Pneumonia

Introduction

Pneumonia in rabbits results when a pathogen - viral, bacterial, fungal or parasitic, invades the lungs. Pneumonia can even be deadly to your rabbit. It is most often caused by the common bacterias Pasteurella moltocida and sometimes Bordetella bronchiseptica. It can be difficult to treat effectively, can progress very quickly and often results in the death of the rabbit.

Snuffles and Pneumonia

Pasteurella causes snuffles - an infection in the upper respiratory tract which results in a runny nose, weepy eyes, sneezing, salivation and sometimes ear infections. However this mild form can progress and then bronchopneumonia develops. Treatment for low grade/chronic Pasteurella with appropriate antibiotics can be effective but the pathogen is not usually eliminated completely and can flair up again. It is best to determine the most effective antibiotic using a culture and sensitivity test. The antibiotic treatment may be required for quite a long time (2 to 3 months). If there are any signs of conjunctivitis it is often useful to flush the tear ducts of the rabbit with saline which is usually done under sedation. In more serious cases where a rabbit develops pneumonia, the symptoms - in addition to those for Snuffles, may include anorexia with subsequent weight loss, lethargy and fever.

Diagnosis

In addition to a thorough examination, tests to help diagnose Pneumonia may include X-Rays, blood and urine tests and cultured swabs of any discharges.

Treatment

Treatment should be aimed at giving your rabbit relief from their symptoms and may include administering fluids and giving oxygen, using a nebuliser or humidifier to relieve blocked airways may help. Medication options will depend upon the causative agent that is discovered to be at work. Drug therapy - usually antibiotics, and supportive treatment such as subcutaneous or IV fluids, will be given however it is unfortunately often ineffective in such cases because the disease may be well advanced before treatment commences.

Contributing Factors

Practicing good hygiene and ensuring your rabbit/s are not stressed by environmental factors such as poor ventilation, temperature extremes (such as bringing an outside rabbit inside into a heated room from cold temperatures outside) or overcrowding is important. Keep your rabbit's hutch or living space really clean because high levels of ammonia may increase risk if your rabbit already have a respiratory problem.

Note - if your rabbit has ever had signs of a respiratory disease it may have a higher chance of developing problems under anaesthetic so your vet should be made aware of this if such treatment is ever necessary.

The following is an extract from Vetstream:

Introduction

• Pneumonia is inflammation of the lung parenchyma.

• Respiratory disease is a major cause of both morbidity and mortality in pet rabbits. It is often presented in advance stages of respiratory compromise.

• Pasteurellosis is historically quoted as the primary respiratory disease of rabbits.

• As more pet rabbits make the transition from the garden hutch to the heated home so changes in temperature, ventilation, humidity and environmental pollutants may alter the epidemiology of respiratory diseases.

• Infectious bronchitis and pneumonia has been well documented since the 1920s.

• May be a secondary or concurrent condition, with underlying disease or immunodeficiency predisposing animals to pneumonia.

• Several bacterial and viral pathogens can cause pneumonia.

• Non-infectious bronchitis and pneumonia may become more important in the home environment and may be caused by:

  • Allergies.

  • Respiratory insults (smoke, aerosols).

• Signs: lethargy and malaise, fever, anorexia and weight loss, dyspnea and tachypnea, oculonasal discharge, pale to congested mucous membranes, sneezing and coughing.

• Treatment: correction of underlying factors including poor nutrition and poor environment, antimicrobials and surgical resection if indicated.

• Diagnosis: based upon history, clinical signs, haematology, radiography, endoscopy, ultrasonography, and lung wash or lung biopsy.

• Prognosis: depends on disease and severity but often guarded given the advanced presentation of most cases.

Presentation

• Presentation depends upon:

  • Nature of the pneumonia, infectious or non-infectious.

  • Virulence of organism.

  • Age and immunocompetence of the rabbit.

• In most cases rabbits present with one or more of the following:

  • Lethargy, malaise and/or unkempt appearance.

  • Fever.

  • Anorexia and weight loss.

  • Dyspnea and tachypnea.

  • Oculonasal discharge.

  • Pale to congested mucous membranes or cyanosis.

  • Sneezing and coughing.

• It is important to realise that many rabbits will mask obvious symptoms of pneumonia until the disease is very advanced.

• Any rabbit showing even mild lower respiratory tract signs should be considered seriously ill until proven otherwise.

• Pasteurellosis may cause a myriad of presentations of which respiratory signs may be only one manifestation.

Acute

• Rabbits with acute or peracute pneumonia may simply present as sudden deaths.

• Signs, if noticed, may include:

  • Severe dyspnea Dyspnea (difficult or laboured breathing) with increased respiratory noise.

  • Lateral or ventral recumbency.

  • Open mouth breathing with extended neck.

  • Cyanotic mucous membranes.

  • Haemoptesis (coughing blood).

  • Anorexia .

  • Fever or shock hypothermia..

Incidence

• The authors are unaware of any studies that have determined the incidence of respiratory disease in pet rabbits.

• Incidence of pneumonia increases with the following:

  • Age.

  • Underlying concurrent disease.

  • Stress.

  • Overcrowding.

  • Poor husbandry.

  • Immunodeficient animals.

Geographic

• The incidence and prevalence of disease is increased where temperature fluctuations occur as is more likely in temperate regions. Rabbits exposed to excessively high temperatures in tropical environments may also suffer respiratory embarrassment.

• Temperature variation will be more significant for hutch-housed rabbits than house rabbits. However, house rabbits may be kept too warm in centrally heated homes.

• Distribution of pathogens:

  • Most bacterial pathogens appear to have a worldwide distribution.

  • Herpesvirus has been reported in Europe and Canada.

  • Coronavirus (pleural effusion disease): worldwide distribution unknown, incidence low, first reported in Scandinavia, appears restricted to labs.

  • Chlamydia: appears to be an experimentally induced infection (human model for Chlamydial pneumonia) but natural infection appears rare.

• Housing and environment may affect disease:

  • Outside hutch and run provide better ventilation but greater temperature fluctuations.

  • House rabbits have a more stable environment but it may be too warm and too dry.

Morbidity

• Incidence of infection varies:

  • With breed, greater in Flemish Giant than in New Zealand White.

  • With season, greater in spring and autumn.

  • With temperature, greater with temperature fluctuations and excessively high temperatures.

• Bordetella bronchiseptica may be co-pathogen or predisposing factor to Pasteurella multocida .

• Bordetella appears to be more common in neonatal/juvenile rabbits while Pasteurella is more common in adults.

• Up to 60% of rabbits may carry subclinical Pasteurella and of that infected population:

  • 40% may develop clinical signs of respiratory disease.

  • 10% may spontaneously recover.

  • 5% may develop pneumonia.

  • 5% may develop bacteremia.

• Pasteurella-free status is possible only in SPE laboratory populations.

• The numbers of rabbits experiencing clinical pneumonia is quite low but subclinical disease, often as an extension of upper respiratory disease, is very common.

Mortality

• Mortality can be high particularly when the disease is:

  • Caused by a virulent strain of Pasteurella multocida , Staphylococcus aureus or Pseudomonas Pseudomonads

  • Acute or peracute in nature.

  • Complicated by bacteremia, septicemia, pericarditis, peritonitis, poor environment.

Cost

• Costs will depend on the level of investigation and the duration of therapy.

• Standard investigation, ie consultation, haematology, anaesthesia, radiographs, endoscopy, lung wash cytology or lung biopsy for histopathology and microbiology, prolonged antibiotic therapy.

• Thoracotomy and abscess removal will necessitate extensive surgery and critical care nursing.

Special risks

• Blood can be collected from the conscious animal, but radiographs, lung wash or biopsy require sedation or general anaesthesia.

• Respiratory disease does add a significant risk to anaesthesia, which must be weighed against the benefits of making a diagnosis. However, short anaesthetic restraint greatly facilitates the collection of diagnostic samples and reduces stress of sample collection, thereby ultimately providing a definitive diagnosis and prognosis.

Source material based from: Vetlexicon Contributor(s): Narelle Walter, Susan Brown, Stephen Hernandez-Divers, Maud Lafortune, Anna Meredith, Vetstream Ltd

Further reading:
Pneumonia in Rabbits - MediRabbit

Also see Snuffles/Pasteurella file