There are a number of possibilities for what may be going on with your little GSD. Sudden onset of vomiting and diarrhea could be caused by a number of different things. I will go over the ones that worry me the most.
1. What you are describing sounds like it could be a severe allergic reaction. This could be due to a spider bite or even more likely a spider *ingestion* where he actually ate the spider and it bit him on the inside of his stomach. This could cause sudden vomiting and diarrhea.
Spider bites can cause quite severe allergic reactions in some animals - swelling around the face, vomiting and low blood pressure can be some of the symptoms. I am so glad that it sounds like he has stopped vomiting for now, and that he doesn't have any swelling around his face or eyes.
Here is more about allergic reactions in dogs:
2. One of the things that I have to consider with your dog is that he may have a Gastrointestinal Foreign Body. Dogs eat the strangest things - plastic bags, children's toys, bones, bits of towel, socks, rocks and other things. Often, these foreign bodies pass through the intestinal tract, but sometimes they do not. They may get caught in the stomach or the small intestines.
The symptoms of a GI foreign body are generally vomiting, loss of appetite, depression and dehydration. If your dog consumed an object that is caught in the small intestines, it might explain the symptoms that you are seeing. The object could be something like a ball that could bob over pylorus (outflow from the stomach) and then move away again. In the case of an obstruction, surgery is often needed to remove the foreign object. I will include further information about GI foreign bodies:
If I examined your dog and was concerned about a foreign body, I would probably recommend x-rays to see if a foreign object were visible. A plastic bag would not show up on x-rays. It does, however, show up very well if the dog is given some barium (a type of milkshake like drink) by mouth. Then a determination can be made about how best to get this out of the dog, or whether it might move through on its own.
3. Another thing that worries me is that your dog may have Pancreatitis. This can be caused by a number of things, such as certain medications, infections (bacteria can climb up into the pancreas from the intestines), high fat meals (getting into the garbage may have triggered it), high amounts of calcium in the blood, trauma and shock (for example it can happen after a dog is hit by a car). Some dogs are more prone to pancreatitis than other dogs with small dogs being more susceptible.
Typically, the symptoms of pancreatitis are abdominal pain, fever, vomiting, diarrhea, lethargy and a very painful belly.
Bloodwork that confirms pancreatitis shows very high levels of amylase and lipase. These are 2 enzymes that the pancreas makes and delivers to the intestines to help digest food. With high fat meals, the pancreas has to work extra-hard to make these, and this can cause it to actually start digesting itself. This is very painful!
Many times, we don't find the exact cause of pancreatitis. An ultrasound is useful to look for a mass in the pancreas (such as a tumor, which is RARE), and to see how severely the pancreas is affected. This can help with giving a prognosis, and estimating how long a recovery will take.
Generally, pancreatitis is treated aggressively with intravenous fluids, intravenous antibiotics, pain killers and resting the intestinal tract. This last means that NO food is given by mouth until symptoms start to resolve. Then, once the pancreatitis is starting to resolve, we usually start the patient with just water and see if that stays down. If there is no vomiting or abdominal pain, we then start *very* small meals of an easy to digest, low fat food and monitor closely.
For long-term management, patients who are prone to pancreatitis are kept on a low fat diet to minimize chances of a flare-up. Antibiotics are continued for 1-2 weeks, as well as other medications as needed (such as anti-nausea medications).
I will give you some links to more information:
4. It is possible your dog simply has gastroenteritis from eating something he shouldn't have (gabage). Gastroenteritis is an inflammation of the stomach and intestines and can be caused by a large number of things, including sudden dietary changes.
Now in terms of what you can do for you GDS:
1. WITH-HOLD FOOD for 24 hours. This gives the intestines a chance to rest and heal.
2. When he is fasting, he can have lots of clear fluids. So, water is fine, but also you can give pedialyte, Gatorade, apple juice diluted 50:50 with water, or chicken or beef broth diluted 50:50 with water. Give the fluids in small amounts frequently. For a dog this size that means about 1 cup per hour.
3. If your boy is keeping the fluids down tomorrow then tomorrow night I recommend a mixture of 75% cooked white rice, and 25% low fat protein. For the protein you could use extra lean ground beef, boiled with the fat scooped off, or chicken breast boiled with fat scooped off or even scrambled egg cooked without fat in the microwave. Feed small frequent meals. For a dog this size, I would suggest 1/2 cup every 3 to 4 hours.
4. After 1-2 days on the rice mix, you would gradually change your dog back to the normal dog food. So, on day 3, give the rice mixture, but bigger meals, spaced further apart. On day 4, mix a little tiny bit of the normal food in there, and decrease the frequency so it is down to 3 meals or so. And so on.
5. Keep your dog as quiet as possible - just out to relieve himself and back in.
If your dog continues to vomit, develops blood in the stool, or shows signs of abdominal pain, please contact a veterinarian immediately. If he becomes lethargic, develops blood in the vomit, or appears bloated also contact your veterinarian tonight.
Good luck with your dog!
I will still be here to answer further questions!