My 15 yr old dachshund is in heat has never acted interested in the males before this year and is secreting something all over her bed sheets and how long will she "go after the males". Thank you so mucj

Time for the vet. She could have a tumor that is messing up her hormones (IF she is actually 'going after males). A 15 year old dog of any size should not be going into heat this late in life.