Pulmonary lesions at the slaughterhouse: how to evaluate them (2/2)

Lung lesion scoring systems are easy and non-invasive methods that provide information on prevalence and extension (but not incidence) in a relatively inexpensive (no extra material is needed) way. However, it is also a non-confirmatory (no etiologic diagnosis) and subjective (training is needed) estimation, that may be difficult to organize (especially when pigs are sent to slaughterhouse in several trucks or when unexpected changes on the arrival or slaughtering time happen) and, in consequence, becomes expensive and time-consuming for evaluators.

There is a plethora of CVPC lung lesion scoring systems, most of them based on a visual estimation of the lung tissue affected (in points or percentages) (Table 1). Other systems use a 3-dimensional approach by normalizing the percentage of the lung tissue affected by the relative weight or volume of each lobe. Regardless of the differences, a good correlation among the main CVPC scoring methods most frequently used at slaughterhouse was demonstrated. Some scoring systems use diagrams or pictures to help to record the lesions, allowing a retrospective and precise analysis but making them unpractical as the plucks travel extremely fast through the slaughter line.

Table 1. Main craneo-ventral pulmonary consolidation (CVPC) scoring systems (adapted from Maes et al., 2023).

Similarly, there are several scoring systems for pleuritis (Table 2).

Table 2. Pleuritis scoring systems to be used at slaughterhouse (adapted from Maes et al., 2023).

CTPA: System by the Centre Technique de Productions Animales
SPES: Slaughterhouse Pleurisy Evaluation System

• The system described by Madec and Kobisch (1982) score pleuritis lesion from 0 to 4, giving the highest score when partial or total ribcage is condemned due to lung adherences.
• Slaughterhouse Pleurisy Evaluation System (SPES) also scores the pleuritis lesions from 0 to 4 but considering their localization, extension and size (diameter).
• The Centre Technique des Productions Animales (CTPA) method only differentiates between fibrinous pleuritis among lung lobes from those pleuritis causing lung adherences to the ribcage.
• The Pointon system (Pointon et al.,1992) separates the interlobular pleuritis from the ones adhered to the ribcage also considering the presence of pneumonia.

The selection of the scoring system to be applied at the slaughterhouse should be determined depending on:

• slaughter line characteristics: speed, flowchart and accessibility
• permissibility of the slaughterhouse to collect samples (for more precise scoring or for diagnostic confirmation)
• type of lesions to be scored
• number of animals to be assessed
• personnel resources available to perform such scoring.

The use of voice recording to register the lesion score may be of great help to counteract the highspeed line allowing the manual palpation of the lungs. Artificial intelligence-based methods to automatically evaluate lung lesions may help to automatize and objectivize the process. However, these systems are still under development as they need to be trained and adapted to capture and analyze the image from a hanging and moving pluck of lungs.