Friend, she is not constipated if she has diarrhea. It sounds like her colon (large intestines) is inflamed, for this reason, she is straining. The drooling is secondary to the abdominal issues that she is having, she could be nausea. This can be caused by many different medical conditions. It will be difficult for me to determine the exact underlying cause without a hands-on examination and some testing. But, common causes are: Dietary indiscretion, ingestion of a foreign body, infections, or even part of a systemic disease to name a few causes. I am a bit concern that she is lethargic, I would want to rule out the ingestion of a foreign body. For this reason I would recommend having her checked tonight by ER veterinarian for a hands-on examination. If you do not have access to ER veterinarian I am going to make some recommendations that you can try until she is seen by family veterinarian:
1- Do not give things like Pepto Bismol or Imodium. Start her on Pepcid AC (famotidine) 10mg 1/4 tablet every 12 hours. You can buy pepcid ac over the counter in any pharmacy.
2- No food or water for 6-8 hours, need to give her gastrointestinal tract time to rest. Then, offer a small amount of water followed by a diet of rice (75%) and boiled boneless chicken or ground beef (25%) until the stool is back to normal then wean her back into the regular diet. Keep her indoors in a cool room and no exercise when fasting.
3- Supplement with a probiotic, these are friendly bacteria that help with regularity. You can buy this over the counter in any pet store.
4- Follow up with your family veterinarian for a hands on examination.
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