Introduction
Pasteurella (snuffles) is a common cause of respiratory
disease in rabbits. Most rabbits are exposed to it and harbor the
organism that causes it. In can become a chronic problem that is
difficult to control.
This disease and GI stasis are some of the more common
problems we encounter in rabbits. Please also read our GI Stasis page also for an understanding of
this problem and for proper diet for a rabbit.
This page contains
graphic pictures of rabbits with severe infections- it might not be
appropriate viewing for all ages.
Cause
The bacteria that causes this disease is
called Pasteurella multocida. This bacteria has several strains that
differ in their ability to cause problems. Most rabbits are exposed to
this bacteria at some time in their lives. Some of them will show
symptoms only when stressed. These carriers can spread the problem to
other rabbits without any symptoms of their own. This can make control
difficult.
Pasteurella is spread by mating, through
general contact (especially respiratory), or through wounds from
fighting.
Symptoms
Symptoms depend on the strength
(virulence) of the specific Pasteurella strain involved, which body
organ(s) are involved and how long the disease is present. One of the
most common symptoms is respiratory, usually manifested as a nasal
discharge. When a rabbit wipes its front paws on its nose to remove the
discharge the hair on the legs becomes matted. These are the symptoms
that lead to the laymen's name for this disease, snuffles. Sometimes
the nasal discharge is so chronic that the fur is actually missing.
Other respiratory signs of Pasteurella
include sneezing, congestion, and conjunctivitis. The tear ducts
(lacrimal ducts) can become clogged with dried discharge, causing
excess tearing and subsequent scalding of the skin around the eyes and
face.
This is an example of how we flush the
tear duct. They eye has been given a local anesthetic, and we are using
a catheter to gently flush a saline solution into the tear duct.
In some cases Pasteurella can localize
in the eye and cause complete loss of function. This eye has to be
removed, since the rabbit cannot see, and it is painful. The white area
in the center of the eye is the infection.
In addition to the respiratory tract,
the bacteria can also infect the reproductive tract, the sinuses, the
eyes, the ears, and the internal organs. It sometimes causes abscesses
under the skin. These abscesses can become chronic and require surgery
to correct. Severe cases can cause central nervous system symptoms like
oscillations of the eyes (nystagmus), circling to one side, and severe
tilting (wry neck or torticollis) of the head.
This rabbit has a neurologic problem
from Pasteurella.
Rabbits with ear infections might paw at
the ears and those with internal organ infections might have poor
appetites and lose weight. If the reproductive tract is infected
discharge is commonly noted.
The following sections contain graphic
surgical pictures, and may not be appropriate for everyone.
This is a healthy uterus during a
routine spay (OVH). The healthy pink
uterine horns are easily seen (white arrow).
The arrows point to the typical
appearance of a uterus infected with Pasteurella. Cancer can also look
like this.
Diagnosis
This problem is so prevalent, and the
symptoms so characteristic, that Pasteurella is part of the tentative diagnosis anytime a rabbit shows the
above symptoms.
During the physical exam a fever might
be present along with an increase in the sounds heard in the lungs with
the stethoscope. Cultures can be performed to confirm that Pasteurella
Multocida is indeed present. Rabbits with a negative culture result
could still be harboring Pasteurella. Blood samples are commonly used
along with x-rays. X-rays might show changes in the chest or infection
in the middle ear.
The arrows below mark the typical
abscesses (the round white areas) that can be seen in the chest of a
rabbit with Pasteurella.
This is what these lungs could look
like on an autopsy. All the white spots correspond to the white spots
on the radiograph above.
Treatment
Most cases are treated with antibiotics.
They sometimes need to be given for weeks or months. The majority of
cases brought for treatment are chronic in nature. In these situations
the bacteria has had time to become well entrenched, and there is no
guarantee that antibiotics will work. If they do work the problem can
recur when the antibiotics are stopped. This emphasizes the need for
routine exams in general (every 6-12 months), and a physical exam any
time the above symptoms are noted.
Other medications are used if your pet
is showing central nervous system or ocular symptoms. Pets that are
circling or are wry necked might respond to oral medication to make
them more comfortable. Plugged tear ducts are flushed and
conjunctivitis is treated with antibiotic drops.
Abscesses are treated surgically.
Rabbits have a very thick and tenacious discharge when they form an
abscess, and require more care than the abscesses of most other
animals. Surgical removal can be difficult, especially in the chronic
cases, because the abscessed area can become extensive in nature.
Multiple surgeries might be needed, and wound care at home is
necessary.
This is a severe abscess on the back of
a rabbit that has been anesthetized and is undergoing surgery to
correct its problem. The wound has just been opened by the scalpel
blade at the top left of the screen (arrow).
The wound is filled with pus (the
correct word is purulent) that must be completely removed. Any
infection that is not removed will cause the abscess to return. It is
very thick and does not lend itself to easy removal.
The underlying tissue that has been
exposed to this infection has to be removed also. It is diseased and
will be a source of further infection if it is not completely removed.
This is the final appearance of the
wound after all the purulent material and diseased tissue has been
removed after 30 minutes of surgery. The rubber tube (arrows) running
from top to bottom is called a penrose drain tube. Its function is to
allow further drainage of the infection. The tube will be removed in 5
days, the sutures will be removed in 10 days.
Some pasteurella abscesses are chronic
in nature, and contain more dead tissue than purulent material. The
following pictures show a case of a rabbit referred to us that had been
treated with routine drainage and antibiotics for several weeks. The
purulent material on the inside was diminished, but the tissue that
remained was either dead or dying and had to be surgically removed.
This is the face of the rabbit that is
laying on its left side. Its mouth is towards the right, the white
arrow points to its right eye. The abscess is the large circlular area
below and to the left of the eye.
The diseased tissue (black arrow) is
gently dissected away from the healthy tissue. The healthy jaw muscle
(white arrow) is apparent .
The dissection has been completed. All
that remains is healthy tissue that will be sutured back together.
A large incision had to be made to
remove all of this diseased tissue. It extends from the base of the ear
all the way under the chin. These sutures will be removed in 10-14 days.
Prevention
Most rabbits are exposed to this
bacteria early in life. Determining which rabbits will develop symptoms
of this problem is difficult. Minimizing stress (heat, overcrowding),
proper diet (high in timoth hay, minimal pellets), a clean environment,
fresh drinking water at all times, along with early neutering can help
in minimizing the chance of this infection.
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