Necrotizing enterotyphlocolitis in dogs treated with a potent antimuscarinic

Area of Science:

• Pharmacology
• Toxicology
• Veterinary Medicine

Background:

• Muscarinic receptor antagonists are investigated for various therapeutic applications.
• Preclinical safety assessments are crucial before human clinical trials.

Purpose of the Study:

• To evaluate the safety of a novel antimuscarinic agent in a repeat-dose oral toxicity study in Beagle dogs.
• To identify potential adverse effects and understand their mechanisms.

Main Methods:

• Beagle dogs received repeat oral doses of the antimuscarinic compound.
• Clinical observations, physical examinations, and post-mortem necropsies were performed.
• Histopathological examination of intestinal tissues was conducted.
• Fecal cultures were analyzed for microbial agents.

Main Results:

• Dogs exhibited profound anorexia and severe bloody diarrhea.
• Necropsy revealed intestinal distension, fluid accumulation, and mucosal reddening.
• Histology showed severe epithelial necrosis and mucosal atrophy, primarily in the ileum and large intestine.
• Clostridium perfringens was identified in fecal samples of affected dogs.

Conclusions:

• The antimuscarinic agent induced significant gastrointestinal toxicity in dogs, likely due to exaggerated pharmacologic effects on intestinal motility.
• The observed intestinal lesions were distinct from those typically associated with Clostridium perfringens-induced hemorrhagic canine enteritis.
• These findings highlight potential safety concerns for this antimuscarinic compound and suggest further investigation into the specific mechanisms of toxicity.