Upper Respiratory Tract Disease in
Rabbits
Esther van Praag, Ph.D.
MediRabbit.com is funded solely by the
generosity of donors. Every donation, no matter what the amount, is appreciated and will aid
in the continuing research of medical care and health of rabbits. Thank
you |
Till recently,
respiratory diseases in rabbits have been connected to the presence of the
bacterium Pasteurella multocida, therefore the disease was called Pasteurellosis. This diagnosis is definitively outdated,
after cultures of samples taken from diseased rabbits revealed the presence
of a variety of bacteria: Bordetella bronchiseptica, Staphylococcus
sp., Pseudomonas sp., Chlamydia sp., Acinetobacter sp., Moraxella
catarrhalis, Mycoplasma sp., etc. Non-bacterial causes can also
lead to respiratory diseases in rabbits: ·
Viral, due to poxvirus, Myxoma virus (see: Myxomatosis), or
Herpesvirus (see: Herpes sp. virus in rabbits); ·
Mechanical or neoplastic obstruction, due to the
presence of a piece of hay, or tumor (polyp, malignant tumor), respectively; ·
Cardiovascular causes; ·
Hypersensitivity to dust or smoke (e.g. ammonia vapors from the litter-box, cigarette smoke,
hay or pellet dust, pollen). Allergic
reactions are rare in rabbits; ·
Presence of a foreign body. Kim Chilson Rune, and the piece of hay that came out of the nostril. Respiratory disease can be divided
into: · Upper respiratory tract disease, which is characterized by nasal and ocular discharge, sneezing and snoring, rarely fever. ·
Lower respiratory tract disease, which is
characterized by anorexia, depression, dyspnea (abnormal or difficult
breathing) and cyanosis (blue discoloration of tongue, lips, gums, due to
shortage of oxygen), fever or hypothermia. Lower respiratory tract disease
can remain undetected for a long time, till the disease develops in an acute
form, with difficult respiration and sometimes coughing. When respiration is
difficult, it can be accompanied by bilateral bulging of the eyes and
excessive appearance of the nictitating eyelid (also called third eyelid). For causes of respiratory disease in rabbits, see: Differential diagnosis
for difficult or noisy respiration �
Clinical
examination
The following points should be checked,
when a respiratory disease is suspected: 1.
Checking the rate of respiration of the rabbit (30
to 60/min). Higher is normal, lower is abnormal. 2. Checking carefully the nostrils for
discharge. This is not always obvious, as rabbits are big groomers and will
clean themselves restlessly. Sometimes matted fur can be found on the front
paw, sign that a discharge has occurred. 3. Examining the eyes for conjunctivitis and
dacryocystitis (excretion of purulent exudate or
lachrymal overflow). 4. Checking the face, the facial bones, to
discover irregularities, presence of abscess, swellings. 5. Rhinoscopy. 6. Taking deep nasal and tracheal samples in
order to do a bacterial culture; for the nostrils, it should be done on both
sides as the infection can be unilateral. The nostril swab can be done with a
flexible-wire calcium alginate tipped swab, 1 to 4 cm into the nostrils or
the nasopharyngeal region. An alternative method is a nasal aspiration.
7.
Examining the ears for infection. X-ray pictures of
the skull may show the presence of an increased opacity in the middle and
external ear. Ear infection is often associated to respiratory infection, via
the passage of bacteria through the Eustachian tube, but it is not an
obligation. Often, the rabbit has a decreased appetite, due to pain. 8.
Microscopical examination of the blood and CBC in
order to reveal hematological changes like neutrophilia (increased level of
neutrophils), or leucopenia (decrease in the amount of white blood cells in
the blood). It may furthermore help detect
secondary organ failure. 9. When a heart problem is suspected, X-rays
and electrocardiography will help to detect cardiomegaly (enlargement of the
heart). 10. X-rays of the thorax will further help
detect the presence of a bacterial infection (increased opacity), bronchitis,
the presence of masses (abscess or neoplasia), or edema (accumulation of an
abnormally large amount of fluid) around the lung(s) or the heart. Infectious
bacteria
Pasteurella
multocida is quite contagious, although some
rabbits seem to show a higher resistance to the bacterium than others. If Pasteurella sp. is present, treatment
must be started ASAP, be aggressive and long, at least two weeks after total
disappearance of the symptoms. It happens that a rabbit never fully recovers
and need to be on maintenance antibiotics for the rest of its life. Pasteurella sp. is
responsible for more than one difficult to treat disease in rabbits, to name
a few: - Pleuritis
(inflammation of the tissue around the lungs); - Pneumonia; -
Pericarditis (inflammation of the lining around the
heart); -
Otitis media or
interna (middle or inner ear infection); -
Dacryocystitis (infection
of the tear duct), - Conjunctivitis; -
Mastitis
(infection of the milk glands). The clinical
signs are multiple, including sneezing and coughing, and nasal discharge. Kim Chilson Sneezing
rabbit This stage can evolve into lower respiratory tract
disease, with pleuro-pneumonia or pericarditis. Bordetella bronchiseptica is typically
a bacterium that shows up, when a rabbit and a guinea pig are housed
together. It may be present asymptomatically in the nasal cavity of the
rabbit, without development of the disease. Its presence may increase the
susceptibility of the rabbit to Pasteurella sp. and the chances of
developing an infection, including bronchopneumonia. The bacterium is fatal
for the guinea pig. Acinetobacter sp. is a bacterium that has
usually a low potential of virulence and thus rarely leads to the development
of pneumonia. Its presence tends to indicate that an animal is colonized by
this bacterium, rather than infected. Since it is colonizing mainly, it is
important to determine if Acinetobacter sp. is the causative agent, or
merely masking the presence of another pathogen.
Treatment
Respiratory tract diseases must be
differentiated from a viral disease, a mechanical or neoplastic obstruction or
hypersensitivity. If nothing is found and the presence of bacteria can be
ruled out, the affected rabbit can be given antihistamines or corticosteroids
(no longer than 3 to 5 days).���������
Successful treatment of upper respiratory infection
needs to be aggressive and long. Often a combination of antibiotics is used,
like oral administration of enrofloxacin or ciprofloxacin, accompanied by gentamycin based nose drops. Trimethoprim sulfadiazine is a bactericidal
antibiotic used in GI tract, respiratory and urinary infections, among
others. It is efficacious against a range of bacteria that affect rabbits,
including Pasteurella sp., Clostridia spp., Staphylococcus
sp., Bordetella sp., etc. It can be used long term, low dose. This
antibiotic often shows poor results in rabbits, and often the disease comes
back worse once the treatment is stopped. This could relate to the fact that
half-life of trimethoprim in a rabbit last only 40 min. Azithromycin, a modified erythromycin, that does not
show the side effects of the later in rabbits, is very efficacious in the
treatment of Bordetella sp. (and so is enrofloxacin). The azithromycin
doses used for rabbits (50mg/kg PO QD (SID) is much higher than that used for
other small animals like cats and dogs (5-8mg/kg). Treatment lasts generally
7 days, after which an evaluation is done and eventual prolongation decided. Cephalosporins are bactericidal broad-spectrum
antibiotics used to treat skeletal, genital/urinary, skin and soft tissue
bacterial and respiratory (associated with Pasteurella sp.)
infections, among others. There are several generations of cephalosporin,
each aiming a more or less specific group of bacteria. Although quite safe
when used in injected form, this drug is potentially nephrotoxic. The therapy against Pseudomonas sp., one of
the most difficult to treat infections, must be aggressive. A sensitivity
test must be done, as this bacterium is known to be multi-resistant to many
antibiotics. Most successful treatments involve a combination of antibiotics,
for example:
Further antibiotics, safe for use in rabbits that
have shown good results in the treatment of respiratory tract disease,
include:
For
more information, see: Antibiotics *safe* �for use in rabbits
Aside a longer systemic antibiotic therapy,
additional therapy comprises: ·
Nasolacrimal flushes; ·
Nebulization
with a saline solution, mucolytics and antibiotics help bring the medication
deep in the bronchia and lungs in cases of rhinitis, sinusitis or pneumonia; ·
Fluid
therapy and assisted force-feeding, when the rabbit refuses to drink and eat. If the
respiratory disease is accompanied by conjunctivitis and/or dacryocystitis, local antibiotic therapy (e.g. enrofloxacin, gentamycin) must accompany the
treatment protocol. A. van
Praag Flora hold above a bowl of hot water to allow her to breath humid air.
Videos about nebulization (A big thank you to Debbie Hanson. Without her help, time and expertise, the making of the nebulizer video would not have been possible. Thanks also very much to Rachel Ihlenfeldt and her rabbit Bunbun for the demonstrations) .
Using a nebulizer in a rabbit affected by upper respiratory infection (URI). .
Nebulizing "chamber", when the rabbit does not like to have a mask, is panicking or aggressive. Acknowledgements
Many thanks to Michel Gruaz
(Switzerland), to Kim Chilson (USA), to Tal Saarony (USA) and to Dr Katleen Hermans, (Kliniek voor Pluimvee en Bijzondere
Dieren, Universiteit Gent, Belgi�) for the
permission to use their pictures to illustrate this article. Further Information
Aoyama T, Sunakawa K, Iwata S, Takeuchi Y, Fujii R. Efficacy of short-term treatment of pertussis
with clarithromycin and azithromycin. J Pediatr.
1996; 129:761-4. Ladefoged O. The
absorption half-life, volume of distribution and elimination half-life of
trimethoprim after peroral administration to febrile rabbits. Zentralbl Veterinarmed A. 1979;
26(7):580-6. Ladefoged O.
Pharmacokinetics of trimethoprim (TMP) in normal and febrile rabbits. Acta Pharmacol
Toxicol (Copenh). 1977;
41(5):507-14. 1.
|