Science Diet Senior Hairball Formula Is For The Older Cat Who Has Hairball Problems. Senior Hairball Formula gives your cat healthy immune functions, helps avoid hairballs, keeps heart and kidney healthy, keeps muscles lean and body weight low, and reduces shedding. Chicken By-Product Meal based. 326 kcal/cup. Crude Protein about 34%, Crude Fat about 20%, Crude Fiber about 8%. 3 Lb.