I have a 7 mo old pit. shes about 40 pounds rt now. I walk her in the morning and run her at night. Feed her Diamond Naturals no soy, no corn. I was having her pull this bucket and run but she just does it with ease. Then i filled a gallon of milk up with water and had her run with that and that seemed perfect for her. Struggle was evident, but could still do it. Well within 5 min the jug was torn up and water started to leak. You think if i tapped it all around it would prevent that or do you guys have a better option of what i can do? I have a tire, but its too heavy for her right now. the gallon of water seemed perfect. Thanks.