Dacryocystitis – Rabbit

Description

Dacryocystitis is one of the most common conditions encountered in practice and can be one of the most difficult to treat due to the persistence of the organism involved and the tendency of the condition to recur. It is very important to examine the teeth and both nasolacrimal ducts of every rabbit irrespective of the reason for which the animal is presented for clinical examination.

Clinical Signs

Clinical signs of dacryocystitis include a milky discolouration of the precorneal tear film, epiphora, crust formation along the affected eyelid margins and a caseous discharge from the nostril. The condition can be unilateral or bilateral. The clinician may have to apply digital pressure on the lacrimal sac to observe a milky discharge from the lacrimal punctum. Keratitis and conjunctivitis are sometimes observed. A white crust on medial canthus is a frequent early clinical sign.

Aetiology

The prime agent of aetiological significance is dental malocclusion. The constant growth of the teeth combined with the low bone density of the rabbit skull results in the migration of the roots of the teeth leading to:

1. Occlusion of the naso-lacrimal duct by the roots of the incisors (welling of the milky discharge up the lacrimal apparatus results in epiphora).
2. Invasion of the eye socket by the roots of the molars leading to retrobulbar infection, buphthalmos or simply ocular irritation and epiphora.

Microbiological investigation yields profuse growth of many organisms, usually Pasteurella multocida (Petersen-Jones and Carrington 1988), but Staphylococcus species and Streptococcus species, can also be frequently involved. Dacryocystitis can be due to an ascending infection from the nasal cavity via the nasolacrimal duct and is a constituent part of the syndrome of Pasteurella infection in rabbits (Whittaker 1989).

A survey conducted by Leo Laboratories in 1994 yielded:

1. Staphyloccus spp. - non-haemolytic, 17 isolates; haemolytic coagulase -ve, 10 isolates; haemolytic coagulase +ve, 5 isolates.

1. Streptococcus spp. - non-haemolytic, 4 isolates; alpha-haemolytic, 2 isolates

1. Pasteurella spp. - Pasteurella aerogenes 2 isolates, Pasteurella multocida 3 isolates, unidentified Pasteurella spp. 2 isolates,

1. Bacillus spp. - 7 isolates,

1. Corynebacterium spp. - 5 isolates,

1. Enterobacter spp. - 3 isolates

1. E coli - (non-haemolytic) 3 isolates

1. Pseudomonas spp. - Pseudomonas vesicularis 2 isolates, unidentified Pseudomonas spp. 1 isolate,

1. Branhamella spp. - one isolate

1. Proteus spp. - one isolate

1. Acinetobacter junii - one isolate

1. No isolates were detected in 12 specimens.

As well as dental disorders, a triggering factor for the establishment and persistence of infection is thought to be the ammonia produced either by the degenera­tion of urinary urea in a poorly absorptive litter (Okerman 1988) or from a pet maintained on an imbalanced (high protein) diet (Jenkins 1991). I always counsel the owners of affected animals to attend to hygiene and diet simultaneously. Peat moss /Turf mould is recommended as hutch litter due to its ability to absorb the ammonia produced by the decomposition of urinary urea.