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Biomedical subjects

C D Thatcher

Publications and source records attributed to C D Thatcher.

At least 19 recordsLinked to original sources
PubMed1998

Oral and parenteral vaccination of mice with protein-ergotamine conjugates and evaluation of protection against fescue toxicosis.

Acremonium coenophialum produces ergopeptide alkaloids in tall fescue (Festuca arundinacea Schreb.). These ergot alkaloids decrease serum alkaline phosphatase (ALP) activity, serum cholesterol and prolactin concentrations, as well as average daily gains (ADG) in cattle. The objective of this study was to evaluate the protection of anti-ergotamine antibodies induced by either oral or parenteral vaccination with protein-ergotamine conjugates or passive vaccination with anti-ergovaline, monoclonal antibodies in a murine model of fescue toxicosis. Ergotamine (EG) was conjugated to bovine serum albumin (BSA) and cholera toxin subunit B (CTB) by the Mannich reaction. Mice were blocked based on weight and randomly allocated into five groups of 10 mice each. Treatment groups were as follows: (1) group vaccinated intraperitoneally (ip) with a BSA-EG conjugate and fed an endophyte-infected (EI) fescue diet (BSA-EG group); (2) group orally vaccinated with a CTB-EG conjugate mixed with free cholera toxin (CT) and fed an EI fescue diet (CTB-EG group); (3) nonvaccinated group fed an EI fescue diet (EI group); (4) group passively vaccinated with anti-ergovaline, monoclonal antibodies and fed an EI fescue diet (MoAB group); and (5) nonvaccinated group fed an endophyte-free (EF) fescue diet (EF group). The EI diet contained 1.5 ppm of Ergovaline (EV), whereas no EV was detected in the EF diet.Respective diets were similar upon nutritional analysis. Unvaccinated mice in the EI group exhibited features of fescue toxicosis as indicated by decreased serum ALP activity and cholesterol, and decreased weight gain as compared to mice in the EF group. Antibodies against EG and EV were present in sera of mice in the BSA-EG and MoAB groups, respectively. Mice orally vaccinated with the CTB-EG conjugate developed secretory IgA (sIgA) antibodies and short-lived, systemic IgG responses against EG. Weight gains were increased in the BSA-EG and CTB-EG groups and tended to be increased in the MoAB group vs. the unvaccinated EI group. Serum ALP activity was decreased in the BSA-EG and MoAB groups as compared to the EF group. Serum ALP activity was further decreased in the BSA-EG vaccinated group as compared to the EI group. Cholesterol concentrations were decreased in the EI, BSA-EG and MoAB groups as compared to the EF group. Prolactin concentrations were similar in all groups.

Acremonium↗
PubMed1998

Monocyte immune cell response and copper status in beef steers that grazed endophyte-infected tall fescue.

A 3-yr study was conducted to evaluate immune response and Cu status of yearling beef steers as a consequence of grazing tall fescue (Festuca arundinacea Schreb.) infected (E+) with the endophyte fungus Neotyphodium coenophialum ([Morgan-Jones and Gams] Glenn, Bacon, and Hanlin). During a preliminary study in 1994, 24 weanling Angus and Angus x Hereford steers were blocked by breed and weight (initial BW 271 kg; SD 25) and were randomized to E+ and low endophyte (E-) fescue in pastures at Glade Spring, VA. Grazing began in April and was discontinued in July. In 1995 and 1996, 24 weanling Angus and Angus x Hereford steers (initial BW 249 kg, SD 20 and 240 kg, SD 15, respectively) were randomized to the E+ and E- pastures at Glade Spring during each year. Grazing began in April and continued until September in 1995 and October in 1996. In 1994, steers that grazed E+ fescue exhibited lower (P < .05) phagocytic activity, major histocompatibility complex (MHC) class II expression, ceruloplasmin, and serum Cu than steers that grazed E- tall fescue. During 1995, steers grazing E+ fescue had lower (P < .05) phagocytic activity and MHC class II expression than steers that grazed E- fescue. In 1996, one-half of the steers within each paddock received a Cu oxide bolus at the beginning of the grazing season. During 1996, phagocytic activity was lower (P < .01) and MHC class II expression tended (P < .07) to be lower in steers that grazed E+ tall fescue than in steers that grazed E- tall fescue. Copper supplementation increased (P < .05) MHC class II expression in July regardless of endophyte status over nonsupplemented steers. Steers that grazed E- tall fescue had higher (P < .05) plasma or serum Cu concentrations than steers that grazed E+ tall fescue in each year of the study. These data indicate that the endophyte compromised the immune function of grazing steers, and the data suggest a relationship with depressed Cu status.

Acremonium↗
PubMed1998

Validation of predictive equations for use of deuterium oxide dilution to determine body composition of dogs.

OBJECTIVE: To validate equations predicting body composition of dogs, using deuterium oxide dilution. ANIMALS: 38 female and 37 male dogs selected by defined body weight and body condition criteria. PROCEDURE: Measured equilibrated deuterium concentration in serum after i.v. administration of isotope was used to determine isotope space and predict body water, fat, nitrogen, and ash contents determined from analysis of homogenized carcass. Equations predicting body composition were derived, using regression analysis, and were validated, using data-splitting techniques. RESULTS: Deuterium space (in kilograms) overestimated kilograms of body water content by mean 21.8% +/- SD of 4.18%. Regression equations were derived and validated to predict kilograms of body water and ash from kilograms of deuterium space, and proportion of body water, fat, nitrogen, and ash from proportion of deuterium space. Coefficients of determination (r2) and means of standard errors of estimating new values (SEE) were, respectively, 0.993 and 0.4 kg for body water content, and 0.942 and 0.08 kg for ash content. For proportions, SEE were 2.0, 2.7, 0.1, and 0.4% for body water, fat, nitrogen, and ash, respectively. Two factors, time for isotope equilibration and whether samples were processed by vacuum sublimation, improved SEE for proportion of body water from 2.0 to 1.3% and of fat from 2.7 to 1.8%. Equations predicting absolute quantities of fat and nitrogen could be derived but not validated. CONCLUSIONS: Deuterium dilution can be used to predict body composition of dogs with precision equal to that determined for other species.

Animals↗
PubMed1997

Prospective study of equine colic incidence and mortality.

A prospective study of one year was conducted on 31 horse farms to obtain population based estimates of incidence, morbidity and mortality rates of equine colic. Farms with greater than 20 horses were enrolled by randomly selecting horse owners from 2 adjacent counties of Virginia and Maryland. Descriptive information for 1427 horses was collected at the initiation of the study and updated at 3 month intervals. Time on the farm during the study was tabulated for each horse. When colic was reported by the owner, investigators visited the farm to obtain information about the colic. The crude incidence density rate of colic was 10.6 colic cases/100 horse-years, based on 104 cases/358,991 horse-days. The median farm specific incidence density rate was 7 cases/100 horse-years, and the range for individual farms varied from 0 to 30 colic cases/100 horse-years. A specific diagnosis was not made for 84 (81%) of colic episodes. Seventy colic episodes (67%) were treated by a veterinarian. Drugs were used in 83 (80%) colic episodes, and 78 (75%) of colic cases were mild, requiring no treatment or resolving after only one treatment. Four horses required colic surgery. Fourteen (13%) horses had more than one episode of colic during the year. Mortality from all causes of death was 2.5 deaths/100 horse-years, mortality rate for colic was 0.7 deaths/100 horse-years. Proportional mortality rate of colic, 28%, was higher than for any other cause of death. Horses less than age 2 years or greater than age 10 years had lower incidence than horses age 2-10 years. No difference in colic risk between genders was identified. Arabian horses had the lowest and Thoroughbreds the highest breed specific incidence rates. Horses used for eventing, or in training had a statistically significant higher incidence rate of colic compared to mature horses with no use (pets, retired, on pasture with no stated purpose). Horses used for lessons or with no use had the lowest incidence rates.

Age Factors↗
PubMed1997

Prospective study of equine colic risk factors.

A 1 year prospective study was conducted on 31 horse farms to identify risk factors for equine colic. Farms were randomly selected from a list from 2 adjacent counties of Virginia and Maryland, USA. The association between colic and farm or individual horse risk factors related to management, housing, pasture, use, nutrition, health and events was first examined by univariate statistical analysis. Individually significant (P < = 0.25 for farm factors, P < = 0.10 for horse factors) variables were used in a stepwise multivariable forward logistic regression to select explanatory factors (P < = 0.05). Analysis was conducted at 2 levels: farm and individual horse with farm specified as a random effects variable. No farm-level variables were significant. Significant horse-level variables included: age, odds ratio (OR) = 2.8 for horses age 2-10 years compared to < 2 years; history of previous colic, OR = 3.6 relative to no colic; changes in concentrate feeding during the year (1 per year, OR = 3.6, more than 1, OR = 2.2) relative to no changes; more than 1 change in hay feeding during the year, OR = 2.1 relative to no changes; feeding high levels of concentrate (> 2.5 kg/day dry matter, OR = 4.8, > 5 kg/day dry matter, OR = 6.3) relative to feeding no concentrate; and vaccination with monocytic ehrlichiosis vaccine during the study, OR = 2.0 relative to no vaccination. Feeding a whole grain with or without other concentrate components reduced risk, OR = 0.4, relative to feeding no whole grain. Results of the study suggest that diet and changes in diet are important risks for colic in a population of horses on farms.

Analysis of Variance↗
PubMed1995

Effect of selenium supplementation on colostral IgG concentration in cows grazing selenium-deficient pastures and on postsuckle serum IgG concentration in their calves.

Effects of selenium (Se) deficiency and supplementation on production of colostral immunoglobulins by beef cows and transfer of antigen-specific and nonspecific immunoglobulins to their calves were examined. Eight beef cows, with marginal to deficient Se status (blood Se concentration, 50 micrograms/L), were allotted by breed and age to 1 of 4 Se treatment groups (n = 20/group): no supplemental Se; parenteral administration of 0.1 mg of Se and 1 mg of vitamin E/kg of body weight; ad libitum consumption of 120 mg of Se/kg of salt-mineral mix (SMM); and parenteral administration of 0.1 mg of Se and 1 mg of vitamin E/kg plus ad libitum consumption of 120 mg of Se/kg of SMM. All cows were inoculated IM with lysozyme. Cows consumed Se-deficient pastures or hay (21 to 62 micrograms/kg) during the study that began at mid-gestation and ended at postpartum hour 24. Although the concentration of specific lysozyme antibodies was not affected, cows given 120 mg of Se/kg of SMM (treatments 3 and 4) had higher colostral IgG concentration (P < 0.002) than did Se-deficient cows (treatments 1 and 2). Calves from cows in treatments 3 and 4 had higher postsuckle serum concentrations of IgG (P < 0.01) than did calves from cows in treatments 1 and 2. Colostral IgM and calf serum IgM concentrations did not differ among treatments.

Animal Feed↗
PubMed1994

Effect of copper and iron on neutrophil function and humoral immunity of gestating beef cattle.

Eighty gestating beef cattle were used to determine the effect of trace mineral salt mixtures containing copper (Cu) and iron (Fe) on selected immune functions and factors affecting copper bioavailability. Pastured cattle were randomly assigned to receive one of the following combinations of Cu and Fe in the free-choice trace mineral salt: (1) 0 mg of Cu/0 mg of Fe/kg of trace mineral salt, (2) 1,600 mg of Cu (CuSO4)/3,000 mg of Fe/kg of trace mineral salt, (3) 1,600 mg of Cu (CuSO4)/0 mg of Fe/kg of trace mineral salt, and (4) 1,600 mg of Cu (CuCO3)/3,000 mg of Fe/kg of trace mineral salt. Total Cu/Fe consumption (from trace mineral salt) was 2/678, 193/1,050, 162/553, and 202/1,140 mg/head/d, respectively, for the 4 groups. After a 1-month period of acclimation and also on day 28 of the 36-day study, copper concentrations in serum were significantly (P < 0.05) lower in group 1 than in groups 3 and 4. Serum copper concentrations did not increase with time for any group, whereas hepatic copper concentrations increased significantly (P < 0.05) with time for all groups except group 1. Hepatic iron concentrations were similar among groups at the time of the initial and final hepatic biopsies on days 0 and 28, respectively. Hepatic iron concentrations increased significantly (P < 0.05) with time in groups 3 and 4. Humoral response to chicken gamma-globulin was high but did not differ among groups on any of the days analyzed.(ABSTRACT TRUNCATED AT 250 WORDS)

Alpha-Globulins↗
PubMed1993

Comparison of kittens fed queen's milk with those fed milk replacers.

Fifteen 2-week-old kittens were randomly assigned to 1 of 3 milk treatment groups as the sole source of nutrition for 4 weeks: queen's milk, commercially available kitten milk replacer (CMR), and an experimental milk replacer (EXP). Kittens fed queen's milk suckled ad libitum, whereas CMR- and EXP-fed kittens were tube-fed every 6 hours. Kittens were weaned at 6 weeks of age and were fed a feline growth diet ad libitum for an additional 4 weeks. Kittens were examined at 2, 4, 6, 8 and 10 weeks of age; the procedure included an ophthalmic examination and blood sample collection for CBC and serum biochemical and amino acid analyses. Kittens fed CMR and EXP diets had weight gain greater than that for queen's milk-fed kittens. The kittens fed CMR, however, had diarrhea throughout most of the milk-feeding trial and developed diffuse anterior and posterior lens opacification and vacuolation at the posterior Y-sutures. The lens opacities noticed in the kittens during the milk treatments resolved to a residual perinuclear halo, and a few incipient cortical opacities were observed by the end of the growth diet-feeding period. Serum arginine concentration was significantly (P < or = 0.05) lower in the CMR-fed kittens, but was not different during the growth diet-feeding period. We concluded that the EXP diet supported normal growth in 2- to 6-week-old kittens; CMR supported normal kitten growth rate, but resulted in diarrhea and cataract formation; and serum amino acid data indicated that low arginine concentration may have been related to the CMR-induced cataract formation.

Animal Nutritional Physiological Phenomena↗
PubMed1992

Comparison of anthelmintic control programs for sheep in Virginia.

Haemonchus contortus is the most serious parasitic problem encountered by sheep producers in southwestern Virginia. Four anthelmintic control programs for grazing lambs were tested. Group TR received monthly SC injections of ivermectin (200 micrograms/kg of body weight). Group SI received the same dose of ivermectin at 0, 3, 6, 9, and 12 weeks after the start of the grazing season. Group SL was given levamisole (8 mg/kg, PO) 0, 3, 6, 9, and 12 weeks after the start of the grazing season, and group TA received ivermectin (200 micrograms/kg) 0, 8, 16, 20, and 24 weeks after the beginning of grazing. None of the 4 programs provided satisfactory control of parasites as indicated by fecal egg counts and serum pepsinogen concentrations, although group-TR lambs gained significantly more weight than lambs in groups SI and TA. Group-TA lambs developed clinical haemonchosis in early August and required additional treatment at that time. These findings suggest that reliance on anthelmintics alone may not provide the most effective and economic control of parasitic infection.

Abomasum↗
PubMed1990

Nutritional factors in bovine gastrointestinal disease.

Gastrointestinal disorders may be prevented through proper nutrition. Attention should be placed on establishing optimum feeding programs for cattle in all stages of the life and production cycle. Normal reticuloruminal development in calves and maintenance of gastrointestinal function in adult cattle is dependent upon adequate nutrition. Nutrition is also an important part of therapy of many gastrointestinal disorders.

Animal Nutritional Physiological Phenomena↗
PubMed1990

Influence of glucocorticoid on macromolecular absorption and passive immunity in neonatal lambs.

The relationship of serum cortisol to immunoglobulin absorption and gut closure in cesarean-derived neonatal lambs was evaluated in two trials. In trial 1, 21 lambs were obtained on d 136 to 138 of gestation, and in trial 2, 17 lambs were obtained on d 140 to 142 of gestation. At birth, lambs were assigned randomly to four treatments: 1) control (CO), 1 ml saline/kg BW every 4 h; 2) a drug to lower cortisol (LC), 5 mg metyrapone/kg BW every 4 h; 3) single-peak cortisol (SP), 10 IU ACTH/kg BW at 0 h; or 4) elevated cortisol (HC), 5 mg cortisol/kg BW every 4 h in trial 1 or 10 IU ACTH/kg BW every 4 h in trial 2. The treatment period was 24 and 48 h after delivery for trial 1 and 2, respectively. Lambs were fed pooled bovine colostrum every 4 h for 48 h after birth at 2 and 3.5% BW for trial 1 and 2, respectively. Compared with CO, HC increased serum cortisol, LC decreased serum cortisol and SP elevated serum cortisol concentrations through at least 8 h for both trials. In trial 1, HC and SP lambs exhibited elevated serum IgG, IgM and IgA concentrations by 20 h compared with CO. However, no difference in serum immunoglobulin concentration was observed at 36 h among CO, HC and SP. Conversely, LC had the lowest immunoglobulin concentration at 36 and 48 h, and precocious closure to immunoglobulin absorption had occurred by 20 h (P less than .05).(ABSTRACT TRUNCATED AT 250 WORDS)

Adrenocorticotropic Hormone↗
PubMed1990

Adaptation of human oscillometric blood pressure monitors for use in dogs.

Two digital oscillometric human blood pressure measuring devices were modified and evaluated as blood pressure monitors in 12 healthy anesthetized dogs. Direct arterial pressures were measured via cannulation of the dorsal pedal artery and were correlated with indirect measurements through an inflatable cuff placed over the dorsal pedal artery below the hock joint of the contralateral limb. Direct and indirect measurements were compared for systolic, diastolic, and calculated mean arterial pressures. Blood pressure ranges between 215/145 mm of Hg and 65/30 mm of Hg were obtained, using combinations of halothane, phenylephrine, calcium, and IV administered fluids. Machine A was found to be insufficient for clinical application, on the basis of correlation coefficients between direct and indirect pressures of 0.78, 0.65, and 0.74 for systolic, diastolic, and mean arterial pressures, respectively. Higher correlation coefficients between direct and indirect pressures (0.77, 0.87, and 0.87, respectively) were obtained with machine B. The results of the study reported here suggest machine B may be an effective blood pressure monitoring device in anesthetized dogs.

Animals↗
PubMed1989

Use of the partial farm budget technique to predict the economic impact of the flock management decision to use B-mode ultrasonographic pregnancy diagnosis.

A computer spreadsheet was developed to predict the economic impact of a management decision to use B-mode ultrasonographic ovine pregnancy diagnosis. The spreadsheet design and spreadsheet cell formulas are provided. The program used the partial farm budget technique to calculate net return (NR) or cash flow changes that resulted from the decision to use ultrasonography. Using the program, either simple pregnancy diagnosis or pregnancy diagnosis with the ability to determine singleton or multiple pregnancies may be compared with no flock ultrasonographic pregnancy diagnosis. A wide range of user-selected regional variables are used to calculate the cash flow changes associated with the ultrasonography decisions. A variable may be altered through a range of values to conduct a sensitivity analysis of predicted NR. Example sensitivity analyses are included for flock conception rate, veterinary ultrasound fee, and the price of corn. Variables that influence the number of cull animals and the cost of ultrasonography have the greatest impact on predicted NR. Because the determination of singleton or multiple pregnancies is more time consuming, its economic practicality in comparison with simple pregnancy diagnosis is questionable. The value of feed saved by identifying and separately feeding ewes with singleton pregnancies is not offset by the increased ultrasonography cost.

Animal Feed↗
PubMed1989

Parenteral nutritional support in the small animal patient.

Malnutrition has a direct relationship to complications associated with ineffective wound and fracture healing, inadequate immune responses, decreased tolerance to cancer therapy, muscle weakness, and certain organ dysfunctions (heart and liver). Malnutrition combined with disease, injury, or stress increases the metabolic rate in patients above that of resting. These patients are undergoing an accelerated form of starvation, which is more common than presently recognized in veterinary medicine and may be responsible for the less than optimal responses to proper therapies. Diseased or injured patients unable to digest or absorb nutrients from the gastrointestinal tract require additional medical support in the form of parenteral nutrition. Advances in parenteral solutions, products, and delivery systems make parenteral nutritional support possible in veterinary medicine, although not possible in all small animal practices. Proper patient selection, well-informed clients, dedicated technicians, and knowledgeable veterinarians are all essential in the successful implementation of parenteral nutritional support.

Animal Nutritional Physiological Phenomena↗