Parasitic Conjunctivitis in the Collie breed


Parasitic conjunctivitis accounts for 1-2% of all conjunctivitis cases. It is important to note that the disease is caused by the Thelazia species nematode, in particular T. Callipaeda, which is most common in canines and with higher incidences in warm areas like Andalusia and Extremadura. We often find it hidden in the ventral conjunctival sac and a thorough ophthalmological exam will help us find them. 

The topical spot-on application of Ivermectin or Moxidectin is a recommended anti-parasitic treatment for Thelazia species.  For the Collie breed, a MDR1 gene test is done to verify that there is no mutation and the usual treatment can go forward. If the test is positive (there is a high incidence in this breed), Ivermectin or Moxidectin will be contraindicated and coadjutant treatments to the mechanical extraction of the parasites, like topical antibiotics and non-steroid anti-inflammatories (AINE) will need to be employed.  

This was the diagnosis and the considerations taken into account for a Collie breed patient that was referred to our ophthalmological team a few days ago and seen by Department Head Lola Torres.  The patient had a clinical history of chronic refractory purulent conjunctivitis with topical treatments.  The MDR1 gene was positive and the results were very satisfactory with a complete recovery after performing the previously mentioned treatment.