Eye worm affections in large animals
Eye worm affections in large animals are Setaria digitata, Setaria equi and Setaria cervi, Thelaziasis etc.
Eye worm affections in large animals are-
Intra ocular eye worms
Setaria digitata and Setaria cervi are isolated as intra-ocular eye worms in horses. Setaria digitata and setaria cervi are parasites of cattle found in the peritoneum. Setaria equi present in horses are seen in the eye of cattle.
Accidentally the larvae infesting the animal migrates to the anterior chamber and causes severe ocular inflammation in horses or cattle.
The antigen present on the surface of the parasite causes an immune mediated response and the condition can initially as uveitis and can proceed to a kerato conjunctivitis and uveitis and end as equine recurrent uveitis.
Clinical Signs
- Photophobia
- Epiphora
- Corneal Edema
- Hypopyon
- Aqueous Flare
- Miosis
Diagnosis
The animal need to be examined in a calm environment in day light, as well as indoor, with a focus light for the eye.
The moving worm could be easily visualized in dark light. In case of pain and blepharospasm restrain of the animal with sedative like xylazine, butorphanol or detomidine and a local nerve block may be essential.
Treatment
Surgical removal
The animal is anaesthetised in GA and casted on the affected side up or given sedation, and given an auriculo palpberal nerve block and retro bulbar nerve block and a topical application of surface anaesthetics.
Technique
The incision is made at the 4’O clock position at the limbus with a No :11or 15 BP blade after retracting the eyelids.
Usually the worm tries to escape along with the aqueous humor and if it does not occur, saline can be injected and lavaged for removal of the worm.and the incision is sutured back with 6-0 or 7-0 absorbable suture material in simple interrupted pattern.
Post operatively topical antibacterials anti-inflammatory agents with administration of flunixin is indicated
Medical management of the condition with Diethyl Carbamazine with antiinflammatory agents have been reported.
Extra ocular eye worms
Thelaziasis is the main affection of extra ocular eye worms in animals.
The main species affected are cattle and horses world wide. The most common site of lodgment is the pouch of the nictitating membrane.
The transmission is through house fly which feeds on the excretions/ lacrimal discharge and the larva develops in the fly and lodges in mouth parts and when the same fly feeds another animal the infestation is established.
Clinical Signs
Conjunctivitis, excessive lacrimation, localized edema, corneal clouding, and occasionally, sub- conjunctival cysts.
Diagnosis
Clinical signs, ocular examination in a dark room with focused light
Treatment
The animal is restrained and a auriculo-palpeberal nerve block and retro bulbar nerve block is administered with 2% lignocaine solution.
The worms are manually removed from the pouch of the nictitating membrane and a lachrymal duct flushing may attempted with normal saline as many of these worm cause dacryocystitis.
Topical antibiotics and anti-inflammatory drugs are indicated along with administration of broad spectrum anthelmintic like ivermectin at 200 μg/ kg body weight.