Renal accumulation of prooxidant mineral elements and CKD in domestic cats

Abstract

felids have a high incidence of chronic kidney disease (cKD), for which the most common renal lesion is chronic interstitial nephritis (cin). cin can be induced by tissue oxidative stress, which is determined by the cellular balance of pro-and anti-oxidant metabolites. Fish-flavoured foods are more often fed to cats than dogs, and such foods tend to have higher arsenic content. Arsenic is a pro-oxidant metallic element. We propose that renal accumulation of pro-oxidant elements such as arsenic and depletion of anti-oxidant elements such as zinc, underpin the high incidence of cin in domestic cats. total arsenic and other redox-reactive metal elements were measured in kidneys (after acid-digestion) and urine (both by inductively-coupled plasma-mass spectrometry) of domestic cats (kidneys, n = 56; urine, n = 21), domestic dogs (kidneys, n = 54; urine, n = 28) and non-domesticated Scottish Wildcats (kidneys, n = 17). Renal lesions were graded by severity of CIN. In our randomly sampled population, CIN was more prevalent in domestic cat versus domestic dog (51%, n = 32 of 62 cats; 15%, 11 of 70 dogs were positive for cin, respectively). cin was absent from all Scottish wildcats. tissue and urinary (corrected for creatinine) arsenic content was higher in domestic cats, relative to domestic dogs and wildcats. Urine arsenic was higher in domestic cats and dogs with cin. Arsenobetaine, an organic and relatively harmless species of arsenic, was the primary form of arsenic found in pet foods. in summary, the kidneys of domestic cats appear to have greater levels of pro-oxidant trace elements, as compared to dogs and wildcats. Since there was no difference in renal arsenic levels in cats with or without CIN, renal arsenic accumulation does not appear a primary driver of excess CIN in cats. Given clear differences in renal handling of pro vs. anti-oxidant minerals between cats and dogs, further in vivo balance studies are warranted. These may then inform species-specific guidelines for trace element incorporation into commercial diets.Chronic kidney disease (CKD) is commonly diagnosed in domestic cats, with a reported prevalence of 1-3% in the overall domestic cat population 1 . One study reported prevalence as high as 50% and 80% in cats of all ages and aged over 15 years, respectively 2 . This contrasts to a reported prevalence of <1% in all dogs 3 and only 10% in dogs over 15 years of age 1 . CKD is defined as the irreversible loss of structure and/or function of one or both kidneys that results from a progressive process occurring over a period of 3 months or more 1 . CKD has various aetiologies, but mononuclear cell tubulointerstitial nephritis -inflammation of the interstitial cells surrounding tubules, predominantly proximal -together with interstitial fibrosis and tubular atrophy is the common histopathological finding in most cases of CKD in cats 4,5 and dogs 6 .Renal tubular epithelial cells are highly metabolically active with high mitochondrial density in order to support oxidative phosphorylation and energy-depe...

Serum Concentrations of Essential Trace and Toxic Elements in Healthy and Disease-Affected Dogs

“…This could be related to the ratio of renal excretion since it is their main excretion route. In a recent study in dogs and cats with chronic interstitial nephritis was observed that the ratio of Mo excretion in urine was lower than in healthy animals [ 39 ]. In humans, it has been suggested that high serum Mo concentrations could contribute to dialysis-related bone disease in patients requiring long term hemodialysis, as massive Mo accumulation causes joint deformity and arthritis [ 40 ].…”

Trace Element Levels in Serum Are Potentially Valuable Diagnostic Markers in Dogs

“…Information on Mo concentrations in serum of renal patients is very scarce. A recent study in dogs and cats with chronic interstitial nephritis demonstrated that less Mo was excreted in urine than in healthy animals [44]. In humans, it has been suggested that high serum Mo concentrations may contribute to dialysis-related bone disease in patients requiring long term hemodialysis, as massive Mo accumulation causes joint deformity and arthritis [45].…”