Introduction A multimodal approach, including diet, psyllium, fecal microbiota transplant (FMT), and glucocorticoids, was used to treat chronic diarrhea in a standard poodle. A guide dog organization had bred the puppy. For the first 10 months of its life, the puppy experienced an imbalance of the microbiome, also called dysbiosis. Intestinal dysbiosis can be defined as an alteration in the composition and/or richness (i.e. the number of unique bacterial species) of the intestinal microbiota.1 The puppy developed diarrhea soon after it was weaned, and even though the stool quality gradually improved over the following months, the dog remained in dysbiosis. Photo courtesy Dr. Michelle van Lienden The diarrhea improved when the dog was five months old. However, the stool remained soft and somewhat challenging to pick up. At 11 months, the dog’s stool finally firmed up, and shortly after, the microbiome became healthy and diverse. Stool samples were taken at regular time points during the first year of the dog’s life to assess the microbiome. A quantitative PCR-based assay was used to calculate the dysbiosis index of the fecal samples. This case illustrates that antibiotic use and underlying digestive disorders can lead to dysbiosis and loss of Peptoactetobacter hiranonis. P. hiranonis is the main bacteria species responsible for the conversion of primary to secondary bile acid. A decrease in the abundance of this species is a major contributor to an abnormal intestinal microbiome. Loss of P. hiranonis will lead to an altered bile acid metabolism. Severe dysbiosis in combination with an altered bile acid metabolism can contribute to inflammation of enteral tissues in dogs with chronic enteropathy. Case report The puppy was initially presented to the veterinarian at eight weeks, with a complaint of one week of diarrhea. On the exam, the puppy was bright and had a good appetite; no significant abnormalities were noted. It showed no dehydration or pyrexia and received routine vaccinations. The pup had been regularly dewormed according to standard protocol. Routine fecal exam (sedimentation and concentration) showed no evidence of ova or parasites. The puppy was prescribed probiotics and a veterinary gastrointestinal diet for two weeks. When this failed to improve the diarrhea, a second diet was tried in combination with psyllium husk. This diet was a hydrolyzed veterinary prescription diet. Even though the frequency and severity had improved somewhat, this also failed to resolve the diarrhea. The patient was given a five-day course of the antibiotic Tylosin as a next step. Unfortunately, this did not improve the fecal score. A fecal sample was taken and analyzed shortly after the antibiotic course was finished. The sample revealed a high dysbiosis index (+7.3) with a loss of P. hiranonis (0.1) (Table 1). These results might be explained by either the pup’s young age or recent antibiotic use. Table 1. A quantitative PCR-based assay of the patient’s fecal microbiome at different time points P. Hiranonis is low at three different time points: the first time point (12 weeks of age) is after antibiotic use (Tylosin); the second time point (18 weeks of age) is due to poor digestive function, the third time point (at one year) is due to antibiotic use (amoxicillin-clavulanate). The veterinary team continued to feed the puppy the same hydrolyzed diet in combination with psyllium husk (0.5 gram/kg BID). At 14 weeks of age, another fecal showed P. hiranonis 4.6 had recovered, and the dysbiosis index lowered to 5.6. A fecal microbiota transfer was administered by retention enema at 1 g/kg. The psyllium dose was increased to 0.5 g/kg TID. Unfortunately, this failed to resolve the diarrhea. At 18 weeks of age, another fecal sample was analyzed, and this showed an increase of the dysbiosis index to 7.5, with loss of P. hiranonis. Diagnostics An initial blood sample was taken and analyzed for routine biochemistry and hematology (Table 2). This was followed by a fasted sample one week later for spec cPL, resting cortisol, cTLI, folate, and cobalamin (Table 3) There was increase in folate, as is seen in patients with small intestinal bacterial overgrowth Spec cPL was <30 (0-200 µg/L) and cTLI 22.1 (5.0 - 35.0 ng/ml). Therefore, pancreatitis appeared less likely, and exocrine pancreatic insufficiency was ruled out. Figure 2. Hematology: RBC, WBC, and platelet morphology are normal; chemistry: hemolysis index +, icterus index normal, lipemia indexnormal (the dog was not fasted). Resting cortisol was 30 (28-120 nmol/L) (Table 3), and in-house urinalysis showed a spec gravity of 1.034. No abnormalities were present on the Chemstrip 9, urine test strip. Therefore, hypoadrenocorticism was presumed unlikely to be an underlying cause of diarrhea. Table 3. Abdominal ultrasound and radiographs were unremarkable. The PCR diarrhea panel was negative for all pathogens and parasites. Treatment A trial with corticosteroids was initiated at 0.5 mg/kg prednisone BID for seven days, then the dose was reduced gradually over the next two weeks and discontinued. Another fecal sample was collected. This sample showed the dysbiosis index had improved to 2.0 and P. hiranonis had returned to the microbiome. The stool had firmed up while the puppy received the prednisone. However, after the prednisone was finished, the stool became softer, and the frequency of the bowel movements increased again. The veterinary team were not able to restart the prednisone due to the PU/D side effects that had resulted in frequent urinary accidents in the house of the caretaker. Because the dog’s clinical condition was deteriorating and we could not improve the diarrhea with a diet formulated for growth, we opted to try a diet for adult dogs “off label.” At five months of age, the puppy was transitioned to an extensively hydrolyzed diet. This diet finally improved the patient’s fecal consistency to a Purina Fecal Score (PFS) of 3. Even though this diet resulted in a significant clinical improvement for this puppy, the authors want to emphasize that this type of diet should never be used as a first choice for treating diarrhea in puppies and should only be considered in cases that do not respond after all other treatment options have been exhausted. Outcome The pup continued to receive psyllium at 0.5 g/ kg TID in combination with the extensively hydrolyzed diet for another three weeks. Six weeks later, the dysbiosis index had increased slightly to 3.2 (P. hiranonis 5.8). The puppy stayed on this diet for the next three months. At seven months, the pup’s BCS was 4.5/9 and his size was now comparable to that of his litter mates. His stool was log-shaped and moist, with little or no segmentation (PFS 3). We opted to try a very gradual transition to a gastrointestinal diet. This was the same diet the pup initially failed to improve on when he was eight weeks old. At 10 months, the dog was able to tolerate a quarter cup of the gastrointestinal prescription diet mixed in with his meals. A fecal sample revealed the dysbiosis index was 4.2 (P. hiranonis 5.7). Over the next two weeks we made a full transition to the gastrointestinal diet and the feces became normal and firm (PFS 2). The dog was unilaterally cryptorchid and was admitted for neuter surgery two weeks after fully transitioning to the gastrointestinal prescription diet. A fecal sample was taken when the dog was admitted. The stool sample was normal (PFS 2) with dysbiosis index of 0.2. (P. hiranonis 6.4). Unfortunately, the dog developed a post-operative infection and was admitted to the clinic five days later with pyrexia and mild dehydration. Another fecal sample was analyzed, showing a dysbiosis index of -5.1 (P. hiranonis 6.1): IV fluids and Ampicilline 22 mg/kg IV every eight hours, were administered for 24 hours, followed by oral Amoxicillin-clavulanic acid 15 mg/kg BID. The young dog’s appetite was suppressed, and it no longer showed interest in the prescription GI diet. However, it was willing to eat a combination of liver treats, high-calorie recovery convalescence, and a non-prescription adult lamb/rice diet. The dog liked this diet and was eating well. However, it had developed diarrhea again. Five days after finishing antibiotics, it still had diarrhea. The dysbiosis index was now 0.4. P. hiranonis 0.1. We opted to administer another Fecal Microbiota Transfer (4 g/kg) via a retention enema, and psyllium was added to the dog’s food. Over the next one to two weeks, the diarrhea resolved. The psyllium was discontinued after two to three weeks, and the feces stayed firm (PFS 2). One month after the FMT, another stool sample was collected. The dysbiosis index was -4.2 with P. hiranonis 6.0. The foster family was able to give treats, which did not impact stool quality. At 14 months, the dog was recalled to the Guide Dog School. Another sample was taken shortly after its arrival. This sample also had a negative dysbiosis index (-3.5), P. hiranonis 5.9. A sample taken one week after recall showed DI -4.7 and P.hiranonis 6.1. The dog continued to have firm stool during the following year. He was successfully trained and graduated as a Canine Vision Dog Guide. Dysbiosis index The gut microbiome is the ecosystem of microbes that live in the intestines. It contains diverse bacteria that are mostly anaerobic. The dysbiosis index (DI) is a quantitative PCR-based assay that measures the fecal abundance of seven common bacterial groups as well as the total bacterial abundance. These bacterial taxa are commonly altered in chronic enteropathies (CE) and after broad-spectrum antibiotic use. The DI provides reference intervals for these bacterial groups and calculates a single number expressing the extent of intestinal dysbiosis. The DI correlates negatively with species richness, i.e. a higher DI indicates lower microbial diversity. A DI above 2 indicates significant dysbiosis in dogs, while a DI between 0 and 2 indicates a mild-moderate microbiome shift. Some animals have a DI <0, but with some bacteria outside their respective reference intervals, and this suggests minor changes. The GI laboratory of Texas A&M University analyzed all samples in this study. Conclusion This case shows that multimodal treatment with diet, psyllium, corticosteroids, and fecal microbiota transfer can be used successfully to treat chronic diarrhea, resulting in resolution of clinical signs, recovery of digestive function, and a return of the microbiome to a healthy state. The microbiome plays a symbiotic, complex, and vital role in the digestive processes that take place within the gastrointestinal system. P. hiranonis, is a microbiome bacterium that is especially important for digestion because of its role in the bile acid metabolism.2 Most puppies convert to a negative dysbiosis index after fully weaning when the gastrointestinal system adapts to solid foods at about two to four months of age. Failure to transition to a negative dysbiosis index after the age of six months is considered abnormal.3 Diarrhea is common in puppies due to their immature digestive system, which has lower gastric acid and digestive enzyme activity and is less developed ability to adapt to food changes. Weaning induces many physiological changes, and there are likely individual differences in a puppy’s ability to adapt to these profound and rapid changes.4 Other factors that contribute to diarrhea in puppies include diet perturbations, including ingestion of indigestible material such as grass and sticks. Stress is another important factor that can directly cause or predispose dogs to diarrhea. Some stress is inevitable when pups transition from the nursery to a home environment, where they must get used to a new routine and develop social and emotional connections. Puppies are keen to explore and become familiar with their new environment. They need the right amount of mental and physical exercise. When their needs are not met, this can lead to chronic or intermittent stress which impacts the gut via the gut-brain axis.9 Antibiotics, such as metronidazole and tylosin, may temporarily resolve diarrhea. However, antibiotics do not support digestive function, and diarrhea tends to relapse shortly after they are discontinued. Metronidazole and tylosin both cause severe dysbiosis with loss of P. hiranonis.6-8 It can take several months for the microbiome to recover after these antibiotics have been discontinued.4 A dysbiotic microbiome will contain more pro-inflammatory bacterial species. Especially when P. hiranonis is lost from the microbiome, unconjugated bile acids end up in the colon. Depending on genetic factors, the inflammation generated by these unconjugated bile acids and opportunistic bacteria may result in a destructive feed-back loop of mucosal remodeling and loss of gastro-intestinal function.5 When followed up long-term, enteropathic dogs treated with antibiotics become refractory to treatment. Antibiotics, therefore, should not be used in dogs with chronic diarrhea, unless there are symptoms that indicate sepsis. Michelle van Lienden, DVM, is a 2001 graduate of the University of Ghent, Belgium. In 2012, she joined the Lions Foundation of Canada Dog Guides to provide on-site veterinary care for the breeding program, foster puppies, and dog guides in training. Jan Suchodolski, DrVetMed, PhD, AGAF, DACVM, is a professor, Purina PetCare Endowed Chair for Microbiome Research, associate director and head of microbiome sciences at the Gastrointestinal Laboratory at Texas A&M University. Dr. Suchodolski received his DrVetMed from the University of Vienna, Austria, and his PhD in veterinary microbiology from Texas A&M University. He is board-certified in immunology by the American College of Veterinary Microbiologists (ACVM). His research is focused on developing biomarkers for gastrointestinal disease and therapeutic approaches for the modulation of the intestinal microbiota. Suchodolski has authored or co-authored more than 400 peer-reviewed articles in veterinary gastroenterology and microbiome research. In 2024, he received the AVMA Career Achievement in Canine Research Award. Fabio Procoli DVM, MVetMed, DACVIM, DECVIM-CA (Int Med), MRCVS is the medical director of Anicura Portoni Rossi Veterinary Hospital in Bologna, Italy. An accomplished author and speaker, Dr. Procoli has shared his expertise in national and international peer-reviewed journals, and is the proud author of the textbook Feline Gastroenterology, published by Edra in 2021.He is a member of the Companion Animal Fecal Microbiota Transplantation Consortium. References Jan S. Suchodolski, Diagnosis and interpretation of intestinal dysbiosis in dogs and cats, The Veterinary Journal, Volume 215, 2016, Pages 30-37 Hooda S, Minamoto Y, Suchodolski JS, Swanson KS. Current state of knowledge: the canine gastrointestinal microbiome. Animal Health Research Reviews. 2012;13(1):78-88. doi:10.1017/S1466252312000059 Amanda B. Blake, Annalis Cigarroa, Hannah L. Klein, Mohammad R. Khattab, Theresa Keating, Patti Van De Coevering, Jonathan A. Lidbury, Jörg M. Steiner, Jan S. Suchodolski Developmental stages in microbiota, bile acids, and clostridial species in healthy puppies. J Vet Intern Med. 13 October 2020 Romuald Zabielski, Isabelle Le Huërou-Luron, Paul Guilloteau. Development of gastrointestinal and pancreatic functions in mammalians (mainly bovine and porcine species): influence of age and ingested food. Reproduction Nutrition Development, EDP Sciences, 1999, 39 (1), pp.5-26. ffhal-00900243f Margaux Marclay, Elizabeth Dwyer, Jan S. Suchodolski, Jonathan A. Lidbury, Joerg M. Steiner, Frederic P.Gaschen. Recovery of Fecal Microbiome and Bile Acids in Healthy Dogs after Tylosin Administration with and without Fecal Microbiota Transplantation, Vet. Sci. 2022, 9(7), 324 Igarashi H, Maeda S, Ohno K, Horigome A, Odamaki T, Tsujimoto H. Effect of oral administration of metronidazole or prednisolone on fecal microbiota in dogs. PLoS One. 20149(9) Suchodolski JS, Dowd SE, Westermarck E, et al. The effect of the macrolide antibiotic tylosin on microbial diversity in the canine small intestine as demonstrated by massive parallel 16S rRNA gene sequencing. BMC Microbiol. 2009 9(210) Stavroulaki EM, Suchodolski JS, Xenoulis PG. Effects of antimicrobials on the gastrointestinal microbiota of dogs and cats. Vet J 2023;291:105929. Kiełbik, P., & Witkowska-Piłaszewicz, O. (2024). The relationship between canine behavioral disorders and gut microbiome and future therapeutic perspectives. Animals, 14(14), 2048.
