Hello & welcome, I am Dr. B, a licensed veterinarian and I would like to help you today. I do apologize that your question was not answered before. Different experts come online at various times; I just came online, read about your wee one’s situation, and wanted to help.
Again I do apologize that my colleagues could not aid you sooner, but I wanted to touch base with you about Zeus.
If he has developed signs of colitis (the mucus/blood in stool) this may be inflammatory, in reaction to his medications, or a secondary bacterial infection. And as colitis can cause nausea (likely what is behind the gagging, appetite loss, and slime he is bringing up), we do need to tread with care. Now give that he is already struggling with Valley fever, we are best to ring his vet as soon as they are open to get him onto treatment (antibiotics, injectable anti-nausea medication, appetite stimulants) +/- check a stool sample to ensure we get these signs settled as quick as we can.
In the meantime, we can try supportive care. To start, to counter nausea, we can try him 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 a known health issues or is on any other medications you haven't mentioned.
Afterwards, you can try an easily digestible diet like cooked white rice with boiled chicken, boiled white fish, cottage cheese, scrambled eggs, or meat baby food (as long as its garlic/onion free). There are also OTC vet diets that can be used (ie Hill’s I/D or Royal Canin’s sensitivity) 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. If his stools are quite loose, fiber (ie canned pumpkin) and OTC probiotics (ie Benebac, Fortiflora) can be added to these meals to firm those loose stools quicker and support digestion.
Finally, as dehydration is a risk in these situations, do keep an eye on his hydration. To check that, there are a few things you can look for. Besides gum moisture, make sure his eyes aren't sunken and that he doesn’t have a "skin tent" when you lift the skin. To see how to check those dehydration signs, here is a good video ( http://www.ehow.com/video_12232503_dog-dehydrated.html ) to look at. If you do see any signs of dehydration already, that's our cue to have him seen before this becomes an additional issue (especially as it is often dehydration that makes them feel unwell).
Overall, Zeus's signs do raise some concerns here. Therefore, we’d want to start the above supportive care now. If he doesn’t respond to the above within 12-24 hours; then we'd want to get his vet involved. They can assess his hydration, check for the above and start appetite stimulants, injectable anti-vomiting medication +/- antibiotics to get him eating for us.
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