I have heard (or read) some off-hand comments in various raw-feeding sites that a high protein raw meat diet raises BUN levels and this is NOT a clinical sign of illness. A 2004 article from Antech Labs explains this here:http://www.antechdiagnostics.com/clients/antechNews/2006/nov06_01.htm
November • 2006
MORE ON RAW FOOD DIETSBackground
In the past 5 years, raw food diets and partially raw food diets for companion animals have been gaining in popularity with the public sector. Many types of home-made and commercial raw diets are used today. One prototype diet recommends feeding a dog 60% raw meaty bones (chicken backs, wings and necks), with the rest of the diet composed of ground vegetables mixed with ground meat, and supplements such as kelp, vitamin E and vitamin C. Nutritional analyses on some commercially available raw diets suggest that the raw meaty bones commonly used provide 40-70% protein, and the meat/vegetable mixtures range from 20-50% protein. Two questions continue to arise in response to this trend: 1) Do such high protein diets have the potential to affect renal function when fed continuously, as high protein diets are reported to induce renal hypertrophy, and increase renal blood flow and glomerular filtration rate? and 2) Is there significant risk for bacterial or parasitic contamination from feeding raw diets? Renal Function and High Protein Diets
Results from a study of 227 healthy dogs of varying ages and breed types fed raw food diets for at least 9 months indicated that dogs fed raw meats (natural carnivores) have higher red blood cell and blood urea nitrogen levels than 75 dogs fed cereal-based food (obligate omnivores) [Antech News, June 2003]. A recently completed detailed analysis of the other laboratory results from this study showed that statistically different parameters also included higher hemoglobin, MCH, MCV, MCHC, total protein, albumin, BUN/creatinine ratio, sodium, osmolality, and magnesium. Statistically lower values were seen for total leukocyte, neutrophil, and lymphocyte counts, phosphorus, and glucose. Thus, the interpretation of laboratory results for dogs fed raw food diets should take these differences into account.
The intake of proportionately large amounts of raw meat protein and the significantly higher BUN and other concentrations found here raise the possibility of spillover into the urine of measurable amounts of urea nitrogen and/or albumin. If so, are there potential short and long term clinical consequences? Accordingly, the presence of micro-albuminuria was assessed in dogs fed exclusively on raw foods for at least 12 months with the Heska ERD ® HealthScreen¨ test kit. The urine of 37 dogs was evaluated and results indicated that feeding a diet of raw ingredients does not appear to cause leakage of albumin into the urine in most of the dogs tested.
In five dogs, there was a low-grade positive reaction in the test, but two of them were found to have urinary tract infections. The other three dogs were lost to follow up.
I believe this applies equally to cats fed a raw meaty diet.