Quantification and evaluation of antimicrobial drug use in group treatments for fattening pigs in Belgium

To control the emergence of antimicrobial resistance, knowledge of antimicrobial drug consumption is essential. Because consumption data are not available in Belgium, a study was conducted between March and October 2003 to investigate the antimicrobial drug consumption in pigs, using the treatment incidence based on the animal daily dose pig (ADDpig), the treatment incidence based on the used daily dose pig (UDDpig) (number of ADDpig or UDDpig/1,000 pigs at risk/day), and the ratio UDDpig/ADDpig. The sampling frame consisted of 821 pig herds that (a) used a closed or semi-closed production system, (b) were located in the most dense pig areas of Belgium, and (c) had at least 150 sows and 600 fattening pigs each. Of 50 randomly selected herds, all group treatments with antimicrobial drugs, applied to fattening pigs that were within 2 weeks of slaughter (median age 187 days), were collected retrospectively. The treatment incidence based on ADDpig for all oral and injectable antimicrobial drugs was 178.1 per 1,000 pigs at risk per day. The treatment incidence based on UDDpig shows that in reality fewer pigs were treated, namely 170.3 per 1,000 pigs at risk per day. Proportionally, the most often applied oral antimicrobial drugs were: doxycycline, amoxicillin, combination trimethoprim-sulphonamides and polymyxin E. The most often applied injectable antimicrobial drugs were long-acting amoxicillin and ceftiofur. The distribution of the UDDpig/ADDpig ratio per antimicrobial drug shows that 50-75% of the oral formulations were underdosed. Injectable formulations were almost always overdosed (>90%).

Routes of yolk utilisation in the newly-hatched chick

1. This study was conducted to study the routes by which yolk is utilised in the chick during the initial posthatch phase. 2. Transfer from yolk to blood was examined by injecting, in the form of labelled compounds, oleic acid, triolein, inulin and dextran into the yolk; movement from yolk to blood was observed up to 72 h posthatch. 3. Transport of these molecules from blood to yolk was also observed by injecting them into the circulation and determining label in yolk. The yolk sac membrane was permcable in both directions for all labelled materials tested. 4. In the newly-hatched chick, blue dextran injected into the yolk sac could be seen moving in pulses into the intestine at irregular intervals. Transport of labelled materials from the yolk sac into the intestine was observed up to 72 h after hatching, and marker was found in the proximal small intestine and gizzard. The yolk stalk provided a pathway for transport to the intestine until lymphoid cells began to accumulate, with passage becoming partially occluded at 72 h posthatch. 5. Yolk utilisation was more rapid in fed than in fasted birds suggesting that the transport of yolk through the intestine could be increased by the greater intestinal activity found in fed chicks.

Principles of ex ovo competitive exclusion and in ovo administration of Lactobacillus reuteri

The data that have been presented indicate that the in ovo use of competitive exclusion (CE) agents is feasible for both chickens and turkeys. However, there are many pitfalls that await the use of in ovo application of CE agents, including the use of nonspecies-specific intestinal microbes and the use of harmful proteolytic, gas-producing and toxin-producing intestinal microbes. Of the potential CE agents that have posthatch application, only Lactobacillus reuteri has been shown to be safe and effective in terms of not affecting hatchability and in having a prolonged effect in the hatched chick or poult. Lactobacillus reuteri administration in ovo increases its rate of intestinal colonization and decreases the colonization of Salmonella and Escherichia coli in both chicks and poults. Additionally, mortality due to in-hatcher exposure to E. coli or Salmonella is reduced with in ovo L. reuteri. Use of antibiotics in ovo may preclude the use of co-administered CE agents, but Gentamicin and L. reuteri are a compatible mixture when administered in ovo in separate compartments. Nevertheless, the intestinal morphology can be affected by both the CE agent and by antibiotics. Lactobacillus reuteri both in ovo and ex ovo will increase villus height and crypt depth, and Gentamicin in ovo causes a shortening and blunting of the villus. Both Gentamicin and L. reuteri in ovo suppress potentially pathogenic enteric microbes, but with diminished antibiotic effects shortening and blunting of the intestinal villi does not correct itself. Goblet cell numbers increase significantly on the ileum villus of chicks treated with Gentamicin in ovo, and this is presumably due to the increase in potentially pathogenic bacteria in the intestinal tract. Diminishing antibiotic effects posthatch would then negatively affect the absorption of nutrients and reduce growth at least in a transitory manner. Thus, L reuteri administration in ovo singly or in combination with Gentamicin followed by L reuteri via drinking water or feed appears to have potential to control many enteric pathogens in poultry. Additional work in the use of in ovo CE cultures is mandated because there is a world-wide movement to reduce antibiotic use in poultry due to increased microbial resistance to antibiotics. Use of naturally occurring intestinal bacterial cultures, either in mixed culture or as single well-defined cultures, has potential for immediate use in the poultry industry.

Applications in in ovo technology

By mid-August 1995, 55% of broiler embryos in North America were vaccinated for Marek's disease using the INOVOJECT system, with 201 INOVOJECT machines placed with 16 of the top 25 poultry producers, providing the industry with the capacity to inject in excess of 400 million eggs per month or about 5 billion eggs per annum. In ovo administration of a bursal disease antibody-infectious bursal disease virus (BDA-IBDV) complexed vaccine to specific-pathogen-free (SPF) embryos was safer and more potent than conventional IBDV vaccine alone because it delayed the appearance of bursal lesions, produced no early mortality, produced higher geometric mean antibody titers against IBDV, and generated protective immunity against challenge. In ovo administration of a BDA-IBDV complexed vaccine to broiler embryos generated antibody titers against IBDV sooner than conventional virus vaccinates, and generated protective immunity against challenge Direct DNA injection of plasmid DNA encoding beta-galactosidase into breast muscle in ovo and posthatch was an effective means to achieve both gene transfer and expression, with potential for the development of gene vaccines using plasmids encoding protective antigens from poultry pathogens. In ovo administration of 800 U chicken myelomonocytic growth factor (cMGF), a chicken hematopoietic cytokine for cells of the monocytic-granulocytic lineages, significantly reduced mortality associated with Escherichia coli exposure within the hatcher when compared to PBS controls (6.1 vs 12.4, P < or = 0.05), but not when compared to a yeast expression control. A procedure was developed enabling injection prior to the onset of incubation without compromising embryo viability. This in ovo injection process has opened up the window of embryo development during incubation for intervention, as illustrated by the 100% male phenotype produced in chicks hatching from eggs injected with aromatase inhibitor prior to incubation. These data illustrate some of the in ovo applications presently in use by the poultry industry, and under development or in research at EMBREX.

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.

Long-term effects of consumption of low-copper diets with or without supplemental molybdenum on copper status, performance, and carcass characteristics of cattle

We used 42 Angus bull calves (7 mo of age) to determine long-term effects of low Cu diets with or without supplemental Mo on performance, carcass characteristics, and Cu status. Twenty-two bulls were injected with 90 mg of Cu 28 d before weaning. After weaning, injected steers were fed a diet supplemented with 7.5 mg of Cu/kg of DM; control steers received no supplemental Cu. At the end of the 40-d receiving phase, supplemental Cu was reduced to 5 mg/kg of DM. One half of the steers in each group were fed 5 mg of supplemental Mo/kg of DM following the receiving phase. The growing phase lasted 196 d. Steers were then switched to a high concentrate finishing diet for 49 d. Copper injection increased (P < .01) plasma Cu concentrations at weaning, and Cu-supplemented steers had greater (P < .05) plasma Cu, ceruloplasmin, superoxide dismutase activity (SOD), and liver Cu at the beginning of the growing phase. Supplemental Mo depressed plasma Cu, ceruloplasmin, and SOD during the growing and finishing phases in non-Cu-supplemented but not in Cu-supplemented steers. Copper supplementation increased DMI during the receiving (P < .05) and growing (P < .08) phases and increased (P < .08) ADG and gain:feed ratios during the finishing phase. Steers fed supplemental Cu produced carcasses with less (P < .06) backfat and slightly larger (P < .09) rib eye areas. The results of this experiment suggest that dietary Cu concentrations may alter cattle performance and carcass characteristics.

Use of surgery and electron beam irradiation, with or without chemotherapy, for treatment of vaccine-associated sarcomas in cats: 78 cases (1996-2000)

OBJECTIVE

To evaluate responses of cats with vaccine-associated sarcomas to treatment with surgery and radiotherapy, with or without adjunctive chemotherapy.

DESIGN

Retrospective study.

ANIMALS

76 cats (78 tumors).

PROCEDURE

Medical records were reviewed. Factors potentially associated with survival time, time to recurrence, and time to development of metastases were evaluated.

RESULTS

Following excision, electron beam radiation, and, in some cases, chemotherapy, 32 (41%) cats experienced recurrence, and 9 (12%) cats developed metastases. One- and 2-year survival rates were 86 and 44%, respectively. Median survival time from onset of disease was 730 days (range, 30 to 2,014 days). Median disease-free interval was 405 days (range, 30 to 925 days). Cats that underwent only 1 surgery prior to radiotherapy had a lower recurrence rate than did cats that underwent > 1 surgery and had a significantly longer disease-free interval. Survival time and disease-free interval decreased as time between surgery and the start of radiotherapy increased. Cats that developed metastases had significantly shorter survival times and disease-free intervals than did cats that did not develop metastases. Castrated male cats had a significantly shorter survival time than did spayed female cats. Cats with larger tumors prior to the first surgery had shorter survival times. Twenty-six cats received chemotherapy in addition to surgery and radiotherapy. Whether cats received chemotherapy was not associated with recurrence rate, metastasis rate, or survival time.

CONCLUSIONS AND CLINICAL RELEVANCE

Results suggest that excision followed by electron beam irradiation may be beneficial for treatment of cats with vaccine-associated sarcomas. Extent of excision prior to radiotherapy did not seem to be associated with recurrence rate.

Embryo growth and amino acid concentration profiles of broiler breeder eggs, embryos, and chicks after in ovo administration of amino acids

Two experiments were conducted to evaluate the effect of in ovo amino acid (AA) injections in broiler breeder eggs on AA utilization of embryos. All AA used in these experiments were pure crystalline AA in free-base form. Treatments in Experiment 1 comprised 1) control eggs (no injection), 2) 0.5 mL sterile-distilled water injected eggs, and 3) eggs injected with an AA solution suspended in 0.5 mL sterile-distilled water. Injections were administered into the yolk at Day 7 of incubation. At hatch, chicks were killed and bled, and plasma AA concentration was determined. Plasma AA concentration of hatched chicks decreased (P < 0.05) when water was injected. In addition, all AA from eggs injected with AA, except Glu and Lys, were decreased (P < 0.05) at hatch as compared to control eggs. However, AA pattern was not affected by in ovo water injection, but the AA ratio to Lys was reduced by in ovo AA injection. Experiment 2 was conducted to evaluate whole internal egg AA concentrations over incubation time in the presence or absence of in ovo AA administration. Treatments in Experiment 2 comprised 1) control eggs (no injection), and 2) eggs injected with a AA solution at Day 7 of incubation. The AA contents of embryo, yolk, albumen, and allantoic and amnion fluids were analyzed over time during incubation (Days 0, 7, 14, and 19 of incubation). On Day 14 of incubation, there were no differences in AA contents of all tissues between the control group and the group injected with AA on Day 7 of incubation. On Day 19 of incubation, AA contents of embryo, yolk, albumen, and allantoic and amnion fluids were increased (P < 0.05) as mediated by in ovo administration of AA at Day 7 of incubation. These results suggest that in ovo administration of AA may increase AA concentrations in chicken embryos and other egg contents.

Effect of graded levels of duodenal infusions of casein on mammary uptake in lactating cows. 2. Individual amino acids

The experiment examined patterns of mammary uptake of individual AA when graded amounts of calcium caseinate (0, 177, 362, and 762 g/d) were infused duodenally into four lactating cows. Six blood samples were collected over 12 h from the subcutaneous abdominal vein and the carotid. Mammary blood flow was measured by an ultrasonic flow probe implanted around the external pudic artery. Infusions of casein linearly increased the arterial concentrations of all essential AA and several nonessential AA (Pro, Tyr, Orn, and Cit) and increased, or tended to increase, linearly the mammary arteriovenous differences of all AA except Glu and Ala. Absorption ability of the mammary gland was not reduced in vivo. Relationships between mammary arteriovenous differences and arterial concentrations were positive and linear in every cow for all AA except Asn, Ser, Gly, and Ala. Some essential AA (Lys, Arg, and branched-chain AA) were therefore taken up in excess of their output into milk proteins, but others (His, Thr, Met, and Phe) were almost exclusively extracted by the udder in a direct ratio to their output. As infusions of casein increase, Phe becomes probably the most critical AA for milk synthesis.

Evaluation of the use of anesthesia and analgesia in reptiles

OBJECTIVE

To determine anesthetic techniques and the drugs used to provide anesthesia and analgesia to reptiles.

DESIGN

Mail-out questionnaire.

SAMPLE POPULATION

367 members of the Association of Reptile and Amphibian Veterinarians.

PROCEDURE

1,091 members listed in the 2002 directory of the Association of Reptile and Amphibian Veterinarians were asked to complete a questionnaire regarding anesthesia and analgesia.

RESULTS

367 of 1,091 (33.6%) individuals completed the questionnaire; 88.8% used inhalants (particularly isoflurane) for anesthesia, and ketamine, propofol, and butorphanol were the most commonly used injectable agents. Intubation, fluids, and having a dedicated anesthetist were most commonly used for patient support, and pulse oximetry and Doppler ultrasonography were most commonly used for monitoring. Respiratory depression, difficulty monitoring anesthetic depth, prolonged recovery, and hypothermia were the most frequent complications. Nearly all respondents believed that reptiles feel pain, but analgesics were used infrequently for many reasons.

CONCLUSIONS AND CLINICAL RELEVANCE

Providing anesthesia in reptiles is difficult, especially regarding anesthetic depth and vital parameters, and methods of support are used less frequently than in domestic species. Provision of analgesia is uncommon. Research regarding pain and its assessment, response to analgesics, and drug pharmacokinetics is needed. Dissemination of this information to practitioners needs to be improved for enhancement of the standard of care for reptiles.

Evaluation of intraperitoneal and incisional lidocaine or bupivacaine for analgesia following ovariohysterectomy in the dog

OBJECTIVE

To determine if intraperitoneal (i.p.) and incisional (s.c.) lidocaine or bupivacaine provide analgesia following ovariohysterectomy (OHE).

STUDY DESIGN

Prospective, randomized, controlled, blinded clinical trial.

ANIMALS

Thirty dogs presenting to the Veterinary Teaching Hospital for elective OHE.

METHODS

Dogs were pre-medicated with acepromazine and butorphanol, induced with thiopental and maintained with isoflurane. They were randomly assigned to three groups: 10 received 8.8 mg kg(-1) 2% lidocaine with epinephrine i.p. (LID); 10 received 4.4 mg kg(-1) 0.75% bupivacaine i.p. (BUP); and 10 received 0.9% saline i.p. (SAL) upon completion of OHE. All i.p. doses were standardized to 0.88 mL kg(-1) with saline. An additional 2 mL of undiluted solution was placed s.c. prior to incisional closure. Dogs were scored at 0.5, 1, 2, 3, 6, 8 and 18 hours post-extubation by one observer. Dogs were evaluated using a visual analogue scale (VAS) for pain and sedation, and a composite pain scale (CPS) that included physiologic and behavioral variables. Dogs were treated with 0.22 mg kg(-1) butorphanol + acepromazine if their VAS (pain) score was >50. Parametric variables were analyzed using Student's t-test or repeated measures ANOVA as appropriate. Non-parametric variables were analyzed by chi2-test.

RESULTS

There were no significant differences in age, weight, incision length, surgery time, anesthesia time, or total thiopental dose among groups. Peak post-surgical pain scores for all groups occurred at 0.5 hours and returned to baseline by 18 hours. Dogs in the BUP group had significantly lower VAS-pain scores overall than dogs in the SAL group. Seven out of 10 dogs in the SAL group, 4/10 in the LID group and 2/10 in the BUP group were treated with supplemental acepromazine and butorphanol. No differences between groups were detected with the CPS. No adverse side-effects were observed.

CONCLUSIONS AND CLINICAL RELEVANCE

Our findings support the use of i.p. and s.c. bupivacaine for post-operative analgesia following OHE in the dog.

Estrus and luteal function in suckled beef cows that were anestrous when treated with an intravaginal device containing progesterone with or without a subsequent injection of estradiol benzoate

The objectives in this study were to determine whether treatment with progesterone (P4) via an intravaginal device would induce estrus and development of corpora lutea (CL) with typical life spans and whether treatment with estradiol benzoate (EB) following device removal would enhance the responses. At treatment initiation (d 0), suckled beef cows (n = 362) that were anestrous received one of the following: 1) an intravaginal device containing P4 for 7 d plus an injection of 1 mg of EB 24 to 30 h after device removal (P4+EB), 2) an intravaginal device containing P4 for 7 d (P4), 3) a sham device for 7 d plus an injection of 1 mg of EB 24 to 30 h after device removal (EB), or 4) a sham device for 7 d (control). Progesterone treatment increased the proportion of cows that formed CL with a typical lifespan (P < .001) and exhibited behavioral estrus (P < .05). Treatment with EB in combination with P4 increased (P < .001) the proportion of cows that exhibited estrus. Treatment with P4 alone had no effect, but the combination of P4 and EB increased (P < .01) the proportion of cows that formed short-lived or typical lifespan CL by the end of the experiment compared with untreated cows. In summary, treatment with P4 increased the incidence of estrus and the proportion of cows that formed CL with a typical lifespan. Treatment with P4 resulted in resumption of luteal function in suckled beef cows that were anestrous, with most cows developing CL with a typical lifespan, whereas EB enhanced the expression of estrus.

Effects of animal age, marbling score, calpastatin activity, subprimal cut, calcium injection, and degree of doneness on the palatability of steaks from limousin steers

Strip loin (longissimus lumborum), sirloin (gluteus medius) and round (semimembranosus) subprimals from 114 purebred and crossbred Limousin steers were used to identify main effects and interactions of animal age, marbling score, calpastatin activity, subprimal cut, calcium injection (5% wt/wt with a 200 mM CaCl2 solution at 48 h postmortem), and degree of doneness on the palatability of cooked beef steaks. Steaks were aged for 14 d, frozen, thawed, cooked to different internal temperature end points, visually scored for degree of doneness, sheared on a Warner-Bratzler shear machine, and evaluated by a trained taste panel. Raw and cooked steaks from carcasses of higher USDA quality grades had higher fat and lower moisture percentages (P < .05). Higher degrees of doneness resulted in lower moisture percentages (P < .05). Lower shear force values were associated with less variation in shear force. Younger slaughter age and lower calpastatin activity both resulted in greater tenderness (P < .05). Shear force was lowest between "medium rare" and "medium" and increased toward both ends of the degree of doneness scale for round and sirloin steaks; however, shear force increased linearly with degree of doneness in strip loin steaks (P < .05). Subprimal cut had the largest effect on taste panel tenderness ratings, and degree of doneness had the largest effect on taste panel juiciness ratings. The improvement in shear force due to CaCl2 injection was greater for strip loin and sirloin steaks than for round steaks (P < .05 for the interaction). Injection with CaCl2 improved all taste panel attributes. In addition, CaCl2 injection reduced the toughening effects of cooking (P < .05).

Optimum site for in ovo amino acid injection in broiler breeder eggs

Three experiments were conducted to evaluate the effect of differences in in ovo amino acid (AA) injection sites in broiler breeder eggs on subsequent hatchability and BW of chicks. In Experiment 1, an AA solution was injected into eggs with 13-mm or 19-mm, 27-ga needles. Uninjected eggs served as controls. Hatchability was decreased (P < 0.05) in eggs receiving AA injections with the 19-mm needle in comparison to the control and 13-mm-injected groups. However, BW of chicks increased (P < 0.05) relative to pre-incubational egg weight by AA injection with the 13-mm needle. In order to evaluate the in ovo location of AA injections from Experiment 1, India ink was injected into eggs in Experiment 2 with a 13-or 19-mm needle. Immediately after injection, the air cell end of the egg was windowed in order to observe effects of injection site. Windowing of eggs was accomplished by removing a piece of the eggshell over the air cell and the underlying membrane at Day 7 of incubation. The amount of injected India ink was higher in the extra-embryonic coelom in eggs treated by both needles. However, the occurrence of India ink in the extra embryonic coelom was higher (P < 0.05) in the group injected with AA solution using a 13-mm needle as compared to that after injection using a 19-mm needle. The observation of India ink in the amniotic cavity was higher (P < 0.05) in the group injected with AA solution using a 19-mm needle rather than that using a 13-mm needle. In Experiment 3, treatments consisted of control (uninjected eggs) or windowed eggs. Windowed eggs received AA to the chorioallantoic membrane, the yolk, extra-embryonic coelom, or amniotic cavity at Day 7 of incubation. Hatchability was reduced, but chicks hatched when eggs were windowed and when AA were injected into the yolk sac or extra-embryonic coelom. However, chicks did not hatch when AA were administered to the chorioallantoic membrane or into the amniotic cavity. These results suggest that the best AA injection sites in ovo may be the yolk and extra-embryonic coelom.

Evaluation of intrarenal mesenchymal stem cell injection for treatment of chronic kidney disease in cats: a pilot study

The feasibility of autologous intrarenal mesenchymal stem cell (MSC) therapy in cats with chronic kidney disease (CKD) was investigated. Six cats (two healthy, four with CKD) received a single unilateral intrarenal injection of autologous bone marrow-derived or adipose tissue-derived MSC (bmMSC or aMSC) via ultrasound guidance. Minimum database and glomerular filtration rate (GFR) via nuclear scintigraphy were determined pre-injection, at 7 days and at 30 days post-injection. Intrarenal injection did not induce immediate or long-term adverse effects. Two cats with CKD that received aMSC experienced modest improvement in GFR and a mild decrease in serum creatinine concentration. Despite the possible benefits of intrarenal MSC injections for CKD cats, the number of sedations and interventions required to implement this approach would likely preclude widespread clinical application. We concluded that MSC could be transferred safely by ultrasound-guided intrarenal injection in cats, but that alternative sources and routes of MSC therapy should be investigated.

Behavioural responses of calves to amputation dehorning with and without local anaesthesia

OBJECTIVE

To assess the pain elicited by amputation dehorning and evaluate the effect of local anaesthesia by using changes in calf behaviour.

METHODS

The behaviour of 6-month-old Friesian calves (n = 60), subjected to control handling, dehorned or dehorned after local anaesthesia treatment, was monitored in this study. The proportion of calves displaying particular behaviours was recorded using instantaneous scan sampling during the first 10 h and between 26 and 29 h after treatment.

RESULTS

The three behaviours of tail flicking, head shaking and ear flicking displayed similar features with time according to treatment and appeared to occur in an inverse relation to rumination. Dehorned calves were highly restless for the first 6 h after treatment. A significantly greater proportion of them displayed tail flicking, head shaking and ear flicking than the control calves, which, by contrast, stood still and ruminated (P < 0.05). The behaviour of calves given local anaesthetic prior to dehorning was similar to that of the control calves for the first 2 h. Thereafter the proportion of calves displaying tail flicking, head shaking and ear flicking increased, rumination decreased, and the behaviour was similar to that of the dehorned calves.

CONCLUSIONS

These results suggest that dehorning is a painful experience that lasts about 6 h and that local anaesthetic alleviates that pain during its period of action. It is recommended that local anaesthetic be administered when conducting amputation dehorning.

Insemination of Holstein heifers at a preset time after estrous cycle synchronization using progesterone and prostaglandin

Two experiments were conducted to study estrous cycle control regimens that combine progesterone administration via an intravaginal device ( PRID ) with a single injection of prostaglandin F2 alpha (PG). In Exp. I, 242 Holstein heifers were assigned randomly to one of three treatment groups at 14 to 18 mo of age. Treatments were: 1) control, 2) PRID -6 + PG-6 ( PRID in place for 6 d plus PG on the day of PRID removal) and 3) PRID -7 + PG-6 ( PRID in place for 7 d plus PG on the day before PRID removal). Heifers were observed for estrous activity and were inseminated at 8 to 20 h after estrus was detected. Estrus and ovulation were effectively synchronized after both PRID + PG treatments. Ninety-nine percent of the heifers in each group were in estrus within 168 h after PG injection. However, the interval from PG administration to the onset of estrus was longer after PRID -7 + PG-6 (75 +/- 2 h) than after PRID -6 + PG-6 (66 +/- 2 h). A lower variance in the interval from PG treatment to estrus was observed after PRID -7 + PG-6, suggesting that the 24 h delay in PRID withdrawal improved the synchrony of the onset of estrus. Pregnancy rates (72 to 82%) did not vary across treatment groups. Two-hundred seventy-four heifers were assigned to Exp. II. Treatments were 1) control, 2) 2 X PG (two injections of PG at an 11 d interval) and 3) PRID -7 + PG-6.(ABSTRACT TRUNCATED AT 250 WORDS)

Inhibition of intrafollicular PGE2 synthesis and ovulation following ultrasound-mediated intrafollicular injection of the selective cyclooxygenase-2 inhibitor NS-398 in cattle1

Ultrasound-mediated intrafollicular injection and aspiration procedures were used to investigate the ability of the selective cyclooxygenase-2 inhibitor, NS-398, to inhibit intrafollicular PGE2 synthesis and suppress ovulation in dairy cattle. Follicular growth and timing of the preovulatory gonadotropin surge were synchronized in 55 Holstein cows and the position of the ovulatory follicle was determined by daily ultrasound scanning. Preovulatory follicular fluid was aspirated from the largest follicle in four animals at 0, 6, 12, 18, and 24 h after GnRH injection (n = 20). The remaining 35 animals were subjected to ultrasound-mediated intrafollicular injection of NS-398 (10 microM final concentration; n = 19) or diluent (n = 16; controls). At 24 h after GnRH injection, follicular fluid was harvested from a subset of NS-398- (n = 9) and diluent-treated animals (n = 6). The remaining NS-398- and diluent-treated animals were subjected to ultrasonography every 6 h for 36 h after intrafollicular injection, and then daily through d 7 of the subsequent luteal phase to monitor ovulation and corpus luteum development. Follicular fluid PGE2 concentrations were increased following GnRH injection and reached a maximum at 24 h (P < 0.05). Follicular fluid PGE2 concentrations were decreased in NS-398- vs. diluent-treated follicles (7.2 vs. 52.2 ng/mL respectively; P < 0.05), but progesterone concentrations did not differ. Intrafollicular injection of NS-398 also inhibited follicle rupture (P < 0.001). All 10 control animals ovulated within 30 h of GnRH injection. Nine out of the ten NS-398-injected animals failed to ovulate. The NS-398-injected follicles developed morphological and endocrine characteristics resembling luteinized, unruptured follicles. Thus, intrafollicular PGE2 synthesis and follicle rupture, but not luteinization, were inhibited in cattle following ultrasound-mediated intrafollicular injection of NS-398. Ultrasound-mediated intrafollicular injection of NS-398 is a useful tool for mechanistic studies of intrafollicular regulation of the ovulatory process in cattle.

Experimental transmission of BSE and scrapie to the common marmoset

Two young male common marmosets (Callithrix jacchus) were injected intracerebrally and intraperitoneally with a crude brain homogenate prepared from a cow with bovine spongiform encephalopathy (BSE). Two other marmosets were similarly injected with brain homogenate from a sheep with natural scrapie. The two animals injected with scrapie material developed neurological signs 38 and 42 months after injection and the two animals injected with BSE material developed neurological signs after 46 and 47 months. Post mortem examination of the brains revealed spongiform encephalopathy especially in the basal nuclei and diencephalon of all the animals and, in addition, involvement of the cerebral cortex of the marmosets injected with scrapie material. The experiment extends the host range of experimental BSE to include a primate species.

Intermittent Bolus Injection versus Continuous Infusion of Furosemide in Normal Adult Greyhound Dogs

Several studies in human subjects have demonstrated greater diuresis with constant rate infusion (CRI) furosemide than intermittent bolus (IB) furosemide. This study was conducted to compare the diuretic efficacy of the same total dose of IB furosemide and CRI furosemide in 6 healthy, adult Greyhound dogs in a randomized crossover design with a 2-week washout period between treatments. For IB administration, dogs received 3 mg/kg at 0 and 4 hours. For CRI administration, dogs received a 0.66 mg/kg loading dose followed by 0.66 mg/kg/h over 8 hours. The same volume of fluid was administered for both methods. Urine output was quantified hourly. Urine electrolyte concentrations, urine specific gravity (USG), packed cell volume (PCV), total protein (TP), serum electrolyte concentrations, total carbon dioxide (TCO2), serum creatinine (sCr), and blood urea nitrogen (BUN) were determined every 2 hours. Urine production and water intake were greater (P < or = 0.05) for CRI than IB. Urine sodium and calcium losses were greater (P < 0.05) and urine potassium loss was less (P = 0.03) for CRI than IB, but there was no evidence of a difference between methods for urine magnesium and chloride losses. Serum chloride concentration was less (P < 0.001), sCr concentration greater (P = 0.04). TP greater (P = 0.01), and PCV greater (P = 0.003) for CRI than IB. No differences in USG, TCO2, BUN, or serum potassium, sodium, and magnesium concentrations were detected between methods. The same total dose of CRI furosemide resulted in more diuresis, natriuresis, and calciuresis and less kaliuresis than IB furosemide in these normal Greyhound dogs over 8 hours, suggesting that furosemide is a more effective diuretic when administered by CRI than by IB.

Development of a retrobulbar injection technique for ocular surgery and analgesia in dogs

OBJECTIVE

To develop and compare 3 techniques for retrobulbar injection of local anesthetic agents for ocular surgery and analgesia in dogs.

DESIGN

Prospective study.

ANIMALS

17 dogs (including 9 cadavers).

PROCEDURES

Inferior-temporal palpebral (ITP), perimandibular, and combined superior-inferior peribulbar injection techniques were compared by assessing the distribution of latex after injection into the orbits of 5 canine cadavers; magnetic resonance imaging (MRI) evaluation of the distribution of contrast agent after injection in the retrobulbar space of 4 canine cadavers; and assessment of the efficacy and MRI evaluation of the anatomic distribution of injections of a lidocainecontrast agent mixture in 4 anesthetized, nonrecovery dogs. By use of the preferred technique (ITP), the ocular effects of lidocaine anesthesia were evaluated in 4 dogs; during a 2-week period after treatment, dogs underwent ophthalmic examination, Schirmer tear testing (STT), intraocular pressure (IOP) measurement, and Cochet-Bonnet esthesiometry.

RESULTS

Of the 3 techniques, the ITP technique was the preferred method for retrobulbar administration of anesthetic agent in dogs because it was efficacious (pupil dilation and central rotation of the globe achieved in all eyes), easiest to perform, and provided thorough coverage of the intraconal retrobulbar space without complication. During the 2-week follow-up period, the ITP injection did not significantly affect STT, IOP, or Cochet-Bonnet esthesiometry values in dogs.

CONCLUSIONS AND CLINICAL RELEVANCE

In dogs, retrobulbar administration of anesthetic agents via the ITP technique is a potential alternative to systemic administration of neuromuscular blocking agents for ophthalmic surgery and provides the additional benefit of local ocular analgesia.

Production of chicken chimeras from injection of frozen-thawed blastodermal cells

To execute a strategy for reconstituting genetic resources from cryopreserved blastodermal cells, experiments were conducted to optimize conditions for producing chimeric chickens from frozen-thawed blastodermal cells. Stage X blastodermal cells were collected from Barred Plymouth Rock embryos and dispersed. Cells were resuspended in 10% dimethyl sulfoxide in Dulbecco's modified Eagle's medium (DMEM) containing 20% fetal bovine serum, and distributed into plastic ampules. Cell suspensions were seeded to induce ice formation at -7 C, cooled from -7 to -35 C at 1 C/min and then ampules were plunged into liquid nitrogen. Thawing was done by plunging the ampules into warm water (37 C) for 3 min. After centrifugation, the supernatant was replaced with DMEM, and dead or broken cells were removed by density gradient centrifugation. Approximately 500 cells were injected into irradiated Stage X White Leghorn recipient embryos. Following incubation, several somatic chimeras were produced. The frequency of somatic chimerism when fresh (unfrozen) cells, or cells that were frozen and selected by density gradient centrifugation on Percoll or Nycoprep were injected into recipient embryos was 84, 79, and 85%, respectively. The percentage of donor-derived pigmentation in the down of these chimeric chickens was 79, 50, and 58%, respectively. Germline chimerism was determined by mating the chimeras that survived to sexual maturity to Barred Plymouth Rocks. Nine of 16 birds (56.2%) injected with fresh cells, 2 of 26 birds (7.7%) injected with cells that were frozen and selected by density gradient centrifugation on a Percoll gradient, and 3 of 26 birds (11.5%) injected with cells that were frozen and selected on a Nycoprep gradient showed germline transmission; the percentage of donor-derived progeny in these chimeras were 29.5, 5.2, and 6.8%, respectively. The Barred Plymouth Rock donor stock was "reconstituted" by inter se mating of germline male and female chimeras. These data demonstrate that the strategy described here for reconstituting genetic resources from cryopreserved blastodermal cells via chimeric intermediates can be performed successfully.

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.