Yes you can develop allergies to dogs at a later time in life especially if you were not around pets as a kid.
Most kids who've been raised around pets and dogs tend to not have the dog or pet allergies as an adult but there's no guarantee of that.
Sometimes the dog allergies or other pet allergies may run in the family so if someone else in your family was or is allergic to dogs then you'll likely be allergic to dogs as well and it can also develop later on in life too.
Having dog allergies is mostly just a nuisance and the good news is that dog allergies are not harmful enough to cause death like some other allergies.
Unless you have some other health issues then it might be possible to die from dog allergies but very unlikely.
If you suffer from dog allergies then the best thing to do no matter how hard it is would be to find another home for the dog you're allergic too.
Because although you may love the dog it's not worth suffering through the allergies because you can't really give the dog enough attention or find much enjoyment in the dog when you're constantly suffering from the dog allergies.
Most people who are allergic to dogs usually experience hives, sneezing, itching, and trouble breathing when coming into contact with a dog they are allergic too.
If you remove the dog and your allergies go away then it's the dog causing the dog allergies and you should try to find a new home for the dog you're allergic too.