Effect of topical administration of 1% morphine sulfate solution on signs of pain and corneal wound healing in dogs.
OBJECTIVE
To evaluate the effect of topical application of a 1% morphine sulfate solution (MSS) on signs of pain and wound healing in dogs with corneal ulcers and examine normal corneas immunohistochemically for the presence of mu and delta opioid receptors.


METHODS
12 dogs.


METHODS
A 7-mm superficial corneal ulcer was surgically created in the right eye (OD) of 10 dogs, after which gentamicin solution and 1% MSS (n = 6) or saline solution (4) was administered topically OD 3 times daily. Blepharospasm, tearing, conjunctival hyperemia, aqueous flare, esthesiometer readings, and pupil size were recorded before and 30 minutes after treatment in all dogs. Ulcer size and days to completion of healing were recorded. Corneas from 4 treated and 3 control dogs were evaluated histologically. Normal canine corneas from 2 dogs not used in the study were evaluated immunohistochemically for the presence of mu and delta opioid receptors.


RESULTS
Dogs treated with MSS had significantly less blepharospasm and lower esthesiometer readings than did control dogs. Duration of ulcer healing and findings of histologic evaluation of corneas did not differ between groups. Numerous delta and infrequent mu opioid receptors were identified in the corneal epithelium and anterior stroma of normal corneas.


CONCLUSIONS
Topical use of 1% MSS in dogs with corneal ulcers provided analgesia and did not interfere with normal wound healing. Both mu and delta opioid receptors were identified in normal corneas of dogs, although the mu receptors were present only in small numbers.
Stiles
Jean
J
Department of Veterinary Clinical Sciences, School of Veterinary Medicine, Purdue University, West Lafayette, IN 47907, USA.
Honda
Christopher N
CN
Krohne
Sheryl G
SG
Kazacos
Evelyn A
EA
D000287:Administration, Topical; D000818:Animals; D003315:Cornea / Q000187:drug effects* / Q000473:pathology*; D004285:Dogs; D008297:Male; D009020:Morphine / Q000008:administration & dosage* / Q000494:pharmacology / Q000627:therapeutic use*; D010146:Pain / Q000188:drug therapy*; D014945:Wound Healing / Q000187:drug effects
D009020:Morphine