First, I am glad to hear that she isn't likely to have eaten something harmful. Though I am concerned to hear that her signs have been ongoing for such a period of time. As well, it sounds like we have more than one issue present now. The urinary blood raises concerns of a bladder infection, but if her urine is pale and she drinks excessively, then it is quite possible that the bladder infection and even her anorexia (which is likely to the same nausea that caused her to vomit) are due to a systemic issue (ie kidney or liver disease, pancreatitis, hyperthyroidism, diabetes, etc). As well, we cannot rule out a secondary opportunistic bacterial or viral gastroenteritis for those GI signs.
To complicate matters, we get very concerned for cats who go off their food (and this is getting worrying here) because cats were not well designed for the anorexic lifestyle. When they are off their food, body fat is broken down and released into the blood stream, causing their liver distress (ie. hepatic lipidosis) that can make getting them better even more difficult for us. Therefore, with the length of time she has had signs, we'd be best to have her seen at this point and have a geriatric blood test to see if those systemic issues are present so we can address them for her. As well, at the same time, her vet could start antibiotics for infection, anti-nausea medication by injection as well as appetite stimulants to get her eating properly.
Any delay and we'd need to start supportive care to break her fast. To do so, we can try her with an OTC pet safe antacid like Pepcid (More Info/Dose @http://www.petplace.com/article/drug-library/library/over-the-counter/famotidine-pepcid), 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. Of course, do double check with your vet if she has a known health issues or is on any medications you haven't mentioned.
Once that has had time to absorb and she is steadier on her stomach, you can consider tempting with an easily digestible diet like boiled chicken, boiled white fish, 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 the signs are settled, and then weaning her slowly back to her normal diet.
Since dehydration is a risk here, 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). And if we can keep her drinking (water, catmilk, low salt chicken broth) that would help flush her bladder and keep that side of her signs comfortable.
Overall, there are a wide range of agents could trigger this GI upset we are seeing but with all you have told me I am worried we have a bigger underlying issue. Therefore, we’d want to start supportive care to settle her stomach. If she 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 her vet involved. They can assess her hydration, test bloods, make sure there are no sinister lumps 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, appetite stimulants, and fluids +/- antibiotics to settle this and give her the best chance of recovery.
All the best,
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