Publications by authors named "Geof W Smith"

Objective: To determine the influence of stage of lactation on the pharmacokinetics in milk when multiple doses of meloxicam were administered alone or in combination with gabapentin to postpartum (PP) and mid-lactation (ML) cows.

Animals: 8 postpartum and 8 mid-lactation dairy cows.

Methods: Cows were randomly divided into 2 groups (n = 8) which included 4 PP cows and 4 ML cows.

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Purpose: Current air-liquid interface (ALI) models of bovine proximal airways have their limitations. They do not simulate blood flow necessary to mimic systemic drug administration, and repeated sampling requires multiple, independent cultures. A bovine lung-on-chip (bLOC) would overcome these limitations, providing a convenient and cost-effective model for pharmacokinetic or pathogenicity studies.

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Flunixin is a nonsteroidal anti-inflammatory drug approved for use in cattle to manage pyrexia associated with bovine respiratory disease, mastitis, and endotoxemia. In the United States, no nonsteroidal anti-inflammatory drugs are approved for use in goats, but analgesics are needed for management of painful conditions to improve animal welfare. The objective of this study was to evaluate the pharmacokinetics of transdermal flunixin in dairy goats to determine a milk withdrawal interval (WDI) to avoid violative residue contamination in the food supply.

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A study was conducted in grazing dairy heifers to assess anthelmintic efficacy and production responses in dairy heifers treated with a single injection of eprinomectin in an extended-release formulation over a 123 day-period. The study was conducted on a pasture-based dairy in the Southeastern United States (North Carolina) over the summer months. Sixty crossbred dairy heifers were weighed and randomly allocated into 2 groups.

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Pneumonia is one of the most economically important respiratory diseases of calves and knowledge of the impact of clinical disease on pharmacokinetics (PK) in young calves is limited. This study was undertaken to investigate the efficacy and PK of two antibiotics, tulathromycin and danofloxacin, in two age groups of calves experimentally infected with Pasteurella multocida. Both danofloxacin, a fluoroquinolone antibiotic, and tulathromycin, a macrolide antibiotic is approved for the treatment of bovine respiratory disease (BRD).

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OBJECTIVE To compare the plasma pharmacokinetics of tulathromycin between 3-week-old (preweaned) and 6-month-old (weaned) calves and to characterize the distribution of tulathromcyin into pulmonary epithelial lining fluid (PELF) and interstitial fluid (ISF) of preweaned and weaned calves following SC administration of a single dose (2.5 mg/kg). ANIMALS 8 healthy 3-week-old and 8 healthy 6-month-old Holstein steers.

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The intent of this study was to determine what influence, if any, increasing age has on the binding of drugs to plasma proteins in cattle. Plasma from three different cohorts of calves were used. The first group (n = 20) had plasma samples taken at 1, 7 and 21 days of age.

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Creating the ideal nutrition program for calves is a demanding task that has undergone tremendous change in recent years. Products and technologies including novel milk replacers and automated calf feeding systems have been developed to facilitate the ability of dairy producers to feed for higher growth rates before weaning. The creation of new feeding programs and milk replacers has to be looked at carefully, not only from a nutrition point of view but also from the perspective of a potential effect on physiologic digestion and calf health.

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OBJECTIVE To describe plasma pharmacokinetic parameters and tissue elimination of flunixin in veal calves. ANIMALS 20 unweaned Holstein calves between 3 and 6 weeks old. PROCEDURES Each calf received flunixin (2.

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Diarrhea due to Salmonella infection is an important cause of neonatal calf diarrhea. The acquisition of passive immunity in the calf by vaccinating the dam has shown some success in previous studies; however, no data exists on the use of currently licensed vaccines in the United States. Therefore, the purpose of this study was to determine whether vaccinating cows in late gestation with a commercially available Salmonella Dublin vaccine would stimulate Salmonella-specific antibodies in the colostrum of cows at calving and whether these antibodies would be transferred to the calf.

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Mastitis remains a critical disease in the dairy industry and the use of intramammary antibiotics plays a critical role in mastitis treatment. Hetacillin is currently approved as an intramammary antibiotic that is used to treat mastitis in dairy cows. It is approved for once a day administration and can be used for a total of 3 d.

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Objective: To determine whether pharmacokinetics and milk elimination of flunixin and 5-hydroxy flunixin differed between healthy and mastitic cows.

Design: Prospective controlled clinical trial.

Animals: 20 lactating Holstein cows.

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Collection of fluid from the lumen of the gastrointestinal tract is commonly necessary for research projects, but presents challenges including intestinal motility and potential for leakage of intestinal contents. In this study, ultrafiltration collection devices were surgically implanted in the ileum and spiral colon of 12 steers for repeated collection of intestinal fluid over 48 hours. There were no significant complications associated with surgery or during the post-operative period, nor were there any significant pathologic changes found at necropsy 3 or 4 days post-surgery.

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Fluid therapy in calves.

Vet Clin North Am Food Anim Pract

July 2014

Early and aggressive fluid therapy is critical in correcting the metabolic complications associated with calf diarrhea. Oral electrolyte therapy can be used with success in calves, but careful consideration should be given to the type of oral electrolyte used. Electrolyte solutions with high osmolalities can significantly slow abomasal emptying and can be a risk factor for abomasal bloat in calves.

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Objective: To determine the effects of 3 commercially available, orally administered electrolyte solutions (OAEs) on abomasal luminal pH and emptying rate in dairy calves, compared with the effect of orally administered milk replacer.

Design: Randomized crossover study.

Animals: 6 male dairy calves (age, 12 to 31 days).

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Objective: To determine the tissue depletion profile of tulathromycin and determine an appropriate slaughter withdrawal interval in meat goats after multiple SC injections of the drug.

Animals: 16 healthy Boer goats.

Procedures: All goats were administered tulathromycin (2.

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Digital dermatitis is a major cause of lameness in many dairy herds and represents a detriment to milk production, reproductive efficiency, productive lifespan and welfare. The purpose of this study was to evaluate the therapeutic use of a Serpens species bacterin in a dairy herd known to have a significant prevalence of lameness due to digital dermatitis. Seventy-six mature lactating Holsteins were enrolled in this study.

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This study evaluated the efficacy of two different doses of amprolium in goats heavily infected with pathogenic Eimeria species. Forty Boer goat kids ranging from 3 to 5 months of age with naturally occurring coccidiosis were randomly divided into 2 groups and treated orally with amprolium at doses of 10mg/kg daily for 5 days (n=20) or 50mg/kg daily for 5 days (n=20). The Eimeria oocyst per gram concentrations were significantly reduced on day 7 in the kids that received amprolium at 50mg/kg, however oocyst concentrations were not significantly reduced in goats that received the 10mg/kg dose.

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Tulathromycin is a triamilide antibiotic that maintains therapeutic concentrations for an extended period of time. The drug is approved for the treatment of respiratory disease in cattle and swine and is occasionally used in goats. To investigate the pharmacokinetics of tulathromycin in meat goats, 10 healthy Boer goats were administered a single 2.

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Objective: To determine elimination kinetics of tilmicosin in milk following intramammary administration in lactating dairy cattle.

Design: Prospective pharmacokinetic study.

Animals: 6 lactating dairy cows.

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Treatment of calf diarrhea: oral fluid therapy.

Vet Clin North Am Food Anim Pract

March 2009

Diarrhea remains the leading cause of mortality in beef and dairy calves. Calves that have diarrhea frequently develop dehydration, strong ion acidosis, and electrolyte abnormalities, and are in a state of negative energy balance. Oral electrolyte therapy is a simple and economical method of addressing all of these potential complications.

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Pathophysiology of diarrhea in calves.

Vet Clin North Am Food Anim Pract

March 2009

Infectious diarrhea in calves is most commonly associated with enterotoxigenic Escherichia coli, Cryptosporidium parvum, rotavirus, coronavirus, or some combination of these pathogens. Each of these agents leads to diarrhea through either secretion or malabsorption/maldigestion, though the specific mechanisms and pathways may differ. Specific pharmacologic control and treatment are dependent on gaining a greater understanding of the pathophysiology of these organisms.

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