endocrinology 2011 eyes

Canis domesticus

The effect of neutering on tear production in dogs

 R Ofri¹, R Ckalifa¹, T Bdolah-Abram¹, L Shore²
Koret School of Veterinary Medicine, Hebrew University of Jerusalem, Israel¹;
Department of Endocrinology, Kimron Veterinary Institute, Ministry of Agriculture, Israel².

 Purpose: There are conflicting reports regarding gender predisposition to keratoconjunctivitis sicca (KCS), with some authors demonstrating the disease to be more prevalent in female dogs. While this finding is disputed by others, there appears to be a consensus that neutered dogs, of either gender, are predisposed to KCS, probably due to decline of sex hormones regulating tear production. Our aim was to evaluate tear production in dogs prior to, and following, neutering and to correlate it with levels of sex hormones. Methods: Study animals included 25 healthy dogs (14 females, 11 males) presented for elective neutering. Schirmer Tear Test I (STT) was performed, and blood samples for progesterone, estrogen and testosterone assays were withdrawn, on days 0 and 14. Fourteen dogs (8 females, 6 males) were re-evaluated 6 months later. Results: Mean±sd STT results on days 0, 14 and 180 were 19.7±4.4, 19.0±3.6 and 20.3±6.9 mm/min, respectively. There were no significant differences between the three readings (P=0.65), or between males and females (P=0.40). Nor was there a significant decrease in STT over time in either neutered males or females (P=0.99). No significant correlation was found between STT and any of the three hormones assayed (P>0.10). Conclusions. We believe this small scale, pilot study is the first one to measure STT over time in the same dog, prior to and following neutering. While the study needs to be repeated with a larger sample, it seems that in dogs, unlike other species, neutering has an insignificant effect on tear production.

European College of Veterinary Ophthalmologists (2011)


Capra nubiana  (pictures courtesy of Ron Ofri)
Ibex  Intraocular pressure 

Panthera leo

Ofri, R., Shore, L.S., Kass, P.H. and Horowitz, L.H. (1999). The effect of elevated progesterone levels on intraocular pressure in lions (Panthera leo). Research in Veterinary Science 67:121-123