Pulse - April 2022 - 13

PRACTICAL PATHOLOGY
Panuveitis and Optic
Neuritis in Cats
Farshid Shahriar DVM, PhD, DACVP - Lore Laboratory, Tustin, CA
History and clinical findings: Enucleated left eye from a 10-month-old, female
spayed cat was presented for histopathological examination. Sections of the eye were made
and examined histologically.
Histopathologic findings: The eye globe has multifocal, moderate, chronic,
lymphocytic, plasmacytic, histiocytic panuveitis (Fig. 1)with anterior uveitis, choroiditis,
scleritis and optic neuritis with focal, moderate, acute periocular hemorrhage. There is
glaucoma with diffuse loss of retinal ganglion cells and marked atrophy of the inner nuclear
layer (Fig. 2) and marked optic nerve atrophy and optic disc cupping (Fig. 3). There is
evidence suggestive of displacement of the lens and a small, early peripheral cortical cataract
with a few eosinophilic globules (Morgagnian globules) in spaces between lens fibers
focally. Buphthalmos develops with chronic glaucoma and may damage the lens supportive
structures / zonular breakdown. There are no visible breaks in Descemet's membrane due to
buphthalmos and there is no exposure keratitis and there is no phacyolysis /tear in the lens.
No organisms, viral inclusions or neoplastic cells are seen and there are no vascular changes
to suggest hypertension or Feline infectious peritonitis/coronavirus.
Diagnosis: Diagnosis of anterior uveitis, choroiditis, scleritis and optic neuritis, chronic,
persistent with glaucoma and a small peripheral cortical cataract was made.
Discussion: Among the causes of panuveitis we may consider: 1) penetrating injuries of the
eye (often from bite wounds) or perforating corneal ulcer with intraocular contamination,
2) systemic viral, bacterial, protozoal or fungal or other types of infection with ocular
involvement, and 3) proptosis of more than few hours' duration 4) lenticular degeneration/
placolysis and 5) uveitis. There is no evidence of a perforating corneal ulcer. Lens phacolysis
or a tear is not noted. Lens luxation is a common sequel to uveitis and/or glaucoma. Some
feline cataracts develop as the result of an animal's inability to metabolize proteins and
other body chemicals, or as a result of diabetes and hypertension. Older cats often develop
cataracts and senile zonular breakdown as a part of the aging process. Other causes of cataracts
include exposure to certain drugs or toxic substances, radiation, or electric shock, uveitis and
glaucoma and there is evidence of uveitis and glaucoma in this globe. Feline ocular sarcomas
develop in cats with ocular trauma/lesions resulting in lens capsule rupture > 1.5 mm but
there is no evidence of a sarcoma in this globe. Tests for FELV, FIV, Feline herpesvirus-1,
Chlamydia, Mycoplasmal infection, Ehrlichiosis or Bartonella spp. are advised. Viral infections
may only initiate feline uveitis, which is then perpetuated by immune-mediated mechanism
/inflammatory phenomena. FHV infection often occurs in combination with feline
calicivirus and/or Chlamydia felis, Bordetella bronchiseptica, Mycoplasma spp. There is no
diagnostic evidence of Toxoplasmosis, Encephalitozoonosis, Blastomycosis, Histoplasmosis,
or Cryptococcosis and the eye is typically one of the last organs to be infected in cats with
FIP, and the eyes are always affected bilaterally and vasculitis which is a diagnostic feature of
FIP is not present in this eye and affected cats die of severe lesions elsewhere before there is
time to develop glaucoma. Lymphoplasmacytic uveitis which remains idiopathic, is the most
common cause of feline glaucoma. No organisms, viral inclusions or neoplastic cells are seen
and there are no vascular changes to suggest hypertension or Feline infectious peritonitis/
coronavirus. Diffuse panophthalmitis is not amenable to medical therapy and enucleation is
the treatment of choice. The affected eye becomes phthisical. P
Reference: Angelie K. Shukla, C.L. Pinard. Feline Uveitis. Cetlearn.com - Compendium, September 2012
PULSE
APRIL 2022
13
Figure 1
Figure 2
Figure 3

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