@elbrant - here is one site, but if you search the internet you can find lots of information on Titers..https://dogtime.com/dog-health/51773-titer-testing-dogs#:~:text=A titer test is a blood test that,body can use to fight off future infections.
Ask your Vet about them, if they don't/can't tell you the information, IMO, find a new Vet. Benefits are that we are not over vaccinating our dogs. And yes they are a bit expensive, but my vets tell me how long the Titers will be valid depending on the antibodies found. That said "I" never do this for rabies... that is the law and I would never/ever take the chance that a bite by accident would take place, because if it requires Dr visit for the human and your dog is not up to date on Rabies, that would be a very, very big problem. So I do rabies as required ever 3 yrs... Benefits are that you are not over vaccinated your dogs that they have the required antibodies. And yes there are dogs, including Basenjis that have issues with Rabies shot that have other medical issues, this needs to be discussed with your Vet (not including the sometimes issue with a small reaction to the shot) but if that is an issue you need to carry proof from your Vet on why Rabies has not been given. Note that there are many Animal Control services in the US will not accept/respect these, but it is the first course to take...Most Vets these days understand that value of titers, some don't. This means owners need to do their research and talk to their breeders, provided they have gotten their pup from a responsible breeder, again a very important thing to do. In the end you need to do the research...