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.     

Congenital polycystic kidney disease in lambs

AIM: To describe the pathology and inheritance of a congenital polycystic kidney disease (PKD) of sheep.

METHODS: Mode of inheritance of PKD was investigated by evaluation of results of the disorder from planned matings in two consecutive years within subsets of a flock that had a high prevalence of PKD in lambs. Gross pathological and histopath- ological studies were based on tissues derived from this study. Haematoxylin and eosin (H&E)-stained paraffin sections of kidney, liver, extrahepatic biliary and pancreatic ducts, pancreas and epididymis were used to describe the lesions.

RESULTS: Twenty-five lambs affected by PKD, of both sexes, were born, numbers in accord with those expected for an autosomal recessive disorder in the population studied. In all cases for which tissues were available, the renal, bile ductal (intrahepatic and extrahepatic), pancreatic and epididymal tissues had widespread dysplastic changes and associated cyst formation.

CONCLUSIONS: The findings of renal cysts in conjunction with cysts in other organs are unifying features in many of the human and animal forms of PKD and suggest a related pathogenic and genetic base consistent with an autosomal recessive disorder.     

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.     

Responses of Selected U.S. Gulf Coast Marsh Macrophyte Species to Oiling and Commercial Cleaners

A shoreline cleaner was tested to determine its effectiveness in removing different types of oil from selected US Gulf coastal marsh macrophytes. Bulltongue (Sagittaria lancifolia L.), three cornered grass (Scirpus olneyi E. & G.) and broadleaf cattail (Typha latifolia L.) were subjected to oil application and cleaning in a greenhouse and the subsequent effects on plant functions were evaluated during the period immediately after treatment initiation. Plant stomatal functioning, photosynthesis, respiration, regeneration, growth and biomass were monitored. Two types of oil, South Louisiana Crude (SLC) or Arabian Medium Crude (AMC) were used. The treatments included: control (no oil or cleaner), cleaner only (COREXIT 9580 only, no oil), oiled with SLC or AMC only (no cleaner), and oiled using SLC or AMC and cleaned with COREXIT 9580 after two days. The existing leaves on the macrophytes at the time of treatment application directly subjected to oiling (but not cleaned) did not recover from the effects of oiling in all of the study species. However, leaves under oil+cleaner treatments or leaves developed during the post-oiling period (new leaves) showed a different pattern of response. For instance, in bulltongue plants, new leaves had stomatal conductances at or close to the values recorded for control plants. However, new leaves and leaves subjected to oil+cleaner treatment in cattail and three-cornered plants, had stomatal conductances significantly lower than their respective control plants. However, photosynthetic and respiration data indicated no overall significant differences within each species across treatments. Thus, the physiological functions of the study species had apparently recovered from the initial adverse effects of oiling within the experimental period. Based on photosynthetic and respiration data, the study species sensitivity ranking is similar. Furthermore, there were no significant differences in physiological responses of the study species to oil types. In addition, above-ground biomass was not affected significantly by the treatments in bulltongue or cattail but was reduced significantly in three-corner plants. Based on the overall physiological and biomass data, bulltongue was the least sensitive of the three species to SLC and AMC oil types than the other species while cattail appeared to be the most sensitive. Any beneficial effects of the cleaner may be more pronounced in plant species highly sensitive to specific oil types than the species studied.     

Mongolian Tree Rings and 20th-Century Warming

A 450-year tree-ring width chronology of Siberian pine (Pinus sibirica Du Tour) growing at timberline (2450 meters) in the Tarvagatay Mountains in west central Mongolia shows wide annual growth rings for the recent century. Ecological site observations and comparisons with instrumental temperature records indicate that the ring widths of these trees are sensitive to annual temperature variations. Low-frequency variations in the Tarvagatay tree-ring record are similar to those in a reconstruction of Arctic annual temperatures, which is based on 20 tree-ring width series from northern North America, Scandinavia, and western Russia. The results indicate that recent warming is unusual relative to temperatures of the past 450 years.