I accidentally poked my dog's stomach under the muscle. Should I be worried?

Typically no this cannot cause internal bleeding. It would take a severe blunt forced traumatic event (stabbing, hit by car, falling off high surface, etc) to cause internal bleeding in a pet. However, with that said I wouldn't push your luck and just start poking your pets belly just for the sake of doing so.

There is a chance that could happen to Jim, but if you didn't close the door hard on his stomach, then it is not likely. You can monitor him for now, and if his stomach appears tender or he acts as if he is in pain, you can take him into the vet for a health check.

It's hard to tell from the pictures, but it looks like there might be a small puncture near the bruised area? This would mean that Rosie was bitten on the abdomen. These types of injuries could be associated with internal damage, and should warrant immediate veterinary care. If there is no wound, then I would still be concerned about the sudden appearance of a bruise. Bruises can form if there is a bleeding or clotting issue or internal bleeding.

if Jaxx is otherwise acting normal, eating, drinking, urinating and defecating normally, and no bruising along the belly then there isn't anything to worry yourself over. He likely will be just fine. If you however are overly concerned then a quick exam by your vet can be done to clear him for any major injuries. Best wishes and I hope everything works out well for Jaxx.

The stomach can get hard from internal damage or severe pain. if Jax seems to have a hard stomach and he isn't himself then you should take him to the vet ASAP in order to get it checked and make sure he isn't injured.

Oh no, poor Lioh! I see your post was about six hours ago, and if Lioh is in pain, having trouble moving or breathing, or is very lethargic, then I would have him seen by an ER vet immediately. If there isn't an ER vet clinic in your area, then there will be a vet on call for emergencies. The information to find that vet is found on a clinic's answering machine or website. If Lioh is behaving normally, eating and drinking, and going to the bathroom normally, then he is likely fine :-)

This very localized lump could be due to a trauma and inflammation/exudation of fluid under the skin in between muscles. Unfortunately it is diffiuclt to be more specific than that without having a feel during physical examination. I would recommend an immediate check up to confirm this clinical suspicion and treat accordingly. Please do not hesitate to contact us again on the forum or by requesting a consultation if you have any more questions or to discuss it any further.