First, we have to be very careful with Dingo. Diabetics are very delicate in situations like this and we need to act quickly here. This is because while this sounds suspicious of a bacterial or viral gastroenteritis, pancreatitis, parasites/protozoa infections, or possible ingestion of harmful items (thankfully less likely); his diabetes make this a much more precarious situation.
Therefore, further to use of the icecream to increase the blood sugars, if he is weak and lethargic at any point, we can try boosting his blood sugar by rubbing a sugary syrup (ie glucose syrup, honey, karo syrup, pancake syrup, or even non-grape jam) onto the gums. Afterwards, since he is starting to keep bits of food/water down, we can try to counter his nausea with an OTC pet safe antacid [ie Pepcid (More Info/Dose @http://www.petplace.com/article/drug-library/library/over-the-counter/famotidine-pepcid), Zantac (More Info/Dose @ http://www.petplace.com/article/drug-library/library/over-the-counter/ranitidine-hcl-zantac)]. Whichever you choose, we’d give this 20 minutes before offering food to allow absorption. Of course, do double check with your vet if he has any other known health issues or is on any other medications you haven't mentioned. Though if he cannot keep it down due to nausea that is usually a red flag that we need to bypass his mouth with injectable anti-vomiting medication from his vet.
Once he is more settled, your light diet is good.Just to note some other protein options, you can also use boiled white fish, or scrambled eggs, or meat baby food (garlic/onion free only) There are also OTC vet diets (ie Hill’s I/D or Royal Canin’s sensitivity) that can be used too. The aim of these diets is that they will be better tolerated/absorbed by the compromised gut. Therefore, it should get more nutrients in and result in less GI upset and less risk with his diabetes. As long as improvement is being seen, I usually advise continuing this until the signs are settled, and then weaning slowly back to what you normally feed.
Finally, since this sounds more like blood due to diarrhea induced inflammation to the colon, we can try to reduce his diarrhea via a pet safe anti-diarrheal. As I am sure you appreciate, these would not be a cure for infectious issues; but it can still be of benefit. It will reduce diarrhea load, allow the body to absorb more water/nutrients, and soothe the upset gut. In regards ***** ***** options, the one we most commonly use is OTC Kaolin/Kaopectate (More Info/Dose @ http://www.petplace.com/article/drug-library/library/over-the-counter/kaolin-and-pectin-kapectolin-k-p)). Avoid Imodium or Pepto Bismol here. Otherwise, Propectalin, Canikur, Fast Balance, and Protexin Pro-Fiber (which is available OTC at vets, pet stores, and even Amazon) would be another option. All will slow diarrhea and those last ones have the added bonus of providing support to the delicate good GI bacteria. So, these can be used as a short-term means of soothing his upset GI.
Overall, a wide range of agents could trigger the signs we are seeing but given the other dog having had signs infectious agents and common exposures would be our main concerns. And with his diabetes he is just much more fragile then the other dog, so we’d want to start supportive care to try to settle his stomach. Though if he cannot keep that or water down, appears dehydrated already, or doesn’t respond to the above within the next few hours; then we'd want to get his vet involved. They can assess his hydration, rule out fever, ensure and start injectable anti-vomiting medication +/- antibiotics to settle this and get him back feeling like himself.
Just in case you need a local emergency vet, you can check @ http://www.vetlocator.com/ or via https://www.veccs.org/facility-directory/
Please take care,
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