ISSN 2398-2969      

Nasolacrimal duct disease

icanis

Introduction

  • Uncommon problem in the dog.
  • Cause: chronic infections (dacrocystitis Dacryocystitis ), serious diseases of adjacent structures or neoplasia, congenital defects, etc.
  • Signs: chronic tear overflow at the medial canthus, sometimes with secondary dermatitis.
  • Diagnosis: clinical signs, lacrimal duct flushing, dacryocystorhinography.
  • Treatment: symptomatic or correct underlying disease.
  • Prognosis: variable, depending upon the cause.

Pathogenesis

Etiology

  • Congenital defects of the puncta and canaliculi:
    • Aplasia, imperforate puncta and micropuncta Micropunctum.
    • Atresia of the canaliculi.
    • Malpositioning of the puncta or canaliculi.
  • Congenital defects of the lacrimal duct: segmental malformation or incomplete formation.
  • Dacrocystitis, obstruction with foreign material Eye: ocular foreign body.
  • Scarring and obliteration of the puncta: secondary to infections, trauma.
  • Trauma to the nasolacrimal duct: often accompanied by nasal, maxillary or malar fractures.
  • Associated with diseased adjacent tissues:
    • Neoplasia of the nose and paranasal sinuses.
    • Stenosis following chronic upper respiratory tract disease.
    • Tooth root abscess.
  • Iatrogenic: from disruption of the lacrimal puncta, canaliculi, lacrimal sac or duct following surgery of the eyelids, nose or medial periorbital area.
  • Primary tumors of the lacrimal sac or duct are very rare.
  • Dacryoma: a cystic structure that develops from an embryonic malformation of the canaliculus or nasolacrimal duct.

Predisposing factors

General
  • Mesocephalic and dolichocephalic dogs.
  • Previous upper respiratory tract infections.
  • Dental disease.

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 open into canaliculi that lead to the lacrimal sac, and then into the nasolacrimal duct which carries the tears into the ipsilateral nasal cavity.
  • Tears are pushed into the puncta by blinking.
  • The canaliculi have their own pumping action and valves.
  • Gravity also aids the flow of tears into the nasolacrimal system.

Congenital defects
  • Congenital anatomic defects such as an imperforate punctum, a hypoplastic punctum or canaliculi, malpositioning of the puncta or canaliculi, or a hypoplastic lacrimal duct decrease or prohibit the normal drainage of tears.
  • Epiphora occurs with an overflow of tears on to the skin adjacent to the medical canthus, often causing a reddish staining to the hair in this area.

Acquired defects

  • Any of the above causes may decrease drainage of the tears through the nasolacrimal system, with secondary epiphora.
  • With dacryocystitis and other infections, purulent discharge is a classic occurrence.
  • Tear staining and excoriation of the skin may occur near the medical canthus, with secondary bacterial and yeast dermatitis.
  • The nose may be dry and crusty on the affected side(s).

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.
  • Whitley R D (2000) Canine and feline primary ocular bacterial infections. Vet Clin North Am Small Anim Pract 30 (5), 1151-1167 PubMed.
  • Ramsey D T et al (1996) Ophthalmic manifestations and complications of dental disease in dogs and cats. J Am Anim Hosp Assoc 32 (3), 215-224 PubMed.
  • Laing E J, Spiess B, Binnington A G (1988) Dacryocystotomy - a treatment for dacryocystitis in the dog. J Am Anim Hosp Assoc 24, 223-226 AGRIS FAO.
  • Lavach J D, Severin G A, Roberts S (1984) Dacryocystitis in dogs- a review of 22 cases. J Am Anim Hosp Assoc 20 (3), 463-67 VetMedResource.
  • Johnston G R, Feeney D A (1980) Radiology in ophthalmic diagnosis. Vet Clin North Am Small Anim Pract 10 (2), 317-337 PubMed.

Other sources of information

  • Munger R J (2002)Disorders of the lacrimal and nasolacrimal system.In: Morgan R V, Bright R N, Swartout M S (eds)Handbook of Small Animal Practice. 4th Ed. W B Saunders, Philadephia, pp 954-963.
  • Barnett K C & Crispin S M (1998)Feline Ophthalmology, An Atlas & Text.W B Saunders, London. ISBN 0 7020 1662 4.

 

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