Titers are blood tests. They check a cat’s (or human’s) immune status to vaccinations or disease which a cat may have received or suffered in the past.
If a titer result is positive the cat or human has sufficient immunity to a particular infectious disease. In which case the cat does not need a vaccination for that disease. To put it another way titer testing tells pet owners if a previous vaccine (or the body’s natural immunity) is still protecting their cat (or dog). It does this by measuring antibodies in the blood.
I have never heard about a veterinarian informing their client that a proposed vaccination may harm their cat and to ask if she would like a titer done to find out if a vaccination is needed.
In fact, I had never heard of titters in relation to vaccinations until today. By contrast, we have all heard about over vaccinating of cats. It occurs less often these days but is still a source of concern to many informed cat owners.
Apparently nowadays there are titer testing kits which are relatively inexpensive. The test can be carried out in house at the clinic rather than at a laboratory. This speeds things up and restrains costs.
If titer testing tells us if our cat needs a vaccine why aren’t these tests carried out routinely rather than the vaccination? There must be two reasons: the extra cost and time involved and the loss of revenue from automatic booster vaccinations and ancillary selling of services. I don’t believe that these are worthy reasons. There may be a third reason: titers don’t provide a guaranteed test as to whether a cat has sufficient immunity against a certain disease. This is what your vet will probably say.