Eye Opener: Pathology - Companion animals

Companion animals

Cherry eye or Haws

Figure 1: Unilateral prolapse of third eyelid gland in an American Cocker spaniel dog.

Source: Mehdi M., Sepehr M., Omid, Kazemi H. and Elnaz (2012) 'Clinical evaluation of the pocket technique for replacement of prolapsed gland of the third eyelid in dogs',Turkish Journal of Veterinary and Animal Sciences, 36(4), pp. 352-356.

Figure 2: Bilateral prolapse of third eyelid gland in a mixed-breed dog.

Figure 3: Unilateral prolapse of third eyelid in a Burmese cat.

Source: Chahory S., Crasta M., Trio S. and Clerc B. (2004) 'Three cases of prolapse of the nictitans gland in cats', Veterinary Ophthalmology, 7(6), pp. 417-419.

Figure 4: Bilateral prolapse of third eyelid in a Persian cat.

Source: Chahory S., Crasta M., Trio S. and Clerc B. (2004) 'Three cases of prolapse of the nictitans gland in cats', Veterinary Ophthalmology, 7(6), pp. 417-419.

Prolapse of the third eyelid gland

Unilateral or bilateral
Unclear cause
Secondary to inflammation
Weakness in connective tissue that anchors the gland

May be heritable

Dogs

More common in dogs than cats
Beagle, English bulldog, American Cocker spaniel, Boston terrier, Poodle, Shar Pei, Pekingese, Neapolitan Mastiff, Basset hound and brachycephalic breeds more susceptible

2-3 years old

Cats

Rare in cats

Strands of smooth muscle around third eyelid provide extra anchorage for the gland to the base of the third eyelid

Burmese cats more susceptible
Adult cats - 2.5-6 years old

Clinical signs

Epiphora
Conjunctivitis
Development of red mass at medial canthus

Figure 3: Conjunctival imbrication or Pocket technique for repositioning of third eyelid gland. A: exteriorize third eyelid with forceps. B: Parallel incisions through bulbar conjunctiva anterior and posterior to the gland. C-D: reposition gland to proper position and suturing it in place.

Treatment

Surgically reposition and suture gland back into proper location

Preserves tear production
Suture gland to adjacent sclera, extraocular muscle tendon or ventral endorbita of orbital rim
Conjunctival imbrication or Pocket technique

Excision of prolapsed gland

30% of tear production
predisposes dog to keratoconjunctivitis sicca (KCS) later in life

Corneal sequestrum

Figure 1: Corneal sequestrum (black/brown pigmentation indicated by arrow) surrounded by vascularisation in a cat.
Source: Claudia Hartley (2010) 'Aetiology of Corneal Ulcers: Assume FHV-1 Unless Proven Otherwise', Journal of Feline Medicine and Surgery, 12(), pp. 24-35.

Figure 2: Central corneal sequestrum in a Burmese cat.
Source: Claudia Hartley (2010) 'Aetiology of Corneal Ulcers: Assume FHV-1 Unless Proven Otherwise', Journal of Feline Medicine and Surgery, 12(), pp. 24-35.

Necrosis of corneal epithelium and stroma in domestic cats
Usually unilateral, but can also occur bilaterally
Sequestrum

Oval or round
Brown pigmentation in affected tissue

Central or paracentral dark brown or black plaque

Susceptible breeds

Brachycephalic cats: Persian, Siamese, Burmese, Himalayan and Domestic Shorthair cats

Associated with

Corneal ulcers
Ocular trauma
Feline herpesvirus-1 infection
Chlamydia psittaci infection
Keratoconjunctivitis sicca
Entropion

Clinical signs

Pain and irritation
Bleopharospasm
Epiphora
Enophthalmos
Elevated nictitating membrane
Chemosis
Conjunctival hyperemia
Photophobia
Decreased appetite and activity

Treatment

If no discomfort or pain

Medical: topical artificial tears 2-6/day and topical broad spectrum ophthalamic antibiotics 4-6.day
Surgical: recommended to minimise duration of discomfort and recurrence rate
Lamellar keratoplasty using canine or feline donor tissue
Corneoconjunctival transposition surgery

provides physical support and blood flow to damaged cornea and grafted tissue facilitates healing

Glaucoma

Figure 4. A diffuse iris melanoma in the right eye of a 14- year old neutered male domestic shot haired cat. The intraocular pressure was 45 mmHg and confirmed the diagnosis of secondary glaucoma.

Source: Bruce H.G., Cheryl L.C. and Robert L.P. (2004) Veterinary ophthalmology essentials, 1st edn., Philadelphia: Elsevier.

Figrue 5. The right eye fo a 12- year old spayed female domestic short hair cat. the eye had been treated for a chronic idiopathic uveitis for several ears and now has secondary glaucoma, buphthalmos, and a subuxated lens.

Source: Bruce H.G., Cheryl L.C. and Robert L.P. (2004) Veterinary ophthalmology essentials, 1st edn., Philadelphia: Elsevier.

Figure 6. Corneal edema associated with glaucoma in a Basset Hound.

Source: Carmichael K.P., Vygantas K.R. and Whitley R.D. (2010) Ophtalmic disease in veterinary medicine, 1st edn., London: CRC Press.

Figure 7. Advanced pannus or scaring in a Wirehaired Fox Terrier with absolute or longstanding glaucoma.

Source: Carmichael K.P., Vygantas K.R. and Whitley R.D. (2010) Ophtalmic disease in veterinary medicine, 1st edn., London: CRC Press.

Optic nerve and retinal pathology resulting loss of vision

Considered as neurodegenerative disease

If prolonged, chronic glaucoma, progressive vision loss and extensive loss of retinal ganglion cell bodies from the inner retina are observed
Causes

Intraoular pressure is the most significant factor
Can be misdiagnosed to ocular hypertension

Clinical signs

Ocular discomfort
Tears in Descemet's membrane
Globe enlargement
Pupil dilation
"Laminar dot signs"

Peri-papillary pigmented or hyper-reflective halo with increased prominence of the laminar pores

Dogs:

Fulminant pain
Dense and diffuse corneal edema

Cats:

Generally maintain normal appetite and normal activity level (no obvious signs exist)
Minor corneal changes

Treatment

Need to consider type of glaucoma (primary or secondary)
Anti-glaucoma drugs (lowers intraocular pressure)

Dorzolamide
Brinzolamide

Beta blocker

Timolol maleate

Adrenergic agonist
Prostaglandin analogs
Surgical management

Chorioretinitis

Figure 8: Chorioretinitis
Source: Pet Health and Nutrition Information (2013) Chorioretinitis, Available at:http://www.petmc.com/2013/04/Chorioretinitis.html (Accessed: 3rd June 2014).

Inflammation of choroid and retina
Also known as retinitis, choroiditis, retinochoroiditis, chorioretinitis,

Difference due to inflammation from the primary tissue and the direction of spread (retina and choroid)

Causes

Pathological processes localized in the eye (infections agents)
Systemic diseases

Blepharitis, conjunctivitis, keratitis and uveitis

Clinical signs

Vitreous abnormalities
Bleeding and tearing

In severe cases

Retinal detachment
Optic nerve modifications

Diagnosis through ophthalmoscope exam & clinical exams

Modifications in tapetal area more expressive

Retina, choroid, tapetum lucidum, blood vessels

Modifications in non-tapetal area

Blood vessels

Treatment

Usually directed as the systemic disease causing the inflammation
May heal by itself in 4-8 days

References

Andrew S.E., Tou S. and Brooks D.E. (2001) 'Corneoconjunctival transposition for the treatment of feline corneal sequestra: a retrospective study of 17 cases (1990–1998)',Veterinary Ophthalmology, 4(2), pp. 107-111.
Bruce H.G., Cheryl L.C. and Robert L.P. (2004) Veterinary ophthalmology essentials, 1st edn., Philadelphia: Elsevier.
Carmichael K.P., Vygantas K.R. and Whitley R.D. (2010) Ophtalmic disease in veterinary medicine, 1st edn., London: CRC Press.
Chahory S., Crasta M., Trio S. and Clerc B. (2004) 'Three cases of prolapse of the nictitans gland in cats', Veterinary Ophthalmology, 7(6), pp. 417-419.
Claudia Hartley (2010) 'Aetiology of Corneal Ulcers: Assume FHV-1 Unless Proven Otherwise', Journal of Feline Medicine and Surgery, 12(), pp. 24-35.
Donisa A., Muste A., Beteg F. and Muste M. (2010) 'Retinochoroiditis in dog: diagnosed and incidence', Veterinary Medicine Scientific Papers, 43(2), pp. 100-103.
Gimenez P.M.T.P. and Fariña I.M. (2002) 'Lamellar keratoplasty for the treatment of feline corneal sequestrum', Veterinary Ophthalmology, 1(2-3), pp. 163-166.
McLellan G.J. and Miller P.E (2011) 'Veterinary ophthalmology', Feline glaucoma – a comprehensive review, 14(1), pp. 15–29.
Mehdi M., Sepehr M., Omid, Kazemi H. and Elnaz (2012) 'Clinical evaluation of the pocket technique for replacement of prolapsed gland of the third eyelid in dogs',Turkish Journal of Veterinary and Animal Sciences, 36(4), pp. 352-356.
Pet Health and Nutrition Information (2013) Chorioretinitis, Available at:http://www.petmc.com/2013/04/Chorioretinitis.html (Accessed: 3rd June 2014).
Raza A., Naeem A., Ahmad M., Manzoor A. and Ijaz M. (2013) 'Cherry Eye: Prolapse of Third Eyelid Gland in Dog- A Case Report ', International Journal of Molecular Veterinary Research, 3(1), pp. 1-3.
Seitz W.R. and Stegmann H. (1981) 'A multifocal serous chorioretinitis in the beagle', Veterinary Pathology, 18(1), pp. 1-12