There are a lot of different possibilities for what may be going on with your dog.
Given that the vomitus smells like feces and he is known to get into the cat box, I do suspect he must have eaten some feces. It is also possible that he ate some feces out in the back yard. Maybe some animal got into the yard?
For humans, we get close to poop and we just smell POOP. For dogs, they can smell all the ingredients in the poop - the chicken, the rice, whatever was in there. And when it is cold the fecal smell isn't so strong, just the smell of the chicken and rice or whatever. So, they give it a try. YUCK!
Poop eating is called coprophagia. Here's some more information:
Now, although it is pretty disgusting, eating feces is not likely to cause any long lasting problems. It is, however, likely to cause gastroenteritis, which is what you are describing (vomiting, belching, gassiness).
Now, that said, if he were on his way in to see me, there are a number of things I would want to check for before deciding this is straightforward gastroenteritis. The things that I would be considering if he came to see me are:
1. One of the things that I think of first in a 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 stomach or small intestines, it might explain the symptoms that you are seeing. This would be particularly true if the object were something like a ball that could bob over pylorus (outflow from the stomach) and then move away again. Thus, water could pass through but not food.
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 boy and was concerned about a foreign body, I would probably recommend x-rays to see if a foreign object were visible. A rock would show up very well on x-rays. 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.
Most mature dogs are more sensible than to eat a foreign body, so this is not really likely, but possible.
2. It is possible your dog simply has gastroenteritis from eating something he shouldn't have, like feces or twigs and leaves! Gastroenteritis is an inflammation of the stomach and intestines and can be caused by a large number of things, including sudden dietary changes.
THIS IS WHAT I THINK IS MOST LIKELY!
3. A bacterial infection:
Dogs can be affected by overgrowths of bacteria in the intestines. In an adult dog these might not be more than a nuisance. The 3 most common are Campylobacter, Salmonella and E.Coli. Here is a link with more information:
Your boy could have a bacterial infection from eating feces.
This is an inflammation of the pancreas, often triggered by a high fat meal. With "acute pancreatitis" dogs are very sick, with severe vomiting, painful belly and fever.
However, with a low-grade, chronic fulminant pancreatitis it is basically a "slow burn" version of acute pancreatitis. The pancreas remains inflamed, with periods of pain and nausea, and vomiting intermittently.
Pancreatitis is a serious medical problem and is diagnosed by having bloodwork done and possibly x-rays. Dogs with pancreatitis may need to go on a course of antibiotics to treat the chronic pancreatitis and may need a prescription food to "put out the fire" of this chronic problem. Typically the diet is ultra-low fat. At first dogs may not want to eat it because of feeling nauseated and it does not tempt her. But with medications they soon feel *much* better and keep feeling well if they stays on an appropriate food.
For more information:
So, with your dog, you have done a great job of keeping him hydrated and looking after him. It seems to me that the steak might have triggered pancreatitis.
The bottom line is that there are a number of possibilities for what may be going on. Your vet would need to do a physical exam and possibly some diagnostic tests to figure out what the underlying problem is. I would start with a fecal sample, blood test and abdominal x-rays.
If he is feeling unwell at the moment, there are some things you can do at home until you can get him in to the vet:
1. WITH-HOLD FOOD until it has been 24 hours since he last vomited. This gives the intestines a chance to rest and heal.
2. When he is fasting, he can have lots of clear fluids. Wait until it has been 4 hours since he last vomited, and give small amounts of plain water to start.
So, water is fine, but if he keeps that down for 2 hours, he can then have 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 an hour.
3. After 24 hours without vomiting, you can start your dog back on a bland diet.
For patients that I see, 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 2 or 3 tablespoons 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.
6. When treating for gastroenteritis and pancreatitis, for patients that I see, I usually have them on something to block stomach acid production. The drug I usually reach for in dogs is ranitidine, which is Zantac. You can buy it at your local pharmacy. Legally, I cannot prescribe medications for a dog that I have not seen!
Here is more about ranitidine, including dose:
If he were my patient, I would add in the Zantac, and continue with the fluids.
7. Another thing which I suggest to patients who are recovering from pancreatitis is that they get some “good bacteria” back into their systems. An easy way to do this is by using a product called Culturelle. It comes as a capsule, and for a dog this size, if he were my patient, I would give him 1 - 2 capsules daily. It can be mixed in with some water and given by syringe. Here is more:
If your dog continues to vomit, develops blood in the stool, is lethargic or shows signs of abdominal pain, please contact a veterinarian promptly.
Again, thanks for your patience and I hope your boy feels better soon!
I hope that this helps you to help your dog!