I work three days a week four hours a day,and my 4 month old shih tzu hates being alone... if he's in his carrier at home while I'm at work he poop/pees in there every time,but if people are around when he's in his carrier he has no accidents... what should I do?

He's a baby - no surprise that he bathrooms in his crate.

When you say carrier, do you mean crate?

Carriers are for carrying, not cooping an animal in for hours!
Give even a tiny dog at least 3 feet in any direction. You can buy a wire crate or put up barriers around an area he likes, such as the living room, with toys, blanket, water, and pee pads if he still isn't housebroken. A wind up Baby Ben alarm clock has worked for many people, the ticking noise is soothing.

He should be totally housebroken by now and if not and you want to know what to do, answer back.

I've had any number of dogs over the years and I've had dogs that were not housebroken at 4 months. Housebroken "most of the time" but not "all of the time."

I like this site which says, "A trustworthy housebroken dog will not eliminate in the home at anytime. Most dogs do not reach this control and understanding of the rules until they are 9 to 18 months of age. And that is only if they have been on a good crate training and house training schedule from day one."

The Dog Training Company, LLC

Of course, maybe your dogs are smarter than my dogs...

It does sound like he realizes when no one is around and has a bit of an anxiety attack.

When you kennel him when you are getting ready to leave, do not do anything differently than you do when someone is still in the house. Dogs like toddlers don't really understand 'good byes'. Do make changes to your routine. If you normally kennel him and then get your things together, get your things together and then put him in the kennel. If you usually leave by the front door, if possible use a back or side door instead. You get the idea.

You can try leaving a radio or TV on to simulate people being around. Since he should be getting close to teething, if he hasn't started already, make sure he has toy he can chew on. Kong is one brand of several that stand up well to teething puppies. The ones that hold treats can also be a good distraction.

Training is where you are going to have to put in the work and it will take time. You need for him to understand that he isn't being abandoned when people leave. Since he is okay while people are there, start with kenneling him and doing what you normally do. After a while go outside and then come back in (try not to be outside long enough for him to potty.) If he is jumping around or acting up, wait until he calms down to let him out. Keep repeating those steps. As he stays clean, lengthen the time that you stay out of the house.

It is going to take time (days to weeks at least) and the whole household working together to see results.

Thanks for the help! If I were to use puppy pads will he think its OK to only go on puppy pads and quit going outside?

It might not cause him to stop going outdoors, but he may not see the difference between a puppy pad and the floor.

What method have you been using for potty training him? When he is out does he have accidents?

If you have an area that he can safely be 'penned' in while you are gone, you might see if he has less of a problem being left alone in a 'pen' while you work on the kennel training.

I am still waiting to find out if we're talking carrier, crate... or possibly a pen.

I don't recommend puppy pads at all. They only lead to confusion, and make house breaking harder. If it's okay to pee on the floor on something laying around, then why not a pile of clothes, or a towel or even the carpet.

My pup would urinate in his trolley every time we left him alone.
I started leaving him in the kitchen (blocked off to the rest of the house with a baby gate) and we have had no more accidents.

Sounds like separation anxiety. 4 month old puppies can show anxiety.

Separation anxiety is tough to beat, especially when they exibit this behavior at such a young age.

While your home, put him in his crate and do everything like you're getting ready to leave... Then come back. Then do it again.. and come back. Show your puppy that you always come back.

There are also herbal medications out for anxiety, such as Rescue Remedy.. it just kind of takes the edge off.

If that doesn't work, there are some medical anxiety meds also. Since he is so young, I would suggest the herbal stuff first and see if it helps. Anxiety meds can be hard on the liver and kidneys.

You're going to have to work with his anxiety the same way you would work with him with obedience.

Good luck