In Adult Dogs , Does Feeding a Raw Food Diet Increase the Risk of Urinary Calculi Formation Compared to Feeding a Complete Dry Kibble Diet ? A Knowledge Summary

PICO question In adult dogs, does feeding a raw food diet alter urine composition compared to a kibble diet? Clinical bottom line The evidence provided by the single study identified is weak and the outcomes can neither support nor challenge the hypothesis that a raw food diet increases the risk of urinary calculi compared to a kibble diet. Therefore, professionals working within the veterinary science or nutrition field should proceed with caution when advising clients and rely on their professional experience until more evidence is generated.


The Evidence
There is currently very little published evidence which studies the effect of raw feeding on urine composition.The literature search returned 129 records of which 120 records were excluded because they were not related to the PICO.A further 5 records were excluded because they investigated the use of meat-meal with carbohydrate biscuit rather than raw meat, 1 record was excluded as it was non-primary research and 1 record excluded for investigating non-urinary parameters.The study by Dijcker et al., (2012) identified that currently, evidence is undetermined on whether a raw food diet maintains healthy urinary composition parameters or increases the risk or urolithiasis in adult canine dogs.The findings from this paper found that feeding a commercially available dry kibble diet was associated with a high urine calcium to creatinine (Ca/Cr) ratio compared to the raw diet which was associated with a lower Ca/Cr ratio.

PICO
In adult dogs, does feeding a raw food diet alter urine composition compared to a kibble diet?

Clinical bottom line
The evidence provided by the single study identified is weak and the outcomes can neither support nor challenge the hypothesis that a raw food diet increases the risk of urinary calculi compared to a kibble diet.Therefore, professionals working within the veterinary science or nutrition field should proceed with caution when advising clients and rely on their professional experience until more evidence is generated.
Study design: Cohort (study 1) and RCT (study 2) in crossover design Questionnaire from private owners Outcome studied: Uox and Uca excretion rates and the dietary and animal related factors which are associated with these parameters.A single urine sample was collected in week 4 of the diet by the owner through natural voiding.Urine sample was divided immediately between a non-acidified vial and an acidified vial containing 2N HCl.Samples were stored at -20 °C until analysis.Uox was measuring using isotope dilution mass spectrometry, whereas Uca was measured atomic absorption spectroscopy.

Main findings: (relevant to PICO question):
Uox concentration was not affected by either diet Uca concentration was higher in dogs fed dry diet (TG2) Urinary creatinine concentration high in dogs fed raw meat diet (TG1)

Limitations:
 High degree of non-completers (38/64) with another 3 dogs excluded as outliers. Small sample size (n = 23)  Questionnaire with high risk of bias.Inconsistencies with urine sampling by owners  Inconsistences in urine storage by owners  Reliance on owners providing research diets

Appraisal, application and reflection
The option to feed a raw diet to dogs has grown in popularity and is now readily available commercially.Historically, there has been concern regarding excessive protein intake and the potential increase of calculi promoting substances such as calcium and uric acid (Robertson et al., 1979).This concern has been steadily increasing (Lulich et al., 1999) which has led to the association of a high protein diet with the increased risk of renal damage (Singer, 2003).Interest in the health benefits of a protein fed diet is increasing, however studies measure the relationship between protein and growth rather than welfare and health.Studies are also based on results from comparatively brief studies of less than 6 months.Furthermore, the majority of research conducted focusing on raw feeding, assesses the transmission rate of zoonotic disease and the risk this poses to human health (Joffe and Schlesinger, 2002;Strohmeyer et al., 2006;Finley, et al., 2006;Lefebvre et al., 2008).It was noted at the British Small Animal Veterinary Association (BSAVA) 2016 Congress, that standardised information and advice is limited and not easily available to veterinarians, which reduces their ability to advise clients correctly.This lack of evidence-based peer reviewed research was addressed by Goh (2016), who found that advice concerning a raw feed diet often stems from anecdotal evidence only.There is currently very little published evidence which studies the effects of raw feeding on urine composition and therefore on urinary calculus formation or urinary tract health.Additionally, there is still little evidencebased scientific research and a lack of feeding trials which supports the hypothesis that raw diets are a healthier or more nutritionally balanced than other diets (Michel, 2006;van Veggel & Armstrong, 2017).