Cross-sectional survey of surgical techniques used to perform dog and cat spays in New Zealand veterinary practice.

Aims: To describe the variation in surgical techniques used by veterinarians to perform routine dog and cat spays in first-opinion veterinary practice in New Zealand, and how these techniques differed with the number of years since the veterinarian graduated.Methods: A cross-sectional survey of veterinarians registered to practice in New Zealand was conducted online between 1 April and 30 May 2018. Respondents were asked their year of graduation and about the procedures, they would use to perform a routine spay of a healthy, 5 kg, young adult, female domestic shorthair cat, and a healthy, 20 kg, young adult, female mixed-breed dog. The number of years since graduation was calculated by subtracting the reported year of graduation from 2018.Results: Overall, 282 respondents provided details about dog spays, and 361 about cat spays, and the median number of years since graduation was 14 (min 0, max 50). Only 54/282 (19.1%) respondents performing dog spays and 43/361 (11.9%) performing cat spays wore a surgical cap, gown, mask, and gloves. For dog spays, 278 (98.6%) respondents used a ventral midline approach and 147 (52.1%) used manual exteriorisation of the uterus. Most used two clamps (168; 59.6%) and used two encircling ligatures (152; 53.9%) for removal of the uterus. For cat spays, 254 (70.4%) respondents used a ventral midline approach and 313 (86.7%) used a spay hook for exteriorising the uterus. Most used two clamps (250; 69.3%) with one encircling ligature (213; 59.0%) for removal of the uterus. Simple interrupted external or intradermal patterns were mostly used for skin closure for both dog and cat spays. For cat spays, the percentage of respondents using the ventral midline approach decreased with increasing years since graduation (p < 0.001). For both dog and cat spays, the percentage of respondents using two encircling ligatures and transfixation ligation of the uterus, and using a simple continuous suture pattern for the closure of the abdomen, decreased with number of years since graduation (p < 0.05).Conclusions and clinical relevance: Veterinarians responding to this survey used a wide range of techniques to perform routine dog and cat spays, some of which were associated with the number of years since graduation. It may be beneficial to provide veterinarians with resources to reflect on their current approaches for performing routine spays. However further research is needed to determine whether any surgical techniques are superior to others.

Outcome of secondary intention healing of full thickness lower eyelid defects in dogs.

OBJECTIVES: To assess healing of the canine lower eyelid without anatomical reconstruction. MATERIALS AND METHODS: Retrospective case series of three client-owned dogs with lower eyelid defects. These dogs that underwent debridement of lower eyelid wounds that were left to heal by secondary intention were assessed for anatomical, functional and aesthetic outcomes. RESULTS: Two of the cases had previously undergone tumour resection with a lip-to-lid reconstruction and, following flap failure, developed a full thickness defect. The third dog presented with a traumatic laceration. Each dog lost approximately 70 to 90% of the lower eyelid margin. Two received topical antimicrobial eye drops after debridement, while the third dog required no further treatment. Follow-up periods of 3 years, 15 months and 4 months were available. All owners were satisfied with the cosmetic outcome and provided pictures. One owner reported epiphora but no other ophthalmic complications occurred. CLINICAL SIGNIFICANCE: The result of this small case series supports the notion that not all lower eyelid injuries or tumour resections require anatomical reconstruction. Selected cases can be left to heal by secondary intention with minimal post-operative complications.

Experience and confidence of final year veterinary students in performing desexing surgeries.

AIMS: To describe the level of experience and confidence of veterinary students in performing canine and feline desexing procedures at the end of their final clinical year. METHOD: A cross-sectional survey was conducted with veterinary students at Massey University in November 2017 after completion of their final clinical year. The questions included career plans after graduation, number of assisted and unassisted desexing procedures performed, approximate time to complete desexing surgeries, level of confidence with different aspects of desexing surgeries, what aspects of their desexing surgery training were most helpful, and what could be done to improve training in desexing surgical skills in veterinary school. RESULTS: The survey was completed by 70/95 (74%) students in their final clinical year. Among respondents, 55/70 (70%) had performed >2 unassisted feline neuters before graduation. However 38/70 (54%) students had never performed an unassisted feline spay, 31/70 (44%) had never performed an unassisted canine neuter, and 44/70 (63%) students had never performed an unassisted canine spay. The median reported times to complete a feline neuter, feline spay, canine neuter, and canine spay were 9, 40, 30 and 60 minutes, respectively. The median level of confidence for these procedures were 9, 6, 7 and 5 (on a scale from 1=least confident to 10=most confident), respectively. The reported time to complete procedures and the confidence in performing procedures did not change markedly with increasing total number of procedures performed. Students were most concerned about their ability to perform the desexing procedures in a reasonable amount of time and to prevent post-operative bleeding from occurring. Students were least concerned with their ability to manage post-operative pain in patients and to select the appropriate suture material. Free-text comments revealed that 62/70 (89%) students wanted more hands-on surgical experience prior to graduation. CONCLUSION AND CLINICAL RELEVENCE: Many students are currently completing veterinary school with limited experience and low confidence with performing routine canine and feline desexing procedures. Further research is needed to identify the most effective ways for addressing this issue within the constraints of the veterinary curriculum and teaching hospital resources.

A survey of dog and cat anaesthesia in a sample of veterinary practices in New Zealand.

AIMS: To survey current anaesthesia practices for dogs and cats in small and mixed animal practices in New Zealand in order to improve anaesthesia education. METHODS: A questionnaire was sent to 440 small and mixed animal practices, including questions regarding the type of practice, preanaesthetic examination, anaesthetic drugs and management, anaesthetic machines, monitoring and topics of interest for continuing professional development. RESULTS: Responses were obtained from 113/440 (26%) practices, with 78 (69%) respondents from small and 35 (31%) from mixed animal practices. A preanaesthetic physical examination was carried out by >95% of respondents and premedication was usually given to dogs (112/113; 99%) and cats (95/113; 85%). Acepromazine was the preferred sedative for dogs and cats, with morphine or buprenorphine. Propofol and alfaxalone were the preferred induction agents, and isoflurane was preferred for maintenance in both dogs and cats. A venous catheter was usually placed for anaesthesia in dogs (59/113; 52%), but less so in cats (39/113; 35%). Perioperative fluid was administered at 10 mL/kg/hour by 62/110 (56%) respondents. Intubation was usually used for anaesthesia in dogs (111/112; 99%), and cats (87/112; 78%). Almost 40% of respondents usually administered supplementary oxygen if patients were not intubated. Local analgesia was used by 69/111 (88%) respondents sometimes or always if applicable. Morphine or buprenorphine, and meloxicam were common choices for post-operative analgesia after neuter surgery in dogs and cats. A semiclosed (non-rebreathing) system was used in animals weighing <10 kg, and a Mapleson E or F non-rebreathing circuit was used by 66/109 (61%) practices. Only 15/111 (14%) practices had a ventilator in their practice. A dedicated anaesthetist was usually used by 104/113 (92%) practices, and apnoea alarms, pulse oximeters, thermometers and oesophageal stethoscopes were the main monitoring devices available in practices. Loco-regional block, pain management, and anaesthetic drugs were the main topics of interest for continuing education. CONCLUSIONS AND CLINICAL RELEVANCE: Responses by the veterinarians taking part in this survey indicated that they had a reasonably good standard of anaesthetic practice. A physical examination was carried out preanaesthesia, and premedication including analgesia was routinely administered to most patients. A dedicated anaesthetist usually monitored patients and most respondents reported they had access to basic anaesthetic monitoring equipment. Areas where changes could lead to improved anaesthetic practice were increased use of I/V catheterisation, endotracheal intubation, and supplementary oxygen, and reduced I/V fluid rates.

Kinetics of Plasma Cell-Free DNA and Creatine Kinase in a Canine Model of Tissue Injury.

BACKGROUND: Cell-free DNA (cfDNA) comprises short, double-stranded circulating DNA sequences released from damaged cells. In people, cfDNA concentrations correlate well with disease severity and tissue damage. No reports are available regarding cfDNA kinetics in dogs. OBJECTIVES/HYPOTHESIS: Cell-free DNA will have a short biological half-life and would be able to stratify mild, moderate, and severe tissue injury. Our study aims were to determine the kinetics and biological half-life of cfDNA and to contrast them with those of creatine kinase (CK). ANIMALS: Three groups of 10 dogs undergoing open ovariohysterectomy, surgery for cranial cruciate ligament rupture (CCLR), or hemilaminectomy. METHODS: Plasma for cfDNA and CK analysis was collected at admission, at induction of anesthesia, postsurgery (time 0) and at 6, 12, 24, 36, 48, 60, and 72 hours after surgery. RESULTS: The biological half-life of plasma cfDNA and CK were 5.64 hours (95% confidence interval [CI 95], 4.36-7.98 hours) and 28.7 hours (CI95, 25.3-33.3 hours), respectively. In the hemilaminectomy group, cfDNA concentrations differed significantly from admission at 6-12 hours after surgery. Creatine kinase activity differed among the surgical groups and reached a peak 6 hours after surgery. In the ovariohysterectomy and CCLR groups, plasma CK activity 72 hours after surgery did not differ from admission activity of the ovariohysterectomy group. In contrast, in the hemilaminectomy group, plasma CK activity after 72 hours did not return to the ovariohysterectomy group admission activity. CONCLUSIONS AND CLINICAL IMPORTANCE: Plasma CK activity has a longer biological half-life than previously thought. In contrast to plasma CK activity, cfDNA has a short half-life and could be a useful marker for peracute severe tissue injury.

Micro- and nano-patterned elastin-like polypeptide hydrogels for stem cell culture.

We show that submicron-sized patterns can be imprinted into soft, recombinant-engineered protein hydrogels (here elastin-like proteins, ELP) by transferring wavy patterns from polydimethylsiloxane (PDMS) molds. The high-precision topographical tunability of the relatively stiff PDMS is translated to a bio-responsive, soft material, enabling topographical cell response studies at elastic moduli matching those of tissues. Aligned and unaligned wavy patterns with mold periodicities of 0.24-4.54 µm were imprinted and characterized by coherent anti-Stokes Raman scattering and atomic force microscopy. The pattern was successfully transferred down to 0.37 µm periodicity (width in ELP: 250 ± 50 nm, height: 70 ± 40 nm). The limit was set by inherent protein assemblies (diameter: 124-180 nm) that formed due to lower critical solution temperature behavior of the ELP during molding. The width/height of the ELP ridges depended on the degree of hydration; from complete dehydration to full hydration, ELP ridge width ranged from 79 ± 9% to 150 ± 40% of the mold width. The surface of the ridged ELP featured densely packed protein aggregates that were larger in size than those observed in bulk/flat ELP. Adipose-derived stem cells (ADSCs) oriented along hydrated aligned patterns with periodicities ≥0.60 µm (height ≥170 ± 100 nm), while random orientation was observed for smaller distances/amplitudes, as well as flat and unaligned wavy ELP surfaces. Hence, micro-molding of ELP is a promising approach to create tissue-mimicking, hierarchical architectures composed of tunable micron-sized structures with nano-sized protein aggregates, which opens the way for orthogonal screening of cell responses to topography and cell-adhesion ligands at relevant elastic moduli.

EFFECTS OF A SEASON OF SUBCONCUSSIVE CONTACT ON CHILD- SCAT3 SCORES IN 8-12 YEAR-OLD MALE ATHLETES.

BACKGROUND: Each year, over 173,000 children and adolescents visit emergency departments due to sports and recreation related concussions, an increase of 60% over the last decade due to the rise in the number of children participating in sport. While numerous authors have sought to address the epidemiology of concussions across multiple age groups who participate in contact sports, a recent review of literature did not reveal a substantial amount of published articles that addressed the issue of subconcussive contact. Multiple tools have been developed to assess acute episodes of concussion. Among the assessment protocols many include an assessment of balance, short and long term memory recall, and balance. The Child-SCAT3 was designed specifically to evaluate concussions in children 5-12 years of age. OBJECTIVE: The purpose of this study was to determine the effect of a season of subconcussive contact on Child-SCAT3 scores in 8-12 year old males compared to their age matched peers who participated in non-contact sports. A secondary purpose was to evaluate how scores of the sub- components of the Child-SCAT3 compare between contact and non-contact athletes. DESIGN: A prospective cohort study was performed of 71 male athletes (58 football, 13 baseball) ages 8-12 (contact mean age 10.30 years, SD 1.20; non-contact mean age 10.03 years, SD 1.26) over the course of a season. METHODS: Portions of The Child-SCAT3 were administered and scored in pre-adolescent athletes prior to and following a season of participation in football (contact sport group) and baseball (non-contact sport group). The outcome measures of interest included the portions related to Cognitive ability, Balance, and Coordination. RESULTS: No statistically significant differences were found in group, time or time and group interaction for any of the utilized portions of the Child-SCAT3. Statistically significant differences were found between groups for preseason cognitive orientation and postseason immediate memory. Cognitive orientation and coordination were also found to be statistically significantly improved across both groups over the course of the season. LIMITATIONS: This study was potentially limited by the number of control subjects tested. CONCLUSIONS: A season of subconcussive contact in football was not detrimental to cognitive and balance scores on the Child-SCAT3. LEVEL OF EVIDENCE: 3.

Rayleigh anomaly-surface plasmon polariton resonances in palladium and gold subwavelength hole arrays.

Surface plasmon polaritons (SPPs) and Rayleigh anomalies (RAs) are two characteristic phenomena exhibited by periodic grating structures made of plasmonic materials. For Au subwavelength hole arrays, SPPs and RAs from opposite sides of the film can interact under certain conditions to produce highly intense, narrow spectral features called RA-SPP resonances. This paper reports how RA-SPP effects can be achieved in subwavelength hole arrays of Pd, a weak plasmonic material. Well-defined resonances are observed in measured and simulated optical transmission spectra with RASPP peaks as narrow as 45 nm (FWHM). Dispersion diagrams compiled from angle-resolved spectra show that RA-SPP resonances in Pd hole arrays shift in wavelength but do not decrease significantly in amplitude as the excitation angle is increased, in contrast with RA-SPP peaks in Au hole arrays. The apparent generality of the RA-SPP effect enables a novel route to optimize resonances in non-traditional plasmonic media.

In vitro hypoxia differentially affects constriction and relaxation responses of isolated pulmonary arteries from broiler and leghorn chickens.

Under normoxic conditions in vitro, isolated pulmonary arteries from broilers exhibit reduced endothelium-dependent relaxation responses when compared with Leghorns. In vivo, hypoxia increases the susceptibility of broiler chickens to pulmonary hypertension syndrome (PHS), whereas Leghorns are considered resistant to PHS. Because L-arginine supplementation decreases the incidence of PHS in vivo and improves the relaxation responses of broiler isolated pulmonary arteries in vitro, we hypothesized that in vitro hypoxia would further reduce the relaxation responses of broilers to endothelium-derived nitric oxide (EDNO)-dependent vasodilators and that L-arginine supplementation would alleviate this impairment. As a test of this hypothesis, pulmonary arteries from broiler and Leghorn chickens were isolated and exposed to normoxia or hypoxia in the presence or absence of L-arginine while their constriction and relaxation responses to vasoactive compounds were recorded. In broilers, hypoxia did not affect the constriction responses of isolated pulmonary arteries but decreased EDNO-dependent acetylcholine-induced relaxation responses. In contrast, in Leghorns hypoxia increased endothelin-1-induced vasoconstriction responses and reduced the EDNO-dependent relaxation responses only to the lowest concentration of acetylcholine used. L-Arginine supplementation augmented the relaxation responses to acetylcholine in broilers and Leghorns under normoxia but failed to augment them under hypoxia. Relaxation responses to the NO donor, sodium nitroprusside, were not affected by hypoxia in Leghorns but were increased by hypoxia in broilers. These results suggest that the increased incidence of PHS in broiler chickens reared under hypoxia may be associated with a hypoxia-induced reduction in the synthesis or activity of EDNO in the pulmonary circulation.

Pulmonary artery vasoactivity in broiler and Leghorn chickens: an age profile.

Vascular function plays a preponderant role in the pulmonary changes that occur with maturation, during birth, and in the development of pulmonary hypertension. This study was designed to characterize the changes in vasoactivity occurring in broiler and Leghorn chickens from late embryonic life to 5 wk of age. Pulmonary arteries were isolated from 19- and 20-d-old embryos, hatchlings, and 1-, 2-, 3-, 4- and 5-wk-old chickens of both lines and subjected to KCl (45.4 mM)- and endothelin-1 (10(-7.5) M)-induced vasoconstrictions followed by acetylcholine (ACh; 10(-5), 10(-6) and 10(-7) M)- and papaverine (10(-4) M)-induced vasodilations. Vasoconstrictions were greatest at hatch and rapidly declined thereafter, whereas vasodilations were greatest in 20-d-old embryos except with 10(-7) M ACh. Broilers grew faster than Leghorns and had lower vasodilation responses to all concentrations of ACh at 2 and 5 wk of age. Broilers also had greater right-to-total ventricular weight ratios at 5 wk of age, whereas ratios were greater in Leghorn embryos at 20 d of incubation and at hatch. Thus, for a brief period before hatch there is a significant increase in pulmonary endothelium-dependent vasodilation capacity in the chicken embryo, which may aid in the transition from chorioallantoic to pulmonary respiration. The absence of differences in vasodilator capacity between broilers and Leghorns before hatch suggests that the differences in pulmonary artery relaxation capacity and pulmonary hypertension observed after hatch in broilers are not necessarily acquired during incubation but may be related to rapid growth of the broiler chicken.

Magnetic clusters on single-walled carbon nanotubes: the Kondo effect in a one-dimensional host.

Single-walled carbon nanotubes are ideal systems for investigating fundamental properties and applications of one-dimensional electronic systems. The interaction of magnetic impurities with electrons confined in one dimension has been studied by spatially resolving the local electronic density of states of small cobalt clusters on metallic single-walled nanotubes with a low-temperature scanning tunneling microscope. Spectroscopic measurements performed on and near these clusters exhibit a narrow peak near the Fermi level that has been identified as a Kondo resonance. Using the scanning tunneling microscope to fabricate ultrasmall magnetic nanostructures consisting of small cobalt clusters on short nanotube pieces, spectroscopic studies of this quantum box structure exhibited features characteristic of the bulk Kondo resonance, but also new features due to finite size.

Characterization of fimN, a new Bordetella bronchiseptica major fimbrial subunit gene.

Fimbrial proteins play an important role in the binding of Bordetella bronchiseptica to mammalian cells, an event that is key to the pathogenesis of this organism. The fimbrial phenotype of B. bronchiseptica isolates is usually defined serologically by Fim2 and Fim3 antigens. In this study, a previously unidentified fimbrial gene, fimN, was cloned and sequenced. The identity of fimN is based on several observations. The predicted FimN protein has 59.4 and 52. 2% homology with B. bronchiseptica Fim2 and Fim3, respectively, and is similar in size to these fimbriae. fimN, expressed as a recombinant protein, is recognized by mAb prepared against Fim2 from Bordetella pertussis. The fimN promoter region contains a stretch of cytosine residues similar in length to those of other fimbrial genes expressed by Bordetella species. It also has an activator binding region, upstream from the C-stretch, that closely resembles a corresponding bvg regulated region in fim2, fim3, and fimX. The fimN gene was isolated from a cosmid prepared with B. bronchiseptica genomic DNA that restored normal properties of cellular adhesion to an adhesion deficient strain of B. bronchiseptica. As such, FimN may be a previously overlooked fimbrial antigen and may play an important role in the pathogenicity of B. bronchiseptica.

Echocardiographic study of pulmonary hypertension syndrome in broiler chickens.

Echocardiography was used to study cardiovascular structure and function during the development of pulmonary hypertension syndrome (PHS) in broiler chickens. Body weight-normalized right and left ventricular diameters at both end-diastole (RVDD, LVDD) and end-systole (RVDS, LVDS) were determined weekly in broilers reared under either normobaric (altitude, 96.7 m) or hypobaric conditions (simulated altitude, 2900 m) until 5 wk of age. Hypobaric-exposed broilers had larger RVDD at 3 and 4 wk of age and larger RVDS at 3, 4, and 5 wk of age. Hypobaric-exposed broilers also had larger LVDD at 2, 3, 4, and 5 wk of age and larger LVDS at 4 wk of age. Right (RVFS) and left ventricular fractional shortening (LVFS) were smaller in hypobaric- vs. normobaric-exposed broilers at 3, 4, and 5 wk of age and at 4 wk of age, respectively. Among hypobaric-exposed birds, PHS-positive (+) broilers had larger RVDD and RVDS than PHS-negative (-) broilers on week 3 and on weeks 1 and 3 after hypobaric exposure, respectively. PHS-positive (+) broilers also had smaller RVFS on week 1 after hypobaric exposure. Electrocardiographic and post-mortem data indicated that PHS+ broilers also developed right ventricular hypertrophy when compared with PHS-negative (-) broilers. These results are consistent with the hypothesis that PHS develops as a result of pulmonary hypertension and cardiac overload and suggest that PHS+ broilers have a greater and more persistent reaction to hypoxia than PHS- broilers.

Proliferative gingival lesion in a cat with disseminated cryptococcosis.

A case of disseminated cryptococcosis with oral, pulmonary, and cutaneous manifestations is described in an eleven-year-old Siamese cat. Marked clinical improvement was noted 2-months following appropriate antifungal therapy. A review of disseminated cryptococcosis and the oral manifestations of fungal disease are provided.

Stapler-facilitated rectal eversion.

Sphincter-preserving procedures have come to play an increasingly important role in colon and rectal surgery. In certain situations, rectal eversion can be an invaluable aid in performing a sphincter-saving operation. We present a new method to evert the rectum using the curved circular stapler.

Application of phonocardiography for detecting hypoxia-induced cardiovascular adaptation in the chicken.

Phonocardiography was evaluated as a noninvasive technique for diagnosis of cardiovascular adaptation and disease in broiler chickens. Heart sounds (HSs) were compared in a fast-growing (FG) commercial broiler line that is highly susceptible to chronic right heart failure resulting from pulmonary hypertension syndrome (PHS) and in a non-selected slow-growing (SG) broiler line that is resistant to PHS. HSs were analyzed in broilers reared in hypobaric hypoxia (HYP) and normobaric (CON) conditions. PHS was induced by a combination of embryonic hypoxia and HYP exposure. HSs were recorded with a microphone placed at the thoracic inlet of each chicken. Electrocardiograms were used to mark the sampling interval for the first, second, and total HS. Digitized HS signals were analyzed for peak frequency, mean peak frequency, and band width. Birds were examined for PHS lesions when 6 wk of age, at the end of each experiment. HSs were compared by line and treatment (Experiment 1) or by treatment and week (Experiment 2). In addition, HS frequencies were analyzed within the HYP treatment group for differences between birds with severe or no gross PHS lesions. HS frequencies generally decreased with age and were also lower in the FG than the SG line. Hypobaric exposure decreased all HS frequencies in the SG line and components of the first HSs in the FG line. The SG line did not develop gross lesions of PHS. In the FG line, significant differences in HS frequencies were observed between HYP and CON groups but not between PHS- and PHS+ broilers. Frequency changes described in humans with PHS were not observed. Further development to maximize the resolution of the HS waveforms and improved matching of the sampling interval to the electrical or hemodynamic output of the chicken heart may allow its use as a diagnostic tool for differentiating broilers with normal cardiac function or physiologic adaptation from those with cardiovascular disease.

Pulmonary artery endothelium-dependent vasodilation is impaired in a chicken model of pulmonary hypertension.

Among chicken strains, broilers are prone to pulmonary hypertension, whereas Leghorns are not. Relaxations to endothelium-dependent (ACh, A23187) and endothelium-independent [sodium nitroprusside (SNP), papaverine (PPV)] vasodilators were compared in preconstricted pulmonary artery (PA) rings from these chicken strains. ACh (10(-7), 10(-6), and 10(-5) M)- and A23187 (10(-6) and 10(-5.5) M)-induced relaxations were smaller (P < 0.05) in broilers than Leghorns. N(G)-nitro-L-arginine methyl ester (10(-3.5) M) caused similar reductions in ACh-induced relaxations in both strains. L-Arginine (10(-4) M) enhanced ACh-induced relaxations more in broilers than Leghorns. Relaxations to 10(-10)-10(-6) M SNP did not differ between strains, but were greater (P < 0.05) in broilers than Leghorns at higher concentrations (10(-5) and 10(-4) M). PPV (10(-4) M)- and SNP (10(-4) M)-induced maximal relaxations were greater in broilers than in Leghorns (176.2 +/- 14.7 vs. 120.9 +/- 14.7% and 201.3 +/- 7.8 vs. 171.2 +/- 10.7%, respectively, P < 0.05). Broiler PA rings appear to have increased intrinsic tone and reduced endothelium-derived nitric oxide activity, both of which may contribute to the susceptibility of broiler chickens to pulmonary hypertension.

Echocardiographic evaluation of cardiac structure and function in broiler and Leghorn chickens.

This study was conducted to validate echocardiography in chickens, and to compare cardiac structure and function between broiler and Leghorn chickens. Diameters of the right and left ventricles, and thicknesses of the left ventricular free wall and the interventricular septum were measured echocardiographically in 5- and 7-wk-old chickens from both lines. Images were obtained from minimally restrained, standing birds using a 7.5 MHz probe placed in a parasternal position. End-systolic and end-diastolic echocardiographic measurements were compared with post-mortem measurements of the same variables. Comparisons resulted in correlation coefficients greater than 0.70 between in vivo (echocardiographic) and post-mortem measurements of the same variables, with post-mortem measurements more closely resembling end-diastolic echocardiographic measurements. After being normalized to body weight, post-mortem myocardial thicknesses, aortic and left ventricular diameters, heart weight at 5 wk of age, and left ventricular weight at 7 wk of age were smaller in broiler than in Leghorn chickens. Echocardiographic parameters, including ventricular wall thicknesses, ventricular diameters, and left ventricular fractional shortening, were also smaller in the broiler chicken. Right ventricular fractional shortening did not differ between the chicken lines. These results indicate that echocardiography is a useful noninvasive technique for in vivo evaluation of cardiac structure and function in the chicken, and that broiler chickens have a relatively smaller structural and functional heart than Leghorn chickens.

Experimental reduction of eggshell conductance during incubation. I. effect on the susceptibility to ascites syndrome.

Two hundred-four fertile broiler chicken eggs were obtained from a commercial source and divided into three equal groups. On day 1 of incubation, 68 eggs were selected randomly and four strips of vinyl tape were applied to the shell below the air cell (tape-day 1) to reduce eggshell conductance. This procedure was repeated with an additional group of 68 eggs on day 14 (tape-day 14). Sixty-eight eggs were incubated without treatment, as controls. One week after hatch, 20 chickens from each treatment group and control group were placed into a hypobaric chamber (simulated altitude of 2500 m) for 5 weeks. The remaining chickens in each group were maintained under normobaric conditions. The hematocrit and the mean frontal resultant electrical vector (MRV) of the heart were measured following 1 week, 3 weeks, and 5 weeks of hypobaric or normobaric exposure. Surviving chickens were euthanized at the end of 5 weeks. The weight ratio of right ventricle to left ventricle plus septum (the hypertrophy index [HI]) and the cardiac index, the HI divided by body weight, were determined. All mortality during the study was subjectively scored for the presence of ascites syndrome lesions. The percentage of chickens dying during, or exhibiting ascites syndrome at the completion of, the 5-week hypobaric exposure was 16.7%, 66.7%, and 58% for control, tape-day 1, and tape-day 14 treatments, respectively. MRV values of birds following hypobaric exposure were significantly different between treatment and control groups of the hypobaric exposure and between the two tape treatments. These results suggest that reducing conductance of the eggshell during incubation significantly potentiates the development of ascites syndrome in the broiler chicken.

Laying hen responses to acute heat stress and carbon dioxide supplementation: II. Changes in plasma enzymes, metabolites and electrolytes.

Exposure of laying hens to an acute heat stress period (38 degrees C) produced a decrease (P < or = 0.05) in blood plasma magnesium compared with pre-heat stress (23 degrees C) levels. Blood plasma glucose, alkaline phosphatase, total protein, uric acid and creatinine were not changed (P > or = 0.05) by exposure to 38 degrees C compared with the first 23 degrees C exposure. Inorganic phosphorus, calcium, potassium and sodium levels were not affected by acute heat-stress exposure or carbon dioxide addition. These results suggest that acute heat stress had no dramatic effect on plasma enzymes, metabolites and electrolytes of laying hens.