Replying to Suzi Bailey 12/05/2025 - 23:27
Hi Suzi,
Thanks so much for your great questions. I really hope you are enjoying the course.
1. Refractory or recurrent Giardia infections
You’re definitely not alone in seeing more of these. My current approach is:
If a dog doesn’t respond to a 5-day course of fenbendazole (50 mg/kg PO SID), I’ll typically repeat the same course first, as I find some dogs need two full rounds before we see clearance—especially in multi-pet households or where environmental contamination is possible.
Only after a second fenbendazole course fails would I consider combining fenbendazole and metronidazole concurrently (the latter at 10–15 mg/kg BID for 5–7 days), although I try to avoid metronidazole unless really necessary due to its potential microbiota impact.
Environmental hygiene is critical—daily bathing, decontaminating surfaces, prompt faeces removal, and sometimes bathing with chlorhexidine-based products if there’s heavy shedding.
I’m increasingly increasing fibre in the diets of these dogs.
I’ve also started incorporating faecal microbiota transplantation (FMT) more routinely for dogs with relapsing diarrhoea or poor recovery post-Giardia—especially those with previous antibiotic exposure or persistent dysbiosis.
2. Acute diarrhoea progressing to chronic enteropathy
Yes, this is something I’m seeing with increasing frequency. Dogs that start out with a single episode of acute diarrhoea (often due to Giardia or dietary indiscretion) seem to lose resilience and go on to develop chronic signs.
Like you, I suspect that:
Early or repeated antibiotic exposure, particularly metronidazole, may contribute to long-term dysbiosis and altered mucosal immune function.
There may be a “tipping point” in genetically susceptible dogs that progresses to immune-mediated enteropathy after an acute GI insult.
This is exactly why I’m cautious now with antibiotics in acute cases. Instead, I often use:
Probiotics (Visbiome, Vivomixx, FortiFlora)
Fibre supplementation (psyllium or canned pumpkin)
Clay binders, and
Close dietary review from the outset.
3. When to use immunosuppressives – before or after biopsy?
You’re absolutely right that this is nuanced. Here’s how I generally approach it:
If there is marked hypoalbuminaemia, GI bleeding, or other red-flag features (weight loss, anaemia, low cobalamin), I prioritise biopsy before steroids.
If the case is moderate and owners are hesitant, I will sometimes trial immunosuppression empirically, but I document the limitations clearly and try to re-approach biopsy if the response is incomplete.
If steroids have already been started and we’re considering biopsies, I usually recommend a washout of 2–4 weeks (depending on severity and taper status) before sampling to avoid histopathological distortion.
4. Metronidazole-responsive or dependent CE cases
Yes—I’ve had similar Golden Retrievers in particular that seem metronidazole-responsive even after extensive trials.
In these truly refractory cases:
I still trial antibiotics—but very much as a last resort, and with awareness of the long-term impacts.
If long-term antibiotics are required, I’m now more inclined to use tylosin over metronidazole, supported by evidence such as the randomized controlled trial by Kilpinen et al. (Acta Vet Scand. 2011):
Tylosin (25 mg/kg SID) was significantly more effective than placebo in dogs with presumed tylosin-responsive diarrhoea, with 85% achieving normal stool consistency during relapse episodes.
PMID: 21489311
I find tylosin to be better tolerated, with less dysbiosis and neurotoxicity risk than metronidazole.
I’ll also continue probiotics alongside to help mitigate any microbiota impact, and will sometimes reintroduce FMT or increase fibre support if relapse occurs on withdrawal.
Thanks again, really appreciated your insight here. Please do keep the questions coming, and I’d love to hear how your Golden cases evolve.
Let me know how you are getting on with the course.
Best wishes,
Scott 🙂
