NGF topical administration in dogs affected by spontaneous keratoconjunctivitis sicca

Purpose: To study the effect of Nerve Growth Factor (NGF) on spontaneous keratoconjunctivitis sicca (KCS) in dogs and to evaluate the potential therapeutic action of this molecule. Methods: The present study has been conducted on a sample of randomized dogs affected by spontaneous KCS. It consists of 6 cases (12 eyes), various ages (from 2 to 10 years old), different sexes (4 males- 2 females). All dogs showed: different stages of muco purulent filaments and redness; they were negative to fluorescein; Schirmer tear test I (STT I) on right eye was 5,8 ± 2,0 mm/1 min on left one was 6,0 ± 1,4 mm/1 min; cytology showed many inflammatory cells. The dogs were topically treated with purified murine NGF diluted in paraffin oil (value: 50 microgram/ml) for 4 weeks (2 drops every 12 hours). Results: The result of these studies showed a significant improvement as evaluated by STT I. Thus, the right eye was 13,1 ± 2,4 mm/1 min (p < 0,05), left eye was 14,0 ± 2,4 mm/1 min (p < 0,05). Moreover, dogs treated with NGF displayed decreased purulent corneal secretion and redness and improvement of corneal transparency. Cytology analysis indicated a significant reduction in the number of corneal inflammatory cells. Conclusions: This report demonstrated that NGF is involved in the regulation of tears production, most probably by acting on tear-producing cells. NGF caused also a marked anti-inflammatory action of the dog’s cornea. This result confirmed and extended previous evidences on human dry eye and previous findings suggesting a potential therapeutic utility of NGF in spontaneous KCS affecting dogs. Neverthless, further clinical studies are necessary to assess the consistency of this clinic approach.