Page 7 - Clinical Connections - Autumn 2022

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Page 7 - Clinical Connections - Autumn 2022
P. 7

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  ºÚÁÏÉç’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 ºÚÁÏÉç Exotics and Small Mammals
            reviewed retrospectively.           entire rabbits.                          Service, please call: 020 7554 3528
                                                                                          Email:
                                                                                         londonreferrals@rvc.ac.uk

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