Conjunctivitis is the irritation and inflammation of the conjunctiva
(the membrane of the inner eyelid and the inner corner of the eye's surface). It can occur unilaterally (in one eye) or bilaterally (in both eyes) in ducks. Conjunctivitis may be caused by:
- Infection: May be of bacterial, viral, or fungal origin
- Parasites: Eye worms (Oxyspirura mansoni, Thelazia spp. and Ceratospira spp.), Plasmodium spp., microsporidiosis, cryptosporidial, or trichomoniasis.
- Exposure to foreign bodies: Such as sand, dust, feather particles, etc.
- Exposure to physical irritants: Such as smoke or chemical fumes.
Conjunctivitis is clinically classified into three general groups, which include:
- Localized conjunctivitis: Resulting from infection with a particular pathogen (virus, bacteria, fungi, parasite), or from the presence of foreign bodies such as feather particles, sand or dust. Unilateral conjunctivitis is often associated with the presence of foreign bodies lodged under the nictitating membrane or lower eyelid.
- Secondary conjunctivitis: Occurs as a secondary manifestation of periorbital or orbital disease, particularly chronic rhinitis and sinusitis.
- Systemic conjunctivitis: Caused by a septicemia (a systemic infection).
Treatment of Conjunctivitis
The initial goal in treatment of conjunctivitis in ducks is to determine the primary cause and remove it. Cases of unilateral conjunctivitis that do not respond to antibiotics should consider the presence of a foreign body. If foreign material is suspected, the duck should be examined by a veterinarian, under general anesthesia, in order to flush the eye repeatedly with saline solution or equivalent eye solution, and remove any visible foreign material with the aid of sterile cotton swabs.
The following diseases can cause conjunctivitis in ducks:
- Avian chlamydiosis: Avian chlamydiosis (AC) is a zoonotic respiratory disease of birds caused by gram-negative bacteria from the Chlamydia genus. The genus consists of 11 different species from the Chlamydiaceae family. Ducks are predominately affected by C. psittaci, C. gallinacea and C. suis. Clinical signs observed in ducks vary depending on the virulence of the chlamydial strain and immune status of the bird. The most frequently reported signs in ducks include nasal and ocular discharges, dyspnoea, diarrhea, weight loss, reduced egg production in female ducks, hyperthermia, lethargy and dullness.
- Aspergillosis: Aspergillosis is a common fungal disease of ducks caused by infection with the genus Aspergillus, which consists of approximately 600 different species. A. fumigatus is the most common species isolated from infected ducks. Aspergillosis manifests as two different forms in ducks. Acute aspergillosis is characterized by severe outbreaks in newly hatched ducklings and is associated with high morbidity and high mortality rates.