Hello, my name is***** and I have over 20 years of experience as a veterinarian. I am sorry to hear that Lily is not herself today, vomiting clear liquid with a little foam, loss of appetite, and experiencing some head shakes.
Her vomit sounds like esophageal or stomach mucous, some of it mixed with air as she retched which would produce the foam.
Has this been a relatively normal heat for her?
Did it seem to come sooner than was expected?
Is her bloody vulvar discharge seemingly thicker or lasting longer than usual, compared to her previous heats?
Is she more lethargic than usual lately?
Is she drinking more water than usual?
These symptoms may point to a uterine infection called a pyometra. Pyometras can rupture, causing peritonitis and/or the infection can spread to her other organs leading to abscesses in her kidneys, liver spleen and even her heart valves. The toxic metabolites from the infection affect her appetite and cause her to vomit. These pups are also usually drinking more water than usual due to the toxins from the infection.
Fever, or changes in electrolyte levels as well as toxins from the bacteria can lead to tremors.
If this is a pyometra the sooner that this is addressed the better chance she has of doing well. Treatment is stabilizing her with intravenous fluids and antibiotics and surgery to remove the infected uterus. The longer that you wait the more opportunity this infection has to spread, and thus more difficult it will be to treat her. I recommend that you have her seen as soon as possible by her veterinarian.
There are other reasons for a lack of appetite and vomiting, including eating something they should not, too much table food, too many treats or something they find outdoors.
More serious causes of vomiting at this age include toxin ingestions, viral or bacterial infections, a dietary allergy or sensitivity, inflammatory bowel disease, internal organ failure (kidney or liver disease), Addison's disease, or a full or partial gastrointestinal obstruction.
In a young dog, especially if she never finished her vaccine series, a viral infection such as parvo virus, eating something that didn't agree with her, or a foreign body leading to a partial or full gastrointestinal obstruction would be the most likely causes. But when we have signs that a heat isn't normal we do need to consider a pyometra too.
Because she isn't eating and is still vomiting ideally she would see a veterinarian now.
If that isn't possible for whatever reason there are some things we can try at home, but if she's not improving quickly she should see a veterinarian for an examination, some diagnostic testing, intravenous fluids and injectable medication to settle her stomach.
To try and settle her stomach you can give either:
1) Pepcid ac (famotidine) at a dose of one quarter of a 10mg tablet per 5 to 10 pounds of body weight every 12 hours
2) Prilosec (omeprazole) at a dose of one quarter of a 20mg tablet per 10 to 20 pounds of body weight every 24 hours
These are acid reducers and may help settle her stomach and get her feeling better and hopefully get her appetite back.
They can be given for several days if necessary.
I would pick up all food for now and water for a couple hours to allow her stomach to settle after the acid reducers.
In a couple hours when you give water make sure it is in small amounts only. If she drinks too much too quickly that can lead to vomiting. You can also offer ice cubes to lick. To get some electrolytes in you can offer her a 50:50 mix of pedialyte and water.
If there is no vomiting for 12 hours offer a bland diet of 1/3 boiled, minced, white skinless chicken or boiled, lean hamburger and 2/3 boiled, white rice mixed with some low salt chicken or beef broth to make it easy to lap up and swallow. If she refuses that you can offer a little meat baby food. If she refuses both then don't push it, she needs veterinary care.
But if things go well and she does eat and doesn't vomit feed her the bland diet for 2 to 3 days then slowly start to mix back in her regular food, a little more at each meal. It should take about 5 to 7 days to slowly convert her back to her regular diet.
If she continues to vomit even with the acid reducers, runs a fever (more than 103F rectally), or has a lower then normal temperature (less then 99F), has a tense painful belly or if she refuses to eat she should see a veterinarian for an examination, diagnostics, injectable anti-nausea drugs intravenous fluids and supportive care.
Please let me know if you have any further questions.