Conjunctivitis

From Dog
Conjunctivitis in a dog with distemper[1]

Conjunctivitis in dogs is any inflammatory or infectious eye disease of the conjunctival lining of the eyelids.

Primary conjunctivitis is the most commonly diagnosed ophthalmic disorder of dogs, but should be differentiated from secondary conjunctivitis due to underlying orbital, periorbital or systemic diseases. This can be confirmed by presence of other diseases within or surrounding the eye as well as systemic symptoms such as fever, gastrointestinal or skin diseases.

Conjunctivitis may lead to inflammation of the cornea (keratitis), sclera (scleritis), episclera (episcleritis) and infections within the globe (endophthalmitis).

Causes include:

- Entropion
- Ectropion
- Uveodermatologic syndrome
- Keratoconjunctivitis sicca[3]
- Chronic superficial keratitis
- Nodular granulomatous episcleritis - Collie, Kelpie[4]
- Chlamydophila spp[5]
- Mycoplasma spp
- Corynebacterium spp
- Canine herpesvirus[6]
- Canine adenovirus[7]
- Canine distemper virus
- Canine influenza virus[8]
- Thelazia callipaeda[9]
- Leishmania chagasi[10]
- Dirofilaria repens[11]
- Aspergillus spp
- Curvularia spp[12]
- Cryptococcus spp
- Blastomyces spp
- Acremonium kiliense[13]

Clinically affected dogs usually present with blepharospasm (squinting), epiphora, photophobia and pawing at the face.

A complete ocular examination should be performed by using a mydriatic drug such as pilocarpine to examine the uvea and fundus. In cases of suspected corneal ulcer, fluorescein dye should be applied to the cornea. With suspected cases of keratoconjunctivitis sicca, a Schirmer tear test should be conducted. Tonometry should also be performed to exclude glaucoma.

Cytology and culture and sensitivity should be done to culture possible etiological agents such as bacteria or fungi, and PCR tests should be considered if viral agents are suspected. In cases non-responsive to conventional antimicrobial/anti-inflammatory treatment, a conjunctival biopsy may be considered.

The eye should be examined for size to exclude an enlarged globe exophthalmos, shrunken globe (microphthalmos), orbital cellulitis and periorbital tumors or carnassial tooth root abscess.

Treatment is usually palliative in dogs with primary bacterial causes, with use of topical ocular ointments containing broad-spectrum antimicrobials.

Underlying etiological agents must also be addressed.

References

  1. Tan B et al (2011) Pathogenesis and phylogenetic analyses of canine distemper virus strain ZJ7 isolate from domestic dogs in China. Virol J 8:520
  2. Lourenço-Martins AM et al (2011) Allergic conjunctivitis and conjunctival provocation tests in atopic dogs. Vet Ophthalmol 14(4):248-256
  3. Murphy CJ et al (2011) The pharmacologic assessment of a novel lymphocyte function-associated antigen-1 antagonist (SAR 1118) for the treatment of keratoconjunctivitis sicca in dogs. Invest Ophthalmol Vis Sci 52(6):3174-3180
  4. Hurn S et al (2005) Oral doxycycline, niacinamide and prednisolone used to treat bilateral nodular granulomatous conjunctivitis of the third eyelid in an Australian Kelpie dog. Vet Ophthalmol 8(5):349-352
  5. Holst BS et al (2010) An investigation on the presence of Chlamydiaceae in Swedish dogs. Acta Vet Scand 52:63
  6. Gervais KJ et al (2012) Acute primary canine herpesvirus-1 dendritic ulcerative keratitis in an adult dog. Vet Ophthalmol 15(2):133-138
  7. Ledbetter EC et al (2009) Virologic survey of dogs with naturally acquired idiopathic conjunctivitis. J Am Vet Med Assoc 235(8):954-959
  8. Song QQ et al (2012) Dog to dog transmission of a novel influenza virus (H5N2) isolated from a canine. Vet Microbiol Aug 3
  9. Vieira L et al (2012) First report of canine ocular thelaziosis by Thelazia callipaeda in Portugal. Parasit Vectors 5:124
  10. Freitas JC et al (2012) Clinical and laboratory alterations in dogs naturally infected by Leishmania chagasi. Rev Soc Bras Med Trop 45(1):24-29
  11. Tarello W et al (2011) Clinical Aspects of Dermatitis Associated with Dirofilaria repens in Pets: A Review of 100 Canine and 31 Feline Cases (1990-2010) and a Report of a New Clinic Case Imported from Italy to Dubai. J Parasitol Res 2011:578385
  12. Qualls CW et al (1985) Mycotic keratitis in a dog: concurrent Aspergillus sp and Curvularia sp infections. J Am Vet Med Assoc 186(9):975-976
  13. Mendoza L et al (1985) Canine mycotic keratoconjuntivitis caused by Acremonium kiliense. Sabouraudia 23(6):447-450