JPC SYSTEMIC PATHOLOGY
SPECIAL SENSES SYSTEM
April 2018
S-M04

Signalment (#2165081):  1 year-old New Zealand White rabbit

HISTORY:  S-M04a: This rabbit had a two week history of buphthalmos and a one day history of excessive lacrimation, corneal ulcer and bilateral marked scleral injection. 

HISTOPATHOLOGIC DESCRIPTION:  Eye:  Changes within the narrowed filtration angle are characterized by a continuous iris stroma that spans the iridocorneal angle and loss of the uveoscleral trabecular meshwork within the ciliary cleft (trabecular hypoplasia) (Note these changes are partially obscured by artifactual separation). Diffusely there is mild to marked thinning of the retina with loss of the afferent nerve fiber layer. Few remaining ganglion cells are shrunken and hyperchromatic with pyknotic nuclei.  Diffusely there is variable thinning of the inner and outer plexiform nuclear layers with accentuation of the Muller fibers (retinal atrophy).  There is marked cupping of the optic nerve head with scattered spongiosis and few dilated myelin sheaths.  Diffusely the fibers of the corneal substantia propria are separated by clear space and lymphatics within the sclera are ectatic (edema).  There is atrophy of the choroid, ciliary body and iris, and the sclera is markedly thin.

MORPHOLOGIC DIAGNOSIS:  Eye:  Goniodysgenesis, with retinal atrophy, optic nerve cupping, uveal tract atrophy, scleral thinning and corneal edema, New Zealand White rabbit, lagomorph.

CONDITION:  Primary (congenital) glaucoma; goniodysgenesis

Signalment (#1505464): A 7 year-old Bassett Hound

HISTORY:  S-M04b: This dog had a sudden onset of buphthalmia of the right eye.

HISTOPATHOLOGIC DESCRIPTION:  There is goniodysgenesis, characterized by a continuous iris stroma that spans the iridocorneal angle and inserts into the termination of Descemet’s membrane (imperforate pectinate ligament), increased connective tissue within the uveal trabecular meshwork, and loss of the uveoscleral drainage angle (trabecular hypoplasia). The anterior aspect of the corneal epithelium is attenuated, and the lateral aspects of the corneal epithelium are hyperplastic, up to 13 cell layers thick, with intracellular edema (hydropic degeneration), intercellular edema (spongiosis), and multifocal superficial squamous keratinization.  Multifocally, small caliber blood vessels extend from the limbus into the corneal stroma (corneal vascularization).  Within the stroma surrounding the blood vessels are moderate numbers of neutrophils (keratitis) and multifocal aggregates of brown, granular pigment (melanin). Multifocally, corneal stroma is separated by increased clear space (corneal edema). Multifocally, within the anterior chamber and vitreous body, there are few to moderate numbers of neutrophils admixed with an eosinophilic proteinaceous exudate (hypopyon). The pupillary margin is everted with protrusion of the posterior iris pigment layer through the pupil (ectropion uveae).  Within the retina, there is multifocal mild to moderate retinal atrophy, characterized by loss of the nerve fiber layer; ganglion cells that are swollen, have clumped Nissl substance and central chromatolysis (dengeneration) there is loss and degeneration of the inner nuclear cell layer, and blending of the inner and outer plexiform layers. The retina is multifocally elevated from the multifocally hypertrophied retinal pigment epithelium (retinal detachment). There is mild cupping of the optic nerve, which contains few dilated axonal sheaths and rare spheroids.  Focally, the sclera is markedly expanded by ectatic lymphatics, abundant eosinophilic homogenous fluid (edema), hemorrhage, and congested blood vessels. Multifocally, the bulbar and palpebral conjunctiva is expanded by a cellular infiltrate composed of lymphocytes, plasma cells, macrophages and neutrophils, markedly congested blood vessels, hemorrhage and ectatic lymphatics (edema). The conjunctival epithelium is hyperplastic, with acanthosis, spongiosis, and intraepithelial neutrophilic pustules (conjunctivitis and blepharitis).

MORPHOLOGIC DIAGNOSIS:  1. Eye:  Goniodysgenesis, with retinal atrophy, multifocal, moderate, and detachment, basset hound, canine.

  1. Eye: Uveitis and keratoconjunctivitis, neutrophilic, multifocal, moderate, with hemorrhage and edema.

CONDITION:  Glaucoma (primary); Goniodysgenesis

GENERAL DISCUSSION: 

PATHOGENESIS: 

TYPICAL CLINICAL FINDINGS:

TYPICAL GROSS FINDINGS:

TYPICAL LIGHT MICROSCOPIC FINDINGS: 

ADDITIONAL DIAGNOSTIC TESTS: 

DIFFERENTIAL DIAGNOSIS:

COMPARATIVE PATHOLOGY: 

REFERENCES: 

  1. Barthold SW, Griffey SM, Percy DH. Pathology of Laboratory Rodents and Rabbits. 4th ed. Ames, IA: John Wiley & Sons; 2016:318.
  2. Bauer BS, Sandmeyer LS, Philibert H, et al. Chronic glaucoma in dogs: Relationships between histologic lesions and the gonioscopic diagnosis of pectinate ligament dysplasia.  Vet Pathol.  2016;53(6):1197-1203.
  3. Dubielzig RR, Ketring KL, McLellan GJ, Albert DM. Veterinary Ocular Pathology: a comparative review. Louis, MO: Saunders Elsevier; 2010:45-48, 419-448.
  4. Graham KL, McCowan C, White A. Genetic and biochemical biomarkers in canine glaucoma.  Vet Pathol.  2017;54(2):194-203.
  5. Jones ML, Beck AP, Dubielzig RR. Bilateral buphthalmia in a 4-Month-Old Texas longhorn steer.  Vet   2012;50(1): 212-214.
  6. Labelle P. The eye. In: Zachary JF, ed. Pathologic Basis of Veterinary Disease. 6th ed. St. Louis, MO:  Mosby Elsevier; 2017:1288-1292.
  7. Miller, PE. The glaucomas. In: Maggs, DJ, Miller PE, Ofri R, eds. Slatter’s Fundamentals of Veterinary Ophthalmology. 4th ed. St. Louis, MO: Saunders Elsevier; 2008:231-255.
  8. Wilcock BP. Special senses. In: Maxie MG, ed. Jubb, Kennedy and Palmer’s Pathology of Domestic Animals. Vol 1. 6th ed. Philadelphia, PA: Saunders Elsevier; 2016:459-464. 


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