic serum, and cholesterol of 1090 mg/dl (135-278 mg/dl). Then what is the most likely diagnosis？
一只6岁的雌性已绝育波音达犬由于无力和体重增加前来就诊。主人说这只狗吃喝的量都正常但体重依旧在增加。体格检查发现其后肢无力，面部神经麻痹，对称性片状被毛以及皮脂溢。血液检查发现正红细胞，正色素性贫血，PCV为29%（33%-57%），脂样血清以及高胆固醇。最可能的诊断是什么？