Catherine Buckley

The Canine Oral Microbiome

Determining the bacterial composition of the canine oral microbiome is of interest for two primary reasons. First, while the human oral microbiome has been well studied using molecular techniques, the oral microbiomes of other mammals have not been studied in equal depth using culture independent methods. This study allows a comparison of the number of bacterial taxa, based on 16S rRNA-gene sequence comparison, shared between humans and dogs, two divergent mammalian species. Second, canine oral bacteria are of interest to veterinary and human medical communities for understanding their roles in health and infectious diseases. The bacteria involved are mostly unnamed and not linked by 16S rRNA-gene sequence identity to a taxonomic scheme. This manuscript describes the analysis of 5,958 16S rRNA-gene sequences from 65 clone libraries. Full length 16S rRNA reference sequences have been obtained for 353 canine bacterial taxa, which were placed in 14 bacterial phyla, 23 classes, 37 orders, 66 families, and 148 genera. Eighty percent of the taxa are currently unnamed. The bacterial taxa identified in dogs are markedly different from those of humans with only 16.4% of oral taxa are shared between dogs and humans based on a 98.5% 16S rRNA sequence similarity cutoff. This indicates that there is a large divergence in the bacteria comprising the oral microbiomes of divergent mammalian species. The historic practice of identifying animal associated bacteria based on phenotypic similarities to human bacteria is generally invalid. This report describes the diversity of the canine oral microbiome and provides a provisional 16S rRNA based taxonomic scheme for naming and identifying unnamed canine bacterial taxa.

Effect of dietary water intake on urinary output, specific gravity and relative supersaturation for calcium oxalate and struvite in the cat

It has been reported that daily fluid intake influences urinary dilution, and consequently the risk of urolithiasis in human subjects and dogs. The aim of the present study was to investigate the role of dietary moisture on urinary parameters in healthy adult cats by comparing nutritionally standardised diets, varying only in moisture content. A total of six cats were fed a complete dry food (6.3 % moisture) hydrated to 25.4, 53.2 and 73.3 % moisture for 3 weeks in a randomised block cross-over design. Urinary specific gravity (SG), urine volume, water drunk and total fluid intake were measured daily; relative supersaturation (RSS) for calcium oxalate (CaOx) and struvite was calculated using the SUPERSAT computer program. Cats fed the 73.3 % moisture diet produced urine with a significantly lower SG (P < 0.001) compared with diets containing 53.2 % moisture or lower. Mean RSS for CaOx was approaching the undersaturated zone (1.14 (sem 0.21); P = 0.001) for cats fed the diet with 73.3 % moisture and significantly lower than the 6.3 % moisture diet (CaOx RSS 2.29 (sem 0.21)). The effect of diet on struvite RSS was less clear, with no significant difference between treatment groups. Total fluid intake was significantly increased (P < 0.001) in the 73.3 % moisture diet (144.7 (SEM 5.2) ml, or 30 ml/kg body weight per d) compared with the 6.3 % (103.4 (SEM 5.3) ml), 25.4 % (98.6 (SEM 5.3) ml) and 53.3 % (104.7 (SEM 5.3) ml) moisture diets, despite voluntary water intake decreasing as dietary moisture intake increased. Cats fed the 73.3 % moisture diet had a higher total daily fluid intake resulting in a more dilute urine with a lower risk of CaOx when compared with the lower-moisture diets.

The impact of home-prepared diets and home oral hygiene on oral health in cats and dogs

Many factors influence the oral health status of cats and dogs. The present study aimed to elucidate the influence of feeding home-prepared (HP) food v. commercial pet food on oral health parameters in these animals and to investigate the effect of home oral hygiene on oral health. The study surveyed 17,184 dogs and 6371 cats visiting over 700 Polish veterinary surgeries in 2006-7 during a Pet Smile activity organised by the Polish Small Animal Veterinary Association. All animals underwent conscious examinations to assess dental deposits, size of mandibular lymph nodes and gingival health. An oral health index (OHI) ranging from 0 to 8 was calculated for each animal by combining examination scores, where 0 indicates good oral health and 8 indicates poorest oral health. Information was collected on age, diet and home oral hygiene regimens. There was a significant effect of diet on the OHI (P < 0.001) whereby feeding the HP diet increased the probability of an oral health problem in both cats and dogs. There was a significant beneficial effect of feeding only commercial pet food compared with the HP diet when at least part of the diet was composed of dry pet food. Daily tooth brushing or the offering of daily dental treats were both effective in significantly reducing the OHI in both cats and dogs compared with those receiving sporadic or no home oral hygiene. Feeding only a dry diet was beneficial for oral health in cats and dogs. Tooth brushing and the offering of dental treats were very effective in maintaining oral health, provided they were practised daily.