ISSN 2398-2985      

Subconjunctival protrusions and swellings

6guinea pig

Synonym(s): Conjunctival fat deposition, Protrusion of inferior conjunctival sac, Pea eye, Fatty eye, Flesh eye, Cherry eye


Introduction

  • Cause: there are three conditions commonly seen in guinea pigs. Various terminology appears in lay and veterinary literature which may cause confusion:
    • Fatty eye: deposition of lipid in the inferior bulbar conjunctiva.
    • Flesh eye: a pink colored mass in the medial canthus, may involve the prolapse of the glans nictitans. This may be equivalent to prolapse of the nictitating membrane in dog/rabbit, ie cherry eye.
    • Pea eye: swelling of the inferior conjunctiva due to inflammatory changes. This may include some glandular tissue as well as depositions of fat.
  • Signs:
    • Fatty eye: white or pink-white lesion protruding from the bulbar conjunctiva.
    • Flesh eye: pink or red-pink mass protruding from the medial canthus.
    • Pea eye: protrusion, swelling of inferior conjunctival sac.
  • Diagnosis: ophthalmological examination, fine needle aspiration for cytology/gram-staining, fluorescein staining, ultrasonography, biopsy.   
  • Treatment:
    • Fatty eye: dietary caloric restrictions.
    • Flesh eye: no surgery is usually needed unless severe/protrusion causing blepharospasm/eye irritation; removal of the material within the glans may alleviate the protrusion; topical ophthalmic non-steroidal anti-inflammatory, flurbiprofen/ketorolac.
    • Pea eye: usually none required.
  • Prognosis: good although may be difficult to totally remove the lipid from the tissues. Some cases of pea eye resolve spontaneously.

Pathogenesis

Etiology

Fatty eye

  • Lipid deposits usually seen in guinea pigs being readied for shows. This is called ‘fattening up’ as show guinea pigs are usually slightly obese - preferred physical body conformation.
  • Deposits within the glans nictitans may cause it to prolapse.

Flesh eye

  • May involve prolapse of the glans nictitans, and appears usually to have fat deposits within it.
  • Inflammation of the glans nictitans may also be present.

Pea eye

  • Unknown etiology.
  • It is suspected that there is a heritable component, possibly a congenital weakness of the ventral periorbital fascia with anterior displacement of large glands through a 'rent'.
  • It is possible that prior trauma to periorbital tissue could cause changes and deposition of fat.

Predisposing factors

General

  • Fatty and flesh eye: guinea pigs being readied for showing, which are fed excessive calories.

Specific

Fatty/flesh eye

  • Lipid deposits in the subconjunctival, bulbar tissue.
  • Lipid deposits within the glans nictitans.

Pea eye

  • May be breed related as purebred American Shorthairs most commonly presented with this.
  • It has been seen in other breeds, although it is suspected there is a heritable component.

Pathophysiology

Fatty/flesh eye

  • Lipid deposits within the subconjunctival bulbar tissue and/or glans nictitans.
  • Deposition within the glans nictitans may lead it to varying degrees of prolapse from the medial canthi.
  • Can be uni- or bilateral.

Pea eye

  • Inflammation of the lacrimal or zygomatic glands may contribute.
  • Subconjunctival fat deposition in lower lateral conjunctival fornix.

Timecourse

  • Fatty and flesh eye: usually gradual.
  • Pea eye: may appear acutely, although it may have been developing slowly and only just reached a size where it protruded.

Epidemiology

  • Pea eye: may have hereditary component as most often seen in American shorthairs.

Diagnosis

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Treatment

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Prevention

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Outcomes

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Further Reading

Publications

Refereed Papers

  • Recent references from PubMed and VetMedResource.
  • Minarikova A, Hauptmann K, Jeklova E et al (2015) Diseases in pet guinea pigs: a retrospective study in 1000 animals. Vet Rec 177 (8), 200 PubMed.

Other sources of information

  • Williams D L (2013) Laboratory animal ophthalmology. In: Veterinary Ophthalmology. 5th edn. Eds: Gellatt K N, Gilger B C & Kern T J. Willey-Blackwell. pp 1692-1725.
  • Williams D L (2012) The Guinea Pig Eye. In: Ophthalmology of Exotic Pets. Wiley-Blackwell. pp 56-72.
  • Willis A M (2011) Pea Eye. In: Blackwell's Five-Minute Veterinary Consult: Small Mammal. Ed: Oglesbee B L. Wiley-Blackwell. pp 306.
  • Harkness J E, Turner P V, Vandewoude S & Wheler C L (2010) Harkness and Wagner’s Biology and Medicine of Rabbits and Rodents. 5th edn. Wiley-Blackwell. pp 216.
  • Montiani-Ferreira F (2009) Rodents: Ophthalmology.  In: BSAVA Manual of Rodents and Ferrets. Eds: Keeble E & Meredith A. British Small Animal Veterinary Association. pp 169-180.

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