Assessment of kidney pathological lesions and associated economic losses due to organ condemnation in cattle at Douala municipal abattoir, Littoral Region, Cameroon

Introduction

Kidney condemnation refers to the rejection of bovine kidneys during post-mortem inspection at abattoirs when pathological lesions render the organ unfit for human consumption according to established meat inspection standards and regulations. Unlike liver and lung condemnation, which have been extensively investigated across numerous abattoirbased surveys in sub-Saharan Africa, renal condemnation has received comparatively limited research attention despite its contribution to overall organ losses and its potential significance as an indicator of systemic diseases affecting the urinary tract and vascular system. The kidney serves critical physiological functions including filtration of metabolic waste products, regulation of electrolyte balance, maintenance of acid-base homeostasis, and endocrine functions including erythropoietin and renin production. Pathological conditions affecting the kidney may arise from infectious agents including bacteria, parasites, and viruses, as well as non-infectious causes such as toxin exposure, metabolic disorders, congenital anomalies, and degenerative changes associated with aging. The gross morphological manifestations of these conditions during post-mortem inspection include nephritis characterized by enlarged, swollen kidneys with inflammatory exudates, hydronephrosis presenting as fluid-filled renal pelvis with cortical atrophy, renal cysts appearing as fluid-filled cavities within the parenchyma, infarction showing wedge-shaped areas of necrosis, and calculi presenting as mineralized concretions within the renal pelvis or ureters. Cameroon possesses a diverse livestock sector with an estimated cattle population of approximately 6.4 million, predominantly managed under extensive and semi-intensive production systems. The Douala municipal abattoir in the Littoral Region serves as the principal meat processing facility for the economic capital of Cameroon, receiving cattle from major production zones in the Adamawa, North, and Far North regions. The long-distance transport of cattle from northern production areas to the coastal city of Douala exposes animals to various stresses that may predispose them to renal pathology, including dehydration, heat stress, and physical trauma during transit. This research was designed to determine the prevalence and causes of kidney condemnation, evaluate the association between renal condemnation and host-related risk factors, compare the physical characteristics of condemned versus normal kidneys, and estimate the direct economic losses attributable to kidney condemnation at Douala municipal abattoir.

Materials and Methods

Materials

The research was conducted at Douala municipal abattoir in Douala, Littoral Region, Cameroon, located at an elevation of approximately 13 meters above sea level with a tropical monsoon climate characterized by an average annual rainfall of 3,600 millimeters and temperatures ranging from 24 °C to 32 °C. The abattoir processes an average of 50 to 75 cattle daily. Ethical clearance was obtained from the Research Ethics Committee of the National Institute of Veterinary Sciences (Reference: NIVS/REC/2022-019), and authorization was granted by the Littoral Regional Delegation of the Ministry of Livestock, Fisheries, and Animal Industries.

Methods

A cross-sectional research was conducted from August 2022 to July 2023. A total of 712 cattle were examined through systematic sampling. Ante-mortem data included sex, age, body condition score, breed, and origin. Post-mortem kidney examination involved visual inspection, palpation, decapsulation, and systematic incision through the cortex, medulla, and pelvis of both kidneys. Pathological lesions were classified according to their gross morphological features. Both kidneys from 50 condemned and 50 normal animals were weighed using a calibrated digital balance to compare physical characteristics. Tissue samples from representative lesions were fixed in 10% buffered formalin for histopathological confirmation. Economic loss was calculated using organ weight and market price data. Statistical analysis used SPSS version 28.0 with chi-square tests, t-tests, and logistic regression.

Results

Discussion

This research documented an overall kidney condemnation prevalence of 18.6% at Douala municipal abattoir, establishing renal pathology as a noteworthy contributor to organ condemnation losses in cattle processed at this Central African facility. Nephritis, hydronephrosis, and renal cysts were identified as the three leading causes of kidney rejection, collectively accounting for 53.9% of all renal condemnations. The kidney condemnation prevalence recorded in this research is comparable to the 16.8% reported by Ngwa and Tanya at Bamenda abattoir in the Northwest Region of Cameroon [3] and the 20.2% documented by Njong and colleagues at Ngaoundere abattoir in the Adamawa Region [7] . These consistent findings across multiple Cameroonian abattoirs suggest that renal pathology affects a substantial proportion of slaughtered cattle nationally and warrants greater attention in veterinary surveillance programs.

In contrast to these comparable findings, lower kidney condemnation rates of 8.4% and 11.2% have been reported at abattoirs in Chad and the Central African Republic respectively [9,12] . The higher prevalence at Cameroonian abattoirs may be related to the greater diversity of cattle breeds processed, longer transport distances involved, and possibly higher exposure to nephrotoxic plants in certain grazing areas. Conversely, higher rates of 24.6% have been reported in certain Ethiopian abattoirs [4] , potentially reflecting differences in the prevalence of kidney-tropic parasites and bacterial infections across ecological zones. The significantly higher weight of condemned kidneys compared to normal kidneys provides a quantitative measure of the pathological changes occurring in affected organs. The inflammatory processes associated with nephritis cause tissue edema, cellular infiltration, and vascular congestion that collectively increase organ weight.

Similarly, the fluid accumulation in hydronephrotic kidneys results in substantial weight increases. These weight differences could potentially serve as an objective screening parameter during meat inspection, supplementing the subjective visual and palpatory assessment currently employed.

The broader implications of these findings include the potential utility of abattoir-based kidney surveillance data for monitoring livestock health at the population level.

Trends in kidney condemnation rates and lesion types over time may reflect changes in water quality, environmental contamination, disease prevalence, and management practices within source livestock populations, providing valuable epidemiological intelligence that extends beyond the immediate food safety function of meat inspection.

Renal Pathology and Water Quality

The association between geographical origin and kidney condemnation rates observed in this research raises questions about the potential role of water quality and mineral content in predisposing cattle to renal pathology. Cattle originating from northern Cameroon, where access to clean water is often limited during the dry season, may be exposed to water sources with elevated concentrations of minerals, heavy metals, or microbial contaminants that predispose to nephrolithiasis, nephritis, and other renal conditions. Future investigations incorporating water quality analysis from source areas would help elucidate this potential relationship.

Comparative Organ Condemnation Analysis

When viewed in the context of overall organ condemnation at Douala municipal abattoir, kidney condemnation at 18.6% ranks as the third most common organ rejection after liver (38.4%) and lung (28.7%). Although kidney condemnation contributes a smaller proportion of total economic losses compared to hepatic condemnation, the cumulative financial impact of 12,540,000 FCFA annually is not negligible and justifies the inclusion of kidneyspecific surveillance in abattoir monitoring programs. The data generated by systematic kidney assessment can complement liver and lung condemnation data to provide a more comprehensive picture of livestock health status in source populations.

Conclusion

Acknowledgement

AcknowledgementsThe Littoral Regional Delegation of the Ministry of Livestock, Fisheries, and Animal Industries and the Douala municipal abattoir management are acknowledged for facilitating this research. JCTM designed the research and wrote the manuscript; MCEN conducted post-mortem examinations; PAFN performed histopathological analysis; CANF contributed to data collection and economic analysis. Funding was provided by the Ministry of Higher Education of Cameroon through Research Modernization.

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