Effects of in ovo injection of organic selenium on the hatchability of broiler breeder hen eggs and resulting chick physiology and performance

BACKGROUND

Selenium is an essential mineral for poultry. The conflicting reports about its in ovo injection are the justification for the more detailed investigation.

OBJECTIVES

The aim of this study was to investigate the effects of in ovo injection of organic selenium on the hatching traits of broiler chickens and their performance.

METHODS

Three hundred and twenty eggs of Ross 308 strain with an average weight of 65 g and 160 chicks were randomly divided into 4 treatment groups (each with 8 replicates of 10 eggs each for hatching parameters and 4 replicates of 10 chicks for broiler farming parameters): negative control (no injection), positive control (in ovo injection of 0.272 mL of normal saline solution) and 2 selenium treatments (in ovo injection of 2.72 or 5.44 μg of organic selenium). Injection was into the amniotic sac on the 10th day of incubation. Effects of in ovo injection on hatching and performance traits, blood parameters, immune responses, carcass characteristics, meat fatty acid profile, cecal microbial population and selenium consternation in the tibia were measured.

RESULTS

Fewer chicks from the injected treatments hatched than from the negative control group (p < 0.01). However, the injection of selenium increased feed intake and the final weight of the birds (p < 0.01). Blood parameters were also affected. Glucose and cholesterol in experimental treatment chicks was lower than those of the controls (p < 0.01), whereas blood lipoproteins (VLDL, LDL and HDL) and the ratio of cholesterol to HDL was significantly increased in the treatments injected with selenium (p < 0.01). There was no significant difference in the immune response or microbial population between the experimental groups, but carcass components, such as thigh, breast, wing and abdominal fat weight, were significantly greater in the selenium treatments.

CONCLUSIONS

Intra-egg injection of organic selenium produced favourable effects on performance of broiler chickens, although it had no effect on immune response or microbial population. However, the negative effect on hatching of chickens needs to be prevented to result in an acceptable economic return for the producer.

Ultrasound-guided and 'blind' sciatic nerve injection techniques: Comparison in rat cadavers

OBJECTIVE

To compare the success rate and extent of sciatic nerve staining with a bupivacaine-dye solution using two injection techniques: 'blind' or ultrasound-guided approach.

STUDY DESIGN

Prospective, experimental, randomized, cadaveric study.

ANIMALS

Adult female Wistar rat cadavers [n = 24, mass 352 g (323-374)].

METHODS

Each sciatic nerve was randomly allocated to one of two groups: 'blind' (group B) or ultrasound-guided approach (group US) to injection. Following injection of bupivacaine-dye solution (0.1 mL), gross anatomical dissection was performed to visualize nerve staining, categorizing it as either positive or negative. The length of nerve staining was then measured and visual inspection conducted to identify potential nerve damage. Fisher's exact test was used to compare positive or negative nerve staining, and the Wilcoxon signed rank test used to compare the length of nerve staining between groups.

RESULTS

In group B, the bupivacaine-dye solution stained 16/24 sciatic nerves (67% success). In group US, staining was successfully observed in all 24 nerves (100% success, p < 0.004). The length of nerve staining [median (interquartile range)] was 2 (2-3) mm in group B and 5 (4-6) mm in group US (p < 0.001). One sciatic nerve in group B had injectate distributed over 16 mm, suggestive of an intraneural injection. No signs of laceration or nerve damage were visible under 6× magnification in either group.

CONCLUSIONS AND CLINICAL RELEVANCE

The ultrasound-guided approach for sciatic nerve injection demonstrated a higher success rate with superior injectate distribution when compared with the 'blind' approach. Ultrasound guidance is recommended over a 'blind' approach for sciatic nerve block in rats when possible.

Carvacrol in ovo delivery optimization and flow dynamics in broiler chicken eggs

In ovo delivery of carvacrol, the primary active compound in oregano essential oil (OEO) has the potential to enhance gut development in broilers. This study aimed to optimize in ovo application of OEO by investigating day and site of injection and delivery of carvacrol to different embryonic tissues. In Experiment 1, 2 d of injection (embryonic day (E) 12 or 17.5) and 3 sites of injection for OEO (air cell, amniotic fluid, or yolk) were evaluated based on hatchability and posthatching performance. Experiment 2 aimed to examine the impact of combining OEO with the nonionic surfactant polysorbate 80 (p80) at ratios to carvacrol of 0:0, 0:1, 0.5:1, and 1:1 on carvacrol concentration in amniotic fluid, blood, and yolk. The concentration of carvacrol was measured at 3, 6, and 9 h after OEO injection either without (0:1) or with (1:1) p80. Injection of OEO on E12 led to a significant lower hatchability compared to E17.5 (P ≤ 0.01; Δ = 9.2%). Injecting OEO into the air cell, amniotic fluid, or yolk at E17.5 did not significantly affect hatchability and posthatching performance. The highest concentrations of carvacrol found in egg tissues were observed when injected together with surfactant at the 1:1 ratio (P ≤ 0.001; 14.45 µM, 16.64 µM, and 124.82 µM, for air cell, amniotic fluid, and yolk, respectively) compared to the 0:0, 0:1 or 0.5:1 ratios. Carvacrol was highest in the amniotic fluid and blood at the first time point (3 h postinjection) and decreased afterward (P ≤ 0.001), whereas the concentration in yolk remained elevated up to 9 h postinjection. In conclusion, the optimization of the in ovo delivery of carvacrol resulted in that early injection (E12) had negative effects on hatchability and should be avoided. The findings also suggest that using a nonionic surfactant was crucial for an effective delivery of carvacrol in ovo and the migration from amniotic fluid to yolk within 3 h. In addition, carvacrol's persistence in yolk may serve as a route for delivery into the gastrointestinal tract via the yolk stalk during the peri-hatching phase, potentially influencing gut development.

Investigation of the effects of in ovo taurine injection on hatching characteristics and stress reduction potential

BACKGROUND

In ovo application is the process of administering some nutrients or components into the egg. The main purpose of this application is to ensure that some nutrients are provided to chicks with a short incubation period. Few studies were conducted with taurine in fertile eggs; especially, no observation of hatchability and chick quality has been found. In addition, taurine has an anti-stress impact that fights oxidative factors.

OBJECTIVE

To assess the hatchability and chick quality after in ovo taurine administration. To determine the stress that may occur as a result of in ovo application and whether taurine has a stress-reducing effect.

METHODS

A total of 1200 fertile eggs from a 34-week-old broiler breeder (Ross 308) flock were categorized into 4 groups with 75 eggs per replicate: control (uninjected), taurine group (0.30 mL dissolved taurine in distilled water), sham control (sterile distilled water) and perforation (eggs perforated and then waxed). On day 14 of incubation, an in ovo injection was administered to the albumen. Data on hatching parameters and hepatic HSP70 levels were obtained using relevant formulas and western blotting, respectively.

RESULTS

Control chicks exhibited higher hatchability than other groups, with the taurine group showing the lowest hatchability. The HSP70 levels were the highest in the perforation group compared to the control group. An increase of 21.37% in the taurine group and 83.45% in the sham control group was observed compared to the control group.

CONCLUSIONS

The findings suggest that in ovo application may induce increased stress, whereas taurine may have positive effects in mitigating the stress caused by in ovo application.

Investigation of a maxillary nerve block technique in guinea pigs (Cavia porcellus): A cadaveric study comparing two injectate volumes

OBJECTIVE

To investigate and describe an extraoral approach to perform a maxillary nerve block in guinea pigs.

STUDY DESIGN

Prospective, randomized, blinded, descriptive, cadaveric study.

ANIMALS

A total of 14 adult guinea pig cadavers.

METHODS

Two cadavers were used for anatomic dissection and determination of maxillary nerve block approach. A maxillary nerve block via infraorbital approach was then performed in 12 cadavers. A low volume (0.1 mL) or high volume (0.2 mL) of diluted methylene blue injectate was randomly assigned to the right or left side, with the other volume used for the contralateral side. The maxillary nerve was dissected after each injection by an investigator blinded to injectate volume. The region of dye distribution was identified, and the degree of staining assigned an accuracy score (0-2). Nerve coverage was considered adequate if ≥6 mm of circumferential staining was present.

RESULTS

Accuracy evaluation indicated successful dye deposition in 10/12 [2 (0-2), median (range)] injections in the low volume group and 8/12 [2 (1-2)] injections in the high volume group. The majority (79.2%) of injections resulted in adequate nerve staining. There were no statistically significant differences between injectate volumes for accuracy (p = 0.64) or adequacy (p > 0.99) of staining.

CONCLUSIONS

The infraorbital approach is a simple and practical method for maxillary nerve blockade in guinea pigs. An injectate volume of 0.1 mL results in adequate maxillary nerve coverage; however, additional studies are needed to assess the efficacy in clinical use.

In-Ovo injection of melittin into Alexandria chicken eggs: a way for early immune acceleration

This study intended to assess the properties of in-ovo administration of Melittin (MLT) on hatchability, chick yield, hematology, immunological indices and relative organs weight of Alexandria chickens at hatch. A total of 600 eggs with an average weight of (45.12 g), were gathered and split into five groups: a non-injected group or negative control (NC), a saline injection group or positive control (PC), and three concentrations of MLT (5, 10 and 15 µg of MLT per egg, respectively). On day 18 of incubation, eggs from the injection groups were injected into the amniotic fluid from the large end with the in-ovo injection solutions (0.2 ml per egg). Results indicated that 10 µg MLT/egg positively affected the weight and yield of chicks. In addition, our findings indicated that the in-ovo administration with 10 or 15 µg MLT/egg was superior in most of the immunological indicators (spleen and bursa relative weights, immunoglobulins IgG and IgM, T cells and B cells). In conclusion, in order to improve the immune efficiency (early immune acceleration) of Alexandria chicks, which may contribute to offering a significant boost to their future performance, this study suggests injecting eggs with 5 or 10 µg MLT/egg.

Decreasing polymethyl methacrylate bone cement concentration extends working and setting times in vitro

OBJECTIVE

To determine setting and temperature properties of diluted polymethyl methacrylate (PMMA) bone cement in vitro to assess utility for vocal fold augmentation in horses.

SAMPLES

4 dilutions of PMMA equivalent to volumes of 15 mL, 20 mL, 25 mL, and 30 mL PMMA powder (PMMAp) in 10 mL solvent.

METHODS

For each volume PMMAp, setting times (tset), peak temperatures (Tmax), and times to peak temperature (tmax) were determined using a temperature data logger in a 4-mL volume of PMMA. Injectability was assessed in vitro by documenting the force required to inject 0.2 mL PMMA through an 18-gauge 3.5-inch spinal needle attached to a 6-mL syringe at 1-minute intervals. Working time (twork) was calculated from a linear regression of injectability.

RESULTS

Peak temperatures increased with increasing volume of PMMAp: 56 °C, 86 °C, 99 °C, and 101 °C. Times for tset, twork, and tmax were inversely proportional to PMMA concentrations, resulting in tset of 23, 21, 17, and 14 minutes; twork of 22.75, 12.25, 7, and 4 minutes; and tmax of 28, 24, 19, and 16 minutes, respectively, for 15, 20, 25, and 30 mL PMMAp. Pairwise comparisons for all analyses were significant apart from Tmax for 25 and 30 mL PMMAp (P = .96) and twork for 20 and 25 mL PMMAp (P = .06).

CLINICAL RELEVANCE

Decreasing the concentration of PMMA bone cement resulted in longer working times and setting times; however, peak temperatures did not differ between the 2 strongest concentrations. Further research is warranted to quantify diluted PMMA properties for in vivo use for vocal fold augmentation in horses.

Accuracy of drawing up liquid medications by veterinary anaesthetists and nurses

OBJECTIVE

To evaluate the accuracy with which veterinary anaesthetists and nurses of different experience draw up small volumes of liquid.

STUDY DESIGN

Prospective blinded randomized study.

METHODS

A group of seven European College of Veterinary Anaesthesia and Analgesia (ECVAA) diplomates, six ECVAA residents and six anaesthesia nurses participated in the study. For each participant, five target volumes between 0.01 and 1.0 mL were randomly allocated. They were drawn up 20 times in random order using a 1 mL syringe attached to a 23 gauge needle. A total of 1900 measurements were analysed. An investigator filled the syringe and needle dead space with water for injection before each experiment. The change in mass of the syringe once filled to the target volume was used to calculate the actual volume of liquid drawn up.

RESULTS

Large errors were made with measurements < 0.04 mL, so they were excluded from the statistical analysis. There was a significant effect of the target volume (p < 0.001) and of the order (p < 0.01). For each mL increase in the target volume, the absolute error decreased by 4% and from the first to the hundredth withdrawal each participant's absolute error decreased by 1%. The target volume was underestimated in 52.3% of measurements, 42% were overestimated and 5.7% were on target. None of the between-subject predictor variables approached significance.

CONCLUSIONS AND CLINICAL RELEVANCE

Accuracy of veterinary anaesthetists and nurses in drawing up medications decreases as the target volume becomes smaller. Small veterinary patients receive small volumes of anaesthetic drugs with higher risks of overdosing compared with larger dogs. Years of experience and staff grade are not associated with greater accuracy. Large percentage errors may be seen with target volumes less than 0.04 mL. Dilutions are recommended for volumes > 0.19 mL in 1 mL syringe.

Blind Versus Ultrasound-Guided Low-Volume Perineural Injection of Tibial and Fibular Nerves in Equine Cadaver Limbs

Techniques for local anesthesia of the tibial (TN) and superficial and deep fibular nerves (FNs) in horses are well established. Ultrasound-guided perineural blocks can identify the nerve location, reduce the anesthetic volume needed and avoid needle misplacement. The aim of this research was to compare the success of blind perineural injection technique (BLIND) to ultrasound-guided technique (USG). Fifteen equine cadaver hindlimbs were divided into two groups. Perineural injection of the TN and FNs was performed using a mixed solution of radiopaque contrast, saline and food dye. BLIND (n = 8) used 15 mL for the TN and 10 mL for each fibular nerve. USG (n = 7) used 3 mL for the TN and 1.5 mL for each fibular nerve. The limbs were radiographed immediately after injections and sectioned transversally to evaluate the diffusion and presence of the injectate adjacent to the TN and FNs. The presence of dye immediately adjacent to the nerves was considered a successful perineural injection. No statistically significant difference was observed between groups for success. Distal diffusion of injectate following perineural injection of the TN was significantly less for USG compared to BLIND. Proximal, distal and medial diffusion of injectate following perineural injection of FNs was significantly less for USG compared to BLIND. Low-volume USG results in less diffusion but similar success compared to BLIND leaving it up to veterinarian preference when selecting a technique.

The investigation of the effects of vitamin A, vitamin E, and β-carotene plus vitamin E on some fertility parameters in ewes

This study was aimed at investigating the effects of vitamin A (VITA), vitamin E (VITE), and combined β-carotene plus vitamin E (βCAR+VITE) injections on some fertility parameters in ewes. Estrus synchronization was performed by treating the ewes with intravaginal FGA sponges impregnated with 30 mg of fluorogestone acetate. On the days of the insertion and withdrawal of the intravaginal sponges, groups VITA, VITE, and βCAR+VITE were administered with 500 000 IU of vitamin A, 50 mg of vitamin E, and a combination of β-carotene plus vitamin E, respectively. The ewes in the control group (C) were maintained for control purposes. Statistically significant differences were determined between groups VITA and βCAR+VITE, groups VITE and βCAR+VITE, and groups C and βCAR+VITE, as well as groups VITE and C, groups VITA and C for the multiple birth rates. While significant differences were determined between groups VITA and C, groups VITE and C, and groups βCAR+VITE and C for the lambing rates, it was ascertained that the ratio of newborn lambs to delivered ewes (litter size) significantly differed between groups VITA and βCAR+VITE, groups VITA and C, groups VITE and βCAR+VITE, groups VITE and C, and groups βCAR+VITE and C. The highest MDA level and lowest GSH level were determined on day 20 after mating in the control group. In conclusion, it is suggested that both multiple birth rates and litter size can be increased by the combined administration of β-carotene and vitamin E.

Determination of the embryotoxic effect of maropitant using an in ovo model

The aim of this research was to determine the embryotoxic and teratogenic effects and lethal dose (LD50) of maropitant in ovo, using fertile chicken eggs. The study was designed in two stages, CHEST-I and CHEST-II. For CHEST-I, 210 fertile eggs were divided into seven equal groups; control, saline solution and 5 different doses of maropitant (10, 5, 2.5, 1.25, 0.625 mg/kg) injected groups. For CHEST-II, 150 fertile eggs were divided into five equal groups; control, saline solution and 3 different doses of maropitant (8, 6, 4 mg/kg)-injected groups. Eggs were opened on day 21 of incubation. Maropitant did not cause teratogenicity at any dose, while higher embryonic death rates were observed at doses above 4 mg/kg. The LD50 dose of maropitant was determined as 7.24 mg/kg. In conclusion, maropitant should only be used after full consideration of risks and benefits in pregnancy.

Comparison of the efficacy and duration of desensitization of oral structures following injection of a lidocaine-bupivacaine mixture via lateral percutaneous and modified infraorbital approaches in dogs

OBJECTIVE

To compare efficacy and duration of desensitization of oral structures with a lidocaine-bupivacaine mixture administered via a lateral percutaneous or modified infraorbital approach.

ANIMALS

6 healthy adult hound-type female dogs.

PROCEDURES

In this crossover study, dogs were randomized for side (left or right) and maxillary nerve approach (lateral percutaneous or infraorbital), with a 2-week washout period. Dogs were anesthetized, and a 2-mL mixture of 2% lidocaine and 0.5% bupivacaine (50:50 [vol/vol]) was administered with a 22-gauge, 4.5-cm-long catheter inserted through the infraorbital canal (infraorbital approach) or with a shielded stimulating needle to the maxillary nerve (percutaneous approach). Reflex-evoked motor potentials were measured for the maxillary canine tooth, fourth premolar tooth, second molar tooth, and hard palate mucosa ipsilateral to the injected mixture and for the contralateral maxillary canine tooth (control) at three 10-minute intervals before injection (baseline) and at predetermined times after injection for up to 6.7 hours. For each oral structure, the proportion of dogs with desensitization (efficacy) and time to onset and duration of desensitization were compared between approaches.

RESULTS

The proportion of dogs with successful nerve blockade did not significantly differ between infraorbital and percutaneous approaches and among the 4 oral structures. Time to onset of desensitization did not differ between approaches, but duration was significantly longer with the infraorbital approach.

CONCLUSIONS AND CLINICAL RELEVANCE

A modified infraorbital approach with the lidocaine-bupivacaine mixture had similar effects to a lateral percutaneous approach but provided a longer duration of desensitization. Neither approach was universally successful at desensitizing all oral structures.

Investigation of a maxillary nerve block technique in healthy New Zealand White rabbits (Oryctolagus cuniculus)

OBJECTIVE

To investigate use of a candidate maxillary nerve block in rabbits.

ANIMALS

13 healthy New Zealand White rabbits (Oryctolagus cuniculus).

PROCEDURES

In phase 1, the maxillary nerve block procedure was performed in 7 sedated rabbits with 2 volumes (0.25 and 0.5 mL) of a saline (0.9% NaCl)-tissue marker dye solution (1 injection/side by random assignment). Rabbits were euthanized and dissected; numeric scales were used to rate injection accuracy and extent of staining. In phase 2, the nerve block was performed with articaine hydrochloride-epinephrine solution (0.5 mL) on a randomly assigned side in 6 sedated rabbits, with the contralateral side used as a control. Sensory function of the relevant dermatome was tested in triplicate with an algesiometer 0, 30, and 90 minutes after recovery from sedation. Statistical methods were used to compare results between injection volumes (phase 1) and between treated and control sides (phase 2).

RESULTS

In phase 1, dye was in contact with the targeted nerve after 13 of 14 injections. Accuracy and extent of staining did not differ significantly between volumes. In phase 2, algesiometer-applied force tolerance differed significantly between treated and control sides 30 minutes after recovery from sedation (56 to 145 minutes after the nerve block procedure). No adverse effects were detected in either study phase.

CONCLUSIONS AND CLINICAL RELEVANCE

The described technique for a maxillary nerve block was accurate and effective for desensitization of the relevant dermatome as assessed by algesiometry in healthy rabbits. Additional studies are needed to assess use of this procedure in rabbits of other breeds and its efficacy for clinical use. (Am J Vet Res 2020;81:843-848).

Efficacy and duration of effect for liposomal bupivacaine when administered perineurally to the palmar digital nerves of horses

OBJECTIVE

To determine the efficacy and duration of effect for liposomal bupivacaine following perineural administration to the medial and lateral palmar digital nerves of horses.

ANIMALS

9 nonlame mares.

PROCEDURES

For each horse, 2 mL of liposomal bupivacaine (13.3 mg/mL; total dose, 53.2 mg or approx 0.11 mg/kg) or sterile saline (0.9% NaCl) solution was injected adjacent to the medial and lateral palmar digital nerves at the level of the distal aspect of the proximal sesamoid bones of a randomly selected forelimb. Twenty-one days later, the opposite treatment was administered in the contralateral forelimb. A digital algometer was used to measure the mechanical nociceptive threshold (MNT) immediately before and at predetermined times for 48 hours after injection of each treatment. The mean MNT was compared between the 2 treatments at each measurement time.

RESULTS

The mean MNT for the liposomal bupivacaine-treated limbs was significantly greater (ie, the limb was less sensitive) than that for the saline-treated limbs between 30 minutes and 4 hours after treatment injection. Following liposomal bupivacaine administration, 1 horse developed mild swelling at the injection sites that resolved without treatment within 24 hours. No other adverse effects were observed.

CONCLUSIONS AND CLINICAL RELEVANCE

Results suggested that liposomal bupivacaine is another option for perineural anesthesia in horses. Further research is necessary to determine the optimal dose and better elucidate the duration of effect for the drug when used for palmar digital nerve blocks in horses.

Vaccination of Tilapia against Motile Aeromonas Septicemia: A Review

The production of tilapia Oreochromis spp. is rapidly growing throughout the world, but atypical motile aeromonad septicemia (MAS) is a current threat to the tilapia farming industry. The etiological agent of this disease is usually Aeromonas hydrophila. Mortality rates due to MAS are frequently high, resulting in a devastating negative impact on this industry worldwide; therefore, proper control measures regarding both prevention and treatment are necessary. Although vaccines against MAS for tilapia are available, their effectiveness is entirely dependent on the specific strain of problematic bacteria. Until now, whole-cell inactivated A. hydrophila vaccines for tilapia have exhibited the highest level of protection over live attenuated and recombinant vaccines. Among the various vaccine administration systems, only intraperitoneal (i.p.) injections of the A. hydrophila vaccine into tilapia were found to provide prominent immune protection. Vaccine efficacy was primarily measured by using the i.p. injection challenge model and estimating the relative percent survival of the immunized tilapia. Freund's incomplete adjuvant showed to be the most effective for tilapia MAS vaccines. In this review, multiple factors that directly or indirectly influence the efficacy of MAS vaccines for tilapia (adjuvants, challenge models, immunization doses and duration, and size of vaccinated fish) are discussed.

Evaluation of injectate distribution after ultrasound-guided peribulbar injections in canine cadavers

OBJECTIVE

To describe a contrast medium distribution pattern after peribulbar injection in cadavers.

STUDY DESIGN

A cadaveric study.

ANIMALS

A group of eight male dogs and four canine cadaver heads.

METHODS

In phase 1, ultrasound-guided peribulbar injections (1.0 mL dye) were performed in four orbits using a subzygomatic approach. After dissection, the procedure was considered successful if 1) no dye was found in the retrobulbar space, 2) the peribulbar compartment was stained and 3) the dye reached the orbital fissure. In phase 2, using 16 orbits, the same technique was used to inject 0.1 mL kg^-1 contrast medium into (group A, n = 8) or outside (group B, n = 8) the peribulbar compartment. After freezing at -20°C, orbits were imaged using computed tomography, and the contrast medium distribution was analysed.

RESULTS

In phase 1, the procedure was successful in all four eyes. In phase 2, two orbits (one in each group) were removed from the study: one was not injected and the other was injected twice. The contrast medium was found inside the peribulbar compartment in six of seven (85.7%) group A orbits and two of seven (28.6%) group B orbits. In all of these cases, distribution to the orbital fissure, rostral alar foramen, mandibular foramen and inside the skull was observed. The oval foramen was reached in three of seven (42.9%) group A orbits and one of seven (14.3%) group B orbits. In one/seven (14.3%) group A orbits and five/seven (71.4%) group B orbits, the contrast medium was found inside the masseter and temporal muscles, and no distribution towards the aforementioned structures was observed.

CONCLUSIONS AND CLINICAL RELEVANCE

Ultrasound-guided peribulbar injection of 0.1 mL kg^-1 contrast medium in canine cadavers can lead to an extensive distribution of the injectate that reaches the orbital fissure, the rostral alar, oval, and mandibular foramina and can be found intra-cranially.

Impact of galactooligosaccharides delivered in ovo on mitigating negative effects of heat stress on performance and welfare of broilers

Galactooligosaccharides (GOS) delivered in ovo improve intestinal health of broiler chickens. This study aimed to demonstrate the impact of in ovo stimulation with GOS prebiotic on day 12 of egg incubation on performance and welfare traits in broiler chickens. The incubating eggs were divided into 3 groups, based on the substance injected in ovo: 3.5 mg of GOS dissolved in 0.2 mL physiological saline (GOS), 0.2 mL physiological saline (S), or uninjected controls (C). Constant heat stress (HS) was induced on days 32 to 42 post-hatch by increasing environmental temperature to 30°C. Thermoneutral (TN) animals were kept at 25°C. The performance (body weight [BW], daily feed intake [DFI], daily weight gain [DWG], and feed conversion rate [FCR]) were measured and mortality was scored for starter (days 0 to 13), grower (days 14 to 27), and finisher (days 28 to 42) feeding phases. Rectal temperature was scored on days 32 to 42. Food-pad dermatitis (FPD) was scored post-mortem (day 42). GOS increased (P < 0.01) BW on day 42 (2.892 kg in GOS vs. 2.758 kg in C). Heat stress significantly reduced (P < 0.01) final BW (2.516 kg in TN vs. 3.110 kg in HS). During finisher phase, DFI was significantly higher in GOS vs. C (173.2 g vs. 165.7 g; P < 0.05). FCR calculated for the entire rearing period (days 0 to 42) ranged from 1.701 in C to 1.653 in GOS (P < 0.05). GOS improved FCR in HS animals during finisher phase (P < 0.05). Rectal temperature of GOS chickens under HS reached 42.5°C 1 day earlier than C and S (P < 0.05), which suggests that those birds recovered earlier from the high environmental temperature. Heat stress increased (P < 0.05) mortality about 5 times compared to TN during finisher phase (from 1.59% in TN to 7.69% in HS). GOS decreased FPD in TN conditions by 20% (no lesions in 81% in GOS vs. 60% in C). GOS delivered in ovo mitigated negative effects of HS on performance and welfare in broiler chickens.

Effects of stage of broiler embryo development on coccidiosis vaccine injection accuracy, and subsequent oocyst localization and hatchling quality

Control of coccidiosis in broiler chickens continues to pose challenges to commercial poultry producers, especially in an era of increased consumer demand for antibiotic-free broiler production. As a result, coccidiosis vaccines are now commonly used in rotation programs to achieve effective coccidiosis control. Inovocox EM1 vaccine (EM1) is a coccidiosis vaccine that allows for earlier immune acquisition through oocyst cycling, which reduces the effects of wild-type coccidia. The EM1 vaccine is administered to embryonated broiler hatching eggs between 18 and 19 D of incubation (doi). In the U.S., commercial broiler hatcheries vaccinate embryonated eggs at either 18.5 or 19 doi. However, it is unclear whether a difference in embryo age at the time of in ovo injection can impact the actual site of vaccine delivery. In addition, it is unclear where oocysts eventually become localized within the embryo following the in ovo injection of EM1. Therefore, the objective of this study was to determine the effects of stage of embryonic development on the actual deposition site of the EM1 vaccine oocysts when they are in ovo injected and to subsequently investigate the movement and eventual location of EM1 oocysts after in ovo injection. Because all eggs were injected at the same time, a 12-h difference in set time was a means to derive 18.5 and 19.0 incubation age of injection (IAN) treatments. The experimental design was a 3 injection treatment (noninjected, diluent-injected, and vaccine-injected) × 2 IAN factorial. There was a significant main effect of IAN on site of vaccine oocysts delivery, and subsequent hatching chick quality. Qualitative histological evaluation revealed the oral uptake of vaccine oocysts through the amnion, with their subsequent presence in the gizzard and intestinal lumen by 24 to 36 h postinjection. In conclusion, physiological development influenced the site of injection, and oocysts imbibed along with the amniotic fluid in late stage broiler embryos are subsequently transported to the gastrointestinal tract.

Acute pain responses in dairy calves undergoing cornual nerve blocks with or without topical anesthetic

Dairy calves are routinely administered medicines, vaccines, and anesthesia via injection. Although injections are painful, little is known about methods to alleviate this pain. The aim of this study was to determine whether lidocaine-prilocaine cream, a topical anesthetic, reduced calves' pain response to a subcutaneous injection around the cornual nerve. Calves were assigned 1 of 2 treatments: lidocaine-prilocaine cream at the sites of injection (n = 10) or no cream (n = 9). Thirty minutes after treatment, calves received a subcutaneous injection of 2% buffered lidocaine hydrochloride around the left and right cornual nerves. Contrary to our hypothesis, calves that received anesthetic cream beforehand displayed more escape behaviors during the injections than control calves. Both treatments had similarly low amounts of head-related behaviors afterward. Maximum eye temperature did not differ between the calves that received anesthetic cream and control calves, although eye temperature increased over time for both treatments. Heart rate increased during the 30 s following the first injection in both treatments. There were no treatment differences for any heart rate measures over the 5-min period after the first injection (mean heart rate, root mean square of successive differences, high-frequency power, and the ratio of low-frequency power to high-frequency power). These results suggest that cornual nerve blocks with buffered lidocaine are painful and that a lidocaine-prilocaine cream was not only ineffective in reducing this pain but that it may also worsen it.

Influence of injection protocol and measurement technique on computed tomographic assessment of glomerular filtration rate in healthy Beagles

OBJECTIVE To compare values of CT-derived glomerular filtration rate (GFR) determined by 3 contrast-medium injection protocols and 4 measurement techniques in healthy Beagles. ANIMALS 9 healthy Beagles (mean ± SD weight, 13.2 ± 1.6 kg). PROCEDURES Each dog underwent 3 iohexol-injection protocols (700 mg of iodine/kg administered at a constant rate over 20 seconds, 700 mg of iodine/kg administered following an exponentially decelerated injection over 20 seconds, and 350 mg of iodine/kg at a constant rate over 10 seconds) during dynamic, whole renal-volume CT in randomized order with an interval of ≥ 7 days between experiments. Values of GFR determined from Patlak plots derived by use of 4 measurement techniques (standard transverse section, optimized transverse section, dorsal reconstruction, and volume calculation techniques) were compared. RESULTS The measurement technique influenced the mean ± SD GFR results (standard transverse section technique, 2.49 ± 0.54 mL/kg/min; optimized transverse section technique, 2.72 ± 0.52 mL/kg/min; dorsal reconstruction technique, 3.00 ± 0.60 mL/kg/min, and volume calculation technique, 2.48 ± 0.51 mL/kg/min). The lower iodine dose resulted in a significantly higher GFR value (3.00 ± 0.65 mL/kg/min), compared with that achieved with either higher dose administration (constant rate injection, 2.54 ± 0.45 mL/kg/min and exponentially decelerated injection, 2.47 ± 0.48 mL/kg/min). CONCLUSIONS AND CLINICAL RELEVANCE In healthy Beagles, the CT-derived GFR measurements obtained after injection of a full dose of contrast medium were reduced, compared with measurements obtained after injection of a half dose. This finding is important with regard to potential nephrotoxicosis in dogs with impaired renal function and for GFR measurement with CT-contrast medium protocols.

Effect of in ovo injection of raffinose on growth performance and gut health parameters of broiler chicken

The effects of in ovo injection of raffinose (RFO) as a prebiotic on growth performance, relative weight of proventriculus, gizzard, drumstick and breast muscles, and ileum mucosa morphology were examined in Cobb 500 broilers. A total of 240 fertilized eggs were divided into 4 groups: a non-injected with intact shell and 3 levels of RFO solution (1.5, 3.0, and 4.5 mg in 0.2 mL of an aqueous diluents). The RFO solution was injected into the air sac on d 12 of incubation. In total 144 birds were fed a standard diet and management and sacrificed at d 21 post hatch for collection of samples. Total RNA was extracted from the small intestine, and RT-qPCR was performed to quantify mRNA levels of marker genes of immune cells. Injection of RFO had no significant effect (P > 0.05) on d one body weight of chicks. On d 21, the relative weight of the proventriculus, drumstick, breast, and gizzard was not affected (P > 0.05) by RFO. On hatch d, the villus height increased linearly (P < 0.01) with an increasing dose of RFO. Also, an increasing dose of RFO increased the villus height and villus height:crypt depth ratio (P < 0.05) but did not affect the crypt depth on d 21. The expression levels of CD3 and chB6, which are T cell and B cell marker genes, respectively, were significantly enhanced by high dose RFO (4.5 mg). In conclusion, although an increasing dose of RFO in ovo injection did not significantly influence growth performance or slaughter yield of broilers, RFO has the potential of enhancing ileum mucosa morphology and improving immunity in the small intestine, which are indicators of improved gut health.

The In Ovo Feeding Administration (Gallus Gallus)-An Emerging In Vivo Approach to Assess Bioactive Compounds with Potential Nutritional Benefits

In recent years, the in ovo feeding in fertilized broiler (Gallus gallus) eggs approach was further developed and currently is widely applied in the evaluation process of the effects of functional foods (primarily plant origin compounds) on the functionality of the intestinal brush border membrane, as well as potential prebiotic properties and interactions with the intestinal microbial populations. This review collates the information of potential nutrients and their effects on the mineral absorption, gut development, brush border membrane functionality, and immune system. In addition, the advantages and limitations of the in ovo feeding method in the assessment of potential prebiotic effects of plant origin compounds is discussed.

Evaluation of a modified infraorbital approach for a maxillary nerve block for rhinoscopy with nasal biopsy of dogs

OBJECTIVE To determine whether a maxillary nerve block via a modified infraorbital approach, applied before rhinoscopy and nasal biopsy of dogs, would decrease procedural nociception, minimize cardiorespiratory anesthetic effects, and improve recovery quality. ANIMALS 8 healthy adult hound-type dogs PROCEDURES In a crossover study, dogs received 0.5% bupivacaine (0.1 mL/kg) or an equivalent volume of saline (0.9% NaCl) solution as a maxillary nerve block via a modified infraorbital approach. A 5-cm, 20-gauge over-the-needle catheter was placed retrograde within each infraorbital canal, and bupivacaine or saline solution was administered into each pterygopalatine region. Rhinoscopy and nasal biopsy were performed. Variables monitored included heart rate, systolic arterial blood pressure (SAP), mean arterial blood pressure (MAP), diastolic arterial blood pressure (DAP), plasma cortisol and norepinephrine concentrations, purposeful movement, and pain scores. After a 14-day washout period, the other treatment was administered on the contralateral side, and rhinoscopy and nasal biopsy were repeated. RESULTS SAP, MAP, and DAP were significantly higher for the saline solution treatment than for the bupivacaine treatment, irrespective of the time point. Plasma cortisol concentrations after saline solution treatment were significantly higher 5 minutes after nasal biopsy than at biopsy. Heart rate, norepinephrine concentration, purposeful movement, and pain score were not significantly different between treatments. CONCLUSIONS AND CLINICAL RELEVANCE Maxillary nerve block via a modified infraorbital approach prior to rhinoscopy and nasal biopsy reduced procedural nociception as determined on the basis of blood pressures and plasma cortisol concentrations during anesthesia. These findings warrant further evaluation in dogs with nasal disease.

Treatment of extraskeletal osteosarcoma at a previous injection site resulting in prolonged survival in 1 dog

A rare presentation of an extraskeletal osteosarcoma at a previous interscapular injection site in a dog is described. Treatment included surgical excision of the tumor followed by 6 rounds of intravenous carboplatin, oral toceranib, and cyclophosphamide. The dog survived for 20.5 months after diagnosis despite early development of pulmonary metastases.

Modes of vaccine administration at a glance

A number of different vaccination techniques are applied in farm animals. The intramuscular, subcutaneous and intradermal injection of vaccines are parenteral application methods that are currently used for different attenuated and inactivated vaccines. The injection may be performed by needle or pressure. Depending on the method of application, the mucosal immunization can be performed intraocular, intranasal and/or oral. In general, the vaccine follows the natural route of infection of the respective pathogen. Attenuated vaccines usually replicate in the primary target organs. Mucosal application of attenuated vaccines via drinking water or spray are routinely applied in poultry. Both techniques offer advantages for mass application. The administration route and the method of vaccination have a great influence on the efficacy and safety of a vaccine. The instructions of the manufacturers must therefore be strictly respected. Unfortunately, there is no ideal administration method applicable for any vaccine in all species.

Perioperative evaluation of tumescent anaesthesia technique in bitches submitted to unilateral mastectomy

BACKGROUND

Tumescent anaesthesia (TA) is a widely used technique in oncologic surgeries necessitating large resection margins. This technique produces transoperative and postoperative analgesia, reduces surgical bleeding, and facilitates tissue divulsion. This prospective, randomised, blind study evaluated the use of TA in bitches submitted to mastectomy and compared the effect of TA with an intravenous fentanyl bolus. A 2.5-mcg/kg intravenous fentanyl bolus (n = 10) was compared with TA using 0.275% lidocaine (n = 10) in bitches submitted to unilateral mastectomy. Sedation was performed by intramuscular (IM) injection of 0.05 mg/kg of acepromazine combined with 2 mg/kg of meperidine. Anaesthesia was induced with 5 mg/kg of intravenous propofol and maintained with isoflurane/O2. Heart and respiratory rates; systolic, mean, and diastolic arterial blood pressures; central venous pressure; SpO2; ETCO2; inspired and expired isoflurane concentrations; and temperature were measured transoperatively. Visual analogue scales for sedation and pain and the Glasgow composite and Melbourne pain scales were used for postoperative assessment. The surgeon investigated the quality of the surgical approach, considering bleeding and resection ability, and the incidence of postoperative wound complications.

RESULTS

The heart rate was lower and the end-tidal isoflurane concentration was higher in dogs treated with fentanyl than in dogs treated with TA. A fentanyl bolus was administered to 8 of 10 dogs treated with fentanyl and to none treated with TA. Intraoperative bleeding and the mammary gland excision time were lower in dogs treated with TA. The maximal mean and individual plasma lidocaine concentrations were 1426 ± 502 ng/ml and 2443 ng/ml at 90 minutes after infiltration, respectively. The Glasgow Composite Pain Scale scores were higher in dogs treated with fentanyl than in dogs treated with TA until 2 hours after extubation.

CONCLUSIONS

Compared with intravenous fentanyl, TA in bitches: may be easily performed in non-inflamed, ulcerated, adhered mammary tumours; has an isoflurane-sparing effect; improves transoperative and immediate postoperative analgesia; is apparently safe for use in clinical conditions as evidenced by the fact that it did not produce any adverse signs or lidocaine plasma concentrations compatible with toxicity; does not modify the recovery time; and facilitates the surgical procedure without interfering with wound healing.

A study to assess the compatibility of simultaneous use of porcine reproductive and respiratory syndrome virus (EU-type) vaccine and Mycoplasma hyopneumoniae vaccine under field conditions

Vaccines against M. hyopneumoniae and PRRSV are often administered at the same time. The administration of the two vaccines mixed in one syringe (simultaneous use) would save labour and increase animal welfare by reducing the number of injections. The aim of this study was to verify under field conditions, if the simultaneous administration of the two vaccines, would be comparable to the administration of the individual vaccines. 1000 piglets were divided into five groups and were either non vaccinated or vaccinated against M. hyopneumoniae and/or PRRSV-EU-type. Body weight, local reactions, morbidity and mortality were measured and clinical examinations were carried out. Blood samples were analysed serologically for the presence of antibodies against PRRSV and M. hyopneumoniae by ELISA. M. hyopneumoniae-induced lung lesion scoring (with a maximum score of 55 points) was performed at the slaughterhouse. In the 1000 pigs included in this study, no clinically relevant local or systemic reactions were observed following vaccination. No significant differences in average daily weight gain (ADWG), mortality, clinical parameters or in the prevalence of pneumonia and pleuritis at the slaughterhouse were detected between the different study groups. Significant differences were observed for the serological results, with M. hyopneumoniae antibody positive pigs in the vaccinated groups being significantly higher than in the non-vaccinated groups. Regarding the severity code of the lung lesions of the affected lungs, the lung scores from the simultaneously vaccinated pigs were significantly lower (0.92) than those from non-vaccinated pigs (1.77). Due to the low infectious pressure of both PRRSV and M. hyopneumoniae on this farm, we have to conclude that efficacy of the vaccines could not adequately be tested.

Effect of copper edetate injection in dry pregnant cows on hematology, blood metabolites, weight gain and health of calves

The objectives of the present study was to investigate the effects of the copper injection and injection timing to pregnant dairy cows at dry period on the hematology, some serum metabolites, health and growth of their calves. Thirty Holstein cows at the dry period were assigned to the three following experimental groups: 1) control (injections of 2.5 ml normal saline), 2) test 1 (125 mg Cu as copper edetate injection at the first week of the dry period) and 3) test 2 (125 mg Cu as copper edetate injection at the third week of the dry period). Ten milliliters of jugular blood was taken from all calves 24-48 h after birth and at 7, 14, 21 and 28 days of age for measuring hematological and biochemical parameters. For evaluation of growth and health, body weight of all of the calves was measured at birth and at the end of the trial, and the health of calves was checked by a technician twice a day and any sign of illness, treatment (if needed) and duration of illness was recorded. Copper treatment was proved to have a significant effect on the counts of WBC (lower in test 2, higher in test 1), lymphocyte (lower in test 2, higher in test 1) and the concentrations of fibrinogen (lower in test 1, higher in test 2), cholesterol (lower in control, higher in test 1) and copper (lower in test 1, higher in test 2) (p < 0.05). Age (sampling time) also influenced most measured parameters (p < 0.05) except values of WBC, neutrophil, monocyte, globulin and concentrations of iron, zinc and copper.

Comparison of 2 methods of centesis of the bursa of the biceps brachii tendon of horses

REASONS FOR PERFORMING STUDY

Centesis of the bicipital bursa using an 8.9 cm long spinal needle has been reported but the alternative of employing a 3.8 cm long hypodermic needle requires validation.

OBJECTIVE

To compare the efficacy of 2 different methods of centesis of the bicipital bursa and to evaluate the usefulness of ultrasonographic imaging to determine the location of solution administered when centesis of the bursa is attempted.

METHODS

For Trial 1, 6 clinicians, who had no previous experience of centesis of the bicipital bursa, attempted to inject a solution composed of an aqueous radiopaque contrast medium and physiological saline solution (PSS) into the bicipital bursae of 2/12 horses using the previously described distal approach to inject one bursa and a proximal approach to inject the contralateral bursa. The bicipital tendon and bursa were examined ultrasonographically before and after injection; and both shoulders were examined radiographically to identify the location of the medium. In Trial 2, another 6 clinicians, also with no previous experience of centesis, repeated Trial 1, using 6 horses, but the radiopaque contrast medium was mixed with air instead of PSS.

RESULTS

Accuracy of centesis using the proximal approach was 39% and that of the distal approach 28%. Ultrasonographic examination of the shoulder allowed the location of solution and air to be accurately predicted in all 12 shoulders examined.

CONCLUSIONS

Clinicians who have had no previous experience performing centesis of the bicipital bursa are unlikely to be successful in centesis using either approach. Radiographic examination after injecting a radiopaque contrast medium may be necessary to assess the success of centesis especially if bursal fluid is not obtained during centesis. Injecting air along with the radiopaque contrast medium provides more accurate ultrasonographic confirmation of centesis and better radiographic definition than does injection without air.

Prognostic Factors for Injection-Site Sarcomas in Cats

In this retrospective study of cases from Italy and Switzerland, the clinical features of injection-site sarcomas in 57 cats were reviewed. In addition to routine physical, laboratory, and radiographic examinations, advanced imaging (computed tomographic scans) was conducted to delineate tumor extent. Treatment was by wide surgical excision including partial scapulectomy, spinous process removal, and amputation (appendicular lesions). Radiotherapy and chemotherapy were also used. The results revealed that cats with grade 3 tumors were most likely to develop distant pulmonary metastases (and to have shorter survival rates); this occurred in 21% of the cases.Median follow-up for cats that survived (51%) was 600 days; for those that died (49%), it was 272 days. In this study, tumor size, as measured manually by calipers, was not a prognostic factor. Furthermore, factors associated with local recurrence were not identified. The authors recognized the limitations of a retrospective study, especially with regard to treatments before referral.

Antimicrobial use on 24 beef farms in Ontario

Understanding risk factors for antimicrobial resistance requires knowledge of antimicrobial selection pressure. The objectives of this research were to develop methodology for collecting quantitative antimicrobial use information from beef producers in Ontario, to document the types and quantities of antimicrobials reported (for a minimum of 12 mo), and to compare 2 metrics for injectable use reporting. Twenty-four volunteer beef producers were asked to complete a questionnaire, document drug use in a treatment diary, and retain empty medication containers. For injectable antimicrobials, producers recorded approximately 60% of the total use in the treatment diaries; oxytetracycline, penicillin, macrolides, florfenicol, and spectinomycin were used in the greatest quantities. Based on estimated weights of active ingredients (calculated according to number of animals exposed, duration, and average dose per day) the antimicrobials most commonly used in feed were monensin, tylosin, lasalocid, and tetracyclines. The antimicrobials most commonly used in water were lincomycin-spectinomycin, chlortetracycline, and oxytetracycline. Based on estimated weights and measured quantities, < 1% of antimicrobials used were in the Canadian category of highest importance to human medicine. A comparison of animal daily dosages to kilograms of active ingredient demonstrated that the relative ranking of use of antimicrobials varied with the chosen metric, and that further investigation into the best measure in relation to antimicrobial resistance is warranted.

Anatomical and experimental studies of brachial plexus, sciatic, and femoral nerve-location using peripheral nerve stimulation in the dog

OBJECTIVE

To investigate the anatomy of the brachial plexus, sciatic, and femoral nerves for the use of a peripheral nerve-stimulator to perform nerve blocks in dogs.

STUDY DESIGN

Prospective experimental trial.

ANIMALS

Four canine cadavers and four healthy adult dogs weighing 23 +/- 2.5 kg.

METHODS

Phase I: in four canine cadavers, an anatomical study was conducted to evaluate accurate needle-insertion techniques. Phase II: the utility of these techniques, and the value of electrostimulation, were evaluated in four anesthetized dogs in lateral recumbency (medetomidine, 5 microg kg(-1)/ketamine 5 mg kg(-1)) using an electrical stimulator and shielded needles.

RESULTS

For the brachial plexus, the needle was inserted cranial to the acromion, medial to the subscapularis muscle, at an angle of approximately 20-30 degrees in relation to a plane vertical to the surface on which the animal was lying, oriented parallel to the long axis of the animal, in a ventro-caudal direction. For the sciatic nerve, the needle was inserted just cranial to the sacrotuberous ligament, through the gluteus superficialis muscle, at an angle of approximately 60 degrees in relation to the horizontal plane, in a ventro-cranial direction, and up to the level of the ischium. For the femoral nerve, the needle was inserted perpendicular to the skin, just cranial to the femoral artery, and directed a little caudally. Using a peripheral nerve-stimulator, all nerves were located, and muscle contractions were elicited at a current of 0.2-0.4 mA. No complications were observed during the procedures.

CONCLUSION

Electrostimulation of peripheral nerves is useful in locating the branches of the brachial plexus as well as the sciatic and femoral nerves in dogs.

CLINICAL RELEVANCE

Peripheral nerve stimulation increases the reliability of a nerve block when compared with blind needle-insertion.

Experimental transmission of scrapie agent to susceptible sheep by intralingual or intracerebral inoculation

Scrapie, a transmissible spongiform encephalopathy (TSE), is a naturally occurring fatal neurodegenerative disease of sheep and goats. This study documents survival periods, pathological findings, and the presence of abnormal prion protein (PrP(Sc)) in genetically susceptible sheep inoculated with scrapie agent. Suffolk lambs (AA/RR/QQ at codons 136, 154, and 171, respectively) aged 4 mo were injected by the intralingual (IL) or intracerebral (IC) route with an inoculum prepared from a pool of scrapie-affected US sheep brains. The animals were euthanized when advanced clinical signs of scrapie were observed. Spongiform lesions in the brain and PrPsc deposits in the central nervous system (CNS) and lymphoid tissues were detected by immunohistochemical and Western blot (WB) testing in all the sheep with clinical prion disease. The mean survival period was 18.3 mo for the sheep inoculated by the IL route and 17.6 mo for those inoculated by the IC route. Since the IC method is occasionally associated with anesthesia-induced complications, intracranial hematoma, and CNS infections, and the IL method is very efficient, it may be more humane to use the latter. However, before this method can be recommended for inoculation of TSE agents, research needs to show that other TSE agents can also transmit disease via the tongue.

Antimicrobial use through feed, water, and injection in 20 swine farms in Alberta and Saskatchewan

Antimicrobial resistance (AMR) is an emerging animal welfare and public health issue linked to antimicrobial use (AMU) in livestock. This study was conducted in 2004 on 20 swine farms in Alberta and Saskatchewan. On-farm records and questionnaires were used to retrospectively describe the antimicrobial exposures of pigs through feed, water, and injection. Antimicrobial use in all production categories was described over 12 months. On-farm records and questionnaires provided sufficient data to describe antimicrobial exposure rates through feed and water. In contrast, on-farm records did not supply sufficient data to describe parenteral antimicrobial exposure rates. Records lacked data on the number of exposures per treatment, therefore parenteral AMU was described as an exposure incidence. Parenteral exposure records were often unavailable for pigs less than 22 kg, in which case questionnaires were used. The incidence of parenteral AMU was significantly higher in herds reporting exposure by questionnaire compared with existing records, suggesting that on-farm records did not reliably describe parenteral AMU. However, because antimicrobial exposures in feed and water were markedly more common than through injection, it was concluded that existing on-farm data would be a valuable resource for investigating AMU and AMR in pigs.

Therapeutic effects of systemic or intramammary antimicrobial treatment of bovine subclinical mastitis during lactation

The short- and long-term treatment efficacy of administrating penicillin for bovine subclinical mastitis during lactation when using intramuscular (IM; 9.5 mg [15,000 IU]/kg bodyweight of benzyl penicillin potassium) injections twice daily for 5 days, or intramammary (IMM; 0.3g [300,000 IU] penethamate hydroiodide) administration once daily for 5 days was compared with a control group receiving no treatment. One hundred and twenty-six cows met the inclusion criteria, which were lack of clinical symptoms, no recent treatment with antimicrobials, and findings of penicillin-sensitive Staphylococcus aureus, Streptococcus dysgalactiae, or Streptococcus uberis in combination with an inflammatory reaction. At follow-up 42-58 days after treatment, the proportion of cows negative for the original infection was significantly higher in IM and IMM groups compared to controls, but the difference between antimicrobial treatment groups was not significant. The udder quarter milk somatic cell count (SCC) was significantly lower at follow-up in IM and IMM groups than in controls, but milk production did not differ between treatments. The culling rate during the 10-month period following treatment was significantly higher in the group treated with IMM penicillin than in the other two groups, but the risk of new mastitis treatments within 10 months did not differ between the three groups. The cure rate was significantly affected by lactation number (lower in older cows), breed (lower in the Swedish Holstein breed), pathogen (lower for S. aureus), and pre-treatment SCC (higher for above average SCC). In conclusion, beneficial long-term effects of antimicrobial treatment during lactation of subclinical mastitis caused by S. aureus, Str. dysgalactiae or Str. uberis were not found in the present study.

Gastrointestinal uptake of cadmium and zinc by a marine teleost Acanthopagrus schlegeli

Gastrointestinal metal uptake represents a potential route for metal bioaccumulation in marine fish. Drinking of seawater for osmoregulation causes constant waterborne exposure of the gastrointestinal tract. Tissue specific Cd and Zn accumulation and distribution were investigated in juvenile black sea bream (Acanthopagrus schlegeli) exposed to waterborne Cd (5.7 nM) and Zn (2.6 nM) for 4 h-7 days. The intestine accumulated a large portion of the Cd (43-58%) and Zn (18-28%), and had the highest Cd (>1.0 nmol g(-1)) and Zn (>1.8 nmol g(-1)) concentrations of all body fractions, suggesting that the intestines were the major uptake sites for these waterborne metals. Among all the segments of the gastrointestinal tract, the anterior intestine played the most important role in Cd and Zn uptake. A gastrointestinal injection assay was conducted to distinguish waterborne metal uptake by the intestines and the gills. The intestine contained over 90% of the Cd in the body after depuration for 3-7 days, suggesting that little waterborne Cd entered the rest of the body through the intestine, and that Cd may exert its toxic effects on the gastrointestinal system. In contrast, intestine retained less than 20% of the total Zn after depuration, suggesting that Zn tended to be transported from the intestine to the internal tissues via the cardiovascular system. The uptake kinetics of waterborne Cd and Zn by the intestines and the gills were determined as a first-order and saturated pattern, respectively, over a wide range of ambient metal concentrations (6.2 nM-4.5 microM for Cd, and 13 nM-15 microM for Zn). An in vitro intestinal perfusion assay investigated the effects of intestinal metal composition and drinking rate on uptake. The presence of EDTA significantly reduced intestinal Zn uptake to 11%, while cysteine improved it by 59%. The intestinal Cd and Zn uptake rates were unaffected by the perfusion rate.

Rabies in vaccinated raccoons from Ontario, Canada

From 1999 to 2006, 132 cases of raccoon rabies, caused by the raccoon variant of rabies virus, were confirmed in eastern Ontario, Canada. Trap-vaccinate-release (TVR) and point infection control (PIC) programs were implemented to control the disease; 43,014 raccoons (Procyon lotor) were vaccinated against rabies by injection (Imrab3) during that period. Two vaccinated raccoons were diagnosed with rabies at 6 mo and at 2 wk postvaccination. One may have been due to a vaccination failure. The other was likely due to the animal being in the late stages of incubation for rabies at the time of vaccination. This information will be useful to wildlife rehabilitators and agencies that hold raccoons in captivity in that a vaccinated raccoon is not necessarily immune to rabies.

Refinement of intrathymic injection in mice

Direct intrathymic injection is a common procedure used in several types of experimental protocols in the mouse. Currently available approaches involve major surgical procedures that expose the thoracic cavity, resulting in an increased risk of poor recovery and postsurgical complications. The authors sought to refine this surgery to reduce animal pain and distress without compromising overall efficiency of the technique. Using a minimally invasive method that does not expose the thoracic cavity, the authors gave accurately placed intrathymic injections, as confirmed by analyses with a reporter dye. They describe this new approach for intrathymic injection in mice that reduces complications associated with lengthy periods of anesthesia and thoracic cavity exposure.

Lidocaine effects on corneal endothelial cell ultrastructure

The purpose of this study was to determine whether intracameral commercial lidocaine 2% induces alterations on the rabbit corneal endothelium. Forty white rabbits received different substances inside the anterior chamber: group (G)1, no substance; G2 and G3 received lidocaine 2% with preservative in aqueous solution; G4 and G5, lidocaine 2% with preservative in gel solution; G6 and G7, the anesthetic preservative (metilparahydroxybenzoate 0.1%); and G8 and G9, lidocaine 2% without preservative in aqueous solution. The animals from G2, 4, 6 and 8 were sacrificed after 1 h, and from G3, 5, 7 and 9 after 24 h after injection of the substance inside the anterior chamber. The corneas were clinically evaluated and assessed by transmission and scanning electron microscopy. G1, 2, 6, 7, 8 and 9 animals had very similar characteristics in clinical, ultrastructural and morphometric evaluations; the G3 and G4 animals showed discrete edema and one animal in G5 had intense corneal edema. We conclude that lidocaine 2% with preservative induces few ultrastructural alterations in the corneal endothelial cells.

Lesions attributed to vaccination of sheep with Gudair for the control of ovine paratuberculosis: post farm economic impacts at slaughter

OBJECTIVE

To determine i) the prevalence of lesions at the site of vaccination with Gudair, and ii) the incidence of discounting of slaughtered sheep carcasses due to the presence of these lesions.

DESIGN

A survey of the prevalence of injection lesions and actual discounts applied to 20 consignments of vaccinates slaughtered in abattoirs in New South Wales.

PROCEDURE

Consignments of sheep previously vaccinated against ovine Johne's disease (OJD) were assessed on the slaughter chain for the prevalence of vaccination site lesions and any costs associated with carcass trimming were estimated. In addition a telephone survey was conducted to determine the experiences and risk attitudes of 8 abattoirs in south east New South Wales likely to have previously processed vaccinates.

RESULTS

The prevalence of lesions observed was 18% for adult (mutton) and 65% for lamb carcasses. The value of the trim removed was insignificant, the labour cost of its removal was nil and no carcass was downgraded to a lower value grade.

CONCLUSION

Under the market conditions existing at the time the study was conducted, in sheep vaccinated at the recommended site high on the neck, it is unlikely that OJD vaccination site lesions will be a significant cost to producers or the processing industry and will represent only a very small proportion of the total cost of OJD control by vaccination.

Efficacy of intrapalpebral and intramuscular application of oxytetracycline in a natural outbreak of infectious bovine kertoconjunctivitis (IBK) in calves

In a herd of 70 bull calves (4-5 months of age) kept on pasture, 56 (80%) animals showed, after natural infection with Moraxella bovis (M. bovis), typical clinical signs of infectious bovine keratoconjunctivitis (IBK). Eyes with epiphora, photophobia, blepharospasm and/or a corneal ulcer with a diameter of less than 5 mm were considered as moderately affected. Those with a corneal ulcer > 5 mm diameter and/or even more profound findings were considered as severely affected. The objective was to study in IBK affected calves in a prospective randomized case control study the therapeutic efficacy of intrapalpebral (i.p.) injections of oxytetracycline (OTC) (200 mg OTC-hydrochloride 10% in the upper eyelid of moderately affected and in both eyelids of severely affected eyes) and intramuscular (i.m.) treatment (long-acting OTC-dihydrate; 20 mg/kg body weight for both moderately and severely affected patients). 29 animals (20 moderately affected, 9 severely affected) were treated i.p. and 27 animals (19 moderately, 8 severely affected) were treated i.m.. For fly control, deltamethrin was applied to all bulls at d 0. The OTC-treatment was repeated at intervals of 3 - 8 d until recovery. All animals recovered within 42 days. The mean number of treatments per animal and the interval between diagnosis and assessment of healing were not affected by the method of OTC administration; the latter averaged out at about 10 d for moderately affected and 17 d for severely affected eyes. Significantly less medication was required per animal for i.p. than for i.m. treatments (moderately affected: 281 vs. 2033 mg; severely affected: 1156 vs. 3982 mg). In conclusion, both methods of OTC administration were found to be similarly effective for the treatment of IBK in calves.