We describe histopathologic abnormalities in the kidneys of small Indian mongoose (Herpestes auropunctatus) on the Caribbean island of Saint Kitts. The lesions observed in moderate to severe cases were suggestive of a chronic nephropathy. Further investigation is needed to explore the magnitude of the problem, potential causes, and predisposing factors.

The Caribbean island of Saint Kitts is a 180-km2 Leeward Island in the West Indies located in the Lesser Antilles, (17°18′N, 62°48′W) with a human population of 40,000. The small Indian mongoose (Herpestes auropunctatus), the smallest of the mongoose subspecies, originally inhabited south Asia and was introduced to the Caribbean region in the 1800s to control rat and snake populations (Barun et al. 2011) and their population has increased to an invasive level due to multiple breeding seasons per year and having no natural predators.

The mongooses were captured and euthanized following a Ross University School of Veterinary Medicine (RUSVM) Institutional Animal Care and Use Committee approved protocol (IACUC protocol no. 15-2-007). The mongooses were trapped using Tomahawk live traps (Tomahawk Live Trap, Hazelhurst, Wisconsin, USA) and were transported to the RUSVM necropsy facility and anesthetized using isoflurane followed by euthanasia via intracardiac injection of potassium chloride. Both kidneys were collected, fixed in 10% neutral buffered formalin, trimmed, processed, and stained (H&E) for histopathology examination.

Kidney sections from 75 mongooses captured and euthanized during the period of July to September 2015 were evaluated. Lesions were described as severe when more than 50% of the renal parenchyma was affected, moderate when multifocal lesions were present with less than 50% of the parenchyma, and as mild when random, focal, and scattered lesions were observed. Mild to severe changes were observed in 25 out of 75 (33%) mongooses examined. Two of the mongooses (3%) had severe changes, seven (9%) had moderate changes, and 16 (21%) had mild changes. In moderate to severe cases, multifocal to coalescing areas with changes in tubules, interstitium, and glomeruli within the renal cortex were observed. The lesions included loss and dilation of tubules; degeneration or attenuation of the tubular epithelium with occasional regeneration (Fig. 1A); protein casts within the lumina; multifocal mineral deposits; multifocal interstitial nephritis characterized by infiltration of mononuclear cells, often surrounding the perivascular, subcapsular, and periglomerular regions (Fig. 1B); and multifocal to coalescing interstitial fibrosis (Fig. 1B). Glomerular lesions consisted of distorted, dilated, and often cystic-appearing Bowman's space with shrunken and sclerotic glomeruli and periglomerular fibrosis (Fig. 1C). One of the mongooses had severe mineralization of the medullary tubules (Fig. 1D). Mild lesions observed often consisted of focal areas of interstitial nephritis or mild mineral deposits. About 35% (26/75) of specimens had scattered pale, vacuolated glomeruli, and the characterization of this change and its pathologic significance needs further investigation. Periodic acid-Schiff staining and Masson's trichrome staining were performed to evaluate the glomeruli; however, the findings were unremarkable.

Figure 1

Representative kidney samples (H&E stain) from small Indian mongoose (Herpestes auropunctatus) captured on the Caribbean island of Saint Kitts during the period of July to September, 2015. (A) Renal cortex (400× magnification); note tubular ectasia and renal tubular epithelial attenuation. (B) Renal cortex (200× magnification); note marked diffuse interstitial nephritis, interstitial fibrosis, thickening of arteries, periglomerular fibrosis. (C) Renal cortex (200×); shrunken cystic and sclerotic glomeruli, loss of tubules, interstitial fibrosis. (D) Renal medulla (400×); widespread mineral deposits within the tubular lumina and within the cytoplasm of tubular epithelia.

Figure 1

Representative kidney samples (H&E stain) from small Indian mongoose (Herpestes auropunctatus) captured on the Caribbean island of Saint Kitts during the period of July to September, 2015. (A) Renal cortex (400× magnification); note tubular ectasia and renal tubular epithelial attenuation. (B) Renal cortex (200× magnification); note marked diffuse interstitial nephritis, interstitial fibrosis, thickening of arteries, periglomerular fibrosis. (C) Renal cortex (200×); shrunken cystic and sclerotic glomeruli, loss of tubules, interstitial fibrosis. (D) Renal medulla (400×); widespread mineral deposits within the tubular lumina and within the cytoplasm of tubular epithelia.

Close modal

Mongoose in general are considered as a vector for many zoonotic pathogens including rabies virus and Leptospira spp. in the Caribbean islands (Matthias and Levett 2002; Berentsen et al. 2015). Leptospira PCR and serum microscopic agglutination tests against 20 Leptospira serovars were performed along with the histopathologic evaluation of the kidneys. Convincing evidence of active Leptospira infection was not present in these animals. There are over 250 serovars of Leptospira, the diversity of which in a particular geographic area is not fully known. Exposure to Leptospira may result in serovar-specific agglutinating antibodies in infected animals, and it is possible that the lesions observed in mongooses might have been a result of previous Leptospira infection caused by a serovar that was not included in the panel.

Our study suggested that a form of chronic kidney disease (CKD) may be present in a percentage of the mongoose population inhabiting the island. Chronic kidney disease is a progressive and often a multifactorial condition resulting in reduction in number and functions of nephrons and may lead to end-stage renal disease. Among domestic animals, CKD is a common metabolic disease in cats (Brown et al. 2016). A variety of factors including congenital defects, chronic bacterial infections, hypertension, immune mediated diseases, acute kidney injury, damage due to infections or toxins, aging, ischemia, and environmental factors are described in the initiation and progression of CKD (Brown et al. 2016). Considering the tropical geographic location of the island, this condition may have similarity to a CKD in humans called Mesoamerican nephropathy reported in some of the Central American and other tropical countries (Wijkström et al. 2017). This disease occurs in epidemic proportions, primarily in men working in extremely hot conditions in agricultural communities, especially those working in sugar cane fields. The lesions associated with this disease have a varied pattern of glomerular and tubular sclerosis. Nephrotoxic medications including nonsteroidal anti-inflammatory drugs, arsenic toxicosis, exposure to heat and dehydration, and Leptospira infection have been speculated as potential causes of this CKD (Murray et al. 2015). Acute kidney insults such as an infection or exposure to nephrotoxin may act as an initiation factor in CKD, and other progression factors may lead to exacerbation of the condition.

Leptospirosis has been considered as a cause of CKD in dogs (Riefkohl et al. 2017), and Leptospira seropositivity was reported to be higher for cats with CKD (Rodriguez et al. 2014). Increased prevalence of CKD and its association with Leptospira infection in humans has been documented (Yang et al. 2015). Leptospirosis is endemic in the Caribbean region and Central America (Rajeev et al. 2017); however, further active surveillance studies are needed to find any correlation between chronic renal lesions and Leptospira infection.

The limitations of this study included a small sample size, limited geographic span within the island, and random selection of the population studied. Hence, the nature of this condition, its clinical significance, and whether or not it represents a single disease entity remains to be elucidated. A study using a larger sample size and stratification based on temporospatial parameters, and evaluation of pathogen exposure using multiple tests, are needed to identify the true magnitude of the problem and factors contributing to this condition.

The project was supported by Intramural funding to S.R. through Ross University School of Veterinary Medicine One Health Center for Zoonosis and Tropical Veterinary Medicine and to L.C.-M. from Center for Conservation Medicine and Ecosystem health. We would like to thank Mr. David Hilchie for providing histopathology technical support.

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