Most people are looking at this title and are thinking to themselves, "That's weird. Firehose? Pudding? How do these relate to each other, or to pets or veterinarians?"
On the other hand, people who work in vet clinics are groaning lightly and facepalming because they know exactly what I am going to write about. I am going to write about diarrhea. And I'm going to try hard not to be too gross about it. It's tough for me, but I am going to try hard.
Even though it may seem obvious, let's start with a definition. From a medical perspective, diarrhea is stool that has enough liquid in it that it can no longer keep its happy log shape. A single abnormal one could be a fluke, but if it happens more than a couple times in a row, we can properly call it diarrhea. And if you want to get all nerdy technical about it you can refer to the "Bristol Stool Scale" and score the poops from 1 to 7:
(Note that where it says "lacking fibre" for stools scoring 5, this just applies to humans. In animals I would consider 5 to be borderline diarrhea.)
6 is what we sometimes refer to as "pudding" and 7, if it is sprayed out, is "firehose". That's it for the gross bits! All done. You can read on safely now.
Once you know your pet has diarrhea there are really just two important questions we need to consider:
1) How long has it been going on?
2) Does your pet have any other symptoms, or is she otherwise happy and normal?
To the first question, we're only going to talk here about diarrhea that has been going on less than roughly two weeks. This is acute diarrhea. The word acute sometimes confuses people as some believe it means severe, but it doesn't, it just means recent onset. Chronic diarrhea is due to a whole other set of causes, needs different tests and has different treatments. Fortunately it is relatively rare, while acute diarrhea is extremely common.
If the only symptom is diarrhea and there is no vomiting, lack of appetite or lethargy, then you can follow the advice here or just phone or email your veterinarian for their advice. There is no need to rush Billy-Bob down for an urgent examination. If, however, any other symptoms are present, then it's best to get him checked over.
Before we get to what to do, a word about causes. Acute diarrhea in previously healthy pets with no other symptoms is almost always due to either a virus or what we like to call a dietary indiscretion. Even if your pet is not in contact with other animals, viral diarrhea is still possible as these viruses can be found out in the environment and be easily transmitted on their paws (dogs especially) or on your shoes. And dietary indiscretion simply means having eaten something their system doesn't tolerate, like five day road-aged dead squirrel, stuffed pizza crust, nasty random thing in the garbage etc. (dogs especially, again). Keep in mind that what they can tolerate will change over time, so just because Ellie-Mae did well on bacon chips for years, doesn't mean that won't cause diarrhea now.
Treatment for this is usually simple because the body has remarkable healing mechanisms. Often all we need to do is turn off the tap and power down the poop making machine. To do this we need to temporarily replace their regular diet with a low residue diet that produces very little stool and therefore allows the gut to rest and heal. For this you have two options. You can either buy a commercial prescription low residue diet from your veterinarian such as "Gastro" or "I/D", or you can cook for your pet.
For dogs the magic recipe is:
1 part extra lean cooked ground beef (boil or fry and drain until it's just dry meat with no fat), or if your dog can't have beef, use lean chicken breast.
2 parts (by volume, just eyeballing it is fine) boiled white rice, not brown.
That's it! Frequent small meals is best. And no treats or anything else other than water to pass their lips. For cats I usually recommend just a pure lean protein source without the rice, such as canned fish packed in water, or cooked chicken or turkey breast.
Feed this until you've had 48 hours without diarrhea. If it is still persisting after that, please call your veterinarian! There may be no stool at all during this period, but that is not constipation, it is just the result of the low residue diet producing very little waste. Once you're past the two days, mix the low residue diet 50/50 with their regular food for a day or two before switching back completely.
One final wrinkle is that diarrhea that has been going on for a few days, but is not chronic yet, may be persisting due to "dysbiosis", which is both a fun word to say and a useful one to know as it describes an imbalance in the normal gut bacteria. We are learning more and more how helpful the bacteria in our large intestine are. That dead squirrel or sidewalk virus can sometimes lead to a change in that bacterial population that impairs the gut's ability to produce normal stools. Consequently, if a couple days of low residue diet haven't done the trick, your veterinarian may recommend a source of pre-biotic, which is something that feeds healthy bacteria, such as canned pumpkin (weird but true), and/or a pro-biotic, which provide large numbers of the good bacteria. Years ago we used to recommend yoghurt for this, but fortunately there are much better, more dog and cat specific, pro-biotics available now from your veterinarian.
With any luck, ta-da, normal poop! (Ahem, Bristol Stool Scale 3 or 4....)