Table 2 Strengths and limitations of slaughterhouse examination for assessing the respiratory health of pigs
From: Review on the methodology to assess respiratory tract lesions in pigs and their production impact
| Â | Strengths | Limitations, critical considerations |
|---|---|---|
Practical aspects | ||
 Practical arrangement with slaughterhouse | Rather easy | Sometimes access to slaughterhouse is not allowed No guarantee of precise time of slaughtering |
 Time needed for assessment | Short, often less than one hour | Speed of slaughter line might be too high to assess all pigs |
 Cost of evaluation | Inexpensive (visual assessment, palpation) | Payment might be required when removing lung plucks |
Assessment of lesions | ||
 Evaluation | Easy for experienced person | Subjective, training needed; presence of lesion (yes/no) less informative than extension of lesion |
 Subclinical infections | Detected in case lesions are present | Only for infections leading to gross lesions |
 Severity/extension of lesions | Possible | Needs more time than detection of presence (yes/no) of lesion |
 Detailed analysis | Possible when plucks are removed from slaughter line | Not possible at the slaughter line |
 Simultaneous assessment of different lesions | Possible e.g. pneumonia, pleurisy | Severe pleurisy may mask evaluation of other lung lesions |
Examined animals | ||
 Representative for farm situation | Easy in case all pigs of a barn are slaughtered (all-out principle) | Difficult when pigs are not marketed at once; evaluation of best or worst pigs might provide biased results |
 Number of animals | Large number possible (minimum 30, preferably more) | Representative sample of slaughtered batch can be selected |
Interpretation of results | ||
 Type of data | Prevalence, as lesions are examined only once (snapshot) | No incidence data (lesions not monitored over time); lesions are dynamic and can heal over time |
 Relevance for diagnosis | Typical lesions may suggest infection (previous or active) | No etiologic diagnosis as lesions are not pathognomonic |
 Benchmarking | Possible, within a farm (time evolution, barn effects), against other farms or national average | Lesions should be examined in a standardized way |
 Assessment of intervention strategies | Possible e.g. vaccinations | Lesions should be examined in a standardized way; association between lesion and carcass characteristics at animal level is not always available |