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Basics ⬇

Outline

BASICS

Definition!!navigator!!

The nasolacrimal system has both secretory and drainage components. Drainage of ocular secretions occurs through the puncta of the upper and lower eyelids into the nasolacrimal canaliculi, and subsequently the nasolacrimal sac, a dilation smaller than in most other species. The sac drains to the nasolacrimal duct in the lacrimal canal of the lacrimal and maxillary bones, then opens into the ventrolateral nasal cavity. Dacryocystitis is inflammation of the lacrimal sac and/or NLD. It is seen frequently in horses.

Pathophysiology!!navigator!!

  • Dacryocystitis may develop as a primary problem or secondary to duct obstruction
  • Usually dacryocystitis occurs as the result of obstruction of the NLD by accumulation of material, followed by secondary retention of tears in the duct and bacterial proliferation in the stagnant tears
  • Congenital abnormalities—eyelid punctal atresia, nasolacrimal duct agenesis or incomplete formation of the duct, nasal punctal atresia, and imperforate nasal puncta
  • Acquired abnormalities—fractures and other traumatic insults, inflammation, strictures, accumulation of environmental debris or foreign bodies, neoplasia, granulomas, sinusitis, upper arcade dental disease, idiopathic

Systems Affected!!navigator!!

Ophthalmic

Genetics!!navigator!!

There are no breed predilections for or known genetic influence on development of dacryocystitis.

Incidence/Prevalence!!navigator!!

Common

Geographic Distribution!!navigator!!

None identified.

Signalment!!navigator!!

  • Dacryocystitis associated with a congenital abnormality of the nasolacrimal system is usually seen within the first 2–6 months of life, but occasionally not until 1–2 years of age, especially if the animal has been turned out after weaning
  • Acquired obstruction may occur at any point during an animal's life; however, for those induced by neoplastic causes, the incidence increases with age
  • No proven sex predilection

Signs!!navigator!!

  • Thick mucopurulent discharge at the medial canthus, reflux exudation upon manipulation of the medial eyelid, mild conjunctival hyperemia
  • May be unilateral or bilateral when associated with congenital causes; acquired obstructions are usually unilateral
  • Atresia of the nasal puncta is most commonly unilateral
  • Globe and conjunctiva are usually not involved, unless chronic dacryocystitis has resulted in blepharoconjunctivitis or keratoconjunctivitis

Causes!!navigator!!

Congenital Obstruction

  • Nasal puncta atresia
  • Nasolacrimal duct agenesis
  • Eyelid puncta atresia

Acquired Obstruction

  • Traumatic disruption
  • Foreign body
  • Neoplasia (especially SCC)
  • Granuloma (habronemiasis)
  • Sinusitis, rhinitis
  • Periodontitis
  • Fibrosis secondary to chronic inflammation
  • Thelazia lacrymalis

Risk Factors!!navigator!!

  • White, chestnut, and palomino coat color and light periocular skin pigmentation predispose to ocular SCC
  • Warm weather and climates with a heavy fly population are a risk factor for habronemiasis and other parasitic causes

Diagnosis ⬆ ⬇

Outline

DIAGNOSIS

Differential Diagnosis!!navigator!!

One must differentiate dacryocystitis from other causes of mucopurulent ocular discharge, including bacterial or parasitic conjunctivitis, neoplasia of eyelid or conjunctiva, secondary infection following ocular or eyelid injury, ocular foreign body.

CBC/Biochemistry/Urinalysis!!navigator!!

Results usually normal.

Other Laboratory Tests!!navigator!!

  • Aerobic and anaerobic bacterial culture and sensitivity of material flushed from puncta
  • Habronemiasis—scraping of the granuloma reveals eosinophils, mast cells, neutrophils, plasma cells, occasionally larvae
  • Biopsy and histopathology of mass lesions are necessary for proper diagnosis

Imaging!!navigator!!

  • Skull radiographs if fracture suspected from history or physical examination
  • Contrast dacryocystorhinography assists in identifying cause and location of obstruction. It involves instillation of 4–6 mL of radiopaque solution into the puncta, followed by radiography or CT. General anesthesia is necessary for this latter diagnostic technique
  • Rhinoscopy is indicated if sinusitis/rhinitis suspected
  • Microvideoendoscopy may be used to directly visualize NLD lesions

Other Diagnostic Procedures!!navigator!!

  • Complete ophthalmic examination is indicated to identify any primary ocular problem causing mucopurulent discharge or secondary ocular involvement
  • Patency of the duct may be assessed initially by the Jones dye test. Fluorescein dye is instilled into the eye, and the nasal puncta is observed for appearance of fluorescein within 5 min. Attempt should be made to flush the duct with saline or irrigating solution from patent nasal puncta. Topical anesthetic should be applied to both nasal mucosa and conjunctiva
  • Cannulation of the nasolacrimal duct is performed using a 5 French urinary catheter or polyethylene tubing (size 160), inserted through the nasal or eyelid puncta. Catheter may hit a blind end several centimeters from the nasal punctal opening where the duct is pressed laterally by a cartilaginous plate in the alar fold, and should be directed laterally
  • Dental and oral examination, and potentially dental radiography, should be performed if dental disease is suspected as inciting cause of dacryocystitis

Pathologic Findings!!navigator!!

  • Habronemiasis—eosinophils, mast cells, neutrophils, plasma cells, rarely larvae
  • SCC—epithelial cells with neoplastic characteristics
  • Other histopathologic findings possible depending on the type of neoplasia present

Treatment ⬆ ⬇

Outline

TREATMENT

Appropriate Health Care!!navigator!!

Patients that require surgical intervention to reestablish patency of the duct would be hospitalized on a short-term basis. Those in which patency is reestablished with simple irrigation or cannulation can be treated on an outpatient basis.

Nursing Care!!navigator!!

Ensure that topical medications can be administered appropriately prior to dispensing.

Activity!!navigator!!

Restriction of activity may be required for a short time following surgical procedures.

Diet!!navigator!!

No change in diet is necessary. Hay should be fed at ground level rather than from elevated hayracks or bags if ocular disease is present.

Client Education!!navigator!!

Clients should be informed of the potential for recurrence in cases of acquired obstruction or when a cause is unidentified.

Surgical Considerations!!navigator!!

  • Uncomplicated obstructions may be relieved by simply flushing the NLD and then applying topical broad-spectrum antibiotics and possibly anti-inflammatory agents
  • Nasolacrimal duct agenesis accompanied by nasal or eyelid punctal atresia necessitates surgical creation of a proximal or distal opening. If the duct is present, flushing of the nasolacrimal system results in dilation of tissue overlying the site of the atretic or imperforate puncta. An incision through overlying tissue will establish patency, and a 5 French catheter placed in the nasolacrimal duct will allow epithelialization of the new puncta. Severe hemorrhage may occur following incision over the atretic nasal puncta. The ends of the catheter/stent are sutured to the skin of the muzzle and near the medial canthus, and the catheter/stent is left in place for 2–3 weeks and sometimes longer
  • Acquired obstructions are treated by removal of the inciting cause when possible, irrigating the duct, and catheterization of the duct for 2–3 weeks. The indwelling stent is sutured to skin as described for congenital lesions
  • Conjunctivorhinostomy involves creation of a mucous membrane-lined fistula between the ventromedial conjunctival surface and nasal cavity. This procedure is indicated for nasolacrimal duct obstruction that cannot be relieved with flushing or cannulation. Alternatively, canaliculorhinostomy involves creating a pathway from the canaliculi to the nasal cavity. Conjunctivosinostomy creates a connection between the conjunctiva and the maxillary sinus. All of these procedures must be performed under general anesthesia and involve drilling a hole through the lacrimal bone into the nasal cavity or the sinus and placing a stent until the connection is permanent and the incisions heal

Medications ⬆ ⬇

Outline

MEDICATIONS

Drug(s) of Choice!!navigator!!

  • Topical triple antibiotic solution (neomycin–polymyxin B–bacitracin) placed in the eye 3 or 4 times daily until the catheter is removed or until culture results specify the need to change antimicrobial agents
  • Topical corticosteroids (1% prednisolone acetate or 0.1% dexamethasone) are recommended to decrease swelling in the NLD as long as there are no ocular surface problems (corneal ulceration) that would make their use contraindicated
  • Systemic antibiotics (trimethoprim–sulfonamide or ceftiofur) are absolutely critical for 7–10 days if surgical establishment of the NDL has been performed. An appropriate antibiotic solution should be flushed through the indwelling stent on a daily or every other day basis

Contraindications!!navigator!!

N/A

Precautions!!navigator!!

N/A

Possible Interactions!!navigator!!

N/A

Alternative Drugs!!navigator!!

N/A

Follow-up ⬆ ⬇

Outline

FOLLOW-UP

Patient Monitoring!!navigator!!

The patient should be rechecked soon after the initial procedure to establish patency (7–10 days), with the specific time frame determined by severity. Subsequent rechecks are dictated by severity of disease and response to treatment.

Prevention/Avoidance!!navigator!!

Fly control in barns and pastures, fly hoods, frequent periocular administration of insect repellent, and regular deworming with avermectins, decreasing environmental dust, debris, and other material that may accumulate in the NLD, and decreasing the amount or exposure to allergens may prevent the development of or decrease the incidence or severity of NLD obstructions and dacryocystitis.

Possible Complications!!navigator!!

Potential complications vary with the inciting cause. They include recurrence of the dacryocystitis and failure to maintain patency of the duct.

Expected Course and Prognosis!!navigator!!

  • The prognosis for NLD obstructions and dacryocystitis is good, but depends upon the location, extent, and cause of the obstruction
  • Acquired obstructions resulting in dacryocystitis are more difficult to treat than congenital abnormalities
  • Foreign body and periodontal causes have the best response to therapy of acquired obstructions
  • Cannulation of the duct may be impossible in cases of neoplasia and maxillary fractures, and permanent correction of the obstruction and subsequent dacryocystitis may not be possible

Miscellaneous ⬆ ⬇

Outline

MISCELLANEOUS

Associated Conditions!!navigator!!

N/A

Age-Related Factors!!navigator!!

N/A

Zoonotic Potential!!navigator!!

N/A

Pregnancy/Fertility/Breeding!!navigator!!

Systemic absorption of topically applied medication is possible. Benefits of treatment should be considered against any risks posed to the fetus.

Abbreviations!!navigator!!

  • CT = computed tomography
  • NLD = nasolacrimal duct
  • SCC = squamous cell carcinoma

Suggested Reading ⬆ ⬇

Brooks DE. Ophthalmology for the Equine Practitioner, 2e. Jackson, WY: Teton NewMedia, 2008.

Gilger BC. Equine ophthalmology. In: Gelatt KN, Gilger BC, Kern TJ, eds. Veterinary Ophthalmology, 5e. Ames, IA: Wiley Blackwell, 2013:1560–1609.

Gilger BC. Equine Ophthalmology, 3e. Philadelphia, PA: WB Saunders, 2017.

Author(s) ⬆

Author: Caroline Monk

Consulting Editor: Caryn E. Plummer

Acknowledgment: The author acknowledges the prior contribution of Caryn E. Plummer.