Diarrhea, Antibiotic Responsive In Canine and Feline


Diarrhea, Antibiotic Responsive In Canine and Feline: Causes, Symptoms and Treatment

Diarrhea, Antibiotic Responsive In Canine and Feline: Causes, Symptoms and Treatment


  • Antibiotic-responsive diarrhea (ARD) referred to as chronic diarrhea, characterized by persistent loose stool without a clear underlying cause which exhibits a positive response to treatment with antibiotics.
  • A condition that used to be called idiopathic (primary) small intestinal bacterial overgrowth (SIBO) has been renamed antibiotic-responsive diarrhea (ARD). This is because diagnostic methods have improved.
  • The earlier term relied on culture techniques to measure bacterial growth in the upper gastrointestinal tract, but more trustworthy PCR-based approaches have since taken their place.
  • We now know that secondary SIBO happens when other digestive problems, like exocrine pancreatic insufficiency (EPI), happen at the same time.
  • Right now, most of the research is focused on the possibility of immunological dysregulation. This could be connected to abnormal CD4+ T-cells, immunoglobulin (Ig) A plasma cells, cytokine production, and, in German shepherd dogs, pattern recognition receptor abnormalities.

Causes of Diarrhea, Antibiotic Responsive In Canine and Feline

Causes and Risk factors

  • The condition has been linked to genetic alterations in pattern recognition genes, including TLR4 and TLR5.
  • Enteropathogenic bacteria like Clostridium perfringens, Escherichia coli, and Lawsonia intracellularis have been suggested as possible suspects but have not been proven.

Pathogenesis of Diarrhea, Antibiotic Responsive In Canine and Feline

  • The existing theories concerning pathogenesis primarily revolve around the potential occurrence of immunological dysregulation.
  • It is possible that this imbalance is connected to CD4+ T cells, IgA plasma cells, cytokine expression, and, in German shepherd dogs, pattern recognition receptors that do not work right.


Symptoms (History & Physical Examination) of Diarrhea, Antibiotic Responsive In Canine and Feline


  • Clinical manifestations of small bowel abnormalities include reduced appetite or anorexia, episodes of vomiting, noticeable weight loss, and the presence of large-volume diarrhea.
  • The clinical manifestations of large bowel involvement include tenesmus, hematochezia, and an increased frequency of feces.

Physical Examination

  • Clinical signs such as weight loss, suboptimal body condition, borborygmus, and flatulence might be observed.
  • The presence of hematochezia may indicate involvement of the large bowel.

Diagnosis of Diarrhea, Antibiotic Responsive In Canine and Feline

1- From History and Physical Examination

2- Diagnostic Procedures


  • This is considered to be within the range of what is considered normal.
  • Hypoalbuminemia is relatively uncommon.


  • Fecal examination to look for parasitic diseases, hematology, biochemistry, and urinalysis to rule out metabolic disorders are some of the tests that should be done during the evaluation process.
  • In cases where Addison’s disease is suspected, an adrenocorticotropic hormone (ACTH) stimulation test may be necessary.
  • Canine pancreatic lipase (cPLI) can be employed to exclude chronic pancreatitis, while TLI can be used to rule out exocrine pancreatic insufficiency (EPI).
  • Abdominal ultrasound can be utilized to exclude chronic partial obstructions, focal lesions, and masses.
  • Fecal analysis for bacterial pathogens is typically not recommended for cases with chronic diarrhea, as positive culture or quantitative PCR (qPCR) findings sometimes indicate low levels of infection that are not the major etiology of the disease.
  • The utilization of these methods should also be avoided for the purpose of guiding antibiotic treatment in ARD, as the diagnosis of ARD is typically determined through an empirical treatment trial.
  • Serum cobalamin levels may exhibit a deficiency, while folate levels may demonstrate either an elevation or a reduction.
  • The diagnostic accuracy of folate and cobalamin levels in identifying ARD is limited due to their lack of sensitivity and specificity.
  • The majority of gastroenterologists typically assess cobalamin levels and administer supplements as necessary, as research has demonstrated a correlation between low serum cobalamin levels and decreased survival rates.
  • The levels of serum trypsin-like immunoreactivity (TLI), which are checked to rule out exocrine pancreatic insufficiency (EPI), are normal in people with ARD.
  • It is recommended to periodically repeat the measurement of TLI (trypsin-like immunoreactivity) every 6–12 months, particularly in younger animals and breeds that are at a higher risk.
  • This is because research has demonstrated that certain dogs may see a decline in their serum TLI levels over time.
  • Canine patients may experience advantageous effects from the supplementation of pancreatic enzymes.
  • It is recommended to conduct routine abdominal imaging, including radiography and ultrasound, in order to exclude alternative etiologies for chronic diarrhea.
  • The findings of these tests are unremarkable in cases of ARD.

3- Differential Diagnosis

  • Secondary small intestinal bacterial overgrowth (SIBO).
  • EPI.
  • Epidemiology of parasitic infections.
  • Inflammatory bowel disease (IBD).
  • Food-induced diarrhea.
  • Neoplasia.

Treatment of Diarrhea, Antibiotic Responsive In Canine and Feline


  • Outpatient care may be effective for managing canines, so hospitalization is typically not advised.
  • The limitation of physical exercise is not recommended.
  • The precise impact of dietary factors on ARD remains uncertain.
  • The current advice suggests giving antibiotics along with a diet that is low in fat and easy to digest, or an elimination or hydrolyzed diet.


  • Tylosin (5–10 mg per kilogram of body weight, administered orally every 24 hours), this treatment should be continued for 4-6 weeks, Long-term maintenance regimens have been described as effective when administered orally at a dosage of 2–5 mg/kg once every 24 hours.
  • Metronidazole (10–20 mg/kg) is administered orally every 12 hours for a duration of 4-6 weeks. In certain circumstances, it has been demonstrated that gradually reducing the dosage to as low as 2 mg/kg orally every 24 hours can be a beneficial approach.
  • Oxytetracycline (10–20 mg per kilogram of body weight, to be taken orally every 8 hours). This treatment should be continued for 4-6 weeks.
  • Enrofloxacin (5 mg/kg PO q 24 h) for 4–6 weeks. In certain instances, the utilization of combination therapy may be deemed necessary.
  • If there is a reduction in serum cobalamin levels, it is advisable to consider pursuing cobalamin supplementation.
  • For dogs weighing less than 15 kg, the recommended dosage of parenteral cobalamin is 500 μg, and for dogs weighing more than 15 kg, the recommended dosage can be increased to a maximum of 1500 μg.
  • The administration of doses occurs through subcutaneous injections on a weekly basis for a duration of six weeks, followed by a reduced frequency of once every other week for an additional six weeks.
  • It is recommended to evaluate serum cobalamin levels at the completion of therapy. There is a lack of data concerning the efficacy of oral cobalamin supplementation.
  • The first guideline of utmost significance is the clinical relief of diarrhea.
  • Relapses commonly manifest with the discontinuation of antibiotic treatment.
  • Certain breeds of dogs have the ability to be sustained on minimal dosages of antibiotics over an extended period of time.
  • The long-term prognosis for ARD is often poorer compared to other types of chronic enteropathy (CE) cases. This may be attributed to the higher frequency of relapses that require veterinarian intervention.

Some Notes:

  • The administration of oxytetracycline has the potential to result in tooth enamel discoloration.
  • In animals with hepatic or renal impairment, it is recommended to reduce the dosage.
  • It has been found that giving oxytetracycline is closely linked to a lot of horizontal gene transfer, especially the passing on of antibiotic-resistant genes between bacterial populations.
  • Metronidazole experiences significant hepatic metabolism, necessitating dosage reduction in animals with hepatic insufficiency.
  • Gastroenterologists are worried about the idea of not using antibiotics for long periods of time because antibiotic resistance is getting worse, especially when it comes to metronidazole.

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