Canine endotheliitis: Clinical characteristics, advanced imaging features, and treatment

Abstract

Objective: To describe the clinical findings, multimodal corneal imaging features and treatment in canine patients diagnosed with endotheliitis.

Animals studied: Four canine patients met inclusion criteria for bilateral corneal disease with endothelial inflammation and secondary corneal edema that responded to topical anti-inflammatory treatment.

Methods: The patients selected underwent a complete ophthalmic examination with emphasis on the cornea including ultrasound pachymetry (USP), Fourier-domain optical coherence tomography (FD-OCT), in vivo confocal microscopy (IVCM), and digital slit lamp photography.

Results: All patients in this study demonstrated thickened corneas due to edema with USP and FD-OCT. With IVCM, mild to severe polymegathism and pleomorphism of corneal endothelial cells, reduced endothelial cell density, hyperreflective keratic precipitates (KPs), and extracellular debris as well as hyporeflective pseudoguttata were observed. With FD-OCT, hyperreflective KPs were commonly observed on the inferior cornea. Clinical examination and advanced imaging results were consistent with a diagnosis of endotheliitis. All patients initially responded to topical anti-inflammatory treatment and required continued therapy; two patients also received topical netarsudil, a rho-associated coiled-coil kinase inhibitor.

Conclusion: Endotheliitis should be considered for canine patients with bilateral edema that is most severe in the inferior cornea. Careful inspection of Descemet's membrane-endothelial complex should be performed for KPs or inflammatory debris. Chronic administration of topical anti-inflammatories may be necessary to prevent flare-ups of endotheliitis.

Keywords: ROCK inhibitor; corneal edema; endotheliitis; in vivo confocal microscopy; optical coherence tomography.

Figure 1.

Clinical course of canine endotheliitis in a 6-year-old male castrated Chihuahua mix with 16 months of follow up. At initial presentation, the patient had bilateral corneal edema (A). One month after the patient was receiving dexamethasone 1% ophthalmic solution TID, the corneal edema was improved OS (B) and resolved OD (not shown) and was completely resolved OU four months later (F). At one month after initial presentation, FD-OCT demonstrated hyperreflective deposits on the endothelium consistent with KPs (C, asterisk). With IVCM, mild to moderate pleomorphism (D, E), endothelial cells with hyperreflective, elongated nuclei (E, black arrowhead), pseudogutatta (D, black arrows) and hyperreflective deposits consistent with KPs (D inset, white arrow) were observed 1 month after initial presentation. Four and ten months later, the corneas were clear (F, J). With FD-OCT, DM-endothelial complex was thickened (G, K) and hyperreflective on FD-OCT. With IVCM, progressive endothelial pleomorphism and polymegathism (M, white arrowhead), hyperreflective KPs (I, white arrow) and pseudogutatta (I, L, M, black arrows) were observed. Sixteen months after initial presentation and after 8 months of topical netarsudil, the endothelial complex was still thickened with FD-OCT (O, yellow arrowhead). Endothelial morphology was improved OS but variable with IVCM (P). Hyperreflective KPs (P inset, white arrow) and pseudogutatta (Q, black arrow) persisted in this patient.

Figure 2.

Active endotheliitis was present in a 2-year-old castrated male Chihuahua receiving topical diclofenac 1% ophthalmic solution twice daily. At initial presentation, the patient was receiving topical NPD ophthalmic ointment with no apparent clinical signs (A, OS). Two weeks after replacement of the NPD ophthalmic ointment by diclofenac twice daily, the patient was presented for ocular discomfort, mild corneal edema, and conjunctival hyperemia (B, OS). KPs were observed with slit lamp biomicroscopy (C, white arrows OS), FD-OCT (D, asterisk, OS) and IVCM (E, white arrows, OD). After replacing topical NPD with diclofenac BID, pseudogutatta (black arrows) and hyperreflective deposits compatible with KPs were observed with IVCM (F, white arrows, OD).

Figure 3.

Changes to the endothelium and Descemet’s membrane were visible in a 1-year-old female Australian cattle dog diagnosed with endotheliitis at 3 months of age. This patient was receiving NPD ophthalmic ointment once daily OU. Subtle opacity was present in the axial cornea OU (A, B) due to increased hyperreflectivity of the DM-endothelial complex observed with slit lamp biomicroscopy at 10X magnification and FD-OCT (C and D, yellow arrowheads). With IVCM, few, mildly pleomorphic endothelial cells (F, white arrowhead) and scant hyperreflective KPs were observed (E, white arrow).

Figure 4.

A 1-year-old female Australian cattle dog with repeated bouts of severe canine endotheliitis demonstrates marked changes to the corneal endothelium OU; corneal edema improved in the less affected OD four months later with topical netarsudil, anti-inflammatory and immunosuppressive therapy. One year after initial diagnosis of endotheliitis, marked inferior edema OD (A) and severe diffuse edema with only sparing of the superior perilimbal OS (B) was observed. With FD-OCT, hyperreflective deposits interpreted as KPs in the inferior cornea attached at the corneal endothelium were observed OD (C, asterisks) and OS (not shown). With IVCM, multifocal hyperreflective deposits partially cover a mildly pleomorphic endothelium (F, black arrowheads). After 4 months of topical netarsudil BID in combination with increased frequency of PA and NaCl to QID and the addition of tacrolimus BID, the corneal edema is improved OD (D) and static OS (E); With IVCM, persistence of hyperreflective deposits consistent with KPs (G, black arrows) were observed.