A challenging case: A dog with a painful red eye
A 7-year-old 19.8-lb (9-kg) intact female Scottish terrier was presented to the Colorado State University (CSU) James L. Voss Veterinary Teaching Hospital for evaluation of redness and pain of the right eye of four days' duration.
Just before the onset of the problem, the dog had been playing outside, but there was no history of known trauma. The dog had been taken to an emergency clinic soon after the red eye had been observed. The emergency clinic veterinarian had diagnosed conjunctivitis and had also found a grass awn in the left ear, which was removed. He had prescribed a triple antibiotic ophthalmic ointment to be given in the right eye two or three times daily.Over the next three days, the eye seemed to worsen, and the dog became lethargic and depressed. Thus, the dog had been taken to its primary veterinarian who had immediately referred it to CSU. The CSU emergency service saw the dog and immediately triaged it to the ophthalmology service.
The right cornea appeared to be yellow-tinged, and a small amount of free blood had collected in the ventral fornix. In addition, a 4-mm, round fibrin clot on the outside of the cornea was present in the ventral fornix near the area of hemorrhage. These changes precluded our ability to evaluate the anterior chamber, pupil, or posterior ocular structures. The intraocular pressures were 33 mm Hg in the right eye and 7 mm Hg in the left (normal = 15 to 25 mm Hg). Despite the lower than normal intraocular pressure, the left eye had no signs of uveitis (e.g. flare, miosis) and was considered normal. The lower intraocular pressure was considered to be age-related. The dog was deemed blind in the right eye because there were no indirect pupillary light reflexes from the eye nor were there tracking or menace responses. There was no obvious foreign material in the conjunctival sac of the right eye, although a thorough examination was difficult.
Because of the severe pain the dog was experiencing, our assessment of probable permanent blindness, the increased intraocular pressure that indicated glaucomatous damage, and the history of possible foreign body exposure, we made a presumptive diagnosis of septic endophthalmitis. We recommended removing the eye immediately. The owner agreed to the transconjunctival enucleation.
Blood was drawn for a complete blood count and serum chemistry profile for a preoperative evaluation; the results of these tests were normal. Preoperative medications included fentanyl (4 µg/kg intravenously), atropine (0.04 mg/kg subcutaneously), and diazepam (0.5 mg/kg intravenously), and anesthetic was induced with intravenous propofol (2 mg/kg). The dog was intubated and placed on isoflurane gas maintenance.
The eye was minimally clipped and then aseptically prepared with dilute (1:30) povidone-iodine solution and draped. A retrobulbar nerve block was performed to help control postoperative pain. The block consisted of injecting a total of 2 ml of a 1:1 mixture of bupivacaine (0.5%) and epinephrine (1:200,000) behind the eye through a 22-ga needle.
A lateral canthotomy was performed for better exposure to the globe, and the nictitating membrane was removed. The eye was dissected out of the orbit by using curved Metzenbaum scissors and a combination of blunt and sharp dissection. Upon ventral dissection, a large amount of purulent, foul-smelling material began to seep from the surgical site, but no ocular perforation was identified despite careful inspection. The purulent material was removed with sterile 4-in-x-4-in gauze sponges. The four rectus muscles, retractor bulbi muscles, and the optic nerve were sharply cut, and the eye was removed.
Postorbital fat and soft tissue were removed from the orbit, and it was inspected carefully for signs of a mass or foreign body. None was seen. Because of the contamination from the purulent material, the orbit was flushed numerous times with sterile saline solution (total of 300 ml). Because of client financial contraints, bacterial culture and sensitivity testing was not performed.
A meshlike web of 3-0 nylon suture material was anchored to the periosteum of the dorsal and ventral orbital margins to prevent the skin from sinking into the orbit. The eyelid margins were trimmed with Mayo scissors. The remaining palpebral margins were brought together by using 3-0 braided absorbable suture material in a simple continuous pattern, and the skin was closed with 3-0 nylon suture material in an interrupted cruciate pattern. The enucleated globe was submitted for histologic examination.
Recovery from anesthesia was uneventful, and the dog was sent home the same day. The owner was given instructions regarding antibiotic and pain control medications: 20 mg/kg amoxicillin trihydrate-clavulate potassium, 4 mg/kg tramadol, and 2 mg/kg carprofen given orally twice a day. An Elizabethan collar was placed on the dog to prevent self-mutilation of the surgery site.