Well, first off, people are wrong... :lol: LOTS of dogs pee on their bed for many reasons. Dogs with a UTI will often choose someplace soft like a bed so this should be ruled out. Also dogs sometimes simply like the rich smells of a place where all are sleeping and will soemtimes pee on your own human bed, or a dog bed, especially when a pup -- or adults may do this as a reaction to having a new pup in the house as well. Or they may be marking it out as part of their territory. One may be submission peeing, especially a puppy mixing with adults (and your pup is just a tiny baby still, in dog terms!). Along the same lines, a 4.5 month old puppy will be very far from being housetrained so could easily be the culprit.
Also you may simply not be getting the pup out enough or at the right time (first thing in the am, last thing at night, after drinking, after eating, after a nap, after playing). A pup that age will likely need to be taken out every 2-3 hours, rewarded thoroughly for doing its business outside, and a person should always go out with the pup -- don't let him go in and out on his own and assume he is doing his business outside as at this age he needs structure, guidance and praise and rewards, every single time.
But here's the main issue I think: The basic rules for puppies are **they should never, ever be beyond arm's reach and under constant watch unless you have the pup crated**. Otherwise puppies frequently will backtrack on housetraining and every time they get a chance to pee inside, this is one small step back in housetraining overall. In other words -- you should be able to be absolutely sure it *isn't* the puppy that is peeing in the bed as if you can't be sure, the puppy has way too much freedom.
A good rule of thumb is to assume a dog will not be reliably housetrained til about one year old. Not until about 6 months will most be reliable within say a *single* room in the house. The puppy then needs to be housetrained, under the same eagle eye, for every single room in the house as it will not make any association between keeping one room clean and your desire that it not go anywhere else in the house (a 'house' is not a concept a puppy is going to understand -- it is just a huge expanse of spaces and as far as it is concerned, just because it knows not to go in the kitchen won't mean it understands that means the living room or bedroom, too). Thus a dog under one shouldn't be allowed to roam at will through a house.
Here's what I'd do:
1) have your dogs checked for UTIs if you cannot verify that it is the puppy that is peeing in the bed
2) keep the puppy under constant watch
3) either throw out the bed or wash thoroughly using enzymatic cleaner or the peeing cuplrit wll keep marking the same place (eg peeing in the bed)
4) Buy Shirlee Kalstone's excellent book on housetraining your dog in seven days, a classic
Good luck! :xfngr: