Felis ISSN 2398-2950

Nasolacrimal duct disease

Contributor(s): Dennis E Brooks, David Godfrey, David Williams

Introduction

  • Disease of the nasolacrimal ducts is common in cats.
  • It is often mild and causes relatively little distress to the cat.
  • Cause: occasionally nasolacrimal duct disease may be associated with severe, chronic infections or serious diseases of adjacent structures or neoplasia; often occurs secondary to facial anatomical defects in brachycephalic cats.
  • Signs: chronic tear overflow can lead to severe periorbital dermatitis.
  • Diagnosis: signs.
  • Treatment: symptomatic or correct underlying disease and flush.
  • Prognosis: good with treatment.

Pathogenesis

Etiology

  • Congenital:
    • Imperforate puncta and micropuncta Micropunctum.
    • Canalicular defect.
  • Trauma.
  • Associated with diseased adjacent tissue and duct obstruction.:
    • Neoplasia and ophthalmia neonatorum.
    • Chronic upper respiratory tract disease.
    • Polyps Nasopharyngeal polyp and tooth root abscess.

Predisposing factors

General

  • Persian-type cats.

Pathophysiology

Normal anatomy

  • The precorneal tear film flows over the cornea and conjunctiva into the medial canthal lake.
  • At the medial canthus there are two entrances into the lacrimal drainage system, the upper and lower puncta. These   →   canaliculi, the lacrimal sac and then the nasolacrimal duct which carries the tears to the ipsilateral rostral nasal cavity. Accessory openings occur behind the upper incisor teeth.
  • Tears are pushed into the puncta by blinking.
  • The canaliculi have their own pumping action and valves.
  • Gravity also aids the flow of tears.

Congenital defects

  • Congenital anatomic defects of either an imperforate punctum, a hypoplastic punctum or a hypoplastic lacrimal duct lead to the lack of normal drainage of tears.
  • In cats the upper punctum and duct are more likely to be affected than the lower.
  • There may be an abnormally situated punctum.
  • Persian cats tend to have a relatively large globe and small orbit. This causes the lower eyelid to be pressed against the front of the orbit which in turn prevents tears flowing into the medial canthal lake and to the puncta (mild entropion may also contribute to this effect).
  • Epiphora, overflow of tears on to the periorbital skin, can lead to persistent wetness, soreness, ulcerative dermatitis and secondary bacterial and yeast infections.

Acquired defects

  • The lacrimal drainage system may be blocked by becoming involved in disease of adjacent structures eg, an abscess of a tooth root, neoplasms of the nasal planum, the nose or sinuses.
  • The puncta may be distorted by ophthalmia neonatorum.
  • Upper respiratory tract infections Viral-induced upper respiratory tract disease with feline herpes virus Feline herpes virus: feline rhinotracheitis virus or calicivirus Feline calicivirus may cause chronic inflammation and scarring of the lacrimal drainage system.
  • Trauma - most commonly by a cat scratch.
  • Iatrogenic damage can occur especially following attempted cannulation
  • Infection of the lacrimal drainage system may occur with no apparent underlying disease.

Timecourse

  • Weeks to years.

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.
  • Ramsey D T, Marretta S M, Hamor R E et al (1996) Ophthalmic manifestations and complications of dental disease in dogs and cats. JAAHA 32 (3), 215-224 PubMed.

Other sources of information

  • Barnett K C & Crispin S M (1998) Feline Ophthalmology - An Atlas & Text. London: W B Saunders. ISBN 0 7020 1662 4.
  • Petersen-Jones S & Crispin S (2002) BSAVA Manual of Small Animal Ophthalmology. 2nd edn. British Small Animal Veterinary Association. ISBN 0 905214 54 4


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