Fourteen dogs had shown chronic or intermittent
diarrhea for more than 1 year.
Diarrhea had been successfully treated with
tylosin for at least 6 months but recurred when treatment was withdrawn on at least 2 occasions.
Tylosin-responsive
diarrhea (TRD) affects typically middle-aged, large-breed dogs and clinical signs indicate that TRD affects both the small and large intestine. Treatment with
tylosin eliminated
diarrhea in all dogs within 3 days and in most dogs within 24 hours.
Tylosin administration controlled
diarrhea in all dogs, but after it was discontinued,
diarrhea reappeared in 12 (85.7%) of 14 dogs within 30 days.
Prednisone given for 3 days did not completely resolve
diarrhea. Probiotic Lactobacillus rhamnosus GG did not prevent the relapse of
diarrhea in any of 9 dogs so treated. The etiology of TRD, a likely form of
antibiotic-responsive
diarrhea (ARD) is unclear. The following reasons for chronic
diarrhea were excluded or found to be unlikely: parasites,
exocrine pancreatic insufficiency,
inflammatory bowel disease, small intestinal bacterial overgrowth, enteropathogenic bacteria (Salmonella spp., Campylobacter spp., Yersinia spp., or Lawsoni intracellularis), and
Clostridium perfringens enterotoxin and Clostridium difficile A toxin. A possible etiologic factor is a specific enteropathogenic organism that is a common resident in the canine gastrointestinal tract and is sensitive to
tylosin but difficult to eradicate. Additional studies are required to identify the specific cause of TRD.