Page 7 - Clinical Connections - Autumn 2022

Exotics
RISK FACTORS FOR DACRYOCYSTITIS IN

PET RABBITS

Joanna Hedley, Victoria Ede and Charlotte Dawson

acryocystitis is relatively common
in pet rabbits and is often present
D concurrently with other diseases.
However, there are relatively few studies
reporting the prevalence of ocular disease
– and particularly dacryocystitis.
We recently conducted a study to
investigate potential risk factors associated
with dacryocystitis in pet rabbits. It was a
retrospective review of clinical records from
all rabbit cases at the RVC’s first opinion
and referral exotics clinic.
Dacryocystitis was identified in 55 of 821
rabbits (6.70%) examined over the study
period. Of those rabbits with dacryocystitis,
dental disease was found in 24 rabbits
(45%), respiratory disease in 20 (38%), aural A Lionhead rabbit
disease in seven (13%) and concurrent Data collected included weight, sex, Fifteen breed categories presented with
ocular disorders in 15 (23%). neuter status, breed and presence of lop dacryocystitis. Significantly, Lop/Dwarf Lop
Breed status was found to be a significant ears. A subset of cases was identified for cross rabbit having dacryocystitis compared
risk factor, with Lionhead/Lionhead cross further analysis, based on the presence to a crossbreed rabbit were 4.57 times and
and Dwarf Lop/Dwarf Lop cross rabbits of the key terms ‘dacryo’, ‘dacro’, ‘naso- 4.26 times higher, respectively.
being more likely to have dacryocystitis. The lacrimal’, ‘tear duct flush’, ‘isathal’, ‘exocin’, Breeds that did not present with
results suggest that a breed predisposition ‘tiacil’, ‘maxitrol’ and ‘chloramphenicol’ in dacryocystitis included the English Lop,
for dacryocystitis could exist, and vets records. Holland Lop, Cashmere Lop, Californian,
should advise their clients accordingly. Additional data recorded from the subset Continental Giant, German Giant, New
Rabbits are thought to be susceptible included age at onset of clinical signs and Zealand White, Beveren cross, Belgian
to dacryocystitis due to the anatomy of the presence of concurrent dental, ear, Hare, Dwarf Hotot, Thrianta, Himalayan,
their nasolacrimal duct, which can easily ocular or respiratory disease. Cases were American Sable cross, Norwegian Dwarf
become obstructed. The duct starts at a categorised as having respiratory disease and Silver Marten.
slit-like opening located in the conjunctiva if there was mention of respiratory signs, Brachycephalic rabbit breeds have
of the lower lid close to the medial canthus, including nasal discharge and respiratory been suggested to be at higher risk of
following a tortuous path to empty into the noise or dyspnoea. Cases were categorised developing nasolacrimal duct disease. In
nares. After the lacrimal sac and canal, the as having dacryocystitis present if it was cats, a study using CT assessed the effects
lacrimal duct reduces from 2 to 1 mm in specified in notes or if there was a relevant of brachycephalic skulls on nasolacrimal
diameter and curves where it passes close description of clinical signs, such as drainage. That study showed that the higher
to the maxillary incisor root. It is there that ‘mucopurulent discharge of tear ducts’. the degree of brachycephaly, the steeper
blockage usually occurs. Of the 821 rabbits presented between the orientation of the nasolacrimal duct
Acute dacryocystitis can occur due 2015 and 2018, 305 were male neutered, and thus the more likely that drainage is
to conjunctivitis causing obstruction 140 were male entire, 242 were female affected. It is therefore possible that, as in
of the lacrimal sac, impaired drainage neutered and 124 were female entire. The cats, a shortened skull leading to a distorted
and secondary bacterial infection. More other 10 were of unknown sex. 53 different nasolacrimal duct applies to rabbits.
typically, chronic dacryocystitis develops breeds or breed crosses were recorded. The Netherland Dwarf, Lionhead and
secondary to dental disease with elongation Mini Lop/Mini Lop cross was the most some Lop breeds are often seen to exhibit
of tooth apices and periductal osteomyelitis. common category (16.93%), followed by marked brachycephalism, although there
Alternatively, infection may ascend from the Lop/Lop cross (13.89%). is currently no defined system for the
nasal cavity. Of the subset of 82 of cases that classification of brachycephaly in rabbits to
underwent further analysis, 55 rabbits met quantify this theory.
The research the criteria for the presence of dacryocystitis
In our study, records of all rabbits evaluated (6.70% of the study population). Those
between February 2015 and February 2018 comprised 29 male neutered, four male
at the first opinion and referral clinic were entire, 17 female neutered and five female For the RVC Exotics and Small Mammals
reviewed retrospectively. entire rabbits. Service, please call: 020 7554 3528
Email:
londonreferrals@rvc.ac.uk

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