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Pneumonia does not necessarily cause bilateral nasal discharge; pus and mucus, that is coughed or moved upward by mucociliary action from the lung is mostly swallowed.
The most likely differential diagnoses in shipboard cattle with nasal discharge include: infectious bovine rhinotracheitis IBR
dusty feed causing irritation of nasal mucosa other respiratory pathogens - a range of pathogens, mainly viral, with upper respiratory
tract infection as part of clinical complex – bovine adenovirus, respiratory syncitial virus,
bovine virus diarrhoea virus, Mycoplasma bovis and Histophilus somni pneumonia
reduced grooming of the nose with the tongue occurs with sick cattle oesophageal or gastrointestinal obstruction may cause reflux to appear at the nares
2.1.1 Infectious bovine rhinotracheitis IBR
Infectious bovine rhinotracheitis is an upper respiratory tract viral infection manifesting as fever, coughing, nasal and lachrymal discharges and salivation. In uncomplicated infections,
lesions are confined to the upper respiratory tract and trachea and recovery occurs within a week. Infectious bovine rhinotracheitis infections can spread through the crowded population
of cattle on a ship in a matter of days. Secondary bacterial pneumonia may follow in cattle that are severely affected or have additional stressors such as simultaneous hot and humid
conditions. Treat severe cases with antibiotics to prevent development of secondary bacterial pneumonias. Vaccines are available to assist prevention.
2.1.2 Dusty feed
Dusty feed will cause nasal discharge and coughing but animals will be bright and alert, appetent and afebrile. Examination of the feed will assist diagnosis. The problem may be
related to a batch of feed which when changed, resolves the problem. No treatment or action is required unless signs become severe, in which case a respiratory pathogen should be
suspected. Dampening the feed may help but may result in mouldiness and palatability problems.
2.1.3 Other respiratory pathogens
There are a range of pathogens, mainly viral, that can cause upper respiratory tract infections and nasal discharge. They include bovine adenovirus, bovine respiratory syncitial
virus, bovine virus diarrhoea virus BVDV, bovine herpesvirus-1, bovine reovirus, enterovirus, coronavirus and rhinovirus. These viruses can serve as initiators of bacterial
pneumonia in stressed cattle. Two bacterial pathogens, Mycoplasma bovis and Histophilus somni may cause nasal discharge, but this would be as part of a more general disease.
Vaccines are not available for prevention of most of these respiratory diseases. BVDV is discussed further under Diarrhoea, Mycoplasma bovis under Lameness and Histophilus
somni under Nervous signs as these three pathogens target other organs more prominently.
2.1.4 Pneumonia
Cattle with viral or bacterial pneumonia will have fever, cough, and varying respiratory impairment. Nasal discharge may be present in some animals. Most tracheobronchial
exudate that reaches the pharynx will be swallowed. Pneumonia is discussed further under Respiratory distress.
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2.1.5 Reduced grooming of the nose with the tongue
