Hello, my name is***** and I have over 20 years of experience as a veterinarian. I am sorry that you have been waiting for a response, but your requested expert isn't online which delayed your question coming up on the list for all to answer. I would like to help if you are still interested in an opinion.I am very concerned to hear that your girl isn't moving, is lethargic, has pale gums, and is breathing hard.Unfortunately her pale gums and weakness point toward shock and poor oxygen exchange. That can be related to a uterine infection (pyometra) if she isn't spayed, a bleeding
abdominal tumor, or exposure to anticoagulant rodenticides or tick borne diseases and internal bleeding. It could be related to poor red blood cell production or heart disease
. Common cancers in dogs that cause low blood pressure and bleeding in the abdomen are hemangiosarcoma of the spleen and lymphoma
. Both can invade the abdominal organs and lymph nodes. These tumors
can press on the stomach
and intestines and make them feel full or, especially the hemangiosarcoma, bleed with increases in blood pressure which would make her feel lethargic and explain her weakness. As sick as she is now I think an emergency examination, some blood tests, some radiographs of her abdomen, and an ultrasound of her abdomen are great places to start. It will allow them to look at organ structure and lymph node or internal organ changes and collect aspirates of any abnormal areas. Radiographs are pretty good at looking at organ size and placement, and seeing big changes, whereas an ultrasound will allow visualization of more subtle changes.Ideally she needs to be seen on an emergency basis tonight.There isn't really anything that you can do for her safely at home today to help her.Waiting to treat is not a good idea as my concern in a dog with pale gums and signs of shock is that she may not make it until tomorrow.Please let me know if you have any further questions.