Journal Scan: Early signs of chronic kidney disease: Are we looking hard enough?

Why they did it

Early intervention for cats with chronic kidney disease (CKD) allows an opportunity to slow disease progression. Identifying risk factors for disease development before the onset of clinical signs would provide clinicians with clues of an emerging problem and facilitate discussion with owners about the need for preemptive screening.

What they did

As part of a retrospective review, researchers evaluated the medical records of 1,230 cats from Banfield clinics across the United States that were diagnosed with CKD between Jan. 1, 2010, and Dec. 31, 2010. Cats included in the study had to have been seen at least once before the qualifying 2010 visit. CKD was diagnosed based on a creatinine concentration > 1.6 mg/dl and urine specific gravity (USG).

What they found

Being a neutered male; having a thin body condition; having a history of previous periodontal disease or cystitis, anesthesia, or documented dehydration in the preceding year; or living anywhere in the United States other than the northeast were all found to be risk factors for the development of CKD. The reason for the regional difference was not elucidated in the study. Cats with a previous history of diabetes mellitus appeared to have a decreased risk of CKD development.

Body condition and diet were recorded for a subset of cats. Among CKD cats and control cats, thin body condition was identified in 66.3% (396/597) and 38.4% (167/435), respectively. Pyuria (which was used as a surrogate marker for the presence of a bacterial urinary tract infection) was identified in 72% (175/243) of cats with CKD and 35.8% of control cats, consistent with the known association between CKD and bacterial urinary tract infections. The exact cause of the pyuria, however, was not determined.

Median weight loss in the preceding six to 12 months was 10.8% and 2.1% among the CKD and control cats, respectively, and was associated with a diagnosis of CKD. Interestingly, there appeared to be no association between type of diet (wet or dry) and the development of CKD despite the belief that a dry diet is more taxing on the kidneys.

Take-home message

These early indicators may provide subtle hints of the need for increased screening for CKD before the development of overt clinical signs. These findings are not evidence of a cause-and-effect relationship; rather they provide a sound basis for recommending more aggressive screening among the older cat population. Specifically, evidence of weight loss > 10%, which may have previously simply been attributed to aging, should now prompt more aggressive screening for emerging disease such as CKD. In older cats, the presence of pyuria should also prompt bacterial culture to rule out occult infection.

In cases of asymptomatic CKD, early intervention with a therapeutic diet may delay the onset of uremic signs, may prolong survival time, and would be easier to implement before the development of CKD-associated gastrointestinal problems.

Greene JP, Lefebvre SL, Wang M, et al. Risk factors associated with the development of chronic kidney disease in cats evaluated at primary care veterinary hospitals. J Am Vet Med Assoc 2014;244:320-327.

Link to article: http://avmajournals.avma.org/doi/abs/10.2460/javma.244.3.320