Now if it has been a week, we do need to be proactive here for Tyson. If this is only happening when given people food or his dog food, then we'd be wary of a possible pancreatitis. Though other causes for what we are seeing include bacterial or viral gastroenteritis, parasites/protozoa infections, general dietary indiscretion, and harmful ingestion (hopefully less likely but a concern if perhaps wet food is all he can pass beyond something he may have in his stomach).
With this all in mind, we can try some home supportive care to try to settle his stomach. To start, if he hasn’t just vomited (since otherwise we’d need to rest his stomach for a few hours first), then you can consider treating him 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),Tagamet (More Info/Dose Here @ http://www.petplace.com/article/drug-library/library/over-the-counter/cimetidine-hcl-tagamet)]. 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 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.
Afterwards, you can consider starting 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. As long as improvement is being seen, I usually advise continuing this until signs are settled, and then weaning slowly back to your normal diet.
Overall, Tyson's signs do raise some concerns and its possible the plant is involved (may cause GI upset) but the others are more of a concern at this stage. Therefore, we’d want to start supportive care to settle his stomach but plan to keep him away from that plant just in case. If he cannot keep that or water down at any point, appears dehydrated already, or doesn’t respond to the above within 12-24 hours; then we'd want to get his vet involved. They can assess his hydration, rule out fever, make sure there is nothing in his stomach that shouldn't be there or any sinister viruses present. Depending on their findings, his vet can treat him with injectable anti-vomiting medication +/- antibiotics to settle his stomach, and get him back feeling like himself.
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