Comparison of histamine release induced by morphine and oxymorphone administration in dogs

Cardiovascular effects (vasodilatation, hypotension) of morphine administration have been attributed to central actions and peripheral histamine release. In the study reported here, we compared plasma histamine (Hm) concentrations after morphine sulfate and oxymorphone HCl administration in conscious dogs. Five healthy adult dogs (mean body weight, 10.1 kg) were randomly administered morphine (2 mg/kg of body weight, IV) or oxymorphone (0.2 mg/kg, IV) by a 5-second bolus injection at weekly intervals. Venous blood samples (5 ml) were collected from jugular veins before and at 1, 2, 5, 15, 30, and 60 minutes after drug administration. Behavioral changes were recorded. Plasma was analyzed by a radioenzymatic technique, using purified histamine N-methyltransferase as an enzyme catalyst (sensitivity of assay, 40 pg Hm/ml). Mean base-line Hm value for all dogs was 0.55 ng/ml. The mean Hm value was significantly higher (P less than 0.05) than the base-line value at 1, 2, 5, 15, and 60 minutes after morphine administration (531.4, 251.0, 113.0, 31.5, and 1.0 ng of Hm/ml, respectively), but there were no significant increases in histamine values from base-line values at any time after oxymorphone administration. All dogs given morphine and 1 dog given oxymorphone showed excitatory behavior; 2 dogs given morphine and 3 dogs given oxymorphone salivated profusely.     

Estimation of genetic parameters for wool fiber diameter measures.

Genetic and phenotypic correlations and heritability estimates of side, britch, and core diameters; side and britch CV; side and britch diameter difference; and clean fleece weight were investigated using 385 western white-faced ewes produced by 50 sires and maintained at two locations on a selection study. Data were analyzed using analysis of variance procedures, and effects in the final model included breed of sire-selection line combination, sire within breed-selection line, and location. Heritabilities were estimated by paternal half-sib analysis. Sires within breed-selection line represented a significant source of variation for all traits studied. Location had a significant effect on side diameter, side and britch diameter difference, and clean fleece weight. Age of ewe only affected clean fleece weight. Phenotypic and genetic correlations among side, britch, and core diameter measures were high and positive. Phenotypic correlations ranged from .68 to .75 and genetic correlations ranged from .74 to .89. The genetic correlations between side and britch diameter difference and side diameter or core diameter were small (-.16 and .28, respectively). However, there was a stronger genetic correlation between side and britch diameter difference and britch diameter (.55). Heritability of the difference between side and britch diameter was high (.46 +/- .16) and similar to heritability estimates reported for other wool traits. Results of this study indicate that relatively rapid genetic progress through selection for fiber diameter should be possible. In addition, increased uniformity in fiber diameter should be possible through selection for either side and britch diameter difference or side or britch CV.     

Incidence of molds and mycotoxins in commercial animal feed mills in seven midwestern states, 1988-1989.

A total of 82 feed manufacturers located within seven midwestern states (Iowa, Nebraska, Minnesota, Illinois, Indiana, Ohio, Michigan) participated in a survey of mold and mycotoxin contamination of corn. Samples were submitted from a composite of the grading samples taken from each incoming load of corn. The survey was initiated in July 1988. During the 12-mo period, moisture content of the corn samples upon receipt at the laboratory ranged from 10.5 to 13.3%. The greatest variation occurred in the springtime. Iowa's corn samples were driest (11.2%), and samples submitted from Ohio were wettest (12.8%). Mold counts averaged 2.63 x 10(4) per gram during the year. The predominant mold found was Fusarium sp. Samples were checked by black light and averaged 25.4% positive during the period. When assayed for mycotoxins, 19.5% of the samples were positive for at least one of the following: aflatoxin, zearalenone, T2 toxin and deoxynivalenol (vomitoxin). Aflatoxin and T2 toxin made up the majority of these samples containing toxin. The highest incidence of mycotoxin-contaminated corn (48%) occurred in samples submitted in July of 1988. Over the 12-mo period, the highest mycotoxin contamination occurred in Iowa, Illinois and Michigan. When samples were subjected to 90% relative humidity and 32 degrees C, an average of 3.9 d was required for mold growth to appear. After incubation, 24.7% of the samples contained one of the four toxins. The data indicate that mold and mycotoxin contamination of mixed samples of corn is widespread, even in the midwestern corn belt of the U.S.     

Use of magnetic resonance imaging identify suspensory desmitis and adhesions between exostoses of the second metacarpal bone and the suspensory ligament in four horses

Four horses were examined because of chronic forelimb lameness. In all horses, the cause of the lameness was localized to the metacarpus by means of physical examination and diagnostic anesthesia, and radiography of the affected limb revealed a small exostosis of the second metacarpal bone. Magnetic resonance imaging revealed suspensory desmitis in the region of this exostosis in all 4 horses. In addition, an abnormal area of low signal intensity, suggestive of an adhesion, was seen between the exostosis and the suspensory ligament. In all horses, an adhesion between the suspensory ligament and the exostosis on the second metacarpal bone was identified and transected at surgery, and the exostosis and distal portion of the second metacarpal bone were removed. All horses were able to return to their previous athletic use following a 6-month rest and rehabilitation program for treatment of the suspensory desmitis. Findings in these horses suggest that adhesions between the suspensory ligament and an exostosis of the second metacarpal bone may be a cause of chronic or recurrent forelimb lameness in horses.     

Histologic comparison of skin biopsy specimens collected by use of carbon dioxide or 810-nm diode lasers from dogs

OBJECTIVE: To compare histologic artifacts caused by carbon dioxide (CO2) or 810-nm diode surgical lasers used to obtain small biopsy specimens of skin from healthy dogs. DESIGN: Prospective study. ANIMALS: 4 dogs. PROCEDURE: 21 skin biopsy specimens were collected from each dog. Three biopsy specimens were obtained with a CO2 or an 810-nm diode laser at 3 operating settings each, and 3 biopsy specimens were obtained with a 6-mm biopsy punch instrument (controls). After processing, biopsy specimens were examined for artifacts related to laser-tissue interactions. Microscopically visible char was measured from the lateral edge of each specimen obtained with a laser. RESULTS: There were no significant differences among mean char distances in biopsy specimens obtained with the CO2 laser at various settings. Mean char distance was significantly greater in all skin biopsy specimens obtained with the diode laser, compared with those obtained with the CO2 laser. Mean char distance was significantly greater in biopsy specimens obtained with the 810-nm diode laser at high power, compared with biopsy specimens obtained with the 810-nm diode laser at low power. CONCLUSIONS AND CLINICAL RELEVANCE: Results indicated that the CO2 laser caused less thermal injury at margins of skin biopsy specimens; therefore, if a surgical laser is used for removal of cutaneous masses or to obtain skin biopsy specimens, use of the CO2 laser is recommended. Veterinarians performing a biopsy by using a surgical laser should be aware that laser-induced artifacts may render small biopsy specimens useless for providing accurate histologic diagnosis.     

Nutrient balance in the diet of spring calving, pasture-fed dairy cows

AIMS: To report the nutrient composition of pastures fed to spring-calving dairy cows in the Manawatu region of New Zealand, and describe changes in the nutrient composition of these pastures over a 12-month period. Having done this we sought to: (1) compare the nutrient composition of the pasture offered with the nutrient requirements of spring-calving dairy cows; (2) identify periods when individual nutrient surpluses and deficits are likely; and, (3) identify nutrients that demonstrate a high level of variability between sampling occasions. METHODS: Seven farms took part in the study. Each farm was visited monthly from August 1996 to July 1997. Samples of pasture were taken at each visit and submitted for estimation of dry matter (DM), metabolisable energy (ME), crude protein (CP), non-structural carbohydrate (NSC), neutral detergent fibre (NDF), acid detergent fibre (ADF), calcium (Ca), phosphorus (P), magnesium (Mg), sodium (Na), potassium (K), chlorine (Cl), sulphur (S), iron (Fe), copper (Cu) and zinc (Zn), and dietary cation-anion differences (DCAD). RESULTS: Sampled pastures were characterised by low to marginal ME, NSC, Ca, Mg, and Zn concentrations when compared with recommended dietary nutrient concentrations for lactating and non-lactating dairy cattle in New Zealand. Analyses revealed relatively high CP, NDF and K concentrations, and DCAD. CONCLUSIONS: These analyses identify broad trends in the nutrient balance of a pasture-only feeding regime and provide a useful reference for planning feed strategies for spring-calving, pasture-fed dairy herds in this region. Recommended changes to on-farm practice should be made after considering the whole farm system, rather than being made solely on the basis of perceived deficiencies or excesses of individual nutrients.