Clinical Deterioration in Dogs with Idiopathic Epilepsy Caused by E. coli Urinary Tract Infection

Idiopathic epilepsy (IE) is a common chronic neurological disorder in dogs, and both its comorbidities and adverse effects of anti-seizure medication (ASM) can markedly reduce quality of life (QoL) for affected dogs and their caregivers. Concurrent conditions such as lower urinary tract infections (UTIs) may mimic ASM side effects or signs of disease progression, potentially leading to inappropriate dose adjustment or treatment discontinuation. This retrospective case series describes eight dogs with IE and <i>Escherichia coli</i> (<i>E. coli</i>) UTI, presenting with suspected worsening of ASM side effects. Reported deterioration lasted 1-55 days (mean 31), with behavioral changes (n = 5), lethargy (n = 5), new or worsened ataxia (n = 5), urinary incontinence (n = 3), polyuria (n = 3), polydipsia (n = 2), and additional signs such as weakness, exercise intolerance, panting, and cluster seizures. All dogs showed bacteriuria; urinary specific gravity was 1.020 ± 0.013 (mean ± standard deviation) [range; 1.002-1.042]. <i>E. coli</i> (>10⁶ CFU/mL) was isolated in all cases. Treatment with amoxicillin-clavulanic acid resulted in clinical improvement within 24-72 h; five dogs experienced UTI relapse, again with clinical deterioration. Findings emphasize the importance of recognizing and treating UTIs in epileptic dogs to avoid misinterpretation as ASM toxicity and possible worsening of seizure control. Prospective studies are needed to clarify potential links between ASM, urinary dilution, immune modulation, and infection risk.