What is the cost of treating corneal ulcers?
In addition to the fees associated with a vet office visit and diagnostic testing, the cost to treat corneal ulcers depends on a variety of factors, including the size of the ulceration and breed of animal. Boxers, for example, are notorious for coming down with very stubborn ulcers. Costs can vary from a few hundred dollars to $1,000 to $2,000 if more advanced procedures or surgical interventions are required, or if the ulcer progresses from a simple ulcer to a more chronic one (also known as an indolent ulcer).
Keep in mind that costs will also vary by geographic location. Bigger cities have higher costs of living, which extend to veterinary care.
What are corneal ulcers in dogs?
The cornea is the clear outer layer of a dog’s eye. While it serves to protect the inner eye, the cornea itself can become damaged or infected.
A corneal ulcer is an open sore in the cornea that exposes the inner layers of the eye. While the most common cause of corneal ulcers in dogs is injury, they can also be a result of an eye infection. Corneal ulcers can worsen with time, and if left untreated, can result in vision loss or even blindness.
The cornea has three layers:
Corneal ulcers can either be superficial, which involves damage to the epithelium, or deep, extending into or through the stroma, resulting in severe scarring and corneal perforation.
The most severe type of corneal ulcer is called “descemetocele” where the two upper layers (epithelium and stroma) are absent and the ulcer has reached the descemet, the deepest membrane of the eye. In the event of a descemetocele, the corneal ulcer will be visible as a divot in the eye, along with the eye having a gray appearance.
Is there a cure for corneal ulcers in dogs?
With proper treatment and care, corneal ulcers are curable in all but the most extreme cases.
Dog Corneal Ulcer Not Healing! Dr. Dan explains why and how to fix.
Corneal ulceration, or a break in the corneal epithelium, can have a variety of etiologies, including trauma, entropion, ocular foreign bodies, and dry eye disease. The purpose of this article is to review corneal anatomy and physiology, basic classifications of corneal ulcers, what owners need to know about caring for dogs with ulcers, and monitoring and rechecking patients with corneal ulcers.
The average canine cornea is 0.62 mm thick (for reference, a dime is 1.35 mm thick). It consists of 4 layers: the epithelium, the stroma, Descemet’s membrane, and the endothelium.1 It is covered by the tear film, an important layer that has many functions. The primary role of the tear film is to provide nutrition and oxygen to the cornea.
The corneal epithelium is made of stratified, nonkeratinized squamous cells. The epithelium is 5 to 7 cell layers thick and can regenerate when injured. Its purpose is to provide a barrier against chemicals, water, and microbes. The epithelium is hydrophobic (water-repelling); therefore, fluorescein stain does not adhere to it.
The stroma is composed of fine, evenly spaced collagen fibers. It is avascular and produces growth factors, extracellular matrix components, and kinases. These are essential for corneal development and homeostasis. The stroma is hydrophilic (water-absorbing); therefore, fluorescein stain adheres to it when there is a break in the epithelium.
Descemet’s membrane is the basement membrane of the posterior epithelium. It is composed of collagen fibers produced by the endothelial cells that lie below it. Descemet’s membrane also repels fluorescein stain. An ulcer that completely penetrates the stroma but has not perforated the endothelium is called a descemetocele. Descemetoceles are often described as “halos” or “donuts,” as the stroma on the sides of the ulcer take up stain and the deep center does not.
The endothelium is a single cell layer. It cannot regrow. The endothelium is responsible for keeping excess fluid out of the cornea through sodium–potassium pumps.2
Any time a dog presents with a red or painful eye or ocular discharge, the cornea should be stained to look for an ulcer. If an ulcer is found and appears to have stromal loss or a cellular infiltrate (i.e., it appears yellow or white), a sample should be collected for cytology and aerobic culture. Proparacaine may be applied before sample collection. A recent article found no significant difference in bacterial isolates before or after application of proparacaine.3 If the ulcer appears to be a descemetocele, great caution should be taken in sample collection. If the case is going to be referred to an ophthalmologist, it is not wrong to wait and let the specialist collect the samples.
Ophthalmologists recommend starting patients with corneal ulcers on broad-spectrum prophylactic antibiotics.4 For an ulcer that is already infected, treatment should be based on cytologic findings until culture results are available. Culture swabs should be refrigerated until plated. Plating should take place as soon as feasible.
It is highly recommended that any canine patient with a corneal ulcer be fitted with an Elizabethan collar (E-collar) until the ulcer is healed.5 Many styles of E-collars are available. For corneal protection, something that will shield the eyes is recommended. Collars made of soft cloth and “donut” styles do not protect the eyes.
Simple, uncomplicated ulcers are superficial, only affect the epithelium, and should heal in 5 to 7 days with or without medical intervention if no complicating factors such as infection or mechanical irritation are present.6
Within an hour of injury to the corneal epithelium, epithelial cells begin to migrate to the defect. New cells slide over in a leapfrog fashion. The new epithelium is loosely attached; therefore, an E-collar is recommended until the ulcer is healed. Owners should watch for increased blepharospasm (squinting) and any of the following color changes: increased redness of the conjunctiva, a blue tint or haziness in the cornea (corneal edema), yellowness in the cornea (cellular infiltrate), or yellow/green discharge.
The patient should become increasingly comfortable over the week. Antibiotics and E-collar use should be continued until the cornea is stain negative.
Ulcers that result in stromal loss are classified as stromal ulcers, and the amount of stromal loss should be noted. Cytology should be performed on stromal ulcer samples to look for bacteria, fungus, and neutrophils. Appropriate antibiotic therapy should be chosen according to cytology results.
If significant neutrophils are seen on cytology, serum should be applied in addition to antibiotics to prevent melting. Serum inhibits collagenase breakdown of the cornea by neutrophils. It is ideal to have frozen serum available to dispense for treatment of possible or already melting ulcers. Serum can be used across species, but serum from cats with unknown feline leukemia and feline immunodeficiency virus status should not be used to treat other cats due to the potential to spread these viruses.7 Serum can be stored frozen at any temperature for up to 180 days without losing efficacy.7 Once thawed, serum should be kept refrigerated for only up to 7 days to avoid possible contamination and bacterial growth. At the author’s practice, equine and canine sera are stored frozen in 0.2-mL aliquots. Twenty 0.2-mL aliquots are dispensed at a time. Clients are advised to only remove 1 or 2 syringes from the freezer at a time and store them in the refrigerator. Three to 4 drops can be administered from a 0.2-mL aliquot.
Stromal ulcers require vascular growth to heal. Vessels start to grow from the limbus 3 to 6 days after insult to the cornea. They continue to grow at a rate of 1 mm per day until the defect is reached. These ulcers should be reexamined at least twice a week to check for progression of healing or worsening.
The corneal stroma is well innervated, so stromal ulcers can be painful and need systemic pain medications. Systemic nonsteroidal anti-inflammatory drugs (NSAIDs) can help with pain as well as any reflex uveitis that may occur secondary to the ulcer. Topical atropine may also be used to relieve ciliary spasm if reflex uveitis is present. Usually, one dose is enough.8
Epithelium regenerates faster than stroma. Occasionally, the epithelium completely covers the surface of the defect before the stroma has a chance to fill in. This defect is known as a facet. The ulcer will no longer be fluorescein positive because the surface epithelium is intact, but the area is still delicate due to the loss of stroma. No further treatment is indicated.
Ulcers that are as deep as Descemet’s membrane are called descemetoceles (Figure 1). If the ulcer penetrates Descemet’s membrane, the cornea is perforated. Aqueous humor will leak out and the hole will become plugged by either the iris or a fibrin clot.
Descemetoceles should ideally be treated surgically with the placement of a graft.9 If owners cannot afford surgery or the patient is not an ideal anesthetic candidate, aggressive medical management can be attempted with the knowledge that the eye may have to be removed (enucleated). Reasons for enucleation are graft dehiscence, corneal perforation under the graft, uncontrollable intraocular inflammation, and intraocular infection.
Perforated eyes may still be salvaged depending on the size and age of the perforation (Figure 2). If the eye still has a positive dazzle response, vision might be able to be saved. If the owners feel very strongly that they want to save the globe with or without vision, a graft can be attempted (Figure 3). Again, surgical intervention is the best chance at saving the globe, but owners should be made aware that the eye may still need to be enucleated or become phthisical (shrunken). If a watertight seal cannot be accomplished, the eye will continue to leak and be a source of pain and possible infection.
Entropion, or rolling in of the eyelids, can cause chronic corneal ulceration due to the haired skin constantly rubbing the delicate cornea. In young dogs that have not reached their adult head size, it is recommended to temporarily tack the eyelids,10 rolling them out and affixing with sutures so the hairs no longer rub the cornea (Figure 4). This may need to be repeated as the dog grows or scratches the sutures out. Once the dog has finished growing, permanent surgical correction should be performed.
If the entropion is secondary to fat loss or muscle wasting, such as in elderly or debilitated dogs, hyaluronic acid subdermal filler can be used. This procedure can be performed without general anesthesia. Resolution of corneal ulceration and epiphora should be seen within a week.11
Abnormal eyelid hairs such as distichia and ectopic cilia can also cause chronic corneal ulceration (Figure 5). Distichia are hairs that erupt from the meibomian gland openings along the eyelid margin. These hairs can be long and soft or short and stout. The long, soft hairs do not often cause corneal ulceration because they float in the tear film. The short, stout hairs can cause breaks in the epithelium if they poke the cornea. If it is unclear if distichia are the cause of an ulcer, they can be epilated. If the ulcer heals before the hairs regrow, permanent removal of the hairs should be recommended. Permanent removal can be accomplished in several ways. If only a few hairs are present, surgically excising the hair follicles is the standard procedure. If multiple distichia are present, electrocautery, cryotherapy, or laser therapy may be used to destroy the follicles.12
If a vertical oval ulcer is chronically present, ectopic cilia should be suspected. These hairs are harder to find as they emerge from the palpebral surface, or the conjunctival side of the eyelid. They occur most commonly on the upper lid. The cilia are often so small that magnification is needed to see them. Surgical excision is the most common method for removal of ectopic cilia.
Tumors of the eyelid may also cause corneal ulceration by constantly rubbing the cornea. Most canine eyelid masses are benign but continue to grow over time. Surgical removal is indicated when corneal health is in jeopardy. Masses that occupy one-third or more of the eyelid margin should be referred to an ophthalmologist, as eyelid reconstruction may be needed.