Keratoconjunctivitis associated withToxoplasma gondiiin a dog

Abstract

A 12-year-old Pug presented with a 3-mm corneal mass OD. The dog was currently being treated for keratoconjunctivitis sicca (KCS) and pigmentary keratitis OU. A superficial keratectomy followed by cryotherapy was performed OD. A histopathologic diagnosis of epithelial dysplasia and suppurative keratitis was made and the lesion resolved. Two months later, a yellow/tan conjunctival mass, diffuse chemosis and conjunctival thickening was discovered OD. Necrotizing conjunctivitis with protozoal parasites was diagnosed with histopathology. Complete blood count and a serum biochemistry panel were normal. Neospora caninum and Toxoplasma gondii titers were negative. The conjunctivitis resolved after a 6-week course of oral clindamycin. Two months later, the patient presented with a similar conjunctival mass OS. Toxoplasma gondii was confirmed as the etiologic agent with immunohistochemical staining. Repeat T. gondii titers were negative. Oral clindamycin was re-instituted. The corneal biopsy was re-reviewed and protozoal organisms were discovered. Three months later, a recurrence was suspected and oral ponazuril was initiated for 28 days. There has been no evidence of recurrence since this treatment. Ocular toxoplasmosis is rare in the dog but reports have included episcleritis, scleritis, retinitis, anterior uveitis, ciliary epithelium hyperplasia, optic neuritis and polymyositis. To our knowledge, this is the first confirmed report of toxoplasmosis causing only corneal and conjunctival disease in the dog. We hypothesize that these localized lesions may be associated with topical immunomodulating therapy for KCS. Toxoplasmosis should be considered as a differential for canine conjunctivitis and corneal disease and has the potential to manifest in one or both eyes.

Review of triazine antiprotozoal drugs used in veterinary medicine

“…In addition, treatment with diclazuril dosed at either 65 or 120 mg/kg demonstrated clinical protection against maternal hepatitis and fetal toxoplasmosis in a mouse challenge study (Oz & Tobin, ). Future therapeutic approaches may include triazines for treatment of toxoplasmosis in veterinary species (Swinger, Schmidt, & Dubielzig, ).…”

A retrospective survey of ocular abnormalities in pugs: 130 cases

“…In one case report, a 12‐year‐old pug was presented with KCS, pigmentary keratitis OU and a corneal mass, caused by Toxoplasma gondii (Swinger et al . ). A recently published study reported on the presence of CP in pugs (Labelle et al .…”

What is your diagnosis? Corneal scrape from a dog

“…The morphology of the protozoal zoites was compatible with what is described for T gondii , although other protozoa, such as Neospora sp. or Sarcocystis spp., could not be entirely excluded . Serology for T gondii (IgG/IgM IFA; TVMDL, College Station, TX, USA) and Neospora caninum (IFA; TVMDL) were negative.…”

“…Canine corneal protozoal infections without systemic involvement are rarely reported in the veterinary literature and documented agents include T gondii , Leishmania mexicana , and amoebas . A recent case series listed 5 cases of ocular protozoal infections in dogs from 1998 to 2014, 2 supportive of T gondii . Both cases were small breed dogs receiving chronic topical immunosuppressive therapy for ocular surface disease that presented for a mass‐like lesion on the cornea or conjunctiva.…”