Intrinsic factors, adrenal gland morphology, and disease burden in captive cheetahs (Acinonyx jubatus) in South Africa

Abstract

Adrenal gland weight (AW) and corticomedullary ratio (ACMR) are used as indicators of stress in animals. Captive cheetahs (Acinonyx jubatus) have higher ACMRs than free-ranging ones and stress has been linked to gastritis, amyloidosis, glomerulosclerosis, and myocardial fibrosis. We reviewed age, sex, body weight (BW), kidney weight (KW), and left AW and ACMR with necropsy findings in 51 South African captive cheetahs. Eleven common histopathologic lesions were counted for each animal as measure of its disease burden. Adrenal corticomedullary hyperplasia was significantly correlated with left AW and ACMR. Males had significantly higher AWs than females; other parameters showed no difference between the sexes. Disease burden, gastritis, and myocardial fibrosis were moderately correlated with adrenal morphology supporting prior evidence that gastritis and myocardial fibrosis are linked to stress. Glomerulosclerosis was not correlated with adrenal morphology and neither kidney nor liver amyloidosis contributed significantly to variation in AW or ACMR on multivariate analyses. Interstitial nephritis showed much stronger correlations with kidney and liver amyloidosis than gastritis. All three adrenal parameters were correlated with age; age was the only significant variable affecting ACMR on the multivariate analyses; and disease burden as well as systemic amyloidosis and kidney disease (except for fibrosis) showed moderate correlations with age. Age may, therefore, be important in the pathogenesis of disease in captive cheetahs, particularly of amyloidosis and kidney disease. None of the intrinsic measurements or adrenal parameters were sufficiently closely linked to disease to be used as ante-mortem proxies for disease burden or specific diseases. Zoo Biol. 36:40-49, 2017. © 2016 Wiley Periodicals, Inc.

Pathology and Epidemiology of Oxalate Nephrosis in Cheetahs

“…At one Southern African institution, urinary oxalate was elevated in an acutely azotemic cheetah later diagnosed with oxalate nephrosis without other renal lesions (8000 mg oxalate/g creatinine, compared with 128 mg/g in a healthy enclosure mate; F. Reyers, Golden VetPath, unpublished data). Since the crystal number was higher in young cheetahs and chronic renal disease in cheetahs is age related, 26,51 oxalate nephrosis should be a primary consideration in younger cheetahs with renal failure.…”

A new perspective on the pathogenesis of chronic renal disease in captive cheetahs (Acinonyx jubatus)

“…Renal medullary amyloidosis was evaluated as the proportion of the outer third of the medulla containing multifocal or diffuse amyloid deposits between tubules: absent (0); 1–33% (1); 34–66% (2); and 67–100% (3). Lymphoplasmacytic interstitial nephritis was not evaluated as this multifocal usually mild lesion is considered to be secondary to glomerular or tubular injury where this is present[ 5 , 13 , 43 ]. Lesions of uremic gastropathy (gastric arteriolar necrosis, infarction, ulceration and interstitial mineralization)[ 43 ] were excluded from the parameter “gastritis”.…”

“…Persistent hyperglycemia due to stress has been suggested as a factor in the pathogenesis of the glomerulosclerosis, due to similarities with diabetic nephropathy in humans[ 12 ] and a strong association between glomerulosclerosis and adrenal gland hyperplasia[ 3 ]. However, the typical vascular lesions of systemic hypertension and diabetes mellitus are rarely seen in cheetahs[ 3 , 5 , 10 ] and no association was found between glomerulosclerosis and three adrenal gland morphology measurements[ 13 ]. Excessive dietary protein (through the omission of non-protein carcass components), frequent feeding in captivity and a genetic predisposition have also been postulated to affect the development of glomerulosclerosis[ 3 , 9 ], since glomerulosclerosis is a feature of chronic progressive nephropathy in several strains of aging rats, the progression of which is sensitive to dietary protein levels[ 14 ].…”

“…Deposited amyloid fibrils disrupt tissue architecture and result in progressive renal dysfunction in humans[ 24 ], domestic cats[ 25 ] and cheetahs[ 5 , 6 , 9 ]. The most common inflammatory condition in captive cheetahs is lymphoplasmacytic gastritis[ 5 , 6 , 9 ], although focal palatine erosions, lymphoplasmacytic interstitial nephritis, enterocolitis, and various other traumatic and infectious causes of inflammation are also recorded [ 5 , 9 , 13 ]. Captive cheetahs suffer from inflammation of maxillary palatine clefts that may lead to chronically inflamed focal palatine erosions and oronasal fistulae[ 26 ].…”

Ultrasonographically determined renal values and comparisons to serum biochemistry renal variables in aged semi-captive cheetahs (Acinonyx jubatus)

“…Nephropathies recorded at post-mortem include glomerulonephritis, glomerulosclerosis, renal fibrosis, acute tubular necrosis, interstitial nephritis, oxalate nephrosis, pyelonephritis and renal amyloidosis [ 4 – 10 ]. Of these, glomerulosclerosis and renal fibrosis tend to be the most common lesions, typically present in 70–80% of renal samples evaluated on histology in adult captive cheetahs [ 4 , 5 , 9 ].…”