| Summary Information |
| Diseases / List of Bacterial Diseases
/ Disease summary |
| Alternative Names |
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|
| Disease Agents |
- Pasteurella multocida (see: Pasteurellosis in Lagomorphs)
(B601.11.w11,
B602.20.w20, B603.3.w3,
B606.13.w13, B614.8.w8,
J495.21.w1,
J495.23.w, J495.27.w1)
- Pasteurella multocida and Bordetella bronchiseptica are
the most common organisms involved in otitis media/otitis interna. (B603.3.w3)
- In one study, Pasteurella multocida was reported to be
isolated from 97% of cases of otitis media, including both clinical and subclinical cases. Bordetella
bronchiseptica and staphylococci were also found in five to
ten percent of cases. (J495.21.w1)
- Other bacteria (B602.20.w20)
including Staphylococcus aureus, Staphylococcus spp., Pseudomonas
aeruginosa, Pseudomonas sp., Bordatella
bronchiseptica, Bacteroides sp. Proteus mirabilis and Escherichia coli.
(J15.28.w1, J60.6.w2)
- Escherichia coli (B601.11.w11,
B603.3.w3)
- Proteus mirabilis (B601.11.w11,
B603.3.w3)
- Pseudomonas aeruginosa (B601.11.w11,
B603.3.w3)
- Staphylococcus spp. (B606.13.w13)
- Staphylococcus aureus (B601.11.w11,
B603.3.w3)
- In pet rabbits, Staphylococcus aureus is commonly
cultured. (V.w122,
V.w65)
- Other bacteria (B602.20.w20)
- Mycoplasma infection (B603.1.w1)
Note: bacterial infection may be secondary to:
- Psoroptes cuniculi
Infection
- There is no evidence to suggest that ear mites are a cause of
otitis media; however, affected animals may have concurrent Pasteurella
multocida infection. (B614.8.w8)
- These mites can cause an otitis externa and this infection can
extend to an otitis media. (B603.1.w1)
- Migration of a foreign body through the tympanum. (B603.1.w1)
- Iatrogenic
aural
injury. (B603.1.w1)
- Lack of normal ear drainage in lop-eared rabbits. (V.w65)
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| Infectious
Agent(s) |
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| Non-infectious
Agent(s) |
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| Physical
Agent(s) |
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| General Description |
Infection that
originates in the middle ear can spread to:
- The ear canal (if the tympanic membrane ruptures). (B602.17.w17,
B602.20.w20)
- The inner ear, leading to labyrinthitis, and then sometimes to the
brain resulting in severe neurological signs including seizures. (B602.20.w20)
Clinical signs
Otitis media is often not clinical and is a common incidental finding
at post-mortem or on radiographs. Clinical vestibular disease is often a
consequence of a spread of infection from an otitis media to an otitis
interna or to the brainstem. (B603.4.w4)
- Head tilt (B602.20.w20,
B606.13.w13, J15.28.w1, J60.6.w2)
- Otitis interna is the commonest cause of head tilt. (B606.13.w13)
- A rabbit may hold its head tilted if it has middle or outer ear
pain. (B603.1.w1)
- The down-tilted eye may have corneal oedema and ulceration. (J60.6.w2)
- Note: if the
condition is bilateral, head tilt may not be present. (V.w65)
- In these cases, there may be no obvious signs but the rabbit
is described by the owner as "not doing right". (V.w65)
- The presence of a head tilt does not mean the condition is
not bilateral, as one side may be worse and the head tilted
reflecting this. (V.w65)
- Soft tissue swelling at
the base of the ear canal can sometimes be seen in cases of severe
otitis media where there is a build up of pus within the ear. (B602.20.w20)
- Pus in the ear canal may be seen if the tympanic membrane has
ruptured (B606.13.w13)
or if there is an otitis externa. (V.w65)
- Facial paralysis or Horner's syndrome - lip, eyelid and ear
drooping may simulate a head tilt appearance. (B603.1.w1)
- Deafness: but this is very difficult to ascertain in rabbits.
(B603.1.w1)
- Signs of pain and the rabbit is described by the owner as
"not doing right". (V.w65)
- These may be the only indications of the disease if it is
bilateral. (V.w65)
- Nystagmus (horizontal). (J60.6.w2)
- With peripheral disease, nystagmus is horizontal or rotary, does
not change direction if the head
position is changed, and has the fast phase in the direction of
the lesion. (B601.11.w11,
J15.28.w1)
- Torticollis, nystagmus and
ataxia. (B602.17.w17)
- Loss of balance may result in the rabbit continuously rolling and
spinning. (J60.6.w2)
- Excessive scratching at the ear base may be noted. (B602.17.w17)
Clinical pathology
- As with other chronic diseases, chronic otitis media can lead to a non-regenerative anaemia. (B603.2.w2)
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| Further Information |
- Peripheral vestibular disease is usually due to otitis interna;
most commonly this occurs subsequent to spread of infection from a
chronic otitis media. (B603.3.w3)
- Primary otitis media can occur by spread of infection from the
upper respiratory tract to the middle ear via the Eustachian tubes. A
concurrent rhinitis or sinusitis is suggestive of this. (B601.11.w11,
B603.3.w3)
- Infection in the middle ear can then spread to:
- The ear canal (if the tympanic membrane ruptures) (B602.20.w20)
- The inner ear, leading to labyrinthitis and then sometimes to the
brain resulting in severe neurological signs including seizures. (B602.20.w20)
Susceptibility
- Lop-eared breeds are more susceptible; in many of these rabbits, the
fold in the ear cartilage is such that the lumen is entirely closed off leading to no
drainage at all of cerumen from the ear. (V.w65)
Diagnosis
- Clinical signs such as head tilt, an ear base abscess, or excessive scratching
at the ear base without parasites being present. (B602.17.w17,
J15.28.w1)
- It is also useful to identify whether there is a primary or
secondary otitis externa, or a ruptured tympanic membrane. (B601.11.w11)
- The ear canal may contain pus. (J60.6.w2)
- If the tympanic membrane rupture has occurred, dried exudate may be
found crusting in the ear canal and white purulent exudate (for Pasteurella
multocida infection) under this. (B602.17.w17)
- Gentle pressure at the ear base may express the exudate. (B602.17.w17)
- Skull radiography (B601.11.w11,
B602.17.w17,
B602.20.w20,
B606.13.w13, J15.28.w1)
- In the tympanic bulla, increased soft tissue density (exudate)
and thickening of the bone. (B602.17.w17,
J60.6.w2)
- Positive contrast may be used in the ear; this will show
if the tympanic membrane is intact. (V.w65)
- Endoscopy with a rigid endoscope may be used to examine
the ear down to the tympanic membrane. (B602.36.w36,
J513.2.w2,
P6.3.w1, V.w65)
See: Imaging in Lagomorph Diagnosis and Treatment
- Culture and sensitivity
- Aural swabs or deep nasal swabs. (B601.11.w11)
- CT scanning if available. (B601.11.w11)
- Histology (Diagnosis of associated encephalitis). (B602.20.w20)
- See:
Differential diagnoses of head tilt include:
Treatment
- Long term systemic antibiotic treatment is needed - often four
to six weeks or longer. (B601.11.w11,
B602.20.w20,
B606.13.w13,
J15.28.w1)
- Topical antibiotics
- If the tympanic membrane is ruptured:
- topical 0.3% gentamicin (B602.20.w20)
Note: this should be used with care due to the
potential of neurotoxicity. (V.w65)
- or 0.5% enrofloxacin / 1.0 % silver sulfadiazine otic solution.
(B602.20.w20)
- Flushing the ear canal
- In cases of severe disease/otitis externa, the patient
should be anaesthetised and the ear canal gently flushed with warm
saline solution.
(B601.11.w11,
B602.20.w20)
- Use a small 3 1/2 -F red rubber catheter. (B602.20.w20)
- NB: avoid flushing when the tympanic membrane is
ruptured. (B602.20.w20)
- Ear wick
- Bulla osteotomy
- This technique can be used in cases of severe otitis media that
are not responding to medical treatment. However, there is a high
risk of postoperative complications e.g., cellulitis, abscessation,
and facial nerve paralysis. Complications can be reduced by using doxycycline gel or antibiotic-impregnated polymethylmethacrylate
beads (see: Production of Antibiotic-Impregnated Beads)
placed in the tympanic bulla, along with long term systemic
antibiotics. (B601.11.w11,
J15.28.w1)
- Neck muscle spasms are common and the rabbit's neck should be massaged regularly.
(B601.11.w11)
- See: Bulla Osteotomy in Rabbits (Techniques)
- Symptomatic treatment for torticollis:
- Consider short-acting corticosteroid (e.g. Dexamethasone
sodium phosphate, 0.5 -
2.0 mg/kg subcutaneously to limit inflammation. (J60.6.w2)
- Supportive care, including feeding if necessary. (J60.6.w2)
- Note: minimise handling, as loss of balance when the
rabbit is picked up may cause it to twist frantically. (J60.6.w2)
- Anti-emetic drugs
- These can be useful for preventing suspected nausea that may
occur secondary to vestibular damage.
- Metoclopramide: 0.5 mg/kg orally or via subcutaneous
injection every eight hours. (B601.11.w11,
J15.28.w1)
- Antihistamines and phenothiazine derivatives can prove useful in
patients with a head tilt because these drugs act on the
vestibular pathways. (B601.11.w11,
J15.28.w1)
- Procloperazine
(Phenothiazine derivative) : 0.25 mg/kg orally every eight to
twelve hours (this dose has been extrapolated from human
medicine). (B601.11.w11)
- Meclizine: 6.25 to 12.5 mg per rabbit orally every
eight hours (this comes from anecdotal reports in the USA). (B601.11.w11)
- Appropriate antibiotic ophthalmic ointment as required for the
down-tilted eye. (J60.6.w2)
- In the longer term, anti-inflammatory treatment such as NSAIDs,
cyclosporins or corticosteroids may be considered. (V.w65)
- Note:
- Rabbits with milder signs of torticollis often compensate well and live a
normal life except for the changed posture. (J60.6.w2)
- Euthanasia is appropriate for severe torticollis cases with complete loss of
balance. (J60.6.w2)
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| Associated Techniques |
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| Host taxa groups /species |
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| Disease Author |
Nikki Fox BVSc MRCVS (V.w103);
Dr Debra Bourne MA VetMB PhD MRCVS
(V.w5) |
| Referees |
John Chitty BVetMed CertZooMed MRCVS
(V.w65) |
