First, I have to warn you that you are at a height where we can see altitude sickness in dogs. GI signs are normal with this but we can also see changes in breathing, paling of the gums, elevation of the heart rate, coughing, dizziness, collapse, and even build up of fluid in the lungs. So, we need to be very careful here. That said, we can also see vomiting with poorly timed bacterial or viral gastroenteritis, pancreatitis, parasites/protozoa infections, general dietary indiscretions, and ingestion of harmful items (ie toxins, plants, non-edible items). And if this started in Las Vegas when she ate something unknown and she has a sore belly, then we'd be especially worried about that here.
With this all in mind, if she cannot keep water down, this is a tricky situation. This is because dogs that nauseous often need injectable treatment to break their nausea cycle. Though if she hasn’t just vomited (since otherwise we’d need to rest her stomach for a few hours first), then you can consider treating her with an antacid. Common OTC pet safe options would be: 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), or 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 food to allow absorption. Though I would note that if you give this and Lenny cannot keep it down due to nausea that is usually a red flag that we need to bypass her mouth with injectable anti-vomiting medication from a local vet (You can find one via http://www.vetlocator.com/) . And given the height you are at, you will need to think about dropping below 8,000 feet or even cancelling the rest of the holiday if she continues to show signs (especially if any of those other signs arise).
Though if we can get her steadier in her stomach, then you can consider starting her on a 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). 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 the signs are settled, and then weaning her slowly back to her normal diet.
Since dehydration is a risk with Lenny's severe vomiting, we need to keep an eye on her hydration. To check that she isn't dehydrated, there are a few things you can test. Further to checking for gum moisture, do make sure she doesn’t have sunken eyes and that she doesn’t have a "skin tent" when you lift the skin. To see how to check these parameters for dehydration, you can find a good video HERE (http://www.ehow.com/video_12232503_dog-dehydrated.html). If you are seeing any signs of dehydration already, then that would be our cue to have her seen before this becomes an additional issue for her (especially as it is often dehydration that makes them feel unwell).
Overall, there are a wide range of agents could trigger this GI upset we are seeing but you are at a height where the altitude is another concern. Therefore, we’d want to start supportive care to settle her stomach. If she cannot keep that down, appears dehydrated already, or doesn’t respond to the above within 12-24 hours; then we'd want to get a local vet involved. They can assess her hydration, rule out altitude sickness and its more severe life threatening signs, make sure there is nothing in her stomach that shouldn't be there or any sinister viruses present. Depending on their findings, her vet can treat her with injectable anti-vomiting medication, fluids, +/- antibiotics to settle her stomach, and get her back feeling like herself.
All the best,
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