As mentioned above, the very serious issue of stomach blockage can cause a dog's breath to have the odor of feces, however eating poop
(Coprophagia) can be the more simpler explanation.
Coming to this conclusion can be a bit tricky if a owner does not see their Pug doing this. However, if a Pug is left home alone, he can have a bowel movement and ingest the evidence, leaving owners to have no clue.
In other cases, if a Pug is being walked or allowed to play in the yard, while it may appear that he is sniffing the ground, he may be eating the feces of other dogs.
How to fix this:
Animal behaviorists and veterinarians alike have various ideas about why dogs do this. Lacking certain vitamins, minerals and nutrients is one popular theory. This may have some truth to it, since low-quality foods are often packed with fillers, which are empty ingredients that pass right though the body and are thought to leave a dog craving more….
And if food is not available, a dog may resort to ingesting feces… in many cases it may be that of a different dog, one that has eliminated food of a different brand.
Another reason may be habit; though some theorize that a dog may eat his own poop to cover up the evidence of a housebreaking
accident, it is more likely that a bored dog eats the poop and in doing so, it becomes a bad habit.
When outside, keeping a close eye on your Pug is a must. Having him on a harness and not a collar, you can quickly move him away from the feces without injury to the neck, before he mouths it. Of course, never allow your Pug to roam the yard (even if it is fenced in) alone; he should always be supervised.
When indoors and having the issue of a Pug doing this when home alone, one effective method is to use a supplement that has no flavor when it goes in, but during the digestive process it adds a terrible taste to bowel movements on the way out. Some top rated products will also freshen a dog's breath.
#7 Foreign object.
Dogs are incredibly curious by nature and for this reason, it is not uncommon for them to mouth things simply to discover what they are, even if eating it is not an intention. This, unfortunately, can lead to non-food objects being swallowed but also can lead to pieces of an object becoming lodged in the mouth or stuck between teeth.
If this happens, the body will react by increasing saliva, which can lead to drooling and is oftentimes mixed with a small amount of blood due to tissue being pierced.
The longer the object is stuck in the mouth, the more of a bad smell it will produce. In some cases, if it has been there for more than a day, infection can set in which can cause an even stronger case of bad breath.
How to fix this:
It is best to have a look in the Pug's mouth by using a flashlight and with the assistance of a helper, since most dogs will not 'open up and say Ahhhh'. If you can spot the culprit, you'll have to make a judgement call as to whether it is feasible to remove it.
Objects that are only stuck between teeth may be able to be removed by using a thin, dry washcloth and with two fingers on either side, doing a firm downward or upward sliding motion.
Thick floss may also be used for some issues. In other cases of an object being stuck like a splinter, it is best to have a veterinarian handle this, since removal of the exposed portion may still leave pieces in the oral tissue.