Mine has this. Her bloodwork showed her liver number and thyroid were off. After starting meds for both, it stopped.

It could be in a neighboring yard or house perimeter treatment or somewhere sniffed or licked along a walk.

It sounds like they may be getting exposed to something. Intermittent but predictable diarrhea sounds strange. Like is there a pest control service or something happening around that time that they are experiencing some kind of exposure?

OP has your dog had bloodwork recently? I would want to see if the pancreas, kidneys, and liver are doing ok. Pancreatitis in particular can be quite painful for dogs even if they don’t show it. Our dog had intermittent GI problems when she got older and was diagnosed with it. If it is that, a low fat diet can be helpful at least early on, but it may not fully address the problem. Toward the end she had an especially bad bout of diarrhea and seemed unwell, and we took her to an emergency vet thinking she just needed 24 hrs of fluids. The vet had told us that may be needed with pancreatitis. Turned out her kidneys were failing. It had progressed quickly as bloodwork just 2 weeks prior showed her kidneys were fine. Things can happen quickly with older dogs and it’s our duty to minimize their suffering as best we can. Data in the form of test results can help with decision making, the downside is it’s so expensive to keep going back for tests. Wishing the best for you dog and your family. It’s hard having an old dog.

My 8 year old dog has bouts of constipation every two weeks. It first manifests itself as dribbling, ie, encopresis, because liquid around the blockage manages to get out. Thankfully with wet food and a maintenance dose of Miralax he can hold it until we get outside, but the first few times he couldn't.

I'm also wondering what's going on in there. He had an ultrasound and X-rays that didn't reveal anything, so I think the next step is a CT scan.

We had this problem when our Aussie was a puppy. For her it was mostly in the form of intense cramping, causing her to vomit and diarrhea.

We started on Hill's Rx Z/D which is Formulated w/ Hydrolyzed Animal Protein to Help Minimize Signs of Adverse Food Reactions.

2x/day we feed her 1/3 Hill's, 1/3 fresh browned ground 99% ground turkey (she can't eat chicken) 1/3 raw carrots. In the morning we sprinkle her food with the fortiflora.

This has helped immensely. However, it turned out she had a cyst in her abdomen. Removing that helped a lot, so her episodes now are rare.

If I realize an episode is coming on I give her a small dose of Cerenia.

She had an episode about 6 months ago that the Cerenia didn't avert. They hydrated her and gave her antibiotics. In an ultrasound (X-ray??) they could see her intestines were inflamed and blood work showed slightly raised white blood cell count. We live in a complex that is cared for by a maintenance crew. I hadn't realized they had put fertilizer down, which in turn caused the problem, we believe.

But it literally had been about 4 years since her last episode.

OP. Thanks, everyone. We do purina pro ID canned food, and it has helped digestion quite a bit -- except for the couple of days, roughly twice a month, that are a mess. I work at home so can get the dog outside most of the time, but it's definitely stressful for all of us.

Not a chihuahua, btw, a border collie/aussie.

At our most recent visit, the vet did suggest Fortiflora probiotic, so we started that 1x/day last week. I can't yet tell if it helps.

Will ask about Metronidazole and the proviable paste. I think Metronidazole is what they've given him when he is unwell enough that he's needed fluids. Maybe we need to have a stash on hand?

Before this thread, I'd been thinking that the cyclical nature of whatever was happening was somehow internal -- I had been researching if there are bodily systems that unfold biweekly in an old dog. But I couldn't find any good potential causes. So I appreciate the reframe that it might be something that's happening externally, like food or cleaning products or something. Although I can't think of anything offhand (house is cleaned every week, not every 2 weeks, for example), I'm going to start paying more attention. (Like, could our semi-regular habit of bringing in Indian takeout have anything to do with it, if we aren't actually giving the food to the dog? Something like that?)

Thinking and watching. Appreciate the insights and recommendations. If any of these things help, or if we figure it out, I'll update.

Is this is Chihuahua by chance?

I’d ask your doc about giving him Metronidazole. We give it to mine as needed but it definitely helps when he has diarrhea, which is pretty regularly.

If it's like clockwork is there something else that happens every 2 weeks? Could be a day or two before the illness?
Cleaners, yard workers, carwash, anything dog could be expose to or lick? Certain foods you serve?

My dog had the same issues the vet suggested purina EN dry food it helped a lot.

Our vet recommended this for our senior dog with diarrhea and the paste worked quickly.

https://a.co/d/0uCMR7r

Do you give him a probiotic? We use a purina pro one from Amazon and it really helped my dog who had a lot of potty issues. Started it per vet when she was having ongoing vomiting. Does he need a different RX food??

I would not find this to be a tenable status quo, for me or the dog. So I would get aggressive about treating or finding a cause, and if that wasn’t possible, I would put the dog to sleep.

I would call the vet and say that, with a time frame. “If we can’t get this worked out by March we’re going to have to put the dog to sleep. This isn’t tenable for us or fair to the dog”

We had to do that once - a cat with uncontrolled diabetes. And we went from a slow pace of trying a fix, giving it two weeks, testing again, playing phone tag with the doctor, eventually trying something else, where each step was 4-6 weeks, to an aggressive plan of attack where we were adjusting meds every ten days. Vets are human, and when they realize the stakes are getting Real, they will react accordingly.

And, if with three months of focused effort, you have no change, it is time to say goodbye to the dog.

If you feel you’re already done that and have hit a wall on options already, then it’s time to call Lap of Love. I’m sorry.

I have a very senior dog who is mostly doing great. But every couple of weeks for the last year, he has gotten terrible waves of diarrhea. It’s like clockwork, it happens so regularly. Each bout lasts a couple of days, is very stressful for him (and us), and leaves him quite weak. The vets don’t really have an explanation. They’ve tested for parasites, and they say his vitals are good during these bouts, though he sometimes needs IV fluids.

They say maybe it’s related to an idiopathic vestibular issue (basically unexplained dizziness) that older dogs sometimes get. But the episodes feel far too regular for something that’s apparently random.

He’s already on prescription dog food, which is otherwise very good for his digestion. Just wondering if anyone dealt with something similar and had an explanation. He’s a very very good dog, and this is the biggest quality of life issue for him, and for our family as we care for him.