Ronald Erkert - Academia.edu (original) (raw)
Papers by Ronald Erkert
Javma-journal of The American Veterinary Medical Association, 2005
Journal of Equine Veterinary Science, Nov 1, 1998
Summary Six broodmares that were genetically tested to be heterozygous (H/N) and six broodmares t... more Summary Six broodmares that were genetically tested to be heterozygous (H/N) and six broodmares that were tested to be homozygous negative (N/N) for Equine Hyperkalemic Periodic Paralysis (HYPP), that were descendents of the same stallion, were used in a replicated 3x3 Latin square experiment to determine the genetic-diet relationships in the HYPP syndrome. The mares were fed rations consisting of 65% pelleted concentrate and 35% Coastal Bermudagrass hay that provided 1.1 (diet A), 1.9 (diet B) and 2.9% (diet C) potassium in the total rations. Symptoms of HYPP, such as repeated yawning, muscle twitching, generalized muscle fasciculations, myotonia, irregular movement, prolapse of the membrana nicitans and involuntary recumbency, were recorded during each 14-day experimental period. There were no HYPP symptoms in the HYPP N/N horses fed any diet, or in the HYPP H/N horses fed the low potassium diet. Symptoms were observed after 52% of the horse-meal combinations when the HYPP H/N horses were fed the medium potassium diet and after 67% of the horse-meal combinations when they were fed the high potassium diet. The onset and longest duration of symptoms were on the head or shoulders 66% of the time. Bi-phasic symptoms were rare and were more frequent after diet C than diet B. Symptoms were twice as common in the day as the night. These results indicate that a genetic-diet interaction exists in the HYPP syndrome and that dietary control of HYPP symptoms is possible in genetically susceptible horses.
Javma-journal of The American Veterinary Medical Association, Jun 1, 2003
Javma-journal of The American Veterinary Medical Association, Feb 1, 2005
American Journal of Veterinary Research, Feb 1, 2005
Objective-To use force plate analysis to evaluate the analgesic efficacies of flunixin meglumine ... more Objective-To use force plate analysis to evaluate the analgesic efficacies of flunixin meglumine and phenylbutazone administered IV at typical clinical doses in horses with navicular syndrome. Animals-12 horses with navicular syndrome that were otherwise clinically normal. Procedure-Horses received flunixin (1.1 mg/kg), phenylbutazone (4.4 mg/kg), or physiologic saline (0.9% NaCl; 1 mL/45 kg) solution administered IV once daily for 4 days with a 14-day washout period between treatments (3 treatments/horse). Before beginning treatment (baseline) and 6, 12, 24, and 30 hours after the fourth dose of each treatment, horses were evaluated by use of the American Association of Equine Practitioners lameness scoring system (half scores permitted) and peak vertical force of the forelimbs was measured via a force plate. Results-At 6, 12, and 24 hours after the fourth treatment, subjective lameness evaluations and force plate data indicated significant improvement in lameness from baseline values in horses treated with flunixin or phenylbutazone, compared with control horses; at those time points, the assessed variables in flunixin-or phenylbutazone-treated horses were not significantly different. Conclusions and Clinical Relevance-In horses with navicular syndrome treated once daily for 4 days, typical clinical doses of flunixin and phenylbutazone resulted in similar significant improvement in lameness at 6, 12, and 24 hours after the final dose, compared with findings in horses treated with saline solution. The effect of flunixin or phenylbutazone was maintained for at least 24 hours. Flunixin meglumine and phenylbutazone appear to have similar analgesic effects in horses with navicular syndrome.
Journal of Veterinary Pharmacology and Therapeutics, Aug 1, 2008
Recent outbreaks of equine herpes virus type-1 infections have stimulated renewed interest in the... more Recent outbreaks of equine herpes virus type-1 infections have stimulated renewed interest in the use of effective antiherpetic drugs in horses. The purpose of this study was to investigate the pharmacokinetics of valacyclovir (VCV), the prodrug of acyclovir (ACV), in horses. Six adult horses were used in a randomized cross-over design. Treatments consisted of 10 mg ⁄ kg ACV infused intravenously, 5 g (7.7-11.7 mg ⁄ kg) VCV delivered intragastrically (IG) and 15 g (22.7-34.1 mg ⁄ kg) VCV administered IG. Serum samples were obtained at predetermined times for acyclovir assay using high-performance liquid chromatography. Following the administration of 5 g VCV, the mean observed maximum serum ACV concentration (C max) was 1.45 ± 0.38 (SD) lg ⁄ mL, at 0.74 ± 0.43 h. At a dose of 15 g VCV, the mean C max was 5.26 ± 2.82 lg ⁄ mL, at 1 ± 0.27 h. The mean bioavailability of ACV from oral VCV was 60 ± 12% after 5 g of VCV and 48 ± 12% after 15 g VCV, and did not differ significantly between dose rates (P > 0.05). Superposition suggested that a loading dose of 27 mg ⁄ kg VCV every 8 h for 2 days, followed by a maintenance dose of 18 mg ⁄ kg every 12 h, will maintain effective serum ACV concentrations.
Journal of Equine Veterinary Science, Oct 1, 1998
Summary Six broodmares that were genetically tested to be heterozygous (H/N) and six broodmares t... more Summary Six broodmares that were genetically tested to be heterozygous (H/N) and six broodmares that were tested to be homozygous negative (N/N) for Equine Hyperkalemic Periodic Paralysis (HYPP), that were descendents of the same stallion, were used in a replicated 3x3 Latin square experiment to determine the genetic-diet relationships in the HYPP syndrome. The mares were fed rations consisting of 65% pelleted concentrate and 35% Coastal Bermudagrass hay that provided 1.1 (diet A), 1.9 (diet B) and 2.9% (diet C) potassium in the total rations. Symptoms of HYPP, such as repeated yawning, muscle twitching, generalized muscle fasciculations, myotonia, irregular movement, prolapse of the membrana nicitans and involuntary recumbency, were recorded during each 14-day experimental period. There were no HYPP symptoms in the HYPP N/N horses fed any diet, or in the HYPP H/N horses fed the low potassium diet. Symptoms were observed after 52% of the horse-meal combinations when the HYPP H/N horses were fed the medium potassium diet and after 67% of the horse-meal combinations when they were fed the high potassium diet. The onset and longest duration of symptoms were on the head or shoulders 66% of the time. Bi-phasic symptoms were rare and were more frequent after diet C than diet B. Symptoms were twice as common in the day as the night. These results indicate that a genetic-diet interaction exists in the HYPP syndrome and that dietary control of HYPP symptoms is possible in genetically susceptible horses.
Journal of Veterinary Pharmacology and Therapeutics, Apr 1, 2002
Journal of Equine Veterinary Science, Dec 1, 1998
Summary Six broodmares that were genetically tested to be heterozygous (H/N) and six broodmares t... more Summary Six broodmares that were genetically tested to be heterozygous (H/N) and six broodmares that were tested to be homozygous negative (N/N) for Equine Hyperkalemic Periodic Paralysis (HYPP), that were descendents of the same stallion, were used in a replicated 3x3 Latin square experiment to determine the genetic-diet relationships in the HYPP syndrome. The mares were fed rations consisting of 65% pelleted concentrate and 35% Coastal Bermudagrass hay that provided 1.1 (diet A), 1.9 (diet B) and 2.9% (diet C) potassium in the total rations. Symptoms of HYPP, such as repeated yawning, muscle twitching, generalized muscle fasciculations, myotonia, irregular movement, prolapse of the membrana nicitans and involuntary recumbency, were recorded during each 14-day experimental period. There were no HYPP symptoms in the HYPP N/N horses fed any diet, or in the HYPP H/N horses fed the low potassium diet. Symptoms were observed after 52% of the horse-meal combinations when the HYPP H/N horses were fed the medium potassium diet and after 67% of the horse-meal combinations when they were fed the high potassium diet. The onset and longest duration of symptoms were on the head or shoulders 66% of the time. Bi-phasic symptoms were rare and were more frequent after diet C than diet B. Symptoms were twice as common in the day as the night. These results indicate that a genetic-diet interaction exists in the HYPP syndrome and that dietary control of HYPP symptoms is possible in genetically susceptible horses.
Equine Veterinary Education, Aug 1, 2007
Journal of Veterinary Internal Medicine, May 1, 2006
The purpose of the study reported here was to describe the bioavailability and pharmacokinetics o... more The purpose of the study reported here was to describe the bioavailability and pharmacokinetics of acyclovir after intravenous and oral administration to horses. Six healthy adult horses were used in a randomized cross-over study with a 3 x 3 Latin square design. Three treatments were administered to each horse: 10 mg of injectable acyclovir/kg of body weight in 1 L of normal saline delivered as an infusion over 15 minutes; 10 mg of acyclovir/kg in tablets by nasogastric intubation; and 20 mg of acyclovir/kg in tablets by nasogastric intubation. A 2-week washout period was provided between each treatment. Serum samples were obtained for acyclovir assay using reversed-phase, high-performance liquid chromatography with fluorescence detection. Deproteinated serum was injected onto a C18 column, and elution occurred under isocratic conditions. The limit of quantification was 0.04 microg/mL. The assay exhibited suitable accuracy, precision, and recovery. The IV data were analyzed by a 3-compartment model, and oral data were analyzed noncompartmentally. Intragastric acyclovir administration at either dose was associated with high variability in serum acyclovir-time profiles, low Cmax, and poor bioavailability. The dosage of 20 mg/kg was associated with mean (+/- SD) Cmax of 0.19 +/- 0.10 microg/mL, and bioavailability was 2.8%. Inhibition of equine herpesvirus has been reported to require significantly higher acyclovir concentrations than those obtained here. The results of this study do not support a therapeutic benefit for the oral administration of acyclovir up to doses of 20 mg/kg.
Journal of Equine Veterinary Science, Dec 1, 1998
Summary Six broodmares that were genetically tested to be heterozygous (H/N) and six broodmares t... more Summary Six broodmares that were genetically tested to be heterozygous (H/N) and six broodmares that were tested to be homozygous negative (N/N) for Equine Hyperkalemic Periodic Paralysis (HYPP), that were descendents of the same stallion, were used in a replicated 3x3 Latin square experiment to determine the genetic-diet relationships in the HYPP syndrome. The mares were fed rations consisting of 65% pelleted concentrate and 35% Coastal Bermudagrass hay that provided 1.1 (diet A), 1.9 (diet B) and 2.9% (diet C) potassium in the total rations. Symptoms of HYPP, such as repeated yawning, muscle twitching, generalized muscle fasciculations, myotonia, irregular movement, prolapse of the membrana nicitans and involuntary recumbency, were recorded during each 14-day experimental period. There were no HYPP symptoms in the HYPP N/N horses fed any diet, or in the HYPP H/N horses fed the low potassium diet. Symptoms were observed after 52% of the horse-meal combinations when the HYPP H/N horses were fed the medium potassium diet and after 67% of the horse-meal combinations when they were fed the high potassium diet. The onset and longest duration of symptoms were on the head or shoulders 66% of the time. Bi-phasic symptoms were rare and were more frequent after diet C than diet B. Symptoms were twice as common in the day as the night. These results indicate that a genetic-diet interaction exists in the HYPP syndrome and that dietary control of HYPP symptoms is possible in genetically susceptible horses.
Javma-journal of The American Veterinary Medical Association, Aug 1, 2002
A 4-year-old 486-kg (1,070-lb) sexually intact female Quarter Horse was referred to the Boren Vet... more A 4-year-old 486-kg (1,070-lb) sexually intact female Quarter Horse was referred to the Boren Veterinary Medical Teaching Hospital because of a 3-day history of recurrent esophageal obstruction. The owner report
Javma-journal of The American Veterinary Medical Association, Jun 1, 2005
Javma-journal of The American Veterinary Medical Association, 2005
Treating horses with atrial fibrillation is most successful when using quinidine sulfate delivere... more Treating horses with atrial fibrillation is most successful when using quinidine sulfate delivered by nasogastric intubation at 2-hour intervals. The therapeutic window for quinidine is narrow. Monitoring plasma quinidine and digoxin levels is highly recommended but not always possible. Successful conversion is possible using 6-hour treatment intervals when 24 hours of steady-state quinidine levels have not resulted in cardioversion. A lack of underlying heart disease is associated with improved success of conversion and prognosis.
Equine Veterinary Education, 2007
Journal of Veterinary Pharmacology and Therapeutics, 2002
Javma-journal of The American Veterinary Medical Association, 2005
Journal of Equine Veterinary Science, Nov 1, 1998
Summary Six broodmares that were genetically tested to be heterozygous (H/N) and six broodmares t... more Summary Six broodmares that were genetically tested to be heterozygous (H/N) and six broodmares that were tested to be homozygous negative (N/N) for Equine Hyperkalemic Periodic Paralysis (HYPP), that were descendents of the same stallion, were used in a replicated 3x3 Latin square experiment to determine the genetic-diet relationships in the HYPP syndrome. The mares were fed rations consisting of 65% pelleted concentrate and 35% Coastal Bermudagrass hay that provided 1.1 (diet A), 1.9 (diet B) and 2.9% (diet C) potassium in the total rations. Symptoms of HYPP, such as repeated yawning, muscle twitching, generalized muscle fasciculations, myotonia, irregular movement, prolapse of the membrana nicitans and involuntary recumbency, were recorded during each 14-day experimental period. There were no HYPP symptoms in the HYPP N/N horses fed any diet, or in the HYPP H/N horses fed the low potassium diet. Symptoms were observed after 52% of the horse-meal combinations when the HYPP H/N horses were fed the medium potassium diet and after 67% of the horse-meal combinations when they were fed the high potassium diet. The onset and longest duration of symptoms were on the head or shoulders 66% of the time. Bi-phasic symptoms were rare and were more frequent after diet C than diet B. Symptoms were twice as common in the day as the night. These results indicate that a genetic-diet interaction exists in the HYPP syndrome and that dietary control of HYPP symptoms is possible in genetically susceptible horses.
Javma-journal of The American Veterinary Medical Association, Jun 1, 2003
Javma-journal of The American Veterinary Medical Association, Feb 1, 2005
American Journal of Veterinary Research, Feb 1, 2005
Objective-To use force plate analysis to evaluate the analgesic efficacies of flunixin meglumine ... more Objective-To use force plate analysis to evaluate the analgesic efficacies of flunixin meglumine and phenylbutazone administered IV at typical clinical doses in horses with navicular syndrome. Animals-12 horses with navicular syndrome that were otherwise clinically normal. Procedure-Horses received flunixin (1.1 mg/kg), phenylbutazone (4.4 mg/kg), or physiologic saline (0.9% NaCl; 1 mL/45 kg) solution administered IV once daily for 4 days with a 14-day washout period between treatments (3 treatments/horse). Before beginning treatment (baseline) and 6, 12, 24, and 30 hours after the fourth dose of each treatment, horses were evaluated by use of the American Association of Equine Practitioners lameness scoring system (half scores permitted) and peak vertical force of the forelimbs was measured via a force plate. Results-At 6, 12, and 24 hours after the fourth treatment, subjective lameness evaluations and force plate data indicated significant improvement in lameness from baseline values in horses treated with flunixin or phenylbutazone, compared with control horses; at those time points, the assessed variables in flunixin-or phenylbutazone-treated horses were not significantly different. Conclusions and Clinical Relevance-In horses with navicular syndrome treated once daily for 4 days, typical clinical doses of flunixin and phenylbutazone resulted in similar significant improvement in lameness at 6, 12, and 24 hours after the final dose, compared with findings in horses treated with saline solution. The effect of flunixin or phenylbutazone was maintained for at least 24 hours. Flunixin meglumine and phenylbutazone appear to have similar analgesic effects in horses with navicular syndrome.
Journal of Veterinary Pharmacology and Therapeutics, Aug 1, 2008
Recent outbreaks of equine herpes virus type-1 infections have stimulated renewed interest in the... more Recent outbreaks of equine herpes virus type-1 infections have stimulated renewed interest in the use of effective antiherpetic drugs in horses. The purpose of this study was to investigate the pharmacokinetics of valacyclovir (VCV), the prodrug of acyclovir (ACV), in horses. Six adult horses were used in a randomized cross-over design. Treatments consisted of 10 mg ⁄ kg ACV infused intravenously, 5 g (7.7-11.7 mg ⁄ kg) VCV delivered intragastrically (IG) and 15 g (22.7-34.1 mg ⁄ kg) VCV administered IG. Serum samples were obtained at predetermined times for acyclovir assay using high-performance liquid chromatography. Following the administration of 5 g VCV, the mean observed maximum serum ACV concentration (C max) was 1.45 ± 0.38 (SD) lg ⁄ mL, at 0.74 ± 0.43 h. At a dose of 15 g VCV, the mean C max was 5.26 ± 2.82 lg ⁄ mL, at 1 ± 0.27 h. The mean bioavailability of ACV from oral VCV was 60 ± 12% after 5 g of VCV and 48 ± 12% after 15 g VCV, and did not differ significantly between dose rates (P > 0.05). Superposition suggested that a loading dose of 27 mg ⁄ kg VCV every 8 h for 2 days, followed by a maintenance dose of 18 mg ⁄ kg every 12 h, will maintain effective serum ACV concentrations.
Journal of Equine Veterinary Science, Oct 1, 1998
Summary Six broodmares that were genetically tested to be heterozygous (H/N) and six broodmares t... more Summary Six broodmares that were genetically tested to be heterozygous (H/N) and six broodmares that were tested to be homozygous negative (N/N) for Equine Hyperkalemic Periodic Paralysis (HYPP), that were descendents of the same stallion, were used in a replicated 3x3 Latin square experiment to determine the genetic-diet relationships in the HYPP syndrome. The mares were fed rations consisting of 65% pelleted concentrate and 35% Coastal Bermudagrass hay that provided 1.1 (diet A), 1.9 (diet B) and 2.9% (diet C) potassium in the total rations. Symptoms of HYPP, such as repeated yawning, muscle twitching, generalized muscle fasciculations, myotonia, irregular movement, prolapse of the membrana nicitans and involuntary recumbency, were recorded during each 14-day experimental period. There were no HYPP symptoms in the HYPP N/N horses fed any diet, or in the HYPP H/N horses fed the low potassium diet. Symptoms were observed after 52% of the horse-meal combinations when the HYPP H/N horses were fed the medium potassium diet and after 67% of the horse-meal combinations when they were fed the high potassium diet. The onset and longest duration of symptoms were on the head or shoulders 66% of the time. Bi-phasic symptoms were rare and were more frequent after diet C than diet B. Symptoms were twice as common in the day as the night. These results indicate that a genetic-diet interaction exists in the HYPP syndrome and that dietary control of HYPP symptoms is possible in genetically susceptible horses.
Journal of Veterinary Pharmacology and Therapeutics, Apr 1, 2002
Journal of Equine Veterinary Science, Dec 1, 1998
Summary Six broodmares that were genetically tested to be heterozygous (H/N) and six broodmares t... more Summary Six broodmares that were genetically tested to be heterozygous (H/N) and six broodmares that were tested to be homozygous negative (N/N) for Equine Hyperkalemic Periodic Paralysis (HYPP), that were descendents of the same stallion, were used in a replicated 3x3 Latin square experiment to determine the genetic-diet relationships in the HYPP syndrome. The mares were fed rations consisting of 65% pelleted concentrate and 35% Coastal Bermudagrass hay that provided 1.1 (diet A), 1.9 (diet B) and 2.9% (diet C) potassium in the total rations. Symptoms of HYPP, such as repeated yawning, muscle twitching, generalized muscle fasciculations, myotonia, irregular movement, prolapse of the membrana nicitans and involuntary recumbency, were recorded during each 14-day experimental period. There were no HYPP symptoms in the HYPP N/N horses fed any diet, or in the HYPP H/N horses fed the low potassium diet. Symptoms were observed after 52% of the horse-meal combinations when the HYPP H/N horses were fed the medium potassium diet and after 67% of the horse-meal combinations when they were fed the high potassium diet. The onset and longest duration of symptoms were on the head or shoulders 66% of the time. Bi-phasic symptoms were rare and were more frequent after diet C than diet B. Symptoms were twice as common in the day as the night. These results indicate that a genetic-diet interaction exists in the HYPP syndrome and that dietary control of HYPP symptoms is possible in genetically susceptible horses.
Equine Veterinary Education, Aug 1, 2007
Journal of Veterinary Internal Medicine, May 1, 2006
The purpose of the study reported here was to describe the bioavailability and pharmacokinetics o... more The purpose of the study reported here was to describe the bioavailability and pharmacokinetics of acyclovir after intravenous and oral administration to horses. Six healthy adult horses were used in a randomized cross-over study with a 3 x 3 Latin square design. Three treatments were administered to each horse: 10 mg of injectable acyclovir/kg of body weight in 1 L of normal saline delivered as an infusion over 15 minutes; 10 mg of acyclovir/kg in tablets by nasogastric intubation; and 20 mg of acyclovir/kg in tablets by nasogastric intubation. A 2-week washout period was provided between each treatment. Serum samples were obtained for acyclovir assay using reversed-phase, high-performance liquid chromatography with fluorescence detection. Deproteinated serum was injected onto a C18 column, and elution occurred under isocratic conditions. The limit of quantification was 0.04 microg/mL. The assay exhibited suitable accuracy, precision, and recovery. The IV data were analyzed by a 3-compartment model, and oral data were analyzed noncompartmentally. Intragastric acyclovir administration at either dose was associated with high variability in serum acyclovir-time profiles, low Cmax, and poor bioavailability. The dosage of 20 mg/kg was associated with mean (+/- SD) Cmax of 0.19 +/- 0.10 microg/mL, and bioavailability was 2.8%. Inhibition of equine herpesvirus has been reported to require significantly higher acyclovir concentrations than those obtained here. The results of this study do not support a therapeutic benefit for the oral administration of acyclovir up to doses of 20 mg/kg.
Journal of Equine Veterinary Science, Dec 1, 1998
Summary Six broodmares that were genetically tested to be heterozygous (H/N) and six broodmares t... more Summary Six broodmares that were genetically tested to be heterozygous (H/N) and six broodmares that were tested to be homozygous negative (N/N) for Equine Hyperkalemic Periodic Paralysis (HYPP), that were descendents of the same stallion, were used in a replicated 3x3 Latin square experiment to determine the genetic-diet relationships in the HYPP syndrome. The mares were fed rations consisting of 65% pelleted concentrate and 35% Coastal Bermudagrass hay that provided 1.1 (diet A), 1.9 (diet B) and 2.9% (diet C) potassium in the total rations. Symptoms of HYPP, such as repeated yawning, muscle twitching, generalized muscle fasciculations, myotonia, irregular movement, prolapse of the membrana nicitans and involuntary recumbency, were recorded during each 14-day experimental period. There were no HYPP symptoms in the HYPP N/N horses fed any diet, or in the HYPP H/N horses fed the low potassium diet. Symptoms were observed after 52% of the horse-meal combinations when the HYPP H/N horses were fed the medium potassium diet and after 67% of the horse-meal combinations when they were fed the high potassium diet. The onset and longest duration of symptoms were on the head or shoulders 66% of the time. Bi-phasic symptoms were rare and were more frequent after diet C than diet B. Symptoms were twice as common in the day as the night. These results indicate that a genetic-diet interaction exists in the HYPP syndrome and that dietary control of HYPP symptoms is possible in genetically susceptible horses.
Javma-journal of The American Veterinary Medical Association, Aug 1, 2002
A 4-year-old 486-kg (1,070-lb) sexually intact female Quarter Horse was referred to the Boren Vet... more A 4-year-old 486-kg (1,070-lb) sexually intact female Quarter Horse was referred to the Boren Veterinary Medical Teaching Hospital because of a 3-day history of recurrent esophageal obstruction. The owner report
Javma-journal of The American Veterinary Medical Association, Jun 1, 2005
Javma-journal of The American Veterinary Medical Association, 2005
Treating horses with atrial fibrillation is most successful when using quinidine sulfate delivere... more Treating horses with atrial fibrillation is most successful when using quinidine sulfate delivered by nasogastric intubation at 2-hour intervals. The therapeutic window for quinidine is narrow. Monitoring plasma quinidine and digoxin levels is highly recommended but not always possible. Successful conversion is possible using 6-hour treatment intervals when 24 hours of steady-state quinidine levels have not resulted in cardioversion. A lack of underlying heart disease is associated with improved success of conversion and prognosis.
Equine Veterinary Education, 2007
Journal of Veterinary Pharmacology and Therapeutics, 2002