Subconjunctival Antibiotic Poloxamer Gel for Treatment of Corneal Ulceration in Stranded California Sea Lions (Zalophus californianus)
Corneal ulcers are commonly encountered in pinnipeds. Prolonged oral antibiotics and eye drops may not be practical to administer, and novel treatment techniques are desired. Thermodynamic gels are a potential solution because they hold antibiotics at the site of injection, releasing the drug slowly.1-4 Twenty-nine California sea lions undergoing rehabilitation at The Marine Mammal Center were included in the study. A poloxamer gel (Thermaffix Gel, Med Specialties Compounding Pharmacy, Yorba Linda, CA) mixed with 2% enrofloxacin was administered via subconjunctival injection into the bulbar conjunctiva. Control animals were treated with doxycycline (10 mg/kg PO BID). Systemic anti-inflammatories and analgesics were administered as needed. Corneal examinations under general anesthesia were repeated weekly, and included sampling for bacterial culture and corneal cytology, collection of high-quality corneal images, and gel treatment administration until the ulcers were healed. There was no gross or histopathologic evidence of a localized tissue reaction to the gel administration in the conjunctiva, and no evidence of systemic reaction to the therapy after examination of study animals that died due to unrelated causes (n = 19). All lesions in animals that experienced a superficial corneal ulcer involving only epithelium or superficial stroma (n = 16) resolved completely, in both case and control groups. Of those animals with deeper or more complex ulcers involving corneal melting or descemetoceles, five of fourteen (four cases, one control) experienced complete lesion resolution. This study demonstrates that subconjunctival antibiotic poloxamer gel administration is a safe and effective alternative therapeutic option to traditional treatments for superficial corneal ulceration.
This project was funded by the California Department of Fish and Game's Oil Spill Response Fund through the Oiled Wildlife Care Network at the Wildlife Health Center, School of Veterinary Medicine, University of California Davis; by the Coypu Foundation; and by NOAA Fisheries in collaboration with The Marine Mammal Center. The authors thank Med Specialties Pharmacy for their compounded product, and thank the staff and volunteers of The Marine Mammal Center for their care of the animals undergoing rehabilitation.
* Presenting author
1. Carceles CM, Serrano JM, Marin P, Escudero E, Fernandez-Varon E. Pharmacokinetics of moxifloxacin in rabbits after intravenous, subcutaneous and a long-acting poloxamer 407 gel formulation administration. Journal of Veterinary Medicine Series A. 2006;53:300–304.
2. Gutierrez L, Vargas-Estrada D, Rosario C, Sumano H. Serum and tissue concentrations of doxycycline in broilers after sub-cutaneous injection of a long-acting formulation. British Poultry Science. 2012;53(3):366–373.
3. Hart SK, Barrett JG, Brown JA, Papich MG, Powers BE, Sullins KE. Elution of antimicrobials from a cross-linked dextran gel: in vivo quantification. Equine Veterinary Journal. 2013;45:148–153.
4. Mathews KG, Linder KE, Davidson GS, Goldman RB, Papich MG. Assessment of clotrimazole gels for in vitro stability and in vivo retention in the frontal sinus of dogs. American Journal of Veterinary Research. 2009;70(5):640–647.