Subpalpebral Lavage Lines: Placement, Management, and When You Need One
Making complicated corneal cases manageable through strategic medication delivery
When treating complicated corneal ulcers requiring frequent medication, every equine veterinarian faces the challenge of ensuring consistent topical treatment when horses are in pain and owners are overwhelmed by hourly medication protocols.
Subpalpebral lavage (SPL) systems transform impossible treatment scenarios into manageable care by delivering liquid medications directly to the eye through a small catheter, eliminating stress and risk of repeated direct eye contact.
When SPL Lines Are Indicated
SPL systems benefit multiple scenarios beyond infected corneal ulcers, including horses with painful eyes requiring various medications, difficult-to-treat patients, and horses with chronic eye issues requiring prolonged treatment¹.
The system proves invaluable when medications must be given 6-12 times daily, a frequency “near impossible to do with ointments or squirting onto the eye,” Dr. Allbaugh notes¹. Many critical medications like antifungals (voriconazole) and compounded antibiotics are only available in liquid form.
For melting corneal ulcers, stakes are particularly high. These cases require serum therapy, aggressive antibiotics, and antifungals at frequent intervals that would be impossible to administer safely without an SPL system.
SPL System Components
The subpalpebral lavage kit contains several key components: a 60-inch silicone line with attached footplate, a 12-gauge trocar for placement, and injection ports for medication delivery¹. Dr. Allbaugh recommends the 60-inch system over shorter alternatives, noting "even if I don’t need as much length, I can just cut the line shorter"¹.
The footplate sits flush against the conjunctiva in the fornix, positioned away from the corneal surface to prevent iatrogenic ulceration. The external line threads through pre-placed mane and forelock braids, terminating near the withers with an injection port.
Placement Technique
SPL placement requires heavy sedation and comprehensive nerve blocks. “You are not going to be able to place a lavage line in an awake horse,” Dr. Allbaugh emphasizes¹. The auriculopalpebral nerve block proves particularly valuable, denervating the orbicularis oculi muscle to prevent fighting eyelid manipulation.
The technique involves creating a pocket with a gloved finger under the eyelid, then advancing the 12-gauge trocar alongside the finger to penetrate the conjunctival fornix and exit through the eyelid skin. Dr. Allbaugh prefers ventral placement for better patient compliance¹.
Critical placement principles include ensuring the footplate sits flush in the fornix, confirming proper orientation (the “MAA” marking should be visible), and securing the line with tape tabs and sutures¹.
Medication Administration Protocol
Through the SPL system, medications are delivered using 0.1 to 2 milliliters of solution followed by 2-3 cc’s of air to advance medication onto the eye¹. This allows individual medication administration with five-minute intervals between different drugs.
For horses receiving multiple medications, sequence matters. “If you have to utilize suspensions like prednisolone acetate or glaucoma medications like dorzolamide-timolol, you need to use those first and you want to use the solutions to follow,” Dr. Allbaugh explains¹. Serum therapy should be administered last, as studies suggest it might alter antibiotic effectiveness.
Some horses prove intolerant of air boluses. For these patients, “loading the line” provides an alternative where sequential doses are placed in the line, and subsequent injections advance the previously loaded medications¹.
Management and Troubleshooting
Daily monitoring ensures proper function and identifies complications early. Owners should verify the MAA marking remains visible and confirm medication reaches the eye¹.
Common complications include line migration, clogged injection ports, and rare footplate entrapment. Most issues are minor and repairable using a 20-gauge catheter as a splice¹.
Environmental considerations include cold weather challenges where solution may freeze. Solutions include indoor housing, protective covers, or manually warming frozen segments¹.
The injection port requires replacement every 5-7 days or when becoming “gummy,” and betadine can be flushed twice daily as a disinfectant¹.
Duration and Removal
SPL systems can remain in place for extended periods. Dr. Allbaugh reports her longest case duration at 11 months for a horse with recurrent equine uveitis and recurring infected corneal ulcers¹. The silicone material proves remarkably biocompatible, allowing prolonged use without tissue reaction.
Removal requires minimal restraint: cleaning the area with diluted betadine, cutting the line near the exit site, and gently wiggling the footplate through the eyelid for retrieval¹. Dr. Allbaugh recommends stopping treatment several days before removal to ensure no disease recurrence.
Clinical Impact
The SPL system transforms case management by enabling optimal treatment regimens otherwise impossible to implement. For complicated corneal ulcers requiring aggressive therapy, the system makes the difference between treatment success and failure.
SPL systems reduce stress for horses, owners, and veterinarians. Treatment becomes a calm procedure performed away from the painful eye, often while the horse grazes or receives positive reinforcement feeding.
The technique represents essential equipment for practitioners managing equine ophthalmic emergencies. As Dr. Allbaugh notes, "lavage lines are absolutely amazing, making your life easier, your horse’s life easier, clients, all family members"¹.
This content is based on lectures by Dr. Rachel Allbaugh, DACVO, presented at VetOnIt CE. Explore Advanced Equine Ophthalmology.
Tags: Ophthalmology, Equine, Large Animal
References
- Allbaugh R. Subpalpebral Lavage Lines: Placement, Management and Troubleshooting. VetOnIt CE Webinar. 2026.