I have received some questions about the shelf life of PET Plus so would like to provide clear information in order to give you peace of mind.
The date that a pot of PET Plus was manufactured is printed on the bottom of each pot. So for example, the following - MFG 6/2021 - would indicate a manufacturing date of June 2021.
Because all the ingredients in PET Plus are dry and only become active once wetted, eaten or mixed with wet food, in reality, the shelf life of PET Plus is many, many years.
Apparently the percentage of viable probiotics decreases slowly over several years but research completed a decade ago shows that the effectiveness of non-viable probiotics is virtually the same as viable ones.
Certainly the unopened pots I kept for 20 years and gave to my own animals were equally beneficial even though the range of ingredients has improved over the years.
The 'dry pack' sachet in each container keeps the powder dry. However, once opened, it is essential to keep PET Plus cool and dry. Every time the pot is opened, humidity from the air can enter, so with repeated opening it is possible for the powder to become damp. I have never seen this happen, but because of this theoretical risk, I had to write, Use within 4 months of opening, on the label.
So, in order to minimise the risk of dampness entering a pot of PET Plus, you could decant some of the powder into a small, airtight container to use with upcoming meals. You could then place the carefully closed large pot of PET Plus back into the cupboard. Afterwards when the smaller container is empty, you could repeat the process. This system minimises the number of times the large PET Plus pot is opened and thereby protects the contents from damp air.