Adrenergic and noradrenergic regulation of poultry behavior and production.

Norepinephrine and epinephrine (noradrenaline and adrenaline) are integral in maintaining behavioral and physiological homeostasis during both aversive and rewarding events. They regulate the response to stressful stimuli through direct activation of adrenergic receptors in the central and sympathetic nervous systems, hormonal activity and through the interaction of the brain, gut, and microbiome. The multiple functions of these catecholamines work synergistically to prepare an individual for a "fight or flight" response. However, hyper-reactivity of this system can lead to increased fearfulness and aggression, decreased health and productivity, and a reduction in overall well-being. Behaviors, such as aggression and certain fear-related behaviors, are a serious problem in the poultry industry that can lead to injury and cannibalism. For decades, catecholamines have been used as a measure of stress in animals. However, few studies have specifically targeted the adrenergic systems as means to reduce behaviors that are damaging or maladapted to their rearing environments and improve animal well-being. This article attempts to address our current understanding of specific, adrenergic-regulated behaviors that impact chicken well-being and production.

Serotonin's role in piglet mortality and thriftiness.

Improving piglet survivability rates is of high priority for swine production as well as for piglet well-being. Dysfunction in the serotonin (5-HT) system has been associated with growth deficiencies, infant mortalities, or failure to thrive in human infants. The aim of this research was to determine if a relationship exists between infant mortality and failure to thrive (or unthriftiness), and umbilical 5-HT concentration in piglets. Umbilical blood was collected from a total of 60 piglets from 15 litters for analysis of 5-HT and tryptophan (Trp; the AA precursor to 5-HT) concentrations. Behavior was scan sampled for the first 2 days after birth. Brain samples were also taken at 8 h after birth from healthy and unthrifty piglets (n = 4/group). The raphe nucleus was dissected out and analyzed for 5-HT and dopamine concentrations as well as their major metabolites 5-hydroxyindoleacetic acid (5-HIAA) and homovanillic acid (HVA), respectively. Data were analyzed by ANOVA. Piglets that died within 48 h of birth (n = 14) had significantly lower umbilical blood 5-HT concentrations at the time of their birth compared to their healthy counterparts (n = 46, P = 0.003). However, no difference in Trp was detected (P 0.38). Time spent under the heat lamp and sleeping were positively correlated with umbilical 5-HT levels (P = 0.004 and P = 0.02, respectively), while inactivity had a negative correlation with 5-HT levels (P = 0.04). In the raphe nucleus, the center for brain 5-HT biosynthesis, unthrifty piglets had a greater concentration of 5-HIAA (P = 0.02) and a trend for higher concentrations of 5-HT (P = 0.07) compared with healthy piglets. Dopamine levels did not differ between thrifty and unthrifty piglets (P = 0.45); however, its metabolite HVA tended to be greater in unthrifty piglets (P = 0.05). Our results show evidence of serotonergic dysfunction, at both the central and peripheral levels, accompanying early piglet mortalities. These data suggest a possible route for intervention, via the 5-HT system, to improve piglet survivability. However, further research is required to validate this hypothesis.

Effect of perches on liver health of hens.

Fatty liver is a common energy metabolic disorder in caged laying hens. Considering that the egg industry is shifting from conventional cages to alternative housing systems such as enriched cages, the objective of this study was to determine the effects of perches on fat deposition and liver health in laying hens. Three hundred twenty-four 17-wk-old White Leghorn hens were housed in 1 of 4 treatments with 9 hens per cage. Treatment 1 hens never had access to perches during their life cycle. Treatment 2 hens had access to perches during the pullet phase only. Treatment 3 hens had access to perches during the laying phase only. Treatment 4 hens always had access to perches. Liver weight, abdominal fat pad weight, BW, liver fat, and circulating alanine transaminase, aspartate transaminase, and adiponectin were determined. Provision of perches during either the rearing or laying phase did not affect liver health in 71-wk-old hens. However, perch access compared with no perch access during the egg laying phase reduced relative fat pad weight. These results suggest that providing perches as a means of stimulating activity reduced abdominal fat deposition in caged hens during the laying period. However, perch access in caged hens was ineffective in reducing fat deposition in the liver and altering enzyme activities related to improved liver function.

Effects of early serotonin programming on behavior and central monoamine concentrations in an avian model.

Serotonin (5-HT) acts as a neurogenic compound in the developing brain; however serotonin altering drugs such as SSRIs are often prescribed to pregnant and lactating mothers. Early agonism of 5-HT receptors could alter the development of serotonergic circuitry, altering neurotransmission and behaviors mediated by 5-HT signaling, including memory, fear and aggression. This study was designed to investigate the effects of early serotonin agonism on later behaviors. An extremely aggressive White leghorn strain (15I5) was used in the study. The chicks were injected with 5-MT (a serotonin agonist) at 2.5mg/kg (low dose), 10mg/kg (high dose) or saline (control) on the day of hatch and a second dose 24h later (n=9/sex/trt). Chicks' fear response and memory were tested at 2 weeks of age. In the fear test, chicks were subjected to a social isolation test for 20min, time to first vocalization and numbers of vocalizations were recorded. In the memory test, chicks were placed in a running wheel and presented with an imprinted object (white box with a red light) and a similar shaped novel object (blue box with a white light), respectively. The distance traveled in the wheel toward each object was measured. At 10 weeks of age birds were tested for aggression and concentrations of catecholamines were determined from the raphe nucleus and hypothalamus by HPLC (n=12). Expression of 5-HT1A and 5-HT1B receptor genes were measured by RT-PCR. Both high and low dose chicks tended to have shorter latency to first vocalization and a greater number of vocalizations compared with control chicks. Memory test showed that chicks from all groups traveled a similar distance toward a familiar object. However, control chicks walked the least toward a novel object, low dose chicks tended to walk further, and high dose chicks walked significantly further for a novel object. In aggression tests, both high and low dose males exhibited greater frequency of aggressive behaviors compared to controls, while no difference in aggression was evident in the females. Norepinephrine concentrations were also reduced in the low dose birds in the hypothalamus and in the raphe nucleus. Serotonin concentrations tended to be lower only in the both hypothalamus and raphe nucleus of the low dose birds. 5-HT1A expression was greatest in the hypothalamus and raphe nucleus of low dose birds. The agonism of the serotonin system during neural development of birds genetically predisposed to aggression alters both the dopaminergic and serotonergic systems further increasing their aggressiveness.

Genetic variations alter production and behavioral responses following heat stress in 2 strains of laying hens.

Genetic differences alter the type and degree of hens' responses and their ability to adapt to a stressor. This study examined the effects of genotypic variations on the productivity and behavior of laying hens following heat stress (HS). Two strains of White Leghorn hens were used: DXL (Dekalb XL), a commercial strain individually selected for egg production and KGB (kind, gentle bird), a strain selected for high group productivity and survivability. Ninety hens (48 DXL and 42 KGB) at 28 wk of age were randomly assigned to either a hot (H: mean = 32.6°C) or control (C: mean = 24.3°C) treatment and housed in pairs by strain for 9 d. Egg production and quality, behavior, body and organ weights, and circulating hormone concentrations were measured. Heat-stressed hens had lower egg production [adjusted (adj) P < 0.001] than their respective controls. Among H-DXL hens, egg weight tended to be reduced at d 1 and was reduced at d 9 (adj P = 0.007), but was reduced only at d 9 among H-KGB hens (adj P = 0.007). Eggshell thickness was also reduced among H hens at d 9 (adj P = 0.007), especially among H-KGB hens (adj P = 0.01). Plasma triiodothyronine concentration was reduced among H-hens (adj P = 0.01), especially among H-DXL hens (adj P = 0.01). Neither temperature nor strain affected the plasma thyroxine and plasma and yolk corticosterone concentrations. Heat-stressed hens spent less time walking (adj P = 0.001) and more time drinking (adj P = 0.007) and resting (adj P = 0.001) than C-hens. The results indicate that although HS reduced production and caused behavioral changes among hens from both strains, the responses differed by genotype. The data provide evidence that genetic selection is a useful strategy for reducing HS response in laying hens. The results provide insights for conducting future studies to develop heat-resistant strains to improve hen well-being, especially under the current commercial conditions.

Effects of different infrared beak treatment protocols on chicken welfare and physiology.

Infrared beak trimming provides an alternative to conventional trimming, purporting to provide a welfare-friendly means of trimming. The infrared system can be adjusted to use multiple plate and power settings. In the present study, we used 2 different plate sizes (27/23C, less severe; 25/23C, more severe) with each of 3 power settings: high (52), moderate (48), and low (44). These birds, along with conventionally (hot blade; HB) trimmed birds were maintained in an industry egg-laying facility. Physiological and behavioral measures were taken at 5, 10, 20, and 30 wk. All birds followed a similar growth curve; birds from the 27/23C (48) protocol were the heaviest across all ages and 25/23C (44) birds were the lightest. Upper and lower beak growth curves showed birds trimmed with 25/23C protocols had shorter upper and lower beaks compared with 27/23C protocols or HB. Birds trimmed using 27/23 (44) and (48) had consistently longer upper and lower mandibles. Amount of feed wasted was greatest in HB and 27/23C birds and tended to be reduced in 27/23 (48) and 25/23 (48) and (52) birds (P < 0.10). Beak-related behaviors (eating, drinking, and pecking) were measured to observe the effects of trimming protocol on beak usage, which could indicate beak pain or morphological changes that inhibit normal behaviors. Walking behavior was also measured to assess overall activity. Behavior analysis revealed that compared with HB-trimmed birds, those of 27/23C protocols walked and drank more at a young age. At 5 and 10 wk of age, a test feather was attached to the cage and pecking at as well as the damage score of the feather were determined. Birds from 27/23C (44) and (48) protocols pecked significantly more at the feather than HB, whereas HB and 25/23C (52) birds had the highest damage score. The results from the study suggest that infrared protocols can be optimized for superior productivity as well as animal well-being.

Genetic variations alter physiological responses following heat stress in 2 strains of laying hens.

Heat stress (HS) is a major problem experienced by the poultry industry during high-temperature conditions. The ability to manage the detrimental effects of HS can be attributed to multiple factors, including genetic background of flocks. The objective of the present study was to determine the genetic variation in HS effects on laying hens' physiological homeostasis. Ninety 28-wk-old White Leghorn hens of 2 strains were used: a commercial line of individually selected hens for high egg production, DeKalb XL (DXL), and a line of group-selected hens for high productivity and survivability, named kind gentle bird (KGB). Hens were randomly paired by strain and assigned to hot or control treatment for 14 d. Physical and physiological parameters were analyzed at d 8 and 14 posttreatment. Compared with controls, HS increased hen's core body temperature (P < 0.05) and decreased BW (P < 0.05) at d 8 and 14. Heat shock protein 70 concentrations in the liver were greater in hens exposed to HS (P < 0.05). Compared with DXL hens, KGB hens had higher heat shock protein 70 concentrations (P < 0.05). The hens' liver weight decreased following HS, with less of a response in the KGB line (P < 0.05). The data indicate HS has detrimental effects on the physiology of laying hens due to genetic variations. These data provide evidence that is valuable for determining genetic interventions for laying hens under HS.

Effects of selective serotonin antagonism on central neurotransmission.

Aggression and cannibalism in laying hens can differ in intensity and degree due to many factors, including genetics. Previous behavioral analysis of 2 strains of White Leghorns, DeKalb XL (DXL) and HGPS (a group-selected line for high group productivity and survivability), revealed high and low aggressive phenotypes, respectively. However, the exact genetic mechanisms mediating aggressiveness are currently unknown. Analysis of serotonin (5-HT) mediation of aggression in subordinate hens of these strains revealed increases in aggression in DXL hens following antagonism of the 5-HT1A receptor and in HGPS hens following antagonism of the 5-HT1B receptor. Here, we investigate the different neurotransmitter response in the hypothalamus and raphe nucleus mediating these aggressive responses to receptor antagonism. Elevated aggressive response to 5-HT1B antagonism by HGPS hens was also accompanied by a decrease in raphe nucleus dopamine (DA) and an increase in DA turnover. Increased aggressiveness in DXL hens did not coincide with a reduction in raphe nucleus 5-HT or turnover (as indicated by 5-hydroxyindoleacetic acid levels) following 5-HT1A antagonism. A reduction in 5-hydroxyindoleacetic acid (but not 5-HT) was seen in HGPS hens treated with 5-HT1A antagonist; however, these hens exhibited no change in aggressive behaviors. Our data show evidence of different heritable mechanisms of neurotransmitter regulation of aggressive response, specifically heritable differences in the interaction between 5-HT and catecholamines in regulating aggression.

The dopaminergic system and aggression in laying hens.

The dopaminergic system is involved in the regulation of aggression in many species, especially via dopamine (DA) D1 and D2 receptor pathways. To investigate heritable differences in this regulation, 2 high aggressive strains [Dekalb XL (DXL) and low group egg productivity and survivability (LGPS)] and one low aggressive strain (low group egg productivity and survivability; HGPS) of laying hens were used in the study. The HGPS and LGPS lines were diversely selected using group selection for high and low group production and survivability. The DXL line is a commercial line selected through individual selection based on egg production. Heritable differences in aggressive propensity between the strains have been previously assessed. The birds were pair housed within the same strain and labeled as dominant or subordinate based on behavioral observation. For both experiments 1 and 2, behavioral analysis was performed on all 3 strains whereas neurotransmitter analysis was performed only on the most aggressive (DXL) and least aggressive (HGPS) strains. In experiment 1, the subordinate birds were treated with D1 agonist, D2 agonist, or saline controls (n = 12). In experiment 2, the dominant birds from a separate flock were treated with D1 antagonist, D2 antagonist, or saline controls (n = 12). Treatment-associated changes in aggressive behaviors and central neurotransmitters were measured. Aggression was increased in all strains in response to D1 agonism but increased only in the less aggressive HGPS birds with D2 agonism. Aggression was decreased and hypothalamic serotonin and epinephrine were increased in birds from all strains treated with D2 receptor antagonist. The D1 receptor antagonism elicited different behavioral and neurotransmitter responses based on the aggressive phenotype of the genetic strains. Aggressive strains DXL and LGPS but not the HGPS strain decreased aggressiveness following antagonism of the D1 receptor. The data show evidence for distinct neurotransmitter regulation of aggression in high and low aggressive strains of hens through different receptor systems. These chicken lines could provide new animal models for the biomedical investigation of the genetic basis of aggression.

Infrared beak treatment method compared with conventional hot-blade trimming in laying hens.

Infrared lasers have been widely used for noninvasive surgical applications in human medicine, and their results are reliable, predictable, and reproducible. Infrared lasers have recently been designed for the express purpose of providing a less painful, more precise beak-trimming method compared with conventional beak trimming. This study was designed to examine the potential of the infrared (IR) beak treatment to provide a welfare-friendly alternative to the conventional hot-blade method for chickens. The birds were beak trimmed by IR at the hatchery or by hot blade at 7 to 10 d of age in a commercial production setting, in accordance with standard procedures. The beak morphology and associated physiological characteristics, including production and aggressive behavior of the birds, were analyzed at 30 wk of age. There was no difference in egg production or bird BW between the 2 beak-trimming treatments. Birds also exhibited no difference in stress physiology measured in the study, such as fluctuating asymmetry and heterophil and lymphocyte profiles. However, birds receiving the IR treatment showed a superior feather condition and reduced aggressiveness under high light intensity, even though they had longer beak stumps. The results may indicate that the IR beak treatment may reduce the damage done by aggressive pecking and feather pecking. Indeed, IR trimming may provide a more welfare-friendly alternative to conventional beak trimming without compromising productivity.

Appearance matters: artificial marking alters aggression and stress.

Artificial marking of animals for identification is frequently employed by researchers in the behavioral, biomedical, agricultural, and environmental sciences. The impact of artificial marking on experimental results is rarely explicitly considered despite evidence demonstrating that changes in phenotypic appearance can modify animal behavior and reproductive success. Here we present evidence that artificial marking of individuals within a social group has frequency-dependent effects on the behavior and physiology of domestic fowl (Gallus gallus domesticus). We demonstrate that when only 20 or 50% of individuals within a group were artificially marked, the marked birds received more aggression and had lesser body mass than the unmarked individuals within the same group. Furthermore, in groups in which only a small proportion of the individuals were marked, we report altered plasma epinephrine and dopamine levels in marked individuals. These effects of marking were imperceptible when all birds in a group were marked. This finding has important implications for animal research because, when only a subset of group members is artificially marked and used for data collection, the results obtained may not be representative of the population.

Different effects of individual identification systems on chicken well-being.

Individual identification is a common method used in animal research. This study was designed to examine if commonly used identification systems (i.e., leg bands, wing bands, neck tags, and livestock markers) have different effects on hens' behavioral and physiological homeostasis. At 18 wk of age, hens were paired in all combinations of treatments and control (unmarked hens; n = 10) in a novel cage for 5 trials of 1 h each to test the effects of identification markers on social behaviors. Wing-banded hens tended to exhibit increased feather pecking compared with control hens (P < 0.10), suggesting a slight increase in social stress. No effect of identification treatment was evident on frequency of aggressive behaviors (P > 0.10). At 20 wk of age, absolute fluctuating asymmetry (FA), but not relative FA, of shank length and width was more significant in leg-banded hens (P < 0.05) and tended to be significant in wing-banded hens (P < 0.10), compared with control hens. Asymmetry of the shank is often a result of high stress levels, including social stress. Body weight measured at 20 wk of age showed that hens with leg bands were significantly lighter than control hens (P < 0.05), possibly as a result of decreased access to resources, increased metabolism, or decreased appetite due to elevated stress. Increased absolute FA and decreased BW could be evidence of a disruption of the hens' physiological homeostasis due to increased stress. Hens with leg bands also tended to have lower percentage of heterophils (P < 0.10), indicative of increased stress and reduced immunocompetence. Our findings provide clear evidence of the negative effects of wing and leg band identification systems on hens' well-being, altering both physiological and behavioral homeostasis. Without knowledge of the effects, the use of individual identification systems could lead to misinterpretation of experimental results.

Serotonergic mediation of aggression in high and low aggressive chicken strains.

Serotonin (5-HT) regulates aggressive behavior via binding to its receptors, such as 5-HT1A and 1B, in humans and rodents. Here we investigate the heritable components of 5-HT regulation of aggressiveness in chickens, utilizing 3 distinct genetic strains. In this study, we used 2 divergently selected strains (high and low group productivity and survivability, respectively; HGPS and LGPS) and a third strain, Dekalb XL (DXL), an aggressive out-group. Hens were paired within the same strain. At 24 wk of age, the subordinate of each pair received a daily i.p. injection of NAN-190 (0.5 mg/kg, a 5-HT1A antagonist), GR-127935 (0.5 mg/kg, a 5-HT1B antagonist), or saline (control) for 5 consecutive days. Frequency of aggressive behaviors was increased in the hens of DXL and LGPS treated with 5-HT1A antagonist and in the HGPS hens treated with 5-HT1B antagonist. The 5-HT1B antagonist-treated HGPS hens and 5-HT1A antagonist-treated LGPS hens also displayed increased feather pecking, but neither antagonist had an effect on feather pecking of DXL hens. This may suggest that multiple mediating factors alter feather pecking behaviors. Among the controls, LGPS hens have higher epinephrine levels than HGPS or DXL hens, indicative of the inferior stress-coping ability of LGPS hens. Treatment with 5-HT1B antagonist reduced epinephrine in LGPS hens but not in DXL or HGPS hens, suggesting a role of 5-HT1B in stress regulation in LGPS hens. The results provide evidence for different heritable serotonergic mediation of aggressive behaviors and stress coping in chickens.

Streamwater acid-base chemistry and critical loads of atmospheric sulfur deposition in Shenandoah National Park, Virginia.

A modeling study was conducted to evaluate the acid-base chemistry of streams within Shenandoah National Park, Virginia and to project future responses to sulfur (S) and nitrogen (N) atmospheric emissions controls. Many of the major stream systems in the park have acid neutralizing capacity (ANC) less than 20 microeq/L, levels at which chronic and/or episodic adverse impacts on native brook trout are possible. Model hindcasts suggested that none of these streams had ANC less than 50 microeq/L in 1900. Model projections, based on atmospheric emissions controls representative of laws already enacted as of 2003, suggested that the ANC of those streams simulated to have experienced the largest historical decreases in ANC will increase in the future. The levels of S deposition that were simulated to cause streamwater ANC to increase or decrease to three specified critical levels (0, 20, and 50 microeq/L) ranged from less than zero (ANC level not attainable) to several hundred kg/ha/year, depending on the selected site and its inherent acid-sensitivity, selected ANC endpoint criterion, and evaluation year for which the critical load was calculated. Several of the modeled streams situated on siliciclastic geology exhibited critical loads <0 kg/ha/year to achieve ANC >50 microeq/L in the year 2040, probably due at least in part to base cation losses from watershed soil. The median modeled siliciclastic stream had a calculated critical load to achieve ANC >50 microeq/L in 2100 that was about 3 kg/ha/year, or 77% lower than deposition in 1990, representing the time of model calibration.

Developing seasonal ammonia emission estimates with an inverse modeling technique.

Significant uncertainty exists in magnitude and variability of ammonia (NH3) emissions, which are needed for air quality modeling of aerosols and deposition of nitrogen compounds. Approximately 85% of NH3 emissions are estimated to come from agricultural nonpoint sources. We suspect a strong seasonal pattern in NH 3 emissions; however, current NH3 emission inventories lack intra-annual variability. Annually averaged NH 3 emissions could significantly affect model-predicted concentrations and wet and dry deposition of nitrogen-containing compounds. We apply a Kalman filter inverse modeling technique to deduce monthly NH3 emissions for the eastern U.S. Final products of this research will include monthly emissions estimates from each season. Results for January and June 1990 are currently available and are presented here. The U.S. Environmental Protection Agency (USEPA) Community Multiscale Air Quality (CMAQ) model and ammonium (NH4+) wet concentration data from the National Atmospheric Deposition Program (NADP) network are used. The inverse modeling technique estimates the emission adjustments that provide optimal modeled results with respect to wet NH4+ concentrations, observational data error, and emission uncertainty. Our results suggest that annual average NH 3 emissions estimates should be decreased by 64% for January 1990 and increased by 25% for June 1990. These results illustrate the strong differences that are anticipated for NH3 emissions.

Dialysis adequacy indices in high membrane transporters treated with short-dwell peritoneal dialysis.

Treatment of high-membrane transporters with continuous ambulatory peritoneal dialysis (CAPD) is associated with ineffective ultrafiltration, increased dialysate protein loss, lower serum albumin levels, and lower protein catabolic rates, suggesting development of inadequate dialysis. The use of short-dwell nightly intermittent peritoneal dialysis (NIPD) and daytime ambulatory peritoneal dialysis (DAPD) has not been evaluated. Patients with inadequate ultrafiltration secondary to rapid membrane transport [peritoneal equilibration test (PET) confirmation] were managed with NIPD and DAPD (group A, n = 32) and compared to patients on CAPD and continuous cycling peritoneal dialysis (CCPD) (group B, n = 53) after at least 3 months of therapy. Groups A and B were similar in age, gender, diabetic status, prestudy months on peritoneal dialysis (PD), and residual renal function. No significant differences were observed between the groups with respect to serum albumin, daily protein loss, normalized protein catabolic rate (PCRN), or weekly KT/V urea indices. Diabetics demonstrated lower levels of serum albumin and PCRN than nondiabetics while maintaining equivalent KT/V urea indices. Reassessment of patients 6 months later also revealed no differences in outcome measures between group A (n = 20) and group B (n = 36). High transporters treated with NIPD and DAPD appear to have similar dialysate protein loss, adequacy, and nutrition indices when compared to patients on CAPD and CCPD. Future studies will determine if delivery of higher target small-solute clearances benefits patients on NIPD/DAPD as contrasted with continuous PD modalities (CAPD/CCPD), or diabetics compared to nondiabetics.

Short-dwell peritoneal dialysis: increased use and impact on clinical outcome.

We reviewed 216 patients on peritoneal dialysis over a 3-year period to assess the effects on patient outcome of short-dwell dialysis (SDD), defined as dwell time below 4 hours with a daily dry (empty peritoneum) interval. Forty-nine patients (23%) required SDD for improved management of ultrafiltration failure (82%), effective blood pressure control (8%), abdominal wall hernia (4%), hydrothorax (4%), and patient convenience (2%). Ultrafiltration failure was recognized as the inability to achieve resolution of clinical overhydration, confirmed by the peritoneal equilibration test (PET), demonstrating high membrane glucose transport (absorption) and observed retention of dialysate volume. Daytime ambulatory peritoneal dialysis (DAPD) was used by 69% of patients and nightly peritoneal dialysis (NPD) with cyclers by 31%. Only one patient (hydrothorax) transferred to hemodialysis. Observations include sustained hydration and blood pressure control in all patients with maintenance of biochemical dialysis adequacy, less reliance on very hypertonic solutions, an increase in dry weight in 25% of patients, decreased use of antihypertensive agents, effective management of hernia and hydrothorax in 3 of 4 patients, and satisfactory patient tolerance of DAPD and NPD regimens, and daily dry intervals. Factors promoting SDD include improved understanding of PET studies, use of disconnect systems, and improvement in cycler design. We anticipate increasing use of SDD as recognition of its usefulness and application techniques expands.

Pre-spiking dialysate bags: improved peritonitis prevention in patients on CAPD.

We review experience with 238 patients over 5.5 years to determine the impact of techniques of spiking dialysis bags in advance of their use (pre-spiking) on peritonitis incidence. Our two units provide peritoneal dialysis therapies only with liberal patient acceptance policies. The Y-set was used almost exclusively over the last 4 years (192/238 patients), peritonitis rate 1:31.5 patient-months (99 episodes/3,122 months). Nineteen patients spiked each exchange, 23 episodes/282 months, 1:12.3; 173 pre-spiked 1-14 days in advance using Y-set and compact exchange device (CXD), 76 episodes/2,840 months, 1:37.4. Peritonitis rates did not worsen with increased pre-spiking intervals: 1 day, 1:16.2; 2-6 days, 1:47.9; 7 days, 1:62.2; 8-14 days, 1:34.3. Similarly, pre-spiking in CCPD patients at 10 day intervals (4 patients) yielded a peritonitis rate of 1:19. We conclude that pre-spiking dialysis bags using the Y-set and CXD promotes significant peritonitis prevention. By spiking at less frequent intervals, technical performance improves, exchanges are simplified and done under more flexible circumstances. Participation by patient-assistants is facilitated. Transfer from CAPD to CCPD is decreased. Low peritonitis rates contribute to excellent patient acceptance and retention. The potential CAPD-eligible population is broadened.