Respiratory tract infections are not very common in hamsters kept as companion animals. The hamster is, however, susceptible to infections by viruses causing the common cold and if infected manifests the clinical signs of sneezing, nasal discharge and, sometimes, pneumonia. The animal usually recovers spontaneously within a week. If a secondary bacterial infection occurs, the signs can worsen, with the development of an abundant nasal discharge, dyspnoea, loss of appetite and dejection. Given their potential hazard, antibiotics should only be used in these cases.
Another form of viral pneumonia is that caused by the Sendai virus, which is a type 1 Paramyxovirus. Infections by this virus are usually asymptomatic in adults, but can be fatal in young hamsters. It is not yet known whether this virus can cause a zoonosis.
Primary bacterial pneumonia is usually caused by Pasteurella pneumotropica, Streptococcus spp, or Yersinia pseudotuberculosis. Such infections are normally acute and manifested by dyspnoea, discharges from the eyes and nose and loss of appetite. Abscesses of internal organs may develop; the theoretical treatment for these would be surgical removal.
The management of respiratory tract infections is supportive therapy, keeping the animal warm and administering fluids and antibiotics parenterally. Sick animals should be isolated immediately from healthy ones.