Objective: To compare acoustic startle reflexes (ASRs) of healthy cats and cats with interstitial cystitis (IC). Animals: 28 healthy cats (11 males and 17 females) and 20 cats with IC (13 males and 7 females). Procedures: To evaluate the effect of neutering on ASRs, ASRs in neutered and unneutered healthy cats were measured. To evaluate the effect of housing facility acclimation on ASRs in cats with IC, ASRs were measured in cats with IC within 1 month after arrival at the housing facility and again 2 to 3 months after arrival. To evaluate the effect of the environment on ASRs, ASRs were evaluated in all cats with and without IC after acclimation but before and then after environmental enrichment. Results: Neutering led to a significant decrease in overall ASR in the healthy cats. Habituation to the housing facility resulted in a significant decrease in overall ASR of female but not male cats with IC. Environmental enrichment led to a significant decrease in ASR in cats with IC but not in healthy cats. Conclusions and Clinical Relevance: The magnitude of the ASR appeared to be sensitive to environmental conditions and affected by sex, both in healthy cats and cats with IC. It was also higher in cats with IC versus healthy cats, except when cats were housed in a highly enriched environment. Impact for Human Medicine: Treatment approaches that include reduction of a patient's perception of environmental unpredictability may benefit humans with IC.