the problem with these calculations is that they're based on pedigree, not genetics. If you're only studying 3-5 generations of pedigree, the COI might look REALLY good, but the animal can still be a genetic mess because those 3-5 generations all had a common (or multiple common) ancestors in generations 6-7.

The point is though that most dog breeds are already too inbred .

I.e. even if your particular dog isn't inbred according to some particular measure - the entire dog breed are already way too much inbred and have very little genetic diversite. Leading up to most dogs of that breed having multiple deficits.

(I don't know if that applies to dachshounds though - in general it applies less to dog breeds used for utility)

I think some pure breeds, due to their slight inbreeding by design, are going through "inbreeding depression". Probably because some breeds just don't have that large of a gene pool to start with.

[0] https://breedingbusiness.com/inbreeding-depression/