Diseases / List of Bacterial Diseases / Disease description:

Pasteurellosis in Lagomorphs 

Head tilt due to pasteurellosis. Click here for full page view with caption

INFORMATION AVAILABLE

GENERAL INFORMATION

CLINICAL CHARACTERISTICS & PATHOLOGY

INVESTIGATION & DIAGNOSIS

TREATMENT & CONTROL

SUSCEPTIBILITY & TRANSMISSION

ENVIRONMENT & GEOGRAPHY

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General and References

Disease Summary

Pasteurellosis is a blanket term for a number of infections, both localised and systemic, caused by Pasteurella spp. and Mannheimia spp. bacteria. (B209.20.w20); particularly Pasteurella multocida and Mannheimia (Pasteurella) hemolytica. (B209.20.w20)
Lagomorphs Pasteurellosis can cause several conditions in rabbits. Pasteurella multocida is commonly found in the nasal cavity resulting in an asymptomatic chronic infection or in rhinitis. Occasionally the infection extends to other parts of the body leading to various clinical manifestations including pneumonia, conjunctivitis, otitis media, abscesses, genital tract infections and septicaemia. (B614.8.w8)

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Alternative Names (Synonyms)

  • Bacterium lepisepticum is a synonym of Pasteurella multocida. (B614.8.w8)
  • "Snuffles" (B614.8.w8) [although not all cases of "snuffles" are due to Pasteurella multocida infection]

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Disease Type

Bacterial Infection

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Infectious/Non-Infectious Agent associated with the Disease

In general these bacteria are considered opportunistic pathogens of mammals (wild and domestic); however some species/strains of Pasteurella and Mannheimia may act as primary pathogens in wild mammals. (B209.20.w20)

Pasteurella multocida 

  • A small gram-negative, non-motile, non-spore forming coccobacillus or short rod/ovoid, with a bipolar appearance on careful staining; found singly, in pairs or in short chains. Aerobic and facultatively anaerobic. (B600.16.w16, B614.8.w8, J16.29.w1)
    • Various serotypes are known, based on capsular and cell wall antigens. (B600.16.w16, B602.17.w17, J4.183.w6, J16.29.w1)
      • Several serotypes may be present within a rabbit colony. (J4.183.w6)
      • Most isolates of Pasteurella multocida from rabbits are capsular type A, particularly serotype A:12; the next most common capsular type is D. (B601.7.w7, J4.183.w6, J93.18.w1, J212.16.w2, J240.46.w1)
    • Isolates can be distinguished based on single-primer PCR fingerprinting. (B602.17.w17)
    • Different strains of Pasteurella multocida vary in their ability to colonise rabbits and in their pathogenicity; some strains are primarily associated with rhinitis and others with septicaemia and pneumonia. (B602.17.w17, B614.8.w8, J16.29.w1, J495.42.w5)
    • Virulence of Pasteurella multocida strains depends on factors such as the presence of adhesins, resistance to phagocytes, presence of endotoxin, exotin, fimbriae, haemagglutinin and factors which are iron-regulated. (J35.159.w3)
    • "More studies are required to determine transmission, serotype, and genotype characteristics of both pathogenic and nonpathogenic strains." (J212.16.w2)
  • In Lagomorphs:
    • Pathogenesis:
      • Pasteurellosis commonly begins in the nasal cavity and then spreads to other tissues either by direct extension to adjacent tissue or via the blood (haematogenous spread). (B602.17.w17, B614.8.w8, J16.29.w1)
      • Intranasally infected rabbits can develop otitis media via direct extension through the eustacian tube. (B602.17.w17, B614.8.w8, J16.29.w1)
      • Intravenous, intra-testicular, and subcutaneous inoculations of Pasteurella multocida have been shown to result in pneumonia via haematogenous spread. (B614.8.w8)
      • Pneumonia or otitis media have been shown to occur when rabbits are inoculated orally or nasally with Pasteurella multocida. (B614.8.w8)
    • In a study reported in 1971, Pasteurella multocida, Bordetella bronchiseptica, and Staphylococcus aureus were isolated from pneumonic lungs, however, it was noted that the latter two bacteria were also present in normal lungs and therefore were probably not the primary cause of pneumonia. (J13.32.w3)
    • In studies of otitis media and interna in commercial rabbits, Pasteurella multocida was isolated from most cases of both clinical and subclinical cases of otitis media and interna (in 98% of young rabbits in one study). Bordetella bronchiseptica and staphylococci were also found in five to ten percent of cases. In another study (of torticollis), Pasteurella multocida was isolated from all 18 laboratory rabbits with otitis media/interna. (B614.8.w8, J83.19.w2, J495.21.w1, J495.27.w1)
    • Note:
      • Pasteurella multocida can also be found in many clinically normal rabbits, i.e. presence of the organism does not necessarily produce disease. Different studies have recovered the organism from the nares as low as 7% and as high as 95% of healthy rabbits. (B600.16.w16, J16.29.w1, J93.18.w1, J212.16.w2)

Pasteurella pneumotropica

  • In laboratory rodents, this organism is a major cause of clinical pasteurellosis. (B614.8.w8)
  • In Lagomorphs: 
    • This organism is not usually pathogenic in rabbits but sometimes colonises the nasopharynx. However, there is one report from 1974 of rhinitis in a rabbit caused by this organism. (B614.8.w8)

Pasteurella aerogenes

  • In Lagomorphs:
    • This organism was recovered from the uterus of a rabbit following abortion due to suppurative metritis. It was thought this was probably an opportunistic infection, since the organism was of low virulence. (B614.8.w8, J495.28.w1)

"Taxon 20"/Pasteurella haemolytica

  • In wild and farmed Lepus europaeus - Brown hares in Belgium, bacteria similar to organisms which had previously been identified as Pasteurella haemolytica. Isolated from purulent conjunctivitis or respiratory lesions. (J1.27.w13)

Infective "Taxa"

Non-infective agents

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Physical agents

-- Indirect / Secondary

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References

Disease Author

Debra Bourne MA VetMB PhD MRCVS (V.w5); Nikki Fox BVSc MRCVS (V.w103)
Click image for main Reference Section

Referees

John Chitty BVetMed CertZooMed MRCVS (V.w65); Aidan Raftery MVB CertZooMed CBiol MIBiol MRCVS (V.w122); Brigitte Reusch BVet Med (Hons) CertZooMed MRCVS (V.w127)

Major References / Reviews

Code and Title List

B209.20.w20, B282.20.w20, B600.16.w16, B602.17.w17, B603.4.w4, B606.13.w13, B614.8.w8
J16.29.w1, J514.1.w1

Other References

Code and Title List

J1.27.w13, J4.183.w6, J4.185.w7, J93.18.w1, J196.70.w1, J212.16.w2, J240.46.w1, J495.28.w1, J495.31.w2, J495.42.w5

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Clinical Characteristics and Pathology

Detailed Clinical and Pathological Characteristics

General Pasteurellosis in a variety of species tends to develop as either a respiratory syndrome or an acute haemorrhagic septicaemia. (B282.20.w20)

Clinical Characteristics

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Lagomorphs There are many clinical manifestations of pasteurellosis and often rabbits will have several syndromes concurrently. This pathogen can be associated with infection of any organ or system and the commonest conditions are described in detail below.
Rhinitis 

This is the most common manifestation of pasteurellosis and is usually a chronic condition. Clinical signs may wax and wane. (B602.17.w17, B614.8.w8, J16.29.w1)

  • Nasal discharge: 
    • Serous, mucoid or mucopurulent (white or yellowish). (B602.17.w17, B614.8.w8)
  • Matted fur on the medial aspect of the fore-paw: 
    • Fur may be damp and discoloured yellowish or yellow-grey where the rabbit has been rubbing its face. Occasionally there may be no apparent discharge from the nostrils and matting of the fore-paws is the only evidence of nasal exudation. (B602.17.w17, B614.8.w8)

There may also be:

  • Audible breathing (B614.8.w8) and sonorous noises. (B602.17.w17)
  • Sneezing (B602.17.w17, B614.8.w8)
    • Exudate may be forcibly expelled from the nares during sneezing. (B602.17.w17)
  • Coughing (B614.8.w8)

Conjunctivitis

This is a common manifestation of pasteurellosis. (B602.17.w17, B614.8.w8)


Abscesses 
  • These abscesses enlarge slowly. (B602.17.w17)
  • Subcutaneous abscesses are the most common form, seen as a firm subcutaneous swelling, sometimes with a soft centre. (B614.8.w8)
    • Commonly seen around the head, neck, and shoulders. (B614.8.w8)
    • Commonly mandibular or around the hock joint. (B602.17.w17)
  • Retrobulbar abscesses are not uncommon. (B602.17.w17)
  • Abscessation may also occur in internal organs (e.g. lungs, reproductive tract, brain and heart); however specific clinical signs are rarely present. (B602.17.w17, B614.8.w8)

Otitis media and interna 
  • Clinical signs are usually absent in otitis media but if the inflammation extends to the inner ear then torticollis may develop. (B602.17.w17, B614.8.w8, J4.183.w6, J16.29.w1)
  • If the tympanic membrane ruptures, infection may extend to the outer ear, with dried exudate crusting in the ear canal and white purulent exudate under this. (B602.17.w17)
  • Infection may extend to produce meningo-encephalitis. (J16.29.w1)

Pneumonia 
  • Poor exercise tolerance, increased respiratory rate - these may not be noticed in e.g. hutch-kept rabbits. (B602.17.w17)
  • Anorexia and depression may occur in severe cases. (B614.8.w8)
  • Respiratory distress is seldom observed. (B614.8.w8)
  • Note: This condition is often seen in rabbit colonies and may also be accompanied by pulmonary abscesses, pyothorax, and pleuritis; Pasteurella multocida is reported to be the commonest aetiological agent. Acute cases and epizootics will sometimes occur but pneumonia in rabbits is usually chronic and asymptomatic. (B614.8.w8, J13.32.w2)
  • Common as an extension of rhinitis. (J16.29.w1)

Genital tract infections 

Any part of the reproductive tract may be affected but most commonly reported infections are metritis/pyometra and orchitis/epididymitis or testicular abscesses. (B602.17.w17, B614.8.w8, J16.29.w1) 

  • Many infections are chronic and asymptomatic. (B614.8.w8)
  • Low conception rates may be seen in breeding animals. (B614.8.w8)
In does:
  • Vaginal discharge particularly in the acute infection. (B614.8.w8)
  • Massive uterine dilatation when pyometra has occurred in chronic infections. Sometimes rupture of the distended uterus can occur. (B614.8.w8)
  • Abortion (also anorexia and a purulent nasal discharge). (J495.28.w1)
In bucks:
  • Swelling of the testicles or the epididymis: may occur in the acute phase of orchitis or epididymitis respectively; in later stages of disease, abscessation may occur. (B614.8.w8)

Septicaemia
  • Sudden death. (J16.29.w1)
    • Usually seen following a stressful experience. (J16.29.w1)
    • Septicaemia may occur as a sequel other forms of pasteurellosis (particularly rhinitis and pneumonia) and is potentially fatal. Clinical signs of septicaemia are not usually seen because death occurs so rapidly. (B614.8.w8)

Other conditions
  • Rarer pasteurellosis infections include:

Incubation

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Lagomorphs
  • Experimentally, one to two weeks from nasal inoculation to development of rhinitis. (B602.17.w17)
  • Usually at least two weeks or longer. (J4.183.w6)

Mortality / Morbidity

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Lagomorphs
  • In endemically infected colonies, a large percentage of rabbits without any clinical signs may be carriers. (J4.183.w6, J16.29.w1)
  • It is common for infected rabbits to remain carriers for long periods of time and show no clinical signs. The occurrence of overt disease depends on the virulence of the organism and and the resistance of the host. (B614.8.w8)
    • In a survey, 50% of rabbits harbouring Pasteurella multocida in the nares did not show clinical signs of rhinitis. (J4.183.w6)
  • Epizootics of disease may occur in an endemically-infected colony. (J4.183.w6)
  • The commonest form of disease is rhinitis, followed by (reducing incidence) conjunctivitis, abscessation and ottis media; pneumonia, sepiticaemia and genital infections are less common. (J4.183.w6)
  • Prevalence of infection increases with age. (J4.183.w6)
  • Note: Spontaneous remission of disease may occur, particularly with rhinitis, but infection is usually persistent. (J4.183.w6)
  • In wild hares, outbreaks can cause up to 80% mortality. (J514.1.w1)
Rhinitis
  • There is a high prevalence of this condition in conventionally managed rabbit colonies; up to 60% of rabbits may be affected with the incidence peaking during the spring and autumn months. (B614.8.w8)
  • In a survey, 50% of rabbits harbouring Pasteurella multocida in the nares did not show clinical signs of rhinitis. (J4.183.w6)
Pneumonia
  • Pasteurella pneumonia common in rabbit colonies. (B614.8.w8)
  • Due to the lack of clinical signs, diagnosis of this condition is usually made at post mortem. In a study, 19.4% of 3,967 apparently healthy eight- to ten-week-old commercially-produced rabbits had macroscopic lesions of pneumonia. (J13.32.w2)
  • Acute to chronic fibrino-purulent pneumonia occurs In wild Lepus europaeus - Brown hare. (J514.1.w1)
Otitis media and interna
  • The prevalence of otitis media at post mortem in conventionally managed rabbit colonies may be up to 33%. However, the number of rabbits that actually exhibit torticollis is usually below 5%. (B614.8.w8)
Conjunctivitis
  • A study in one rabbitry in 1983 reported the incidence of conjunctivitis was second only to rhinitis. (B614.8.w8)
Abscesses
  • Well capsulated, containing thick white exudate. (B602.17.w17)
Septicaemia
  • This is a potentially fatal sequel to the other forms of pasteurellosis particularly rhinitis and pneumonia. (B614.8.w8)
  • Peracute septicaemia occurs In wild Lepus europaeus - Brown hare. (J514.1.w1)

Pathology

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Lagomorphs Gross and microscopic lesions of this disease are characteristic of acute or chronic suppurative inflammation. 
  • Gross: exudate may be seen and is usually purulent but may be mucoid or serous depending on the duration of infection. (B614.8.w8)
  • Microscopic: large numbers of neutrophils can be seen in the affected tissue. (B614.8.w8)
Rhinitis 
  • Gross: 
    • Upper respiratory mucosal oedema and hyperaemia. (B614.8.w8)
    • Mucosal erosions may sometimes be seen (B614.8.w8)
    • Mucopurulent exudate in the nasal cavity and sinuses. (B614.8.w8)
    • Eroded or atrophic nasal turbinates. (B614.8.w8)
  • Microscopic:
    • Vascular congestion, oedema and focal mucosal erosion. (B614.8.w8)
    • An inflammatory cell infiltrate (primarily neutrophils). (B614.8.w8)
    • Abnormally small and irregular turbinate bones with increased numbers of osteoblasts and osteoclasts. (B614.8.w8)
Pneumonia 
  • Gross: 
    • Dark red and consolidated areas of lung. (B614.8.w8)
      • Cranioventral lobes are most commonly affected. (B614.8.w8)
      • There is often a sharp line of demarcation separating the affected tissue from the adjacent normal tissue. (B614.8.w8)
    • Sometimes areas of atelectasis or abscesses. (B614.8.w8)
    • Fibrinous pleurisy. (J16.29.w1)
      • Fibrinopurulent exudate may be present both in the airways and on serosal surfaces. (B602.17.w17)
  • Microscopic:
    • Fibrinopurulent necrotising bronchopneumonia is the most typical acute lesion. (B614.8.w8)
      • Fibrinopurulent exudate in the airways and the alveoli; the primary inflammatory cells are neutrophils but macrophages and erythrocytes are also abundant. (B602.17.w17, B614.8.w8)
      • Peribronchial and perivascular lymphcytic cuffing. (B602.17.w17, B614.8.w8)
      • In chronic cases: abscesses surrounded by fibrous tissue are commonly seen (B614.8.w8)
      • Necrosis of the airway epithelium; this may extend into the adjacent lung parenchyma. (B614.8.w8)
    • There is often accompanying fibrinopurulent pleuritis, pericarditis, and pyothorax. (B614.8.w8)
    • In wild Lepus europaeus - Brown hares, fibrino-purulent pleuropneumonia, peritonitis. (J514.1.w1)
    • In wild and farmed Lepus europaeus - Brown hares in Belgium, mucopurulent or purulent tracheobronchitis, bronchopneumonia with abscess formation, purulent pneumonia or bronchopneumonia, and a 10 cm abscess, associated with Pasteurella sp. (J1.27.w13)
Otitis Media 
  • Gross: 
    • Early lesions include reddening of the tympanic membrane and serosanguinous fluid accumulating in the middle ear. (B614.8.w8)
    • As the disease progresses, thick creamy exudate fills the middle ear and becomes inspissated in chronic cases. (B614.8.w8)
  • Microscopic:
    • Suppurative inflammation of the tympanic bullae including massive accumulations of necrotic cell debris and neutrophils in the tympanic cavity. (B614.8.w8)
      • Infiltration of neutrophils and lymphocytes into the submucosal tissue. (B614.8.w8)
  • Suppurative meningoencephalitis may occasionally occur if the middle ear infection extends to the inner ear and the brain. (B614.8.w8)
Other Forms of Pasteurellosis 

Other forms of this disease are characterised by the accumulation of purulent exudate (the amount and consistency varies depending on the duration and severity of the infection) in the affected organ or tissue. (B614.8.w8)

  • Gross:
    • Abscesses that may become enlarged and encapsulated. (B614.8.w8)
    • Genital tract infections may develop to testicular abscessation or pyometra. (B614.8.w8)
    • In wild and farmed Lepus europaeus - Brown hares in Belgium, with respiratory lesions associated with Pasteurella sp., peritonitis, endocarditis, splenomegaly and hepatomegaly were also seen in various hares, with the same bacteria isolated from these lesions. (J1.27.w13)
  • Microscopic: 
    • Suppurative inflammation is the characteristic lesion. (B614.8.w8)
    • In organs that are lined by epithelium there may be cell debris and neutrophils in the lumen, epithelial ulceration, and inflammatory cell infiltration of the underlying tissue. (B614.8.w8)
    • In subcutaneous tissue, there may be a thick fibrous capsule surrounding the area of inflammation. (B614.8.w8)
Septicaemia
  • Lesions are seldom seen although there will usually be evidence of other forms of the disease. (B614.8.w8)
  • Gross and microscopic lesions: congestion of visceral organs may be seen and also focal serosal or subcutaneous haemorrhages. (B614.8.w8)
  • In wild Lepus europaeus - Brown hares, septicaemia with haemorrhages. (J514.1.w1)

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Human Health Considerations

This organism can cause disease in humans, e.g. following bites from infected carnivores. (B282.20.w20)

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Susceptibility / Transmission

General information on Susceptibility / Transmission

  • Pasteurella multocida is shed in saliva and faeces, and contaminates the environment. (B282.20.w20)
  • The major routes of infection are thought to be by droplet inhalation or ingestion. (B282.20.w20)
Lagomorphs
Susceptibility
  • Host susceptibility is influenced by both genetic and environmental factors. (B614.8.w8)
  • Note; there are also differences in virulence of different strains of Pasteurella multocida. (B601.7.w7)
  • Stressful conditions may reduce host immunity and precipitate the development of clinical signs; such stresses include experimentation, shipping, inclement weather, nutritional stress (inadequate nutrition), poor management and environment, changes in management and social changes. (B600.16.w16, B602.17.w17, B614.8.w8, J16.29.w1)
    • Normal physiological stresses such as pregnancy, parturition and lactation may also increase susceptibility. (B600.16.w16, J16.29.w1)
  • Loss of barriers:
    • Susceptibility is increased in rabbits with mucous membranes exposed to ammonia or to dilute acetic acid. (B602.17.w17)
    • Mucosal barriers to infection may be compromised by e.g. dental disease. (V.w65)
  • Strain and breed (genetic differences): different strains of rabbits may vary in their susceptibility, with some rabbits more genetically susceptible to development of disease than others. (B600.16.w16, J16.29.w1)
    • "the incidence of rhinitis and the mortality rate from pasteurellosis were three times higher for the Chinchilla breed than the Blue Beveren breed". (B614.8.w8)
  • Hydrocortisone treatment, concurrent disease or immunodeficiency will increase the susceptibility of rabbits to pasteurellosis. (B602.17.w17, B614.8.w8)
  • Sex: infections of the reproductive tract may occur in either sex. (B614.8.w8)
  • Age: infections with this organism can occur at a very young age as organisms can be transmitted from infected dams to their offspring during birth or lactation. It is thought that maternally acquired antibody helps to prevent many rabbits becoming colonised for the first several weeks of their life but then the prevalence of infection rapidly increases with age. One study showed that just after weaning, over 75% of rabbits that were nursing infected dams were positive by pharyngeal culture. However, another study showed that nasal cultures that were performed at the same age were less likely to be positive suggesting the pharynx is the earliest colonisation site with the spread to nasal passages occurring later. (B614.8.w8)
    • The proportion of rabbits that are infected with Pasteurella multocida is reported to increase as the rabbits mature; "up to 90% of adult rabbits from enzootically infected colonies may harbor the organism in the nasal passages...Additional animals may be free of P. multocida in the nasal passages, yet still harbor the organism in the pharynx". (B614.8.w8)
    • Infection is rare in pre-weaning age rabbits. (J4.183.w6)
    • Many infected rabbits will develop clinical pasteurellosis but the majority will remain asymptomatic carriers. (B614.8.w8)
  • Immunity: The protective effects of antibody seem to be limited to pneumonia and the other severe manifestations of this disease. Apparently neither actively nor passively acquired antibody will protect against the development of the carrier state or rhinitis; Pasteurella multocida has been reported to persist in the presence of significant serum IgG and secretory IgA levels. It is thought that this organism has managed to develop mechanisms to circumvent the host's antibody response, at least at the level of the mucosa. (B614.8.w8)
    • Low infection rates in pre-weaning rabbits may be due to passively transmitted antibodies. (J4.183.w6)
Transmission
  • Aerosol, direct contact and transmission via fomites all occur, as well as venereal transmission. Generally infection occurs through the nares or via wounds. (B600.16.w16, B602.17.w17)
    • Direct contact (nose-to-nose) and aerosol are common methods of transmission. (J16.29.w1)
    • Venereal transmission and transmission via fomites are possible but uncommon. (J16.29.w1)
    • Spread via contaminated water may be relatively common. (J16.29.w1)
    • Shedding of the organism and contact transmission may occur more from rabbits with acute disease than from those with chronic infection. (J495.37.w3)
  • Oral or respiratory route:
    • Pasteurella multocida is most easily passed from animals with acute infections. 
    • Direct contact between uninfected and infected animals is the quickest means of spread and results in transmission in a minimum of eight days. 
      • Animals with acute infection are more likely to transmit the disease than are those with chronic infection. (B602.17.w17)
      • Females with genital infection sometimes transmit the organism to their kits at birth. (B602.17.w17)
    • Aerosol transmission is much slower, taking up to twelve weeks when infected and uninfected animals are kept in separate cages but in the same room.
    • Fomites: long-term studies have shown that housing non-infected and infected rabbits in rabbits in separate rooms may still result in transmission of Pasteurella multocida within three to six months. It is not clear what mediates the spread of infection under these conditions, but fomites are likely to be involved. Rabbits with rhinitis can often contaminate the watering devices with this organism, and it is likely that other objects act as fomites as well.
  • Venereal: 
    • Genital tract infections were reported in does that were bred to a buck that had a testicular abscess.
    • Does frequently carry Pasteurella multocida in their vaginas thus acting as a potential infection source for other rabbits during mating and parturition - rabbit kits born naturally (per vagina) are therefore inoculated with this organism during delivery.
    • Note: Pasteurella multocida-free rabbits can be produced by delivering kits by caesarean section. (J16.29.w1)
  • Specifically for the development of:
    • Conjunctivitis
      • It is likely that conjunctivitis occurs as an extension of infection from the nose via the nasolacrimal duct. (B614.8.w8)
    • Abscessation
      • Bacteria gain access to the site by one of the following routes:
        • Direct extension
        • Haematogenous spread
        • Wound contamination
    • Genital tract infections
      • Infections are often transmitted venereally, however, haematogenous spread from other sites can also occur. (B614.8.w8, B602.17.w17)

(B600.16.w16, B602.17.w17, B614.8.w8, J16.29.w1, J495.37.w3, V.w65)

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Disease has been reported in either the wild or in captivity in:

Further information on Host species has only been incorporated for species groups for which a full Wildpro "Health and Management" module has been completed (i.e. for which a comprehensive literature review has been undertaken). Host species with further information available are listed below:

Host Species List

(List does not contain all other species groups affected by this disease)

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Disease has been specifically reported in Free-ranging populations of:

  • Lepus europaeus - Brown hare in Switzerland. (B282.20.w20)
  • In wild and farmed Lepus europaeus - Brown hares in Belgium, bacteria similar to organisms which had previously been identified as Pasteurella haemolytica. Isolated from purulent purulent conjunctivitis, respiratory and other internal lesions. (J1.27.w13)

Further information on Host species has only been incorporated for species groups for which a full Wildpro "Health and Management" module has been completed (i.e. for which a comprehensive literature review has been undertaken). Host species with further information available are listed below:

Host Species List

(List does not contain all other species groups affected by this disease)

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Environment/Geography

General Information on Environmental Factors/Events and Seasonality

  • The survival length of Pasteurella multocida on inanimate objects is unknown. (B614.8.w8)
  • Temperature fluctuations: daily temperature fluctuations between 55 F and 90 F has been reported to result in a significant rise in mortality and incidence of rhinitis. (B614.8.w8)
  • Ammonia in the ambient air (50 ppm) increases the susceptibility to pasteurellosis. (B614.8.w8)
  • Rhinitis: the incidence of this condition has been reported to peak during the spring and autumn months. (B614.8.w8)
  • Mainly winter and early spring in wild hares. (J514.1.w1)

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Regions / Countries where the Infectious Agent or Disease has been recorded

  • Found in many regions. (J16.29.w1)

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Regions / Countries where the Infectious Agent or Disease has been recorded in Free-ranging populations

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General Investigation / Diagnosis

General Information on Investigation / Diagnosis

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Lagomorphs Clinical signs are suggestive but not sufficient for diagnosis. (B601.7.w7)
  • Rhinitis: clinical signs; rales and rattles on auscultation of the nares and trachea (due to the presence of URT exudate). (B602.17.w17)
  • Pneumonia:
    • Lower respiratory tract disease should be suspected in rabbits with anorexia, weight loss, depression and rapid tiring. (B602.17.w17)
    • Auscultation of the thorax may reveal areas of absent lung sounds (consolidated lung or abscessation). (B602.17.w17)
    • Radiography may show the extent of disease. (B602.17.w17)
    • Due to the lack of clinical signs, diagnosis is usually made at post mortem examination. (B614.8.w8)
  • Abscessation:
    • If the abscess is subcutaneous then diagnosis can be made by aspiration of the swelling which will reveal a thick tan to creamy white exudate. (B614.8.w8)
    • Radiography may reveal internal abscesses. (B602.17.w17)
    • Diagnosis of internal abscesses are usually made at necropsy. (B614.8.w8)
  • Cellulitis: culture. (B602.17.w17)
  • Septicaemia: diagnosis is made by recovery of Pasteurella multocida from the parenchymal organs or blood. (B614.8.w8)
Isolation of the organism 
  • Pasteurellosis is diagnosed on the basis of clinical signs and the isolation of Pasteurella multocida from infected tissue. (B602.17.w17, B614.8.w8)
    • Note: for control of pasteurellosis in a colony it is necessary to also detect the subclinically infected animals. This can often be carried out by nasal culture: insert a calcium alginate urethral swab 1 cm into both nares and then plate on plain blood agar with clindamycin (2 g/mL) to inihibit the growth of most of the other rabbit nasopharyngeal flora. There are a few strains of Pasteurella multocida that are inhibited by clindamycin so it is also worthwhile plating a sample on just plain blood agar. Alternatively, nasopharyngeal culture may be performed instead: pass the swab four to five centimetres through the nares. This method may detect infected rabbits that are negative on nasal culture because the colonisation of the pharynx sometimes occurs before nasal cavity colonisation. (B614.8.w8)
      • Advantages of nasal culture: cheap and easy to perform. (B614.8.w8)
      • Disadvantages: culture from the nares may not detect scant Pasteurella organisms or organisms located in other parts of the body. Studies that have evaluated the reliability of nasal cultures suggest that around 30% of infected rabbits may not be detected on the basis of a single culture. Ideally three sequential cultures should be performed before an animal is accepted as Pasteurella-free. (B614.8.w8)
        • In an individual with clinical disease, it must be remembered that isolation of Pasteurella multocida does not necessarily mean this organism is responsible for the clinical signs. (V.w65)
Serodiagnosis
  • ELISA and dot-blot assays can detect antibody to Pasteurella multocida in infected rabbits which have tested negative on nasal culture. (B614.8.w8) See: Clinical Pathology of Lagomorphs
    • False negatives can occur; repeated tests performed several weeks apart are needed to ensure Pasteurella-free status. (B614.8.w8)
    • Seroconversion is usually detectable two to four weeks after infection. (B614.8.w8)
    • False positives can occur when juvenile animals have passively acquired antibody to this organism; serological tests may be unreliable in rabbits under two months of age. (B614.8.w8)
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Similar Diseases (Differential Diagnosis)

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Lagomorphs For uterine enlargement:

For abscesses see

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Treatment and Control

Specific Medical Treatment

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Lagomorphs
  • Treatment of this disease is difficult because although clinical signs may subside, the organism is apparently rarely eliminated from the host and reoccurrence of disease is common, even following prolonged antibiotic treatment. (B614.8.w8, J16.29.w1)
  • The clinical forms of this disease that are most likely to respond to treatment are rhinitis, conjunctivitis, and subcutaneous abscesses. (B614.8.w8)
  • Systemic antibiotics should be given for at least 7-14 days and in chronic infection longer courses may be needed. (B601.7.w7)
  • Rhinitis: systemic antibiotics alone can be used to treat this condition. (B614.8.w8)
  • Conjunctivitis: antibiotic ophthalmic ointment should be used as well as systemic antibiotics. (B614.8.w8)
  • Abscesses: drain, flush and administer antibiotics. (B614.8.w8)
  • Other forms of pasteurellosis: often response is poor to treatment probably because the disease is often far advanced by the time that a diagnosis is made. (B614.8.w8)
  • Note: culture and sensitivity testing is important for appropriate treatment. (B601.7.w7, B602.17.w17)
Choice of antibiotic
  • Pasteurella multocida is generally sensitive to a wide variety of antibiotics in vitro, but treatment is rarely effective. (J16.29.w1)
  • Pasteurella multocida isolates are usually sensitive to chloramphenicol, enrofloxacin, erythromycin, gentamicin, oxytetracycline, penicillin G and . (B601.7.w7, B602.17.w17)
  • Resistance to clindamycin and lincomycin is common. (B602.17.w17)
  • There is high resistance to trimethoprim/sulphonamide. (V.w127)
  • Nearly all isolates of Pasteurella multocida are sensitive to Penicillin G. However, it is difficult to maintain therapeutic blood levels of this drug and this may partially explain why treatment of this disease is often unsuccessful. (B614.8.w8)
    • NOTE: Fatal antibiotic-associated enterotoxaemia can occur, sometimes even with a single dose of penicillin given subcutaneously. (V.w127)
    • Procaine penicillin must be administered EVERY EIGHT HOURS to maintain adequate levels in blood and nasal secretions. (B614.8.w8)
    • Combined preparations of procaine and benzathine penicillin: these can be administered just once a day. (B614.8.w8)
    • Experimentally, treatment with penicillin G (60,000 units/kg intramuscularly once daily for 10 days or by intranasal spray) resulted in significant remission of clinical signs during treatment, but without a significant difference in prevalence of rhinitis compared with untreated rabbits in the period following treatment, and without any elimination of infection. (J495.31.w2)
  • Gentamicin must be used with care due to potential nephrotoxicity. (B601.7.w7)
  • Most antibiotics offer few advantages over penicillin, e.g. one study that was reported in 1991, showed that penicillin was preferable to gentamicin for treating rhinitis. (B614.8.w8)
  • Enrofloxacin may be more effective than penicillin in some cases. 
    • A study found a high rate of response in rabbits with respiratory signs due to Pasteurella multocida infection when this drug was administered either by injection or orally. With parenteral enrofloxacin, 5 mg/kg every 12 hours for 14 days, 87% became culture-negative within three days. With oral treatment in drinking water (200 mg/litre of drinking water for 14 days), clinical signs were eliminated and rabbits became culture negative within 3 - 7 days, but the organism could still be recovered from several sites in three of six rabbits. (B614.8.w8, J495.41.w2)
    • This drug was also reported to be effective in an experimental model of the septicaemic form of pasteurellosis. (B614.8.w8)
    • Note: while enrofloxacin may be clinically effective, a study using 5 mg/kg subcutaneously every 12 hours for 10 days found that it was not effective in eliminating the organism from either naturally or experimentally infected rabbits. It was thought that this was due to colonisation of tissues in which the drug did not reach effective concentrations. (J83.29.w1)
    • Dosing two or three times a day is necessary for this drug depending on the administration route. (B614.8.w8)
Precautions
  • Whatever the antibiotic used for treatment of this condition, therapy should be discontinued if anorexia, diarrhoea, or reduced faecal production occurs because antibiotic therapy can lead to gastrointestinal disturbances and fatal enterocolitis. (B614.8.w8)
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General Nursing and Surgical Techniques

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Lagomorphs --
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Preventative Measures

Vaccination --
Lagomorphs No commercially available vaccines are presently available to prevent rabbit pasteurellosis. (B601.7.w7, B614.8.w8)
  • Vaccines have been trialled; some of these these provided protection against clinical disease, but none prevented colonisation of the upper respiratory tract. (B601.7.w7, B602.17.w17, B614.8.w8, J10.36.w1)
Prophylactic Treatment

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Lagomorphs
  • Antimicrobials including furazolidone, sulfaquinoxaline, sulfamethazine, and chlortetracycline, have been used in the drinking water or feed of pregnant or lactating does to prevent pasteurellosis. However, although this may reduce the incidence of disease in does and their offspring, the antimicrobials are probably not able to eliminate the infection. (B614.8.w8)
  • Diet: In one study in 1927, dietary supplementation with fresh vegetables was reported to result in fewer asymptomatic carriers of Pasteurella multocida; however, there was apparently no reduction in rhinitis or mortality in the group that received the dietary supplementation. (B614.8.w8)
  • Hyperimmune rabbit serum that has been prepared against extracts of Pasteurella multocida reportedly protects rabbits against intranasal challenge. (B614.8.w8)
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Environmental and Population Control Measures

General Environment Changes, Cleaning and Disinfection --

Lagomorphs

  • Good husbandry is important. (B601.7.w7)
  • Provide stable environmental conditions. (J495.31.w2)
    • Avoid large temperature fluctuations. Preferably maintain at 18 C +/- 2 C. (J16.29.w1)
    • Maintain relative humidity at 50 - 70%. (J16.29.w1)
  • Ensure good ventilation with adequate air changes. (B601.7.w7, J16.29.w1)
  • Ensure good general hygiene with appropriate disinfection and sterilisation. (B601.7.w7, J16.29.w1)
    • Sodium hypochlorite is effective. (B601.7.w7)
    • Benzalkonium chloride is effective. (B601.7.w7)
  • Avoid/minimise stresses. (B601.7.w7, J16.29.w1)
Population Control Measures --
Lagomorphs
  • In a colony situation, cullling of affected individuals may be effective during an epizootic. (J4.183.w6)
Isolation, Quarantine and Screening --
Lagomorphs
  • Maintaining rabbits at least six feet apart (sneeze distance) can help control transmission. (J16.29.w1)
  • Quarantine new rabbits before introducing them to other rabbits. (B602.17.w17)
Barrier housing is used to establish and maintain Pasteurella-free rabbit colonies. (B602.17.w17, B614.8.w8)

To obtain a Pasteurella-free rabbit colony:

  • Choose only Pasteurella-free animals, based on culture and serological testing. (B602.17.w17)
    • Cull animals that have positive nasal cultures or clinical signs of pasteurellosis. Some rabbits that are harbouring this organism can have consistently negative cultures so serological testing for antibodies to Pasteurella multocida can be used in addition to nasal culture. (B614.8.w8)
    • House Pasteurella-free rabbits away from other rabbits and prevent people or materials moving from infected to uninfected rabbits. (B602.17.w17)
  • Early weaning helps in the selection of Pasteurella-free stock as preweanling rabbits are reported to have a relatively low infection rate possibly due to the effect of passively acquired maternal antibodies. (B614.8.w8, J16.29.w1)
    • Note: early weaning and movement may stress young rabbits and increase the incidence of enteric diseases. (J16.29.w1)
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