One thing to note about purchasing bottles of urine reagents (often called dip sticks) is that the reliability is compromised by the air, sunlight etc. every time the lid is opened.
Bottles of strips are made to be used up in 3-4 months. If the pet owner is testing often–every day or every other day as if often the case when an animal has been diagnosed with diabetes…then there will not be a problem.
But for preventative care, if the bottle is opened every few weeks, then in just a few months, they results may no longer be effective. That is why it is critical to have specially packaged test strips if you are using the strips to practice preventative medicine.