Pathomorphological studies on staphylococcal pneumonia in a male golden jackal

Introduction

The golden jackal is a medium-sized predator and omnivore found in the southern parts of the Palearctic, South Asia and Northeastern Africa. Presently, the jackal population is restricted to a few clusters and divided into seven sub-areas based on criteria like connectivity and isolation. The decline in their population is mainly due to habitat loss resulting from changes in human agro-pastoral activities, leading to reduced day-cover availability and possibly a diminished food base (Moehlman and Hayssen, 2018; Negi, 2014) [6,7] . Jackals are highly vulnerable to diseases via spread by free-ranging as well as wild dogs. They can share the same environment and scavenging behaviors with the overlapping populations of wild canids and stray dogs, which facilitates severe spillover (Bojarska et al., 2026) [2] . In wild canids, stress, malnutrition, environmental exposure, and immunosuppression may predispose the animals to opportunistic bacterial infections. Bacterial pneumonia remains one of the most common clinical conditions in dogs with acute or chronic respiratory illness. There is a complex relationship between viral respiratory diseases, environmental factors, and the development of bacterial and mycoplasmal pneumonia in dogs (Dear, 2020) [4] . Among the various bacterial agents, Staphylococcus aureus is a common commensal bacterium that survives within the nasal passages, throat and on the skin of humans and a wide variety of animals. The organism produces severe suppurative and necrotizing lesions in the lungs due to the production of necrotizing toxin and rapid inflammatory response. S. aureus can spread via direct contact or indirectly mediated by fomites. It can also be transmitted zoonotically via direct contact with animals or animal products including raw meats (Kadariya et al., 2014) [5] . It can also be maintained in the environment in manure, water, or the air (Smith et al., 2010) [10] . Among the infections caused by Staphylococcus organisms in dogs, the respiratory infections such as pneumonia and bronchitis can be particularly severe. Many strains have zoonotic potential, moving between humans and animals, including livestock, pets, and wildlife. Besides human, animals also have the potential to harbor novel strains of S. aureus and it may transmit to the human population, or conversely, humans may also transmit strains of S. aureus to other animal species (Price et al., 2012) [9] . The pneumonic condition is usually associated with opportunistic invasion by S. aureus or other coagulase-positive staphylococcal organisms following stress, immunosuppression, trauma, parasitism, or concurrent respiratory infection. The pneumonia induced by S.aureus is a serious but relatively uncommon condition with a high case fatality rate. It often complicates viral infections viz. influenza. S. aureus produces a series of necrotising exotoxins that induce a marked neutrophil response resulting in suppurative tissue necrosis (Hayashida et al., 2009) [3] . Currently, there are limited publications available on diseases affecting Jackals in India and the present article describes the pathology of Staphylococcal pneumonia in a golden jackal.

Materials and Methods

Case History

A male Dhole was presented to the Department of Veterinary Pathology, Veterinary College and Research Institute, Namakkal for post mortem examination which was submitted by the Forest Range Officer, Forest Range, Namakkal with a history of being found dead near Neikkaranpatty village, Mohanur block, Namakkal district of Tamil Nadu.

Necropsy Examination

Necropsy was performed as per the standard procedure and the gross lesions were recorded. The representative tissue pieces from the organs viz. lungs, liver, kidney and heart were collected in 10% neutral buffered formalin.

Histopathological Examination

The tissues were processed as per the standard histological technique. The tissue sections were cut at 3-5µ thickness and stained by the Haematoxylin and Eosin staining technique (Bancroft et al., 1992) [1] .

Cultural Examination

Heart blood swab and lung tissues were collected aseptically in the sterile container for microbiological examination (Watts et al., 1990) [12] .

Results and Discussion

On necropsy, the carcass was in poor body condition (Fig. 1) with scanty subcutaneous fat and visible mucous membranes were congested. Grossly, the heart showed dilatation with severe engorgement of coronary blood vessels. The trachea, bronchi and bronchiolar lumen were filled with whitish frothy fluid mixed with blood clots and mucosa showed congestion (Fig. 2). The lungs were dark red, firm and had diffuse miliary grey nodules in all lobes (Fig. 3). The cranial and middle lobes of lungs revealed haemorrhagic patches. On the section, the cut surface showed multiple miliary grey areas with oozing of reddish frothy fluid and the cut pieces from these areas sank into the water. The visceral pleura showed thickening with mild fibrin deposition. These post mortem findings are in line with previous finding of Vieson et al. (2012) [11] who observed rubbery, mottled, dark to bright red coloured lungs accompanied by severe hemothorax and areas of lung collapse in dogs with streptococcal pneumonia. The gross examination of liver and kidney revealed congestion (Fig. 4). The stomach was empty and the gastric mucosal folds showed congestion. The small intestine contained a little amount of brownish contents and the intestinal mucosa showed thickening. The lumen of the large intestine was also empty.

On histopathological examination, the lung showed severe congestion, edema and necro-haemorrhagic pneumonia characterized by varying degrees of haemorrhage and extensive infiltration of neutrophils. The interalveolar septa of lungs were thickened with inflammatory exudates, inflammatory cells and necrotic debris (Fig. 5). The bronchiolar epithelium showed desquamation as well as necrosis and bronchopneumonia (Fig. 6) were also observed. The pleura showed severe thickening with mononuclear cell infiltration which indicative of pleuritis. Vieson et al. (2012) [11] observed the severe suppurative like changes and hemorrhagic bronchopneumonia characterized by diffuse alveolar neutrophilic infiltration, abundant hemorrhage and edema, with chains of gram positive cocci shaped bacteria in dogs with bacterial pneumonia. The liver and kidney showed congestion on histopathologial examination. The cultural examination of heart blood and lung swab samples was carried out by using selective media. The inoculation of swabs on mannitol salt agar yielded golden yellow pigmented colonies suggestive of suggestive of Staphylococcus species. Further, microscopic examination of bacterial colonies revealed Gram positive cocci arranged in clusters, consistent with the morphology of Staphylococcus species (Fig. 7 &8). The outbreaks of hemorrhagic pneumonia were frequently reported in farmed foxes in the eastern region of Hebei Province and the bacteria isolated and identified in the pneumonia foxes, includes E. coli, Pasteurella spp., Pseudomonas spp. Streptococcus spp. and Staphylococcus spp. (Zhang et al., 2025) [13] . Streptococcus spp. was the most common bacteria associated with canine respiratory disease followed by Staphylococcus spp. (Kadariya et al., 2014; Nisha et al., 2020) [5,8] . Based on the gross lesions, histopathological and cultural examination, the present case was confirmed as "Staphylococcal pneumonia". The severe pneumonic lesions observed in the lungs were consistent with the pathogenic effects of the toxin produced by Staphylococcus spp. and inflammatory mediators. The organism produces various exotoxins and enzymes that contribute to tissue destruction, abscess formation, and systemic toxaemia. The presence of necro-haemorrhagic pneumonia with extensive neutrophilic infiltration, edema and pleuritis supported the diagnosis of bacterial pneumonia. The systemic congestion in the visceral organs suggested progression toward septicaemia and toxaemia. The stress associated with existing environment, nutritional deficiency and concurrent infections may have predisposed the jackal to opportunistic bacterial invasion.

Conclusion

Based on gross pathological, histopathological and bacteriological findings, the case was diagnosed as staphylococcal pneumonia in a male golden jackal. The infection resulted in extensive pulmonary damage and systemic toxic alterations leading to death.

References

1. Bancroft JD, Stevens A, David RT. Theory and practice of histological techniques. 4th ed. London: Churchill Livingstone; 1992. p.
2. Bojarska K, Kondratek K, Leszczynska A, Sionek K, Hatlauf J, Karamon J, et al. Golden jackals as hosts of zoonotic parasites: preliminary findings from southern Poland. Journal of Veterinary Research. 2026;70:67-74. doi:10.2478/jvetres-2026-0018.
3. Hayashida A, Bartlett AH, Foster TJ, et al. Staphylococcus aureus beta-toxin induces lung injury through syndecan-1. American Journal of Pathology. 2009;174(2):509-518.
4. Dear JD. Bacterial pneumonia in dogs and cats: an update. Veterinary Clinics of North America: Small Animal Practice. 2020;50(2):447-465.
5. Kadariya J, Smith TC, Thapaliya D. Staphylococcus aureus and staphylococcal food-borne disease: an ongoing challenge in public health. BioMed Research International. 2014;2014:827965. doi:10.1155/2014/827965.
6. Moehlman PD, Hayssen V. Canis aureus (Carnivore: Canidae). Mammalian Species. 2018;50(957):14-25.
7. Negi T. Review on current worldwide status, distribution, ecology and dietary habits of golden jackal, Canis aureus. Octa Journal of Environmental Research. 2014;2(4):338-359.
8. Nisha, Rana YS, Charaya G, Jain VK, Agnihotri D. Isolation of bacterial pathogens associated with canine respiratory disease. Haryana Veterinary Journal. 2020;59(1):51-54.
9. Price LB, Stegger M, Hasman H, Aziz M, Larsen J, Andersen PS, et al. Staphylococcus aureus CC398: host adaptation and emergence of methicillin resistance in livestock. Microbiology and Immunology. 2012;3(1):e00305.
10. Smith TC, Moritz ED, Leedom Larson KR, Ferguson DD. The environment as a factor in methicillin-resistant Staphylococcus aureus transmission. Reviews on Environmental Health. 2010;25:121-134.
11. Vieson MD, Pineyro P, LeRoith T. A review of the pathology and treatment of canine respiratory infections. Veterinary Medicine: Research and Reports. 2012;3:2539.
12. Watts JL, Lowery DE, Teel JF, Rossbach S. Identification of veterinary pathogens by use of commercial biochemical testing kits and bacteriologic culture methods. Journal of Clinical Microbiology. 1990;28(5):106-110.
13. Zhang C, Li H, Zhao Q, Wang L, Hou G, Shi Q, et al. Drug resistance and pathogenicity characteristics of Escherichia coli causing pneumonia in farmed foxes. Frontiers in Science. 2025;12:1567009. doi:10.3389/fvets.2025.1567009.