Hello, my name is***** and I have over 20 years of experience as a veterinarian. I am sorry to hear that Lucy is eating poorly for the past few days after getting into the garbage and eating some things that she should not have.
Chocolate can be toxic, but they must eat a certain amount per pound of body weight to get sick. Symptoms of toxicity range from nausea, vomiting, diarrhea, tremors, an elevated heart rate, hyperactivity, seizures, coma and death. They generally get sick within 4-8 hours of ingestion, and if they don't eat enough to cause seizures or extreme heart rate and rhythm changes then they improve over 24-48 hours and should be back to themselves in 2-3 days. Her symptoms don't really fit with chocolate toxicity and are lasting longer than I would expect them to.
Grapes are toxic, but again a certain amount per pound must be eaten.
Toxic symptoms from ingesting grapes include nausea, vomiting, diarrhea, then increased water consumption, lethargy, and kidney failure in dogs. Some dogs are more sensitive than others but a toxic dose is usually 3 grapes per kilogram of body weight (3 grapes per 2.2 pounds).
In very sensitive dogs they report that dangerous doses begin at about 0.18 ounces of grapes per pound of dog weight. There are about 5-6 medium grapes per ounce. That’s 1.8 ounces (ten grapes) for a 10-pound dog, and 3.6 ounces (20 grapes) for a 20-pound dog.
If you think she ate enough grapes to cause toxicity then she should see her veterinarian to have bloodwork and urine checked to look for signs of kidney failure, which should be present by now.
I'm not sure what to make of her cough. It may be related to acid reflux from eating something in the garbage that irritated her stomach. It may be related to primary heart disease or lung disease. She is a bit older so either one would be possible, and both would suppress her appetite.
A cough simply means she is experiencing airway irritation.
A cough can be related to heart disease, including heartworm, lung disease secondary to a viral, bacterial, fungal or parasitic infection or tracheal irritation due to a bacterial, viral or fungal infection.
The most common cause of a cough in dogs that do not have heart disease is infectious disease. Of those kennel cough or infectious tracheobronchitis is one of the most common causes. If she was exposed to other dogs recently (boarding kennel, dog park, groomer) ago kennel cough would be high on my list of possible problems. And if they run a fever and get sick enough their appetite will be suppressed.
At this point because there are several possible causes of her symptoms, some very serious like kidney failure from eating grapes or heart disease, it is best that Lucy see her veterinarian today. This has been lingering too long, past the normal 24-48 hours that we normally see with simple stomach upset.
At home now to try and settle her stomach you can give either:
1) Pepcid ac (famotidine) at a dose of one 10mg tablet per 20 to 40 pounds of body weight every 12 hours
2) Prilosec (omeprazole) at a dose of one 20mg tablet per 40 to 80 pounds of body weight every 24 hours
These are acid reducers and may help her feel better. They are quite safe and can be used for several days if necessary.
A couple of hours after giving the acid reducer I recommend offering soft foods mixed with water to make eating and swallowing more comfortable.
If she is refusing to eat even soft foods you can try offering meat baby foods or a bland diet of 2/3 boiled minced white skinless chicken and 1/3 boiled white rice mixed with some low salt chicken broth to make it easy to lap up and swallow.
Please let me know if you have any further questions.