Cystocentesis – Image from University of Minnesota CVM

Cats and urinary problems go paw in paw, from the obstruction emergency in males, to common urolithiasis. As a cat owner, it is always important to search for a medical problem before blaming behavioral issues for “accidents” in the house. There’s a whole world of disease out there that can manifest itself as litter box trouble. This article in JAVMA discusses the protein analysis of both healthy cats and those with idiopathic cystitis, urolithiasis, or a UTI.

I’ve actually been thinking about performing a similar study now that I’m at a veterinary clinic with digital records, but do not have the control or finances to have as specific inclusion criteria as this study did (each patient that met inclusion criteria had urine cultures, bladder biopsy, and additional lab work to identify components of the urine performed). The results from this simple small study (n=60) are interpreted well and not only identify a protein present in urine correlated with idiopathic cystitis, but propose a mechanism for it’s presence. Clearly simple, specific, and thorough analysis of blood/urine chemistry have been paying off well for identifying these indicators.

The protein of interest the study found was fibronectin, a protein that plays a role in creating the extracellular matrix and adhesion, and is found in abundance around all cells. This adhesion role implies that fibronectin is crucial within epithelial tissues such as those lining the bladder and urinary tract. What’s interesting is that according to the article, while fibronectin plays large roles in wound healing, blood clot formation, and tumor invasion (Lemberger Et Al., 2011), it was not found in the same high concentrations in any of the cats in the study with conditions other than idiopathic cystitis. One would expect with any inflammation or blood present there would be the same abundance of this protein, but that was not the case. The authors proposed the mechanism that, with chronic idiopathic cystitis, there is significant fibrosis in the urinary tract which damages the epithelial walls. This damage is corrected by increased expression of the fibronectin gene so that the tight junctions between epithelial cells in the cell matrix can be repaired. Thus, with an abundance of fibronectin available to repair chronic damage in the urinary tract, some of it is released and flushed out with urine.

Further study is obviously needed with a larger sample size and more variability in cases, but if the authors’ prediction is correct, fibronectin could be an indicator of epithelial damage in other areas of the body as well. I’m not sure how exactly to go about identifying localized damage, but I am interested in the role that fibronectin could play in anticipating chronic renal failure in cats, as urine chemistry will often not yield an obvious diagnosis until loss of renal function is severe.
ResearchBlogging.orgLemberger SI, Deeg CA, Hauck SM, Amann B, Hirmer S, Hartmann K, & Dorsch R (2011). Comparison of urine protein profiles in cats without urinary tract disease and cats with idiopathic cystitis, bacterial urinary tract infection, or urolithiasis. American journal of veterinary research, 72 (10), 1407-15 PMID: 21962285