Impact of stress on the tear production of healthy cats.

Objectives: This study aimed to determine the impact of acute stress on tear production in companion cats to provide a basis for minimizing stress-inducing stimuli during ophthalmic evaluations.

Methods: A total of 24 healthy owned cats (12 males, 12 females) of mixed breed, aged 8 months to 7 years, with no history of ocular diseases, were selected for the study. The cats were housed in individual cages under controlled conditions for 6 days. The Schirmer tear test-1 (STT-1) was performed in the morning (between 9:00 am and 11:00 am) using test strips from the same batch. The first test (without stress) was conducted on the fifth day of acclimation, and the second test (with stress) on the sixth day. The stress stimulus consisted of recordings of barking dogs, cats fighting and the murmuring of people. For both tests, the heart rate was assessed with a stethoscope before, during and after the tests, and the environmental stress level was also evaluated. Results are presented as mean ± SD and 95% confidence interval (CI).

Results: The study found that STT-1 values were significantly higher (P = 0.009) with stress (22.2 ± 6.0 mm/min [95% CI 19.9-24.6]) than without stress (17.5 ± 6.9 mm/min [95% CI 14.8-20.2]). Similarly, the heart rate was significantly higher (P = 0.028) in stress vs non-stress conditions (213.4 ± 37.5 beats per minute [bpm] [95% CI 198.7-228.1] vs 171.5 ± 28.6 bpm [95% CI 160.3-182.7], respectively), and the environmental stress score was significantly higher (P <0.001) in stress vs non-stress conditions (3.3 ± 0.5 [95% CI 3.1-3.5] vs 1.2 ± 0.4 [95% CI 1.1-1.4], respectively).

Conclusions and relevance: Stress increased tear production in cats. Although the mean STT-1 value obtained under stress conditions was within the normal range, stress can influence the test results. The use of cat friendly handling techniques facilitates execution of the STT-1.