Comparative cardiovascular, analgesic, and sedative effects of medetomidine, medetomidine–hydromorphone, and medetomidine–butorphanol in dogs

The purpose of this study was to determine the cardiovascular, analgesic, and sedative effects of IV medetomidine (M, 20 µg kg^?1), medetomidine–hydromorphone (MH, 20 µg kg^?1 ? 0.1 mg kg^?1), and medetomidine–butorphanol (MB, 20 µg kg^?1 ? 0.2 mg kg^?1) in dogs. Using a randomized cross‐over design and allowing 1 week between treatments, six healthy, mixed‐breed dogs (five males and one female) weighing 20 ± 3 kg, were induced to anesthesia by face‐mask administration of 2.9% ET sevoflurane to facilitate instrumentation prior to administration of the treatment combinations. Dogs were intubated and instrumented to enable measurement of heart rate (HR), systolic arterial pressure (SAP), mean arterial pressure (MAP), diastolic arterial pressure (DAP), mean pulmonary arterial pressure (PAP), pulmonary arterial occlusion pressure (PAOP), central venous pressure (CVP), pulmonary arterial temperature (TEMP), and cardiac output via thermodilution using 5 mL of 5% dextrose, and recording the average of the three replicate measurements. Cardiac index (CI) and systemic (SVR) and pulmonary vascular resistances were calculated. After instrumentation was completed, administration of sevoflurane was discontinued, and the dogs were allowed to recover for 30 minutes prior to administration of the treatment drugs. After collection of the baseline samples for blood gas analysis and recording the baseline cardiovascular variables, the test agents were administered IV over 10 seconds and the CV variables recorded at 5, 10, 15, 30, 45, and 60 minutes post‐injection. In addition, arterial blood was sampled for blood gas analysis at 15 and 45 minutes following injection. Intensity and duration of analgesia (assessed by toe‐pinch response using a hemostat) and level of sedation were evaluated at the above time points and at 75 and 90 minutes post‐injection. Data were analyzed using anova for repeated measures with posthoc differences between means identified using Bonferroni's method (p < 0.05). Administration of M, MH, or MB was associated with increases in SAP, MAP, DAP, PAP, PAOP, CVP, SVR, and TEMP and with decreases in HR and CI. No differences in CV variables between treatment groups were identified at any time. PaO₂ increased over time in all groups and was significantly higher when MH was compared with M. At 45 minutes, PaO₂ tended to decrease over time and was significantly lower when MH and MB were compared with M at 15 minutes. Analgesia scores for MH and MB were significantly higher compared with M through 45 minutes, while analgesia scores for MH were significantly higher compared with M through 90 minutes. Sedation scores were higher for MH and MB compared with M throughout 90 minutes. Durations of lateral recumbency were 108 ± 10.8, 172 ± 15.5, and 145 ± 9.9 minutes for M, MH, and MB, respectively. We conclude that MH and MB are associated with improved analgesia and sedation and have similar CV effects when compared with M.     

The use of Oral Milbemycin Oxime (Interceptor®) in the Treatment of Chronic Generalized Canine Demodicosis*

Abstract— The purpose of this clinical study was to evaluate the efficacy of orally administered milbemycin oxime (Interceptor®, Ciba-Geigy, Greensboro, U.S.A.) in the treatment of 46 dogs with chronic generalized demodicosis. Two dosage protocols were followed with milbemycin oxime dosed at 0.5–2.3 mg.kg^-1 once daily (low dose) or twice daily (high dose). Seventy six per cent of the dogs on the low dose protocol achieved negative skin scrapings (remission) within 90 days, 24% were failures, and 19% remain negative with 1 year follow-ups. Seventy five per cent of the patients that achieved remission on the low dose protocol relapsed within 1 year when the milbemycin was discontinued. Ninety six per cent of the dogs on the high dose protocol achieved negative skin scrapings within 90 days, 4% were failures, and 42% remain negative with 1 year follow-ups. Twenty nine per cent of the patients that achieved remission on the high dose protocol relapsed within 1 year when the milbemycin was discontinued. Résumé— Le but de cette étude clinique était d'évaluer l'efficacité de la mylbémycine par voie orale (Interceptor®, Ciba Geigy, Greensboro, U.S.A.) dans le traitement de 46 chiens atteints de démodécie généralisée. Deux posologies ont été utilisées: 0.5–2.3 mg.kg^-1 une fois par jour (dose faible) et deux fois par jour (dose forte). Soixante dix ourcent des chiens ayant subi le protocole faible dose ont présenté des raclages cutanés négatifs (rémission) au bout de 90 jours, 24% n'ont jamais répondu et 19%étaient toujours négatifs un an après le traitement. Soixante dix pourcent des animaux ayant répondu à ce traitement ont rechuté dans l'année suivant l'arrêt de la milbémycine. Quatre vingt dix pourcent des chiens ayant subi le protocole à dose forte ont présenté des raclages négatifs au bout de 90 jours, 1% n'ent jamais guéri et 42% sont restés négatifs un en après l'arrêt du traitement. Vingt neuf pourcent des patients ayant guéri à cette posologie ont rechuté dans l'année suivant l'arrêt de la mylbémycine. Zusammenfassung— Das Ziel der vorliegenden Untersuchung war die Ermittlung der Wirksamkeit von oral angewendetem Milbemycinoxim (Interceptor®, Ciba-Geigy, Greensboro, USA) bei der Behandlung von 46 Hunden mit chronischer generalisierter Demodikose. Bei der Dosierung von Milbemycinoxin wurden zwei Dosierungsprotokolle eingesetzt, bei der niedrigen. Dosierung wurde 0.5–2.3 mg/kg einmal täglich, bei der hohen zweimal täglich verabreicht. 76% der Humde mit der niedrigen Dosierung zeigten negative Hautgeschabsel (Remission) innerhalb von 90 Tagen, 24% sprachen nicht an. Bei 19% der Hunde blieben die Geschabsel negativ bei den Kontrolluntersuchungen über 1 Jahr Dauer. Bei 75% der Patienten, die mit der niedrigen Dosierung zur Remission gebracht wurden, traten Rückfälle innerhalb von 1 Jahr nach Absetzen des Milbemycin auf Bei 96% der Hunde aus der Gruppe mit der hohen Dosierung waren die Hautgeschabsel innerhalb von 90 Tagen negativ, 4% sprachen nicht auf die Behandlung an. Bei 42% der Tiere blieben die Geschabsel negativ bei den Kontrolluntersuchungen über 1 Jahr Dauer. Bei 29% der-Patienten, die unter der hohen Dosierung zur Remission gebracht waren, traten Rückfälle innerhalb von 1 Jahr nach Absetzen des Milbemycins auf. Resumen El propósito del siguiente estudio clínico fué la evaluación de la eficacia de la administración oral de óximo de milbecina, (Interceptor®, Ciba-Geigy, Greensboro, U.S.A.) en el tratamiento de 46 perros con demodicosis crónica generalizada. Los protocolos de dosificación con óximo de milbezina fueron los siguientes: 0.5–2.3 mg/kg una vez al día, (dosis baja), o dos veces (dosis alta). Setenta y seis por ciento de los perros que siguieron el protocolo a la dosis menor presentaron raspados cutáneos negativos, (remisión), en noventa dias, el 24% resulto en fracaso y el diecinueve por ciento permaneció negativo después de un año. El 75% de los pacientes que alcazaron la remisión a la dosis baja sufrieron un relapso al año de tratamiento cuando fue discontinuado. Noventa y seis de los perros con el protocolo de la dosis alta presentaron raspados cutáneos negativos a los noventa dias, el 4% fue un fracaso y el 42% permaneció con resultados negativos despues de un año. Veintinueve por ciento de los pacientes que alcanzaron la remisión a la dosis mayor presentaron relapso después de un año cuando el tratamiento fue discontinuado.     

Different Doses of Porcine Luteinizing Hormone in Precocious Puberty Induction in Gilts

The use of hormonal protocols in puberty induction and synchronization of oestrus has lead to an increase in the efficiency of replacement gilts. The aim of this study was to evaluate different doses of porcine LH in precocious puberty induction and oestrus synchronization in a homogeneous group of gilts. Sixty-seven homogeneous prepubertal gilts (Camborough 22) at 137 +/- 4 days of age and 87 +/- 7 kg were treated with three different hormonal protocols: T1--600 UI of equine chorionic gonadotrophin (eCG; Novormon) and after a 72-h period 5 mg of LH (Lutropin); T2--600 UI of eCG and a 72-h period 2.5 mg of LH; T3--600 UI of eCG and a 72-h period 1.25 mg of LH. The ovaries were examined at slaughter, on day 6 after the hormonal treatment. There were no statistical differences (p > 0.05) between the different LH doses in the percentage of the detected oestrus (T1 = 42.85%; T2 = 60.87%, T3 = 52.18%), oestrus duration (T1 = 41.44 +/- 16.30 h; T2 = 48.57 +/- 16.29 h, T3 = 39.33 +/- 11.42 h), number of corpora lutea (T1 = 9.61 +/- 5.43; T2 = 9.86 +/- 3.32, T3 = 8.13 +/- 5.52) and percentage of animals presenting ovarian cystic degeneration (T1 = 33.33%; T2 = 39.13%, T3 = 39.13%). The T2 (2.5 mg of LH) presented the lowest dispersion (p < 0.05) of the LH-ovulation interval (T1 = 37.17 +/- 4.07 h; T2 = 38.26 +/- 2.84 h; T3 = 36.25 +/- 5.69 h). The LH dose reduction to 2.50 and 1.25 mg presented equal results with the recommended dose of 5.0 mg, and could be used in the precocious induction of oestrus in gilts. The 2.5-mg LH dose showed the lowest dispersion of ovulation and it can be used in fixed-time artificial insemination programmes.     

Effects of 2.0% end-tidal isoflurane with and without atropine prior to dexmedetomidine administration on cardiovascular variables in dogs

The purpose of this study was to determine the cardiovascular effects of 2.0% end‐tidal isoflurane in dogs administered dexmedetomidine (DEX). Using a randomized crossover design and allowing at least 2 weeks between treatments 12 adult hound dogs of either sex weighing 22 ± 1.7 SD kg were anesthetized by face mask administration of either sevoflurane or isoflurane to facilitate instrumentation prior to administration of treatment drugs. Dogs were intubated and instrumented to enable measurement of heart rate (HR), systolic (SAP), mean (MAP) and diastolic (DAP) arterial pressures, mean pulmonary arterial pressure (PAP), pulmonary capillary wedge pressure (PCWP), central venous pressure (CVP), pulmonary arterial temperature (TEMP), and cardiac output (CO) via thermodilution using 5 mL of 5% dextrose, and recording the average of three replicate measurements. Cardiac index (CI) and systemic (SVR) and pulmonary vascular resistances were calculated. Following completion of instrumentation, dogs were allowed to recover for 40 minutes. After collection of baseline data, dogs were administered one of four treatments at T‐10 minutes prior to injection of DEX (500? g M^–2 IM): 1) saline (SAL); 2) atropine [ATR, 0.02 (n = 6) or 0.04 (n = 6) mg kg^–1 IM]; 3) ISO (2.0% end tidal concentration); or 4) ISO + ATR. Cardiovascular data were collected at T‐20 and T‐5 minutes prior to administration of DEX, and at 5, 10 , 20, 30, 40, and 60 min following DEX. Data were analyzed using anova for repeated measures with post‐hoc differences between means identified using Bonferroni's method (p < 0.05). Differences in ATR dose were not found to be significant and thus results for ATR dose groups were pooled. Administration of SAL (dexmedetomidine alone) was associated with decreases in HR and CO and increases in SAP, MAP, DAP, CVP, and SVR. Administration of ATR was associated with an increase in HR and CO compared with SAL. Administration of ISO was associated with an increase in HR and a decrease in SVR, MAP and CVP compared with SAL. Administration of ISO + ATR was associated with effects similar to that of ISO or ATR alone. We conclude that administration of ISO reduces the increase in SVR associated with administration of DEX and does not adversely affect CO.     

Influence of nitrogen on competition between cereals and their natural weed populations

The effects of nitrogen fertilizer on the growth and density of natural weed populations in spring barley (Hordeum vulgare L.) and winter wheat (Triticum aestivum L.) were investigated in the absence of herbicide. An increased level of applied nitrogen did not enhance: weed germination, tended to decrease the total weed biomass and had a differential effect upon the biomass of individual weed species in both wheat and barky. In competition with barley, Chenopodium album L. and Lamium spp. had lower nitrogen optima than the crop, while Urtica urens L. had a higher nitrogen optimum. In competition with wheat, Stellaria media (L.) Vill., Lamium spp. and Veronica spp. had lower nitrogen optima than the crop. The systematic changes in nitrogen effect with time were analysed by fitting orthogonal polynomials to the growth and density curves. The methodology could be recommended for other studies in which time or other systematic factors are included, as it supplies information which a traditional analysis of variance cannot provide. Since seed production is positively correlated with biomass, so nitrogen level affects seed production and, hence, the seed pool and future weed population, suggesting that fertilizer usage can be exploited in an integrated programme of crop: weed management. A trend towards lower N fertilizer application owing to concerns about the environment willfavour most of the weed species investigated in these experiments and change the composition of weed populations.     

Research progress on the role of melatonin and its receptors in animal reproduction: A comprehensive review

Melatonin and its receptors play a crucial role in the regulation of the animal reproductive process, primarily in follicular development. However, the role that melatonin performs in regulating hormones related with reproduction remains unclear. Melatonin and its receptors are present both in female and male animals’ organs, such as ovaries, heart, brain and liver. Melatonin regulates ovarian actions and is a key mediator of reproductive actions. Melatonin has numerous effects on animal reproduction, such as protection of gametes and embryos, response to clock genes, immune‐neuroendocrine, reconciliation of seasonal variations in immune function, and silence or blockage of genes. The growth ratio of reproductive illnesses in animals has raised a remarkable concern for the government, animal caretakers and farm managers. In order to resolve this challenging issue, it is very necessary to conduct state‐of‐the‐art research on melatonin and its receptors because melatonin has considerable physiognomies. This review article presents a current contemporary research conducted by numerous researchers from the entire world on the role of melatonin and its receptors in animal reproduction, from the year 1985 to the year 2017. Furthermore, this review shows scientific research challenges related to melatonin receptors and their explanations based on the findings of 172 numerous research articles, and also represents significant proficiencies of melatonin in order to show enthusiastic study direction for animal reproduction researchers.     

Interannual variability of the South Georgia marine ecosystem: biological and physical sources of variation in the abundance of krill

Interannual variability is a characteristic feature of the Southern Ocean ecosystem, yet the relative roles of biological and physical processes in generating these fluctuations are unknown. There is now extensive evidence that there are years when there is a very low abundance of Antarctic krill ( Euphausia superba ) in the South Georgia area, and that this variation affects much of the ecosystem, with the most obvious impacts on survival and breeding success of some of the major predators on krill. The open nature of the South Georgia ecosystem means this variability has large-scale relevance, but even though there are unique time series of data available, information on some key processes is limited. Fluctuations in year-class success in parts, or all, of the krill population across the Scotia Sea can generate large changes in the available biomass. The ocean transport pathways maintain the large-scale ecosystem structure by moving krill over large distances to areas where they are available to predator colonies. This large-scale physical system shows strong spatial and temporal coherence in the patterns of the interannual and subdecadal variability. This physical variability affects both the population dynamics of krill and the transport pathways, emphasizing that both the causes and the consequences of events at South Georgia are part of much larger-scale processes.     

Nutritional responses in rainbow trout (Oncorhynchus mykiss) fed diets with different physical qualities at stable or variable environmental conditions

Rainbow trout with initial body weight 1144 g were fed two diets with high (feed A) or low (feed B) water stability for 6 weeks. During the last 2 weeks either stable or fluctuating oxygen saturation, salinity and temperature was introduced. High water stability of the feed was associated with harder pellets, less dust formation and less broken pellets compared to feed with low water stability. During the first 4 weeks, feed intake was 23% higher in trout fed diet B than in those fed diet A. Fluctuating environment resulted in a severe drop in feed intake for both dietary groups. At termination of the trial, stomachs of trout fed feed B contained mashed pellets and free water and oil. Stomachs of trout fed feed A contained more intact pellets and little fluid. The apparent digestibility of protein, starch, dry matter and energy was highest in feed A. The apparent digestibility of P and Zn was highest at stable environment, and the absorption of P was highest from feed A. In conclusion, physical quality affected the nutritional value of the feeds, and differences in nutritional value at stable or fluctuating environment appeared to be related to feed intake.