Hello & welcome, I am Dr. B, a licensed veterinarian and I would like to help you with your wee one today. I do apologize that your question was not answered before. Different experts come online at various times; I just came online, read about your wee one’s situation, and wanted to help.
Now just like people, when dogs can have loose stools that can be caused by a range of agents. These include bacterial viral, parasitic (worms but also protozoa like Giardia, Coccidia, Tritrichomonas), toxins (sounding less likely here), nutritional, and general dietary indiscretions type causes. Now hopefully, Walter's fecal changes are just that latter dietary indiscretion that will just settle over 24 hours; but as you are seeing a bit of blood and mucus (which are signs that the colon is irritated here), we do need to keep a close eye on this situation over today.
While monitoring Walter, you can also consider starting him on a light/easily digestible diet. Examples of an easily digestible diet include cooked white rice with boiled chicken, boiled white fish, scrambled egg, or meat baby food (as long as its free from garlic or onion powder).. There are also veterinary prescription diets that can be used in cases of gastroenteritis (ie Hill’s I/D or Royal Canin’s sensitivity). The easily digestible diet will be better tolerated and absorbed by the compromised gut and should get some nutrients in and help firm up the feces. Also feed this as small frequent meals to further decrease the volume loose feces he is passing. As long as improvement is being seen, I usually advise that the diet be continued until the diarrhea is settled, and that they are then slowly weaned back to their normal diet over a week.
Just to note, if he isn't up to date on worming (not been wormed in the past month), it would be prudent to cover your bases and at least rule out the GI worms that could be initiating GI irritation. To treat worms, you can buy worming products over the counter at your local vet or pet stores. There are a range on the market, but you want to use a good quality wormer that covers both round worms and tapeworms. In this situation, it would be ideal for you to treat with Panacur, Drontal or Milbemax as it will cover all the worms in question. Do make sure to have an idea of his weight before purchase wormer to make sure you get the correct dose for his size.
Now while one loose stools isn't likely to dehydrate Walter, I do just want to advise you on how to monitor his hydration and make sure there is no threat of dehydration. To check his hydration status, there are a few things we can test. One is whether the eyes appear sunken, if the gums are tacky instead of wet/moist, and whether he has a "skin tent" when you lift the skin. To see how to check these parameters for dehydration, you can find a wee video on this HERE. If you see any signs of dehydration at any point, then you do want to have him seen by the vet before makes him feel poorly. (since it is often the dehydration that starts to tap their energy level and actually makes them feel ill)
If you were concerned that he was becoming dehydrated, you can try and encourage him to drink but offering fresh water or even low-sodium chicken broth. If he isn’t amenable to these, you can syringe feed pedialyte. Pedialyte is nice (though aim for a flavorless one) because it will get some of those lost electrolytes back into him as well. A typical maintenance rate for hydration in an animal is 48mls per kilogram of weight a day. If you do give syringe pedialyte, this should obviously be divided up into multiple offerings through the day rather then all at once. This value will give you the total he needs for the day and is a good starting point to give you an idea of a dog's daily requirement. (we aren’t calculating losses, so you can add an equivalent volume to match how much diarrhea is being producing). If he vomit when you have given pedialyte, then therapy should be discontinued (since we don’t want vomiting because of our intervention). So, not likely necessary after one loose stool but just so you have a plan of attack if he were to have any dehydration issues.
Overall, there can be many triggers for loos stools of this nature. Since he is young (and doesn't have the reserves of an adult), even one loose stool means we need to keep an eye on him. So, I would advise the above and monitoring him over today. If he hasn't been wormed recently, that would be a consideration just now as well. If he has just had a wee dietary indiscretion or if GI worms are to blame, these steps should settle this for him. Though if you do treat and his signs do not settle, then it would be worth following up with his vet tomorrow. They can examine him +/- test a fecal sample to determine if those aforementioned infectious agents are triggering his stool change. Depending on the causative agent, then will be able to dispense appropriate treatment to clear this effectively and get him back to passing normal feces.
I hope this information is helpful.
If you need any additional information, do not hesitate to ask!
All the best,
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