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狗的尿道健康
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Key Message

关键信息

WALTHAM has contributed to the understanding of urinary tract health in dogs by:

通过以下方式,威豪®成功地促进了对猫尿道健康领域的理解:

  • Developing novel methodologies for urine collection and analysis.

  • Discovering that the increased risk of urolithiasis in smaller breeds is in part because they pass more concentrated urine with a higher pH less often than larger breed dogs.

  • Demonstrating the benefits of urinary dilution through dietary moisture (small dogs) and dietary sodium (all dogs), and generating insights around the benefits of wet foods for urinary tract health in small dogs.

  • Establishing that dietary calcium is relatively more important than dietary oxalate in influencing the risk of calcium oxalate formation in small breed dogs.

  • Demonstrating that a diet with controlled levels of dietary calcium and oxalate reduces the risk of calcium oxalate urolith recurrence in dog.

  • 开发出小便收集与分析的新方法;

  • 发现较小体型的犬种发生尿石症的风险有所增加的部分原因是,这些犬种尿液更加浓缩、pH值较高以及次数较少;

  • 证明通过饮食中的水分含量(小型犬)与钠(所有犬种)的控制进行尿液稀释是有益的解决方案,并形成关于湿性食物对小型犬的尿道健康的作用方面的见解;

  • 确立在影响小型犬草酸钙形成风险方面,饲粮中的钙含量比其中的草酸盐相对更加重要的论断;

  • 证明钙与草酸含量受限的饮食有助于降低狗的草酸钙尿石复发风险。

Background

背景

Urolithiasis can be defined as the formation of sediment anywhere within the urinary tract, consisting of one or more poorly soluble crystalloids of urine. The condition starts with the formation of urinary crystals that may in the right conditions, progress to form uroliths (stones) within the urinary tract. In dogs, uroliths are most commonly found in the bladder; kidney uroliths have also been diagnosed, but to a far lesser extent. Uroliths form when urine becomes supersaturated with respect to the ionic components of a specific stone type, leading to crystal precipitation, coagulate and growth.

尿结石是指在尿道中某处形成的由一种或多种难溶性尿液晶体所组成的沉淀物。该疾病的症状从尿结晶形成开始,尿结晶在一定的条件下可以在尿道中发展成为尿石(结石)。对于狗而言,膀胱是最常生长尿石的器官;此外,肾尿石也有发生,但几率要远远低于膀胱尿石。在某种结石离子成分过度饱和的状态下,尿液中就会形成这种结石的晶体,然后不断凝结和增大,最后就会形成尿石。

 

Factors influencing the risk of urolithiasis in dogs include the concentration of the solutes involved, urine pH, genetic or metabolic disorders, lifestyle and body condition, and the presence or absence of various promoters (such as bacteria) and inhibitory factors (such as citrate and pyrophosphate). Breed, age and sex can also have a significant effect (Ling et al. 2003).

狗的尿石症的影响风险因素包括相关溶质的浓度、尿液pH值、遗传性或代谢性疾病、生活方式与身体状况、各种启动子(如细菌)以及各种抑制因素(如柠檬酸盐与焦磷酸盐)的存在与缺失状况。犬种、年龄与性别也对尿石症的形成具有重要影响(Ling等,2003年)。

Although urinary crystals are frequently associated with clinical signs of cystitis, the presence of crystals in urine does not itself cause disease, and crystalluria can occur in healthy dogs that never go on to develop lower urinary tract disease. However, implementing strategies that help reduce or prevent crystal formation will greatly reduce the risk of urolithiasis and will support effective disease management in clinical cases.

The most common uroliths in dogs are composed of calcium oxalate or struvite (magnesium ammonium phosphate) (Ling et al. 2003; Rogers et al. 2011; Markwell et al. 2000). 

尽管尿结晶经常会导致狗患上膀胱炎,但尿液中存在的结晶本身并不会导致这种疾病,晶尿症也会发生在从未患有下泌尿道疾病的健康狗身上。然而,实施有助于防止晶体形成的策略能够在很大程度上降低尿石症的风险,对在临床病例中更好地对有效疾病管理也具有支持作用。

狗最常见的尿石种类是鸟粪石(磷酸铵镁)或草酸钙(Ling等,2003年;Rogers等,2011年;Markwell等,2000年)。

 

Calcium oxalate

草酸钙

Calcium oxalate urolithiasis is increasingly important in dogs. From 1981 to 2001, the proportion of canine uroliths containing calcium oxalate rose from 1% to 31% of submissions in females and 18% to 82% in male dogs (Ling et al. 2003). Similarly, calcium oxalate submissions increased relative to other stone types at a Canadian laboratory between 1998 and 2008 (Houston and Moore 2009). Calcium oxalate uroliths are particularly prevalent in small breed male dogs (Houston and Moore 2009) of middle to old age (Stevenson and Rutgers 2006). Increasing water intake resulting in urinary dilution is an important part of reducing the risk of calcium oxalate formation. The role of urine pH in calcium oxalate formation is more controversial. Current thinking suggests that calcium oxalate uroliths can form across the physiological urine pH range indicating that control of urine pH is not a critical factor in managing and reducing the risk of calcium oxalate formation in dogs (Stevenson and Rutgers 2006).

近年来,草酸钙尿石症在狗的尿石症中的比例不断增加。1981-2001年,在所有报告的尿石症病例中,含草酸钙的狗尿石病例比例从1%(雌犬)和18%(熊犬)分别增加至31%和82%(Ling等,2003年)。与此相似,根据一家加拿大实验室所收集的1998-2008年的相关数据,所报告的草酸钙尿石病例相对于其他类型的尿石病例也呈现上升趋势(Houston与Moore, 2009年)。中年至老龄(Stevenson与Rutgers,2006年)的小型雄性犬(Houston 与 Moore, 2009年)特别容易患有草酸钙尿石症。增加水的摄入量具有稀释尿液的作用,因此是降低草酸钙尿石形成风险的重要方法之一。尿液pH值对草酸钙形成的作用至今仍颇受争议。目前的观点认为,草酸钙尿石在整个生理尿液pH值范围内均可能形成,从而表明在管理与降低狗的草酸钙尿石形成风险方面,控制尿液的pH值并非一种关键因素(Stevenson与Rutgers, 2006年)。

Figure 1: 100% calcium oxalate uroliths – male dachshund, 7 years of age

1:100%草酸钙尿石——7周岁雄性达克斯猎狗

Struvite

鸟粪石

The relative incidence of this urolith type has declined in recent decades as the percentage of calcium oxalate has increased (Osborne et al. 2009). Struvite stones are most common in young to middle aged female dogs (Stevenson and Rutgers 2006), and in contrast to cats, most (>85%) canine struvite uroliths are associated with urinary tract infection (Markwell et al. 2000). Effective treatment of the bacterial infection is critical. Diet can support effective treatment of struvite urolithiasis, promoting the production of more acidic urine and stone dissolution and reduction of crystal formation. Dietary management for prevention of struvite formation is less relevant in dogs.

近几十年来,随着草酸钙尿石病例比例的增加,鸟粪石尿石病例的相对发病率有所降低(Osborne等,2009年)。鸟粪石尿石最常见于青年至中年雌犬(Stevenson与Rutgers,2006年);与猫不同,大多数(>85%)狗的鸟粪石尿石症会导致尿路感染(Markwell等,2000年)。此时,对狗进行有效的抗菌感染治疗具有关键作用。适当的饮食有助于狗体内增加酸性尿的尿量,从而有助于减少晶体形成的几率和溶解结石,因此饮食对有效治疗鸟粪石尿石症具有支持性作用。通过饮食管理预防狗体内鸟粪石的形成近年来并不为人所重视。

Figure 2: Struvite crystals

2鸟粪石晶体

 

Figure 3: 100% struvite urolith – female Japanese spitz, 7 years of age, entire

3:100%完整鸟粪石——7周岁雌性日本狐狸犬

 

Figure 4: 100% struvite uroliths – female cross-breed dog, 7 years of age

4:100%鸟粪石——7周岁雌性杂种犬

 

 

Urolithiasis and the role of nutrition

尿石症与营养素的作用

It is possible to influence some of the risk factors associated with calcium oxalate uroliths through diet and feeding regimen. WALTHAM has focussed on understanding the influence of dietary ingredients and feeding patterns on the volume, pH, and solute concentration of the urine in order to support effective disease management or reduce the risk of calcium oxalate formation in dogs. 

饮食与喂养方法有可能能够影响导致草酸钙尿石形成的部分风险因子。为了有效支持疾病管理并降低草酸钙形成几率,威豪®一直致力于饮食成分与喂养方式对狗的尿液量、pH值与溶质浓度影响的相关研究。

Diet can positively impact on the urinary tract health of dogs in two ways:

饮食可以通过以下两种方式对狗的尿道健康产生积极影响:

1.    Therapeutic diets that support the veterinary care of clinical cases with urolithiasis. Existing struvite uroliths can be dissolved when appropriate antimicrobial treatments are used in conjunction with an acidifying diet (Calabrò et al. 2011). To date, calcium oxalate uroliths must be mechanically removed and a therapeutic diet can then be used to reduce the risk of recurrence in susceptible individuals. Diets that encourage urine with a low level of saturation – ideally undersaturated – are ideal for supporting the management of urolithiasis.

1. 对患有尿石症的狗的临床兽医护理具有支持作用的治疗饮食。适当的抗菌疗法辅以酸化饮食能够溶解已经形成的鸟粪石尿石(Calabrò 等,2011年)。迄今为止,草酸钙尿石还只能通过机械手段移除,因此可以采用治疗饮食的方法以降低敏感个体的草酸钙尿石复发几率。有助于使尿液保持较低饱和状态(理想状态为欠饱和状态)的饮食是辅助尿石症管理的理想选择。

2.    Diets that reduce the risk of calcium oxalate formation in healthy dogs. Diets formulated to produce urine within the metastable zone of supersaturation will help maintain urinary tract health in healthy dogs.

3. 能够降低健康狗体内形成草酸钙风险的饮食。有助于狗生成处于饱和介稳态尿液的狗粮有助于促进健康狗的尿道健康。

 

Why WALTHAM is Interested

为何威豪®有兴趣从事该领域的研究

Calcium oxalate urolithiasis is an important cause of urinary tract disease in dogs that has grown in importance over the last few decades. It is important to understand the risk factors and to assess the impact of dietary components such as minerals and moisture content on calcium oxalate urolith formation to help develop diets that reduce the risk of, or aid in the management of, this disease.

草酸钙尿石症是狗的尿道疾病的重要原因之一,并且在过去几十年内的发病率呈现逐渐升高的态势。因此,了解草酸钙尿石症的风险因子并评估饮食成分(如矿物质与水分含量)对草酸钙尿石形成的影响有助于开发出能够降低该疾病发生风险几率或有助于对其管理的狗粮。

Approach

方法

For studies investigating the influence of nutrition on the risk of urolithiasis an ethical method of urine collection was required that allowed repeated assessment of naturally voided urine. This methodology allows constant urine pH monitoring and relative supersaturation assessment, critical for establishing the influence of diet on the risk of calcium oxalate formation. 

以考察营养素对尿石症风险的影响为目标的研究要求研究人员采用符合医学伦理的方法收集尿液并能够对自然排泄的尿液进行重复性评估。该方法能够对尿液剂型持续pH监测与相对过度饱和度评估,因此对于确定狗粮对于鸟粪石与草酸钙的形成风险具有关键性意义。

 

Key areas of investigation within this programme include uncovering reasons why smaller breeds may be at greater risk of calcium oxalate urolithiasis, assessing the relative influence of dietary calcium and dietary oxalate intake on the risk of calcium oxalate formation, and investigating the benefits of urine dilution on urinary tract health.

该研究项目的关键研究领域包括确定体型较小的犬种可能更容易患有草酸钙尿石症的原因、评估通过饮食所摄取的钙与草酸量对草酸钙形成风险的影响以及考察尿液稀释对尿道健康的益处。

 

Capability Development (Urine Collection)

能力开发(尿液收集)

In order to investigate urinary tract health, WALTHAM developed a novel methodology for collecting urine samples from dogs, enabling urine pH monitoring and relative supersaturation (RSS) assessment. 

为了研究狗的尿道健康,威豪®开发出一种新方法用于收集狗的尿液样本,从而使尿液pH值监测和相对过饱和度评估成为可能。

A system was developed to collect naturally voided urine samples. When the dogs at WALTHAM are participating in studies, they may be housed individually in purpose-built pens. This set-up was modified for urine collection, with each pen comprising two rooms – one floored with vinyl that provided a sleeping and feeding area, and the other comprising a large fibreglass tray (Stevenson et al. 1998). The tray slopes so that urine rapidly drains through a hole in one corner into a collection bottle beneath. The dogs are readily trained to urinate on the tray. This set-up allows the non-invasive collection of urine samples. It can also be modified to freeze the urine as soon as it is voided to enable RSS assessment.

研究人员已经开发出一套用于收集自然排泄尿液样本的系统。在参加相关研究过程中,威豪®宠物中心的狗可以选择单独住在特别设计的狗窝中。该狗窝系统经过改装以方便进行尿液收集,每个狗窝均有两个房间构成——其中一个房间的地面铺有乙烯以作为狗的睡眠与喂食区,另一个房间由大型玻璃纤维盘构成(Stevenson 等,1998年)。玻璃纤维盘底部呈斜面形,从而使尿液可以通过位于边角处的小孔流入安装于下方的尿液收集瓶中。工作人员对狗进行良好培训以使其能够通过该玻璃纤维盘排尿。该装置使工作人员可以采用非侵入方式收集到猫的尿液样本。通过一定的修改,该方法还可以对排泄后的尿液进行迅速冷冻,从而对其进行相对过度饱和度评估。

 

Urine pH monitoring

尿液pH值监测

In order to monitor pH, urine passes through a purpose built glass U-tube containing a temperature/pH probe over which urine passes on its way to the collection bottle (Stevenson et al. 1998). The pH probes are connected via pH meters to a computer to log the data. A rise in temperature signals urination and triggers data capture. The system developed for dogs was built upon success in methodology development for cats.

为了监测尿液pH值,研究人员需要使尿液通过特殊设计的U型玻璃试管,试管中装有温度/pH值探测器,尿液在流经探测器之后进入尿液收集瓶(Stevenson等,1998年)。该pH值探测器通过pH计与电脑相连以记录相关数据。如果检测到温度升高,则表示狗在排尿,此时系统就会自动进行数据采集。该套系统以已经成功开发的猫的类似系统为基础进行开发。

 

This system has advantages over traditional alternatives such as cystocentisis because it is non-invasive, does not interfere with the dog’s normal urination patterns, and allows the rapid and repeated analysis of pH without storage delays. However, measuring urine pH offers little value for assessing the risk of calcium oxalate formation since calcium oxalate stones can form across the physiological urine pH range.

由于该系统系非侵入性检测法,不会对狗的正常排尿方式形成干扰,而且允许研究人员能够对狗的尿液pH值进行快速、重复分析而不会因为贮存延误检测时间,因此相对于传统尿样采集方法(如穿刺法),该系统具有多种优点。然而,由于草酸钙可以在尿液的整个生理pH值范围内形成,因此测量尿液的pH值对于评估草酸钙形成风险几乎毫无意义。

Figure 5: Schematic diagram of the WALTHAM system for monitoring the urine pH of dogs

5威豪®的狗尿液pH值监测系统示意图

 

 

Relative supersaturation assessment has been regarded as the gold-standard in the human field for decades. However, its adaptation for predicting the crystallisation potential of dog urine is much more recent. WALTHAM utilised the dog urine collection system for both urine pH assessment and to collect urine samples for RSS assessment in dogs (Stevenson et al. 1998).

几十年以来,相对饱和评估一直被认为是人类泌尿系统结石诊断的金标准。然而,将相对饱和评估用于预测狗的尿液结晶形成的可能性却是近期才采用的方法。威豪®宠物中心采用专门的尿液收集系统对狗的尿液样本进行收集和pH值评估以及相对过饱和度评估(Stevenson等,1998年)。

 

In collaboration with Dr WG Robertson, a world leading human urologist at University College London, WALTHAM researchers validated the methodology for measurement of RSS of dog urine (Robertson et al. 2002). Two frequently used programs (SUPERSAT and EQUIL2) were evaluated as to their suitability for calculating calcium oxalate and struvite RSS in dog urine (Robertson et al. 2002). EQUIL2 and SUPERSAT both calculated reasonably accurate RSS values for calcium oxalate in dog urine, whereas only SUPERSAT provided an accurate measure of struvite RSS (Robertson et al. 2002). This study suggests that, for dog urine, SUPERSAT is the most accurate and repeatable method for calculating RSS.

通过与WG Robertson医生(英国伦敦大学学院国际著名人类泌尿专家)合作,威豪®的研究人员对狗的尿液相对过饱和度测量方法进行了验证(Robertson等,2002年)。研究人员还对SUPERSAT与QUIL2两种常用程序在计算狗的尿液中草酸钙与鸟粪石相对过饱和度的适用性进行了评估(Robertson等,2002年)。这两个项目均能够对狗尿液中的草酸钙的相对过饱和度进行合理与准确的计算,但只有SUPERSAT项目能够对鸟粪石的相对过饱和度进行准确测量(Robertson 等,2002)。该研究表明,在狗的尿液测量方面,SUPERSAT是测量相对过饱和度方面的最准确的可重复性方法。

 

Accurate RSS measurement and interpretation underpins the canine urinary tract health research programme at WALTHAM. All researchers in the field agree that urine has to be over(super)saturated with at least one stone-forming mineral for uroliths to form. RSS falls within three definable zones of relative supersaturation (Stevenson and Rutgers 2006).

对相对过饱和度进行准确的测定与解释是威豪®尿道健康研究项目的基础。所有该领域的研究人员均认为,只有在尿液中至少存在一种能够形成尿石的超(过)饱和状态矿物质的条件下,尿石才可能形成。相对过饱和度的三种可定义状态如下图所示(Stevenson与Rutgers, 2006年)。

Figure 6: Zones of urinary relative supersaturation and the crystallisation processes that occur in each zone (Stevenson and Rutgers 2006)

6尿液相对过饱和度状态与各状态的结晶过程(Stevenson与Rutgers, 2006年)

 

 

Zone of undersaturation

欠饱和状态

Any crystals added to urine in this state will dissolve. If urine is maintained within this zone uroliths cannot form.

向处于欠饱和状态的尿液加入的任何晶体均会被溶解。如果尿液一直能够保持在这一状态,则尿石永远不会形成。

 

Zone of metastable supersaturation

亚稳过饱和状态

Urine of normal healthy subjects is often in this zone and crystals can be passed with no harm. As the level of metastable saturation approaches the formation product the length of time before crystallisation commences is reduced. The time between urine formation and crystallisation may also be shortened by the presence of nucleating material such as cell debris or crystals of other mineral types. Any pre-existing crystals are likely to grow in the metastable zone.

正常、健康的试验对象的尿液往往处于亚稳过饱和状态,晶体可以通过该种尿液排出且不会造成任何伤害。由于亚稳过饱和状态的浓度接近晶体形成状态,因此晶体开始形成之前的时间相对较短。尿液形成与晶体形成之间的时间间隔可能也由于成核物质(如细胞碎片或其他矿物晶体)的存在而被缩短。而且,已经形成的晶体还可能在亚稳过饱和状态的尿液中继续生长。

 

Zone of oversaturation

过饱和状态

This is a highly unstable environment in which spontaneous crystal formation occurs along with crystal clumping and growth. Within this zone urolith formation is highly likely.

过饱和状态是一种高度不稳定状态。在这种状态中,晶体可以自发形成、聚集和生长。因此,在过饱和状态尿液中,鸟粪石形成的可能性非常高。

 

Discovery (Breed Size)

The increased risk of urolithiasis in smaller breeds is in part because they produce more concentrated urine and urinate less often than larger breed dogs

发现与结论(犬种体积)

体型较小的犬种可能更容易罹患尿石症的原因之一是,相对与大型犬种,小型犬种产生的尿液更加浓缩,频次更少。

Data from many urolith analysis centres provides evidence to suggest that smaller breeds of dog such as the Yorkshire terrier, miniature schnauzer, Shih Tzu and Pomeranian are at greater risk of calcium oxalate urolithiasis than larger breeds. However, the reasons for this were unclear.

多家尿石分析中心所提供的数据证据表明,小型犬种(如约克郡犬、迷你雪纳瑞犬、狮子狗与波美拉尼亚种小狗)罹患草酸钙尿石症的风险高于大型犬。但目前这一现象的原因尚不清楚。

In phase 1 of a study at WALTHAM, 16 healthy adult dogs (8 Labrador retrievers and 8 miniature schnauzers) were fed the same nutritionally complete dog food for 24 days and their urine was monitored (Stevenson and Markwell 2001). In phase 2, the study was repeated with 8 Labrador retrievers and 7 Cairn terriers (Stevenson et al. 2001).

威豪®所进行的一项研究的1期试验中,研究人员向16只健康成年犬(拉布拉多犬与迷你雪纳瑞犬各8只)喂食营养成分完全的相同狗粮,喂食期为24天,然后收集试验犬的尿液进行监测(Stevenson与Markwell ,2001年)。在第2期试验中,试验对象换为8只拉布拉多寻回犬和7只凯恩犬;试验内容与第1期完全相同(Stevenson等, 2001年)。

In phase 1, dogs were monitored continuously over six 48 hour periods enabling construction of diurnal profiles in addition to monitoring urine pH and RSS. In phase 2 only an RSS assessment was conducted.

在第1期试验中,研究人员在超过48小时的时间段内对试验犬保持不间断监测,从而制成试验犬日间状况曲线图并监测期尿液pH值与相对过饱和度。在第2期试验中,研究人员仅进行相对过饱和度评估。

In phase 1, miniature schnauzers urinated significantly less often than Labrador retrievers producing urine with a lower volume (mL/kg body weight per day) and a significantly higher urine pH (Stevenson and Markwell 2001). When comparing the diurnal profiles miniature schnauzers had a higher urine pH and tended to have a higher specific gravity (mean over 24 hours, 1.030 ± 0.008) than Labrador retrievers (1.023 ± 0.010) through the majority of the 24-hour period (Stevenson and Markwell 2001). In addition, mean daily urinary calcium concentration was significantly higher in the miniature schnauzers (0.93 ± 0.25 compared with 0.61 ± 0.23 for Labradors, P<0.05) (Stevenson and Markwell 2001).

在第1期试验中,迷你雪瑞纳犬的排尿频率显著低于拉布拉多犬,但后者的尿量相对较低(毫升/公斤体重/日)且尿液pH值显著高于前者(Stevenson与Markwell,2001年)。比较两者的日渐曲线图后,研究人员发现,迷你雪瑞纳犬的尿液pH值较高,而且在24小时内的大多数时间内,迷你雪瑞纳犬(24小时平均值: 1.030 ± 0.008)的尿液比重往往高于拉布拉多犬(1.023 ± 0.010) (Stevenson与Markwell, 2001年)。此外,迷你雪瑞纳犬的日间尿液钙浓度平均值也显著高于拉布拉多犬(分别为0.93 ± 0.25和0.61 ± 0.23,P<0.05)(Stevenson与Markwell, 2001年)。

In phase 2, Cairn terriers produced urine with a significantly higher calcium concentration and calcium oxalate RSS (Stevenson et al. 2001).

在第2期试验中,凯恩犬的尿液中钙浓度与草酸钙相对过饱和度均显著高于拉布拉多犬(Stevenson等,2001年)。

These findings show that there are differences in urine composition between different breeds of dog fed the same diet. Some of these factors – such as lower urine volume, higher calcium concentration and higher calcium oxalate RSS – seen in small dogs may contribute to the increased prevalence of calcium oxalate urolithiasis in this group.

上述发现表明,喂食相同饲粮的不同犬种在尿液成分方面存在差异性。部分差异因素——如小型犬所表现出的更低尿液量、更高钙浓度以及更高草酸钙相对过饱和度等因素——均可能导致该犬种的草酸钙尿石症发病率的增加。

 

Discovery (Urinary Dilution)

发现与结论(尿液的稀释)

A moderate level of dietary sodium is an effective strategy for encouraging urinary dilution and reducing the risk of calcium oxalate urolith formation in all dogs. Increasing dietary moisture results in urinary dilution in small breed dogs only 

钠含量适度的饮食是能够促进各类犬种的尿液稀释与草酸钙尿石形成风险降低的有效策略。增加饮食中的含水量仅对小型犬种具有尿液稀释的作用。

The simplest way of reducing RSS and therefore the risk of urolithiasis is through increasing urine volume. In humans, low urine volume has been established as a risk factor for stone formation. WALTHAM investigated two approaches to increasing urine volume through increasing water intake: namely dietary sodium and dietary moisture. 尿液稀释是降低相对过饱和度最简单的方法,因此,增加尿液量有助于降低甚至消除尿石症的风险。对于人类而言,较低的尿液量已经被确定作为结石形成的风险因素之一。威豪®已经成功开发出了两种通过增加水的摄入量而提高尿液量的方法:即调控饮食中的钠与水分含量。

In this series of studies, a nutritionally complete dry dog food (7% moisture, 0.06 g Na per 100 kcal), supplemented with water (to provide 73% moisture) or sodium (to deliver 0.20 or 0.30 g Na per 100 kcal), was fed to 31 Labradors and miniature Schnauzers for 24–36 days and urinary RSS assessed (Stevenson et al. 2003b).

在系列试验中,在向干性狗粮(水分含量7%,钠含量0.06克/100千卡)中添加水分(最终水分含量73%)或钠(最终钠含量0.20 或 0.30克/100千卡)后,研究人员将该狗粮喂食给31只拉布拉多犬和迷你雪纳瑞犬,喂食期为24–36天,然后对上述试验狗的尿液进行相对过饱和度评估(Stevenson等,2003b)。

 

Dietary sodium

饮食中的钠含量

Early studies at WALTHAM showed that dogs (like humans) respond to dietary sodium by drinking more (Burger et al. 1980). Subsequently, it was shown that increased dietary sodium led to the production of urine with a significantly lower calcium oxalate RSS in both Labrador retrievers and miniature Schnauzers (Stevenson et al. 2003b). These data show that a moderate level of dietary sodium can reduce the risk of calcium oxalate formation in large and small breeds of dog.

威豪®早期所进行的研究结果显示,与人类相似,饮食中的氯化钠(盐)会促使狗增加饮水量。随后以拉布拉多犬和迷你雪纳瑞犬为对象进行的试验结果表明,增加狗粮中的钠含量会增加上述两种犬的尿液量并且能够显著降低其尿液中的草酸钙相对过饱和度(Stevenson等,2003b)。上述试验数据表明,钠含量适度的狗粮有助于降低大型和小型犬的尿液中形成草酸钙的风险。

 

Figure7: The effect of dietary sodium on urinary calcium oxalate RSS in Labrador retrievers (LR, n=7) and miniature Schnauzers (MS, n=8) (Stevenson et al. 2003b). Significant differences within a breed indicated by different superscript letters (P<0.05)

7饮食中的钠含量对拉布拉多犬(LR,n=7)与迷你雪纳瑞犬(MS, n=8)尿液中草酸钙相对过饱和度的影响(Stevenson等,2003b)。同一犬种之间的显著差异以不同的上标字母表示(P<0.05)

 

Dietary moisture

饮食中的水分含量

In miniature Schnauzers, increasing dietary moisture content increased total moisture intake, and reduced urine specific gravity, urinary oxalate concentration, and calcium oxalate RSS (Stevenson et al. 2003b). In contrast, there was no effect on the urinary concentration of Labradors (Stevenson et al. 2003b), indicating they may regulate water balance more effectively. These data show that small breeds that tend to be at greater risk of calcium oxalate formation may benefit from increased dietary moisture in order to help maintain urinary tract health or manage calcium oxalate urolithasis.

增加饮食中的水分含量能够增加迷你雪纳瑞犬的总水分摄入量、降低尿液比重与尿液中草酸钙浓度及其相对过饱和度(Stevenson等,2003b)。与此相反,增加饮食中的水分含量对拉布拉多犬的尿液浓度没有任何影响(Stevenson等,2003b),从而表明拉布拉多犬体内的水分平衡调节的效率更高。上述数据表明,小型犬尿液中草酸钙的形成风险往往更高,因此增加饮食中的水分含量有助于其保持尿道健康,也有助于其草酸钙尿石症的管理。

Figure 8: The effect of dietary moisture on urinary calcium oxalate relative supersaturation in Labrador retrievers (LR, n=7) and miniature Schnauzers (MS, n=8) (Stevenson et al. 2003b). Significant differences within a breed indicated by different superscript letters (P<0.05)

8饮食中的水分含量对拉布拉多寻回犬(LR,n=7)与迷你雪纳瑞犬(MS, n=8)尿液中草酸钙相对过饱和度的影响(Stevenson等,2003b)。同一犬种之间的显著差异以不同的上标字母表示(P<0.05)

 

 

Insight Generation

Feeding 25% of the daily caloric requirement as wet diet is associated with beneficial effects on urinary tract health

独特见解

以湿性狗粮的形式满足狗的每日热量需求(每日热量需求的25%)具有保持狗的尿道健康之功效。

The benefit of urinary dilution using dietary moisture in small dogs had been demonstrated (Stevenson et al. 2003b), but the amount of wet diet required to achieve this in practice was unknown.

增加饮食中的水分对小型狗的尿液稀释的益处已经得到证明(Stevenson等,2003b),但目前尚未确定出湿性狗粮的数量以用于指导实际操作。

This study assessed the impact on calcium oxalate RSS of feeding different proportions of wet and dry diets to small dogs in order to identify the proportion of wet format required within the daily ration to elicit a significant urinary tract health benefit (Buckley et al. 2010). A panel of 8 healthy small breed dogs (4 cocker spaniels, 3 miniature Schnauzers and 1 Cairn terrier) were fed four different combinations of wet and dry food in a four phase crossover trial with each phase lasting for 10 days. The diet combinations were A, 100% dry; B, 25% wet calories and 75% from dry; C, 50% wet calories and 50% from dry; and D, 100% wet. Complete data sets were obtained for 5 dogs which contributed to the analyses (Buckley et al. 2010).

该项研究评估了向小型犬喂食的不同比例的湿性与干性狗粮对其尿液中草酸钙相对过饱和度的影响,研究的目标是确定出每日狗粮中所需的湿性饲粮的比例,从而实现狗的尿道健康方面的重大受益 (Buckley等,2010)。在该项4期(每期10天)、交叉试验中,研究人员向一组8只健康小型犬(曲卡犬4只,迷你雪纳瑞犬3只,凯恩犬1只)4种不同的干性与湿性组合狗粮。这4种组合狗粮的构成如下:A型:100%干性狗粮;B型:25%湿性狗粮与75%干性狗粮;C型:50%湿性狗粮与50%干性狗粮;D型:100%湿性狗粮。试验共收集到5只狗的完整数据集并将其用于分析(Buckley等, 2010年)。

Calcium oxalate RSS was significantly reduced in dogs receiving as little as 25% of their calories from wet diet (9.33 ± 3.74) compared with dry diet alone (19.92 ± 7.36) (Buckley et al. 2010). The urinary calcium oxalate RSS of dogs fed on 100% dry diet in this study was categorised as oversaturated (defined as calcium oxalate RSS>12), which is associated with a high risk of spontaneous stone formation and growth of any existing stones (Buckley et al. 2010). Introducing 25% of calories from wet diet results in a metastable supersaturation (calcium oxalate RSS 1–12) where growth of existing stones will not occur and new stone formation is not possible (Buckley et al. 2010). Principal component analysis showed that this effect was largely attributed to the higher sodium and moisture levels contributed by the wet format (Buckley et al. 2010).

试验结果表明,与只食用干性狗粮的试验狗的尿液中草酸钙相对过饱和度(19.92 ± 7.36)相比较,食用湿性狗粮最低含量为25%的饲粮的狗的尿液中草酸钙相对过饱和度(9.33 ± 3.74)显著降低(Buckley等,2010年)。在该试验中,只被喂食100%干性狗粮的狗尿液中的草酸钙相对过饱和度被鉴定为“过饱和”状态(标准为草酸钙相对过饱和度>12),从而导致这些狗在自发性结石形成以及现有结石生长方面处于高风险状态(Buckley等,2010年)。被喂食湿性狗粮比例为25%的饲粮的狗的尿液处于界稳态(草酸钙相对过饱和度为1-12),这种状态的尿液中的现有结石不会继续生长,也不存在新结石形成的可能性(Buckley等,2010年)。主成分分析表明,上述功效在很大程度上是由于湿性狗粮中的钠与水分含量均有所增加的结果(Buckley等, 2010年)。

 

Figure 9: Mean calcium oxalate relative supersaturation with 95% confidence intervals for different dietary regimens. Same letter indicates no significant difference (Buckley et al. 2010)

9实施各种饮食疗法后试验犬的草酸钙相对过饱和度平均值(95%置信区间)。

字母相同表示不具有显著差异性(Buckley等, 2010年)

 

This study suggests that feeding as little as 25% of the daily food ration as wet diet is associated with beneficial effects on urinary tract health.

该研究表明,湿性狗粮含量占每日饮食总量25%的饲粮疗法对狗的尿道健康具有功效。

Discovery (Dietary Calcium and Oxalate)

Dietary calcium is relatively more important than dietary oxalate in influencing the risk of calcium oxalate urolithiasis in dogs

发现与结论(饮食中的钙与草酸盐)

饮食中的钙含量对狗的草酸钙尿石症形成风险的影响程度高于饮食中的草酸盐含量。

The main risk factors for calcium oxalate urolithiasis are urinary supersaturation with calcium and oxalate. Urinary concentrations of both calcium and oxalate may be influenced by dietary intakes. It is important to understand the relative importance of dietary calcium and oxalate contents on urinary tract health in order to develop diets for prevention and treatment of the disease.

草酸钙尿石症的主要风险因素是尿液中钙与草酸盐。尿液中钙与草酸盐的浓度均可受到饮食摄取量的影响。了解饮食中的钙与草酸盐成分对于尿道健康的相对重要性有助于预防与治疗尿石症饮食的开发,因此具有重要意义。

A study at WALTHAM assessed the relative effects of dietary calcium and oxalate on the urine composition of 7 miniature Schnauzers and Cairn terriers (Stevenson et al. 2003a). For 24 weeks, they were fed a nutritionally complete dry dog food supplemented with different combinations of dietary calcium and oxalate (in the form of oxalic acid) commonly found in dry commercially-prepared dog foods.

在一项威豪®开展的研究中,研究人员以7只迷你雪纳瑞犬和凯恩犬为试验对象对饮食中的钙与草酸盐对其尿液成分的相对作用进行了评估(Stevenson等,2003a)。在为期24周的试验中,研究人员向试验犬喂食营养成分完全的干性狗粮,并辅助喂食钙与草酸盐含量不同(草酸形式)(干性商业狗粮中的常见成分)的狗粮。

Urinary calcium concentration increased significantly with dietary calcium content (Stevenson et al. 2003a). Urinary oxalate increased, although inconsistently, with dietary oxalic acid only when the dietary calcium content was low (Stevenson et al. 2003a). Calcium oxalate RSS was lowest when both dietary calcium and oxalate were low, and was highest when dietary calcium content was high and dietary oxalate content was low (Stevenson et al. 2003a). Although the data showed variability, a low calcium diet with increased dietary oxalate also tended to increase calcium oxalate RSS (Stevenson et al. 2003a).

研究发现,试验犬尿液中的钙浓度会随着饮食中钙含量的升高而显著升高(Stevenson等,2003a);仅在饮食中钙含量较低的条件下,试验犬尿液中的草酸盐浓度会随着饮食中草酸含量的升高而升高(但不具有一致性)(Stevenson等,2003a)。在饮食中钙与草酸盐含量均较低的条件下,试验犬尿液中草酸钙的相对过饱和度达到最小值;在饮食中钙含量较高而草酸盐含量较低时,试验犬尿液中草酸钙的相对过饱和度达到最大值(Stevenson等,2003a)。尽管试验数据仍存在一定的差异性,但试验结果仍表明,在钙含量较低的饮食中增加草酸盐的含量往往能够导致试验犬尿液中草酸钙相对过饱和度的升高(Stevenson等,2003a)。

This study showed that dietary calcium is relatively more important than dietary oxalate in the risk of calcium oxalate urolithiasis. However, both dietary calcium and oxalate contents require consideration, since a reduction in dietary calcium without a concomitant decrease in dietary oxalate may increase the risk of calcium oxalate crystallisation in susceptible dogs.

该项研究表明,饮食中的钙含量对草酸钙尿石症形成风险的影响程度高于饮食中的草酸盐含量。然而,鉴于只降低饮食中的钙含量而不相应地降低其中的草酸盐含量有可能增大够尿液中草酸钙结晶的风险,所以对饮食中的钙与草酸盐的含量必须同时兼顾。

Discovery (Calcium and Oxalate Dietary Levels)

A diet with controlled levels of calcium and oxalate reduces the risk of recurrence in calcium oxalate stone forming dogs

发现与结论(饮食中钙与草酸盐的含量)

The benefits of a canned, moderately-acidifying diet with controlled levels of calcium and oxalate have been shown in several studies with dogs that have a history of calcium oxalate urolithiasis.

多项研究成果均证明,适度酸化且限定钙与草酸盐含量的罐头饲粮对有草酸钙尿石症病史的狗具有良好的功效。

In collaboration with the Institute of Urology and Nephrology in London, a clinical study was conducted to investigate whether there were differences in dietary nutrient intakes or urine composition between 17 calcium oxalate stone-forming dogs and 17 age-, breed-, and sex-matched healthy dogs (Stevenson et al. 2004). All stones were surgically removed at the dog’s usual veterinary practice. Diet diaries were kept for these client-owned dogs for 1 week and an initial 24-hour urine sample was collected. The dogs were then fed a commercially-available canned acidifying diet for 1 month before providing another urine sample.

在一项威豪®与伦敦泌尿学与肾脏学研究所合作开展的研究中,研究人员以17只体内已经形成草酸钙结石的狗与17只在年龄、犬种与性别上均与前者相同的健康狗为对象研究了两组试验狗在饮食营养素摄取以及尿液成分方面是否存在差异性(Stevenson等,2004年)。试验犬体内的结石均在常规兽医治疗过程中通过手术予以清除(Stevenson等,2004年)。研究人员对这些由客户养育的宠物狗保持1周的饮食记录,并采集试验最初24小时内的尿液样本。在随后的1个月中,研究人员向试验犬喂食商业灌装酸化饲粮,然后再次采集试验犬的尿样进行分析。

At baseline, stone-forming dogs had significantly lower dietary intakes of sodium, potassium, calcium, and phosphorus and significantly higher urinary calcium and oxalate concentrations and calcium oxalate RSS (Stevenson et al. 2004). After 1 month on the treatment diet, intakes of moisture, sodium and fat were increased, and potassium and calcium intakes were decreased, and urinary calcium and oxalate concentrations and calcium oxalate RSS were decreased (Stevenson et al. 2004). Follow up urine samples were collected at 3 months, 6 months and 12 months. There were no clinical signs of disease recurrence in these calcium oxalate stone-forming dogs during 12 months’ feeding of the diet (Stevenson et al. 2004).

试验显示,在入组时,体内有结石的试验犬通过饮食所摄取的钠、钾、钙与磷均显著低于对照组,而且前者的尿液中钙与草酸盐浓度以及草酸钙相对过饱和度均显著高于对照组(Stevenson 等,2004年)。在被喂食1个月的治疗饮食后,试验犬的水分、钠与脂肪摄入量均有所增加,钾与钙的摄入量有所降低,尿液中该与草酸盐浓度以及草酸钙相对过饱和度均有所降低(Stevenson等,2004)。随后,在试验第3、6和12个月研究人员对试验犬进行了随访并采集尿液样本。试验表明,在被喂食上述饲粮的12个月试验期内,体内已经形成结石的试验犬并未出现结石症复发的临床迹象(Stevenson等, 2004年)。

This study demonstrated that feeding a high-moisture, moderately-acidifying diet with controlled levels of calcium and oxalate to dogs that have formed calcium oxalate uroliths had beneficial effects on urine parameters and helped prevent recurrence for the 12 months they were under observation.

该项研究表明,喂食水分含量较高、限定钙与草酸盐含量的适度酸化饲粮对体内已经形成草酸钙尿石的狗具有改善其尿液参数的作用,同时在12个月的试验期(被观察期)内也有助于防止其尿石症的复发。