Pasteurellosis - Rabbit

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Also known as: Snuffles

Caused by: Pasteurella multocida  — and/or less commonly Bordetella bronchiseptica

Introduction

Pasteurella multocida can reside in the nasal cavity of rabbits without causing disease. Such rabbits are carriers and can infect in-contact animals.
It seldom causes disease in pet rabbits, but can cause serious infection in colonies of rabbits kept for breeding, meat or fur production or in laboratories.
Pregnancy, parturition, lactation, poor husbandry, overcrowding, stress, nutritional deficiencies, genetic predisposition and bacterial virulence all affect the course of the disease, which can lead the bacteria to multiply uncontrollably and overwhelm respiratory tract defences.
The bacterium is spread to newborn rabbits shortly after birth by infected does which harbour the infection in their nasal cavity.

The incidence of disease increases with age up to about 5 months of age. Infection can extend from the upper respiratory tract to the rest of the respiratory tract and tympanic bulla.
Transmission of disease occurs by direct contact and by airborne spread. Fomite spread and contaminated water supplies have also been implicated.

Clinical Signs

Infection can be acute, subacute or chronic.

The most common presentation of disease is rhinitis (snuffles) manifested by serous then purulent nasal discharge, sneezing and coughing, audible respiratory noise (snuffling) and yellow staining and matting of fur on the forelimbs.

Other syndromes include:

Pneumonia: Either acute and rapidly fatal or chronic with incidental pneumonic lesions found during post-mortem examination of apparently healthy rabbits.
Genital infection: The bacteria can be found in the vagina of a high number of carrier animals and can be spread at mating. Pyometra can be a manifestation of pasteurellosis.
Wound infections and abscesses: The organism can contaminate tissues during licking and grooming and is often isolated from infected bite wounds and abscesses. Also in facial abscesses due to dental disease.
Dacryocystitis: Purulent infections of the nasolacrimal duct lead mainly to nasal discharge and conjunctivitis.
Otitis media: Pasteurella multocida can spread to the tympanic bulla, affecting the vestibulocochlear nerve and causing vestibular disease, manifesting as head tilt, rolling and nystagmus.

Diagnosis

Clinical signs are suggestive, but diagnostic tests are required to isolate the organism and detect subclinical carriers.

Deep nasal swab under sedation or anaesthesia can be taken for bacterial culture. False negatives can occur as the samples are not always deep enough or rabbits might have already received antibiotics. Pasteurella multocida can also be difficult to grow in a laboratory setting.

Serological and PCR testing (in the USA): Rising antibody titres demonstrate exposure to infection.

It is important to note that other organisms and diseases can cause clinical signs similar to those of pasteurellosis. Most importantly:

Treatment

Treatment depends on the clinical symptoms and the emotional value of the rabbit affected by the disease.

Rabbits should receive long-term systemic antibiotics selected for their efficacy against the organism (preferably through culture and sensitivity testing). These include antibiotics such as: Cefalexin, Enrofloxacin, Tetracycline, Trimethoprim-sulpha.

Supportive care such as ensuring adequate hydration, nutrition and the prevention of ileus can also contribute to a successful outcome.

Control and Prevention

This will focus mainly on control in breeding, laboratory and commercial rabbit colonies, which are most severely affected by the disease.

Good husbandry is an essential part of disease control. Stress, intercurrent disease, poor air quality and overcrowding can trigger the flare up of latent infections. A clean, dry, well-ventilated environment is required with no draughts. Rabbits can withstand cold better than heat, and fluctuations in temperature should be avoided with a temperature maintained at around 16-20°c.
Affected cases should be isolated and treated or culled promptly. Keeping batches separate and minimising contact between groups reduces disease transmission.
Disease free status can be achieved in colonies through barrier-housing and quarantine of any new stock. Rabbits are placed in isolation for 2-4 weeks and multiple samples from their nasal cavities are submitted for culture. Only rabbits with negative cultures are then used for breeding.
Serology and PCR can also be used to detect disease-free stock.
Antibiotics have been used prophylactically to prevent Pasteurella infection by administering them in the feed of water of pregnant does.
There appears to be a genetic resistance to Pasteurella infection and attempts have been made to produce disease-free strains of rabbits.
Vaccines are still being developed but protection seems to be incomplete and results have been disappointing.


Pasteurellosis - Rabbit Learning Resources
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References

Keeble, E. (2006) Common neurological and musculoskeletal problems in rabbits, In Practice 28: 212-218

Sant, R. Rowland, M. (2009) Skin disease in rabbits, In Practice 31: 233-239

Harcourt-Brown, F. (2002) Textbook of rabbit medicine, Elsevier Health Sciences

Harkness, J. Turner, P.(2010) Harkness and Wagner's Biology and Medicine of Rabbits and Rodents, Wiley-Blackwell

Baker, D. (2003) Natural pathogens of laboratory animals: their effect on research. ASM Press




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