CLINICAL VIEW h h PEER REVIEWED

Chorioretinitis

David A. Wilkie, DVM, MS, DACVO The Ohio State University

d Active feline 1 and secondary to systemic cryptococcosis. Multifocal areas of subretinal and peripapillary edema elevate the and blur the underlying tapetum.

Chorioretinitis, or posterior hematogenously disseminated disease , refers to inflammation of (eg, neoplasia, bacteremia, viremia, BEFORE tick-borne disease, disseminated mycosis, YOUR EYES the and retina. Because parasitism, algal infection, protozoal these posterior ophthalmic infection), and immune disease (eg, Watch a video of tissues are so intimately uveodermatologic syndrome).1–9 Whereas active chorioretinitis chorioretinitis is most often bilateral, secondary to associated, it is difficult to affect disseminated unilateral disease can occur and does not cryptococcosis as 1 without affecting the other, and preclude systemic disease. seen by indirect inflammatory disease of either Examination of the posterior segment of results in chorioretinitis. at brief.vet/ the eye is indicated in animals with vision chorioretinitis disturbance, when anterior uveitis is The choroid is the posterior aspect of the present, in cases of known systemic or vascular tunic; it contains blood disease, and in patients with systemic vessels, melanin, and, dorsally, the abnormalities of unknown cause as in tapetum. The choroid supplies nutrition fever of unknown origin. and removes waste material from the retina; provides a cooling function, Active chorioretinitis is typically an helping to dissipate heat generated by the ocular manifestation of a systemic visual process; and facilitates vision in disease with a hematogenous cause. dim light. To perform these functions, Baseline data should include a complete the choroid has a tremendous blood flow, history, including travel history and far more than that simply required for vaccination status, as well as a physical oxygenation. Although this ensures the examination, CBC, serum chemistry health of the retina, it also results in profile, urinalysis, diagnostic testing for significant risk to the retina and choroid relevant infectious diseases, thoracic and from vascular abnormalities (eg, hyper- abdominal imaging, and cytology. tension, hyperviscosity, vasculitis),

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2 3 4 d Active canine chorioretinitis d Active feline chorioretinitis d Active feline chorioretinitis secondary to systemic secondary to systemic secondary to feline cryptococcosis. The retina is blastomycosis. The dark infectious peritonitis. The elevated by large areas of areas are the result of large retinal vessels appear exudate that obscures the pyogranulomatous dilated and elevated by underlying tapetum. choroidal infiltrates, and the the underlying exudate perilesional gray areas are that alters the tapetal retinal folds and wrinkles coloration. secondary to edema and retinal elevation.

5 6 7 d Active canine chorio- d Perivascular exudate or d Complete retinal secondary to cuffing involving a large detachment with lymphosarcoma. Retinal, venule in a cat with active subretinal exudate as peripapillary, and feline infectious peritonitis. a result of choroiditis perivascular edema in a dog with active are noted. uveodermatologic syndrome.

36 cliniciansbrief.com September 2015 8 9 10 d The same eye in Figure 7 d Following immuno- d A large, focal following immuno- suppressive therapy, chorioretinal scar suppressive therapy and depigmentation and following an episode retinal reattachment. pigment clumping are of chorioretinitis of Multifocal tapetal seen in the nontapetal unknown cause. hyperreflectivity and fundus in Figure 7. hyperpigmentation are noted.

Given the predilection for chorioretinitis in The eyes should many systemic diseases, a dilated fundic be examined in examination should also be a routine part of a dark room the physical examination in animals with fever using an indirect, of unknown origin and when disseminated direct, or PanOptic neoplasia, mycosis, vasculitis, tick-borne diseases, or similar conditions are considered ophthalmoscope. as possible differentials.

To examine the posterior aspect of the eye, the must first be dilated using a short-acting mydriatic, such as 1% tropicamide. The eyes 11 should be examined in a dark room using an indirect, direct, or PanOptic ophthalmoscope d Tapetal necrosis, extensive depigmentation, optic (WelchAllyn.com). The veterinarian should be nerve pallor and retinal familiar with normal posterior segment vascular attenuation are variations associated with species, coat, eye seen as results of previous color, and age of the animal. An accurate severe immune-mediated fundic examination allows direct, noninvasive chorioretinitis. visualization of the arteries, venules, capillar- ies, and central nervous system.

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Clinical Signs identified first. The safest nonspecific treat- Chorioretinitis appears clinically as a color ment option pending diagnosis is administra- change or loss of clarity of tissues on fundic tion of systemic nonsteroidal antiinflammato- examination. With active chorioretinitis, the ries (NSAIDs) while test results are pending. addition of fluid, protein, and cells within the Systemic should be adminis- retina and subretinal tissues will obscure the tered only after infectious causes have been tapetum or pigment of the choroid (hypore- ruled out or are being appropriately treated. If flective) and may elevate or detach the retina indicated, the dose of systemic corticosteroids and blur the image. Vascular involvement may range from antiinflammatory to immu- may result in perivascular cuffing, vasculitis, nosuppressive, depending on cause. If the hemorrhage, and exudate (Figures 1–7). With cause is immune-mediated, then additional active chorioretinitis, anterior segment immunosuppressive therapy with azathio- involvement is common, resulting in aqueous prine, cyclosporine, or other similar medica- flare, , , keratic precipitates, tions may be required. If there is concurrent , corneal edema, and intraocular anterior uveitis, then topical corticosteroids, pressure (IOP) changes. With chronicity, NSAIDs, and 1% atropine may also be IOP = intraocular pressure chorioretinitis leads to focal or diffuse retinal indicated. With anterior uveitis, determina- degeneration, tapetal hyperreflectivity, tion and monitoring of IOP is also indicated. depigmentation, hyperpigmentation, and vascular attenuation (Figures 8–11). The sequelae of chorioretinitis include , retinal degeneration, blindness, Treatment , cataract, , vitreal Although treatment of chorioretinitis requires degeneration, atrophy, and loss of systemic medication, its cause must be the eye. n

6. Chavkin MJ, Lappin,MR, Powell CC, Roberts SM. References Seroepidemiologic and clinical observations of 93 cases of 1. Sapienza JS, Simó FJ, Prades-Sapienza A. Golden retriever uveitis in cats. Prog Vet Comp Ophthalmol. 1992;2:29-36. uveitis: 75 cases (1994-1999). Vet Ophthalmol. 2000;3(4):241-246. 7. Gelatt KN. Essentials of Veterinary Ophthalmology. 3rd ed. Ames, 2. Massa KL, Gilger BC, Miller TL, Davidson MG. Causes of uveitis in IA: Wiley-Blackwell, 2014. dogs: 102 cases (1989-2000). Vet Ophthalmol. 2002;5(2):93-98. 8. Narfstrom K, Petersen-Jones S. Diseases of the canine ocular 3. Lappin MR, Marks A, Greene CE, et al. Serologic prevalence fundus. In: Gelatt KN, Gilger BC, Kern TJ, eds. Veterinary of selected infectious diseases in cats with uveitis. JAVMA. Ophthalmology. 5th ed. Ames, IA: Wiley-Blackwell; 2013:1303- 1992;201(7):1005-1009. 1392. 4. Peiffer RL Jr, Wilcock BP. Histopathologic study of uveitis in cats: 9. Stiles J. Feline ophthalmology. In: Gelatt KN, Gilger BC, Kern 139 cases (1978-1988). JAVMA. 1991;198(1):135-138. TJ, eds. Veterinary Ophthalmology. 5th ed. Ames, IA: Wiley- 5. Davidson MG, Nasisse MP, English RV, Wilcock BP, et al. Feline Blackwell; 2013:1477-1559. anterior uveitis: A study of 53 cases. JAAHA. 1991;27:77-83.

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