There are quite a number of things that could be going on here from an acute gastroenteritis (from getting into the trash, or something he shouldn't have - or even from raw meat - particularly if it was chicken), a toxicity or something like an obstruction (partial or complete within his bowel) . If this has been going on all day and your dog has not had anything to eat or drink, then I would definitely encourage you to get your dog examined at your local Vet or emergency vet. It is much better being safe than sorry in these situations as there could be a myriad of things going on here and only a full Veterinary physical examination can help pinpoint the cause of the problem in order to instigate a treatment and of course set your mind at ease and give your Shih Tzu boy some comfort from todays events! if other dog's you know he has been around have had a similar problem then it is most likely he has an acute infectious gastroenteritis.
Mucus membranes - flip his lip and look at the color of the gums. They should maintain a nice salmon pink color. Get your dog to the emergency Vet if they appeal white or very pale pink, or if they are a dark deep red color.
Capillary Refill time - this measures blood perfusion and test this by putting your thumb on his gum to apply pressure. After you release your thumb you will see the gum blanch. Capillary refill time is the amount of time it takes (in seconds) for the gum to return to a healthy pink color from the blanced white color. If 2 seconds or less don't worry - if it is taking significantly more time, again - off to the emergency Vet.
Respiratory Rate - if he is continuously panting throughout the night this is a sign of shock and or pain and a signal for a trip to the emergency Vet.
Please get in touch with your Vet or emergency Vet if these symptoms are ongoing or if you are overly concerned about your dog's current state of health. Please keep in touch and let me know how you get on. In the meantime, continue with bland food only - chicken and rice and plenty of fresh water.
I hope this has been of help to you and do try and get some sleep tonight. If you can't sleep because you are worried - this is enough for me to tell you to visit your emergency vet now.
Thank you and please now click ACCEPT.
Dr M D Edwards