Pasteurella Multocida & 'Snuffles'

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Pasteurella Multocida & 'Snuffles'

Post by Happy Hoppers on Sun Jun 22, 2008 11:33 am

Pasteurella multocida

A History of Pasteurella
In August 2006 a young farmer, thought to have been handling dead wild rabbits whilst sporting a blister on his thumb, developed septicaemia (blood poisoning) from a resulting Pasteurella infection and died (the news reports labelled Pasteurella as ‘rabbit flu’ which is not strictly true. Flu is caused by a virus whereas Pasteurella is a bacterium). Humans can catch Pasteurella, usually from dogs and cats but it is uncommon and deaths are very rare. In fact, there have only been four reported human fatalities from a Pasteurella infection (between 1993 and 2005).

What is Pasteurella?
Pasteurella multocida is a small, rod-shaped bacterium which enters the body via a nasal cavity or open wound and begins to grow. Pasteurella usually resides in the respiratory tract but can also be found in the sinal cavities, lacrimal (tear) ducts, middle ears, genitalia and internal organs. 30%-90% of rabbits have been explosed to Pasteurella at some point but most are asymptomatic, i.e. they do not become ill or show symptoms. As a result, the bacterium is endemic in most rabbit populations and only becomes pathogenic if the rabbit’s immunity is low (for example at times of stress). Once an infection develoips it is known as Pasteurellosis.

There are different strains of Pasteurella bacterium, each responsible for different ailments in the rabbit, although P. multocida is notoriously difficult to culture in vitro due to its tendency to die in transport, hence often the exact strain cannot be identified or a false negative result will come back. Some strains of Pasteurella produce endotoxins (toxins contained by the bacterial cell wall which are released into the host when the bacterium is destroyed), often responsible for problems away from the site of infection itself as toxins can travel in the bloodstream. Often the sites of these secondary problems are hard or impossible to culture, throwing up more problems. Degeneration of the nasal mucous membrances (atrophic rhinitis) ornasal bone structure can result from Pasteurella toxin release alongside fever, depression and shock.

Occasionally Pasteurella will spread from the nasal passages to the bodily organs or internal tissues and the rabbit will become completely asymptomatic of respiratory problems. This is a problem as the bacterium will now not register from a nasal swab and the disease may be misdiagnosed or missed altogether.

How is it spread?
Pasteurella is spread through bodily contact – mating (venerial contact), fighting, nose-to-nose contact and open wounds; through aerosol dispersion of mucous particles containing bacteirum (sneezing releases said particles into the air); direct contact – often through fomites (inanimate substances or objects which act as carriers for disease) such as toys, bowls, food etc; and is also thought to be passed from doe to kit as the kit passes through the birth canal.
The bacterium itself can survive for days in water or wet secretions and so it is easily spread from rabbit to rabbit.

What problems does it cause?
The most common result of a Pasteurella infection is ‘snuffles’. However there are a whole host of other associated problems, most of which are listed below.

Snuffles
A bracket term for upper respiratory disease. Symptoms include sneezing and a nasal discharge (which can also often be seen as ‘crusting’ on the forepaws due to contact when washing). Snuffles is a relatively common ailment, much the equivalent of the human cold, and can be treated relatively easily with Baytril. If the rabbit’s mucus turns from clear to pus-like though, this usually indicates a progression to a lower respiratory tract infection

Pneumonia
A progression from an upper to a lower respiratory infection. This is a lower respiratory infection (i.e. the infection has spread to the lungs) and is a serious condition. Symptoms include gasping for breath, the head thrown back to maximise oxygen intake, loss of appetite, elevated temperature Pneumonia is treated with broad spectrum antibiotics, although it is not a guarantee that a rabbit will recover and will often have tissue scarring if it does. If the disease is allowed to take hold and progress, the prognosis is bleak.

Abscesses
Filled with a dense pus, the consistancy of toothpaste, Pasteurella abscesses can appear anywhere on the body, although the tooth roots are most common (other areas include mouth/cheeks, bones, joints, genitalia, and subcutaneous tissues). The pus within an abscess contains dead bacterial cells and dead white blood cells (the body’s defense cells, whose function is to fight infection) and, if left untreated, can lead to blood poisoning. Abscesses usually need surgery to ensure all the thick pus is removed along with any dead or infected tissue to ensure the abscess does not recur. Antibiotics and painkillers are usually prescribed.

Conjunctivitis
Although Pasteurella is naturally present on the conjunctiva in 6% of healthy rabbits* , often the lacrimal (tear) ducts can become clogged with dried discharge caused by excess tear production – the body’s attempt at fighting the infection. Conjunctivitis is treated with antibiotics although if ulcers have developed, sometimes the eye will be removed completely to avoid spreading the infection further.

Torticollis (head tilt) and ear infections
Torticollis has many causes, but if Pasteurella is the culprit, it is caused, in this case, by an inner ear infection, affecting the rabbit’s sense of balance. Believed to migrate from the nasal cavity along the Eustachian tube, inner ear infections are tricky to treat due to their internal, contained nature. Middle and inner ear infections are almost indistinguishable in symptoms, the rabbit flicking its ears and scratching. With middle ear infections a discharge is often noticeable. Inner ear infections are often characterised by ataxia (stumbling, rolling etc), head tilt (torticollis) and repeated, horizontal eye movement. Inner ear infections are usually treated with anti inflammatories, aggressive antibiotics.

Genital infections
Mastitis – breast abscesses on does, often post partum; Pyometria – a uterine infection, and Orchitis – testicle infections. These are often transmitted either during coprophagy (the rabbit eating its own faces – caecotrophs), copulation or during kindling, passing from doe to kit. Pyometria is harder to spot as it is obviously internal but there is frequently a swelling of the abdomen, often accompanied by vaginal discharge and excessive drinking and urination. In males there is usually swelling of the testicles and penis covering, often accompanied by visible abscesses in the later stages of the infection.
These conditions are usually treated by complete neutering of the rabbit (another good reason to get pets spayed and castrated early on) followed by a course of antibiotics and pain medication

Neurological damage
Although sparsely documented, Pasteurella can also be responsible for splayed legs in rabbits, affecting the nervous signals between the brain and the legs, causing the rabbit to lose motor control in their limbs and leading to a loss of co-ordination and/or ataxia. It may also lead to a lack of general responsiveness and deterioration into total paralysis in extreme cases.

Prevention & Treatment
Before treatment can occur, a vet will usually run a Culture & Sensitivity (C&S) test to determine exactly what is causing the problem. As mentioned before, Pasteurella can be notoriously tricky to cultivate in a lab due to its tendency to die during transport or be overrun with other inherent nasal flora also present on the swab. In this way, a false negative will often come back from the lab (i.e. an ‘all-clear’ when there is, in fact, a Pasteurella infection present), resulting in a misdiagnosis. A newer detection method is called PCR (polymerase chain reaction) which, simply put, involves extracting even a minute amount of DNA from a sample (in this case the Pasteurella on the nasal swab of the afflicted rabbit) and using a combination of heating-cooling cycles and enzymes to amplify the DNA contained in a sample**. This is a very useful tool, often used in forensics to profile the smallest traces of DNA. It is being used more frequently now in veterinary medicine to identify stubborn ailments such as Pasteurella, although it is not common practice yet.

Treatment is usually in the form of Baytril, an antibiotic commonly used when treating rabbits. In most cases, however, Baytril will only keep the infection under control, not destroy it completely and often the rabbit will need repeated courses of drugs to keep the infection at bay. Sometimes a rabbit will have to spend the remainder of its life on antibiotics, this of course vastly increasing the risk of the bacterium becoming resistant to the drug and flourishing anew. Each case of pasteurellosis is unique and should be treated as such.

Prevention is difficult, in that most rabbit already have some strain of Pasteurella lodged somewhere in their bodies. The main preventative actions are listed below:

Wash hands – after handling any other rabbits, cats, dogs or even people. Other pets can be asymptomatic carriers of the bacterium too and it is important to avoid spreading the disease wherever possible.
Minimise stress – avoid high temperatures, overcrowding, ensure your rabbit has adequate housing space
Diet – ensuring your rabbit is on the optimum diet ensures it is in the optimum health. A healthy immune system is much more capable of fighting off infections than one compromised by poor diet. Good quality pellets and unlimited hay are a must, alongside the occasional fresh vegetables.
Clean out hutches regularly – ammonia has been known to aid the spread of Pasteurella by affecting a rabbit’s respiratory system, facilitating the establishment of the bacteria. Ensure that there is no detectable ammonia smell in your hutches and that urine and faeces are not allowed to build up, making sure the hutch is not damp as humidity is another factor in the spread of this disease.
Ensure good ventillation – all hutches should have adequate air flow to encourage the removal of airborn Pasteurella bacteria.
Treat injuries promptly – any open wounds are an entry point for Pasteurella. Make sure your rabbit is treated for any cuts, bits, scratches or insect bites as soon as you notice them.
Keep your happy rabbit – studies show that stroking animals causes human blood pressure to drop, so there is no reason not to shower attention on your bunny! A rabbit needs to be emotionally healthy as well as physically so and attention helps keep your rabbit well-balanced and happy, ensuring its immune system is in the best possible shape.
Regular vet visits – do not be afraid to make an appointment with your vet if you suspect your bunny is unwell, that is what they are there for! It is much better to be an overly owner cautious as rabbits, like most prey animals, are notorious for showing few or no signs of illness and then suddenly dropping dead, leaving the owner confused and heatbroken.
An inexperienced owner will not necessarily think anything much of the few signs or symptoms that are exhibited, often putting them down to a “bad day” or grumpy demeanour. This is nothing to be ashamed of, rabbit illnesses can be very hard to spot but you must give your bunny every possible chance of good health by ensuring that if you do suspect anything you take them straight to the vet.

.........................................................................................
* - Cooper et al. (2001) ‘Conjunctival flora observed in 70 healthy domestic rabbits (Oryctolagus cuniculus)’ The Veterinary Record, 149, (8), 232-235

** - This is done by ‘unzipping’ the DNA down the middle and adding new nucleotide bases to each strand, thus doubling the amount of DNA present in each cycle. This exponentially increases the amount of DNA present in the sample with each heating/cooling cycle.

References

BBC News (2006) ‘Man first ‘rabbit flu’ victim’ (http://news.bbc.co.uk/2/hi/uk_news/england/suffolk/5269766.stm )

Dr Linda Dykes (2006) ‘Pasteurella multocida, rabbits, and human health: FAQs’ (http://www.houserabbit.co.uk/resources/content/info-sheets/pasteurella_multocida.htm )

Astrid M. Kruse ‘Your bunny probably has it – Pasteurella’ (http://www.rabbitnetwork.org/articles/past.shtml )

Margaret A. Wissman (2006) ‘Rabbit Medicine’ (http://www.exoticpetvet.net/smanimal/rabbit.html )

Cooper et al. (2001) ‘Conjunctival flora observed in 70 healthy domestic rabbits (Oryctolagus cuniculus)’ The Veterinary Record, 149, (8), 232-235 (http://veterinaryrecord.bvapublications.com/cgi/content/abstract/149/8/232 )

Wikipedia (2008) ‘Polymerase Chain Reaction’ (http://en.wikipedia.org/wiki/Polymerase_chain_reaction )

Zoologix (2008) ‘Pasteurella multocida’ (http://www.zoologix.com/rodent/Datasheets/PasteurellaMultocida.htm )

Barbara Deeb ‘Pasteurella mutlocida infection in rabbits’ (http://www.rabbit.org/care/pasteurella.html )

Esther van Praag (2008) ‘Otitis media and interna’ (http://www.medirabbit.com/EN/Neurology/otitis_interna_media.PDF )

Esther van Praag (2007) ‘Endometritis, Orchitis and Pyometria’ (http://www.medirabbit.com/EN/Uro_gen_diseases/Bacterial_diseases/endometritis.PDF)

“Charky & Ash” (2005) ‘Rabbit References’ (http://homepage.mac.com/mattocks/morfz/rabrefs.html )

Long Beach Animal Hospital (2007) ‘Pasteurellosis’ (http://www.lbah.com/rabbits/pasteurella.htm ) – **be warned, graphic photos**


This Document is Copyright © Helen Coulson, HappyHoppers Forums Uk . June 2008.UK. ALL RIGHTS RESERVED.
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