I've been seeing them on the forum, but not sure what they are. Do they test different levels of things in urine? Are they good to have on hand? Thanks
Test strips can be used to test for blood and protein (i.e. infection) in the urine. The problem is that they won't contribute to the healing process. Urinary tract issues like IC are often connected with off and on blood in the urine and repeated acute infections. Testing regularly won't change that. It is also worth noting that guinea pigs with urinary tract problems can have intensely red urine, which looks like blood, but it isn't; it is just oxidation, but you can have blood in next clear pee.
If you have a tendency of being overprotective or have anxiety/obsession issues, test strips can open a whole new dimension of obsessive testing and panicking for you! In this case I would most strongly recommend to stay off them. Scales can be bad enough with some members flying in a panic if a piggy is just the odd gram off (not counting that the weight swings around 30-40g in the course of 24 hours; but trust me, there is nothing like testing with strips to set you off!
When your whole life starts turning around looking and testing for health issues, you know that you have lost the joy that your piggies should bring you. There is a line with keeping a casual eye out for potential trouble and actively seeking for trouble. If you have mental health issues, it is all too easy to cross into second and make things a lot worse for yourself and those who live with you and love you.
Personally, I don't use test strips. If I have a suspicion that something is not quite right, I take my piggies to the vets and have them tested (and if necessary treated) there. If I have a piggy with IC (and I have had several), I just treat the acute phases and otherwise leave be. IC eventually goes away on its own, but at the moment we cannot cure it. It is in the end as effective, but a lot less hard on the nerves.
