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Other Names: ORT Infection

Ornithobacteriosis (ORT) is an acute, contagious bacterial disease caused by Ornithobacterium rhinotracheale, which has been isolated from commercial and backyard flocks of chickens worldwide. O. rhinotracheale is a Gram-negative, rod-shaped, highly contagious bacterium that has been isolated from a number of domestic and wild avian hosts.

Infection with O. rhinotracheale is primarily associated with the respiratory system, but can sometimes cause ear or joint infections. Concurrent infections with other pathogens also impact the severity and range of signs, duration of the disease, and mortality rate in outbreaks of flocks. Respiratory lesions associated with O. rhinotracheale are similar to many other bacteria, including E. coli, Pasteurella multocida, R. anatipestifer, Avibacterium paragallinarum, and Chlamydophyla psittaci.


O. rhinotracheale is transmitted to susceptible chickens via horizontal and vertical routes. Chickens can become infected through direct and indirect contact through fomites, feed and water, or aerosols. Since wild birds can be carriers of O. rhinotracheale, contamination of the flock's environment with feces from wild birds is a common source of introduction.


Since the clinical signs and postmortem lesions of O. rhinotracheale are similar to many other bacterial and viral infections, in order for your veterinarian to obtain a definitive diagnosis, they will need to send samples from certain organs to a diagnostic lab which offer O. rhinotracheale testing in order to isolate and identify the causative agent. This may be achieved through the following diagnostics:
  • Bacterial Isolation and Identification: The trachea or lungs are the best tissues to isolate O. rhinotracheale from. The infraorbital sinus and nasal cavity are also suitable for culture.
  • Antigen Detection: PCR testing of tracheal swabs may be useful for detecting O. rhinotracheale.
  • Serological tests: The presence of antibodies against O. rhinotracheale can be detected by ELISA, if taken within 1 to 4 weeks after the bird was first infected.


O. rhinotracheale is somewhat inconsistent in sensitivity to antibiotics, and varies depending on the source of the strain. However, there has been some success with chlortetracycline, amoxicillin, and tylosin.

Clinical Signs

Nasal discharge
Facial swelling
Wet eyes
Labored breathing
Misshaped or smaller eggs
Decreased egg production
Poor eggshell quality
Loss of appetite
Joint swelling
Muscle weakness


  • History
  • Clinical signs
  • Physical exam
  • Bacterial culture
  • PCR
  • Serology
  • Necropsy

Reported Cases

  • Case 1: Otitis and cranial osteomyelitis in a Partridges A flock of red-legged partridges developed neurological signs, consisting of abnormal head position, torticollis (wry neck), had difficulty standing (ataxia), and difficulty walking or flying. Pathological, microbiological and molecular genetic data supported an association with Ornithobacterium rhinotracheale (ORT) infection. Clinical signs persisted for several days and were accompanied by weight loss leading to death. Morbidity was approximately 20% and most birds died if untreated. Lesions were mainly characterized by a severe osteomyelitis of the cranial bones and purulent inflammation of the external, middle and inner ears. O. rhinotracheale was isolated from ear samples, skull and brain stem in pure culture. Genetic characterization by pulsed-field gel electrophoresis of the clinical isolates showed that the outbreak was caused by a single strain of ORT. Ref

  • Case 2: Airsacculitis due to Ornithobacterium rhinotracheale in a Pheasants Outbreaks of respiratory disease were investigated in reared pheasants aged approximately 18 to 32 weeks, released into the semi-wild on four shooting estates in southern England. The clinical signs in the affected birds included swelling of the face and eyes, loss of condition, gasping respirations and coughing. The gross pathology findings included sinusitis, airsacculitis, pleural oedema and lung lesions. The histopathological findings in the affected lungs were characterized by a granulomatous pneumonia. Ornithobacterium rhinotracheale (ORT) was isolated from respiratory tract tissues, and 16S rRNA gene sequencing on three isolates revealed two distinct genotypes, one previously associated with some electrophoretic type (ET) 1 strains and the other a novel genotype that clustered among sequences previously associated with ET 3, ET 4, ET 5 and ET 6 isolates. In each case, ORT was identified as part of a complex of other respiratory agents including avian paramyxovirus type 2, avian coronavirus, Mycoplasma gallisepticum, Mycoplasma synoviae and other Mycoplasma species, Escherichia coli, Pasteurella multocida, other Pasteurellaceae and Syngamus trachea, suggesting synergism with other agents. Exposure to other intercurrent factors, including adverse weather conditions and internal parasitism, may also have exacerbated the severity of disease. Ref

  • Case 3: Infectious coryza complicated by Ornithobacterium rhinotracheale in a Chickens The coinfection of Avibacterium paragallinarum and Ornithobacterium rhinotracheale in two outbreaks of infectious coryza from Peru was reported. The diagnosis was confirmed by bacteriologic isolation, PCR testing, and sequencing of the 16S rRNA gene. The susceptibility of the isolates to 12 antimicrobial agents was tested by a disk diffusion method. The isolates were susceptible to amoxicillin/clavulanic acid and florfenicol and were resistant to oxacillin and sulfamethoxazole/trimethoprim. The coinfection of Av. paragallinarum and O. rhinotracheale and the severity of clinical signs were evaluated by experimental infection of specific-pathogen-free chickens. The group inoculated with O. rhinotracheale alone presented minimal clinical signs in 3 of 10 chickens. However, the groups inoculated with both Av. paragallinarum and O. rhinotracheale induced the most-severe clinical signs compared with the group inoculated with Av. paragallinarum alone. Ref


Supportive careIsolate the bird from the flock and place in a safe, comfortable, warm location (your own chicken "intensive care unit") with easy access to water and food. Limit stress. Call your veterinarian.
AntibioticsBased on sensitivity results



  • Minimize exposure to wild birds
  • Prevent feed and water from contamination with wild bird feces.
  • Vaccination: An inactivated vaccine is available and found effective.
  • Provide good ventilation
  • Practice good sanitary management
  • Provide clean, dry litter routinely.
  • Good biosecurity

Scientific References

Risk Factors

  • Overcrowding
  • Poor sanitation
  • Exposure to wild birds or their feces contaminating the environment.