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In the report “Daily endogenous cortisol production and hydrocortisone pharmacokinetics in adult horses and neonatal foals” (Am J Vet Res 2012;73:68–75), there is an error on page 71 in the P value and the SD reported for foals in the last

Full access
in American Journal of Veterinary Research

Abstract

Objective—To determine concentrations of IgA and IgG subclasses in serum, colostrum, milk, and nasal wash samples of adult horses and foals.

Animals—Seven 2-year-old Welsh ponies, 27 adult mixed-breed horses, and 5 Quarter Horse mares and their foals.

Procedure—Serum was obtained from ponies and adult horses. Colostrum and milk were obtained from mares and serum and nasal wash samples from their foals immediately after parturition and on days 1, 7, 14, 28, 42, and 63. Nasal wash samples were also obtained from 23 adult horses. Concentrations of immunoglobulins were determined by use of inhibition ELISA. To determine transfer of maternal isotypes to foals, concentrations in colostrum and milk were compared with those in foal serum. Serum half-lives of isotypes in foals were also determined.

Results—IgGb was the most abundant isotype in serum and colostrum from adult horses, whereas IgA was the predominant isotype in milk. The major isotype in nasal secretions of adult horses and foals ≥ 28 days old was IgA, but IgGa and IgGb were the major isotypes in nasal secretions of foals ≤ 14 days old. Serum half lives of IgGa, IgGb, IgG(T), and IgA in foals were 17.6, 32, 21, and 3.4 days, respectively.

Conclusions and Clinical Relevance—The early immunoglobulin repertoire of neonatal foals comprised IgGa, IgG(T), and IgA; endogenous synthesis of IgGb could not be detected until 63 days after birth. The restricted repertoire of immunoglobulins in foals may influence humoral immune responses to vaccination. (Am J Vet Res 2000;61:1099–1105)

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in American Journal of Veterinary Research

Abstract

Objective—To evaluate the effect of daily oral administration of decoquinate to neonatal calves experimentally challenged with various numbers of Cryptosporidium parvumo ocysts.

Design—Clinical trial.

Animals—75 calves.

Procedure—Calves were purchased from a commercial dairy during a 5-week period. Calves were housed in individual hutches and fed milk replacer with or without decoquinate (2 mg/kg [0.9 mg/lb per day]). Calves were randomly assigned to treatment and 1 of 5 challenge groups (0, 50, 100, 1000, or 10,000 C parvum oocysts in 60 mL of saline [0.9% NaCl] solution administered PO on the day after arrival). Calves were maintained in the study for as long as 28 days. Calves were clinically assessed for diarrhea and dehydration. Fecal samples were submitted for oocyst enumeration 3 times each week.

Results—Treatment did not affect number of days to first watery feces (diarrhea), number of days to first oocyst shedding, or duration of diarrhea or oocyst shedding. Duration of oocyst shedding was significantly associated with challenge dose of oocysts administered to calves and number of days to first oocyst shedding. Duration of diarrhea and number of days to first oocyst shedding were significantly associated with week of arrival and number of days to first watery diarrhea.

Conclusions and Clinical Relevance—Daily treatment with decoquinate at the dosage used in this study did not affect oocyst shedding or clinical signs associated with cryptosporidiosis. However, there was an indication that if the number of oocysts calves received could be reduced, then the duration of oocyst shedding and, hence, environmental loading of C parvum oocysts could be reduced. (J Am Vet Med Assoc 2003;223:839–845)

Full access
in Journal of the American Veterinary Medical Association

SUMMARY

Objective

To determine the effect of diet on energy intake, loss, and metabolism in foals 2 to 7 days old.

Animals

14 pony foals.

Procedure

Group-A foals suckled their dams, group-B foals were fed milk replacer, and group-C foals were fed by total parenteral nutrition (TPN). Energy balance studies were performed over 8-hour periods on postpartum days 2, 4, and 7.

Results

Mean gross energy (GE) intake of group-A foals increased between days 2 and 7. Approximately 3% of GE was excreted in urine and feces, and energy expenditure remained constant. These foals were in positive energy balance, and mean body weight increased. From day 4 onward, group-B foals consumed more energy than did group-A foals because the milk replacer had a higher energy content than did mares’ milk. Mean energy loss in group-B foals was 14% of GE on day 2, but this value decreased subsequently. Energy expenditure in group-B foals was less than that in group-A foals, and energy balance was positive. Group-C foals had the lowest energy intake and expenditure; energy balance was negative on postpartum day 2. These foals also had gastrointestinal tract problems.

Conclusions

Mares’ milk is highly digestible and is correlated with positive energy balance in neonatal foals. Milk replacer initially is less digestible than mares’ milk. In this study, TPN was associated with negative energy balance.

Clinical Relevance

The data indicate the advantages of enteral feeding with mares’ milk and highlight the clinical and technical difficulties associated with TPN. (Am J Vet Res 1997;58:1243–1251)

Free access
in American Journal of Veterinary Research

SUMMARY

Ceftiofur hydrochloride was tested for effectiveness against induced colibacillosis in neonatal swine. In this model, pigs < 12 hours old were inoculated via stomach tube with a virulent, K99+, nalidixic acid-resistant strain of Escherichia coli. Six hours after challenge exposure, 1 dose of ceftiofur was administered either IM or orally in experiment 1 and orally only in experiment 2. Mortality, shedding of bacteria, fecal consistency scores, and body weight changes were monitored for 10 days. In experiment 1 (n = 383 pigs), all treatments at dosage that ranged between 0.5 and 64.0 mg of ceftiofur/kg of body weight significantly (P < 0.001) reduced mortality, bacterial shedding, and diarrhea and increased weight gain, compared with findings in untreated controls. There were no detectable differences between oral and IM routes, except that there was greater reduction in bacteria shedding associated with the oral route of administration. In experiment 2 (n = 505 pigs), ceftiofur was administered orally either once at 6 hours after challenge exposure or twice at 6 and at 48 hours after the first dose. Dosage of ceftiofur was 0, 5, 10, 20, 30, or 60 mg/kg administered once, or half the same dose was administered at each of 2 times. At the optimal dosage (10 mg/kg), a single dose was as effective as 2 doses. The single administration at all dosages reduced mortality, bacterial shedding, and diarrhea scores and increased body weight gain, compared with findings in untreated pigs (P < 0.01). In this induced infection model, the optimal treatment dosage was determined to be 10 mg/kg administered once.

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in American Journal of Veterinary Research

Abstract

Objective

To test the ability of porcine respiratory coronavirus (PRCV) to induce protective immunity to antigenically related transmissible gastroenteritis virus (TGEV) in neonatal pigs.

Design

Neonatal pigs were exposed to PRCV when they were 2, 4, or 6 days old and challenge-exposed to virulent TGEV at 10 days of age.

Animals

34 hysterectomy-derived, colostrum-deprived pigs.

Procedure

After challenge exposure, clinical signs were observed, body weight, antibody response, and virus shedding were measured, and mortality was determined.

Results

After exposure to PRCV, principals had a slightly slower rate of weight gain than did controls; with 1 exception (a PRCV-exposed pig that was dyspneic for 1 day), principals and controls remained clinically normal until shortly after challenge exposure, when all pigs became listless and anorectic and developed watery diarrhea. However, by day 3, most of the pigs that had been exposed to PRCV when they were either 2 or 4 days old began to recover and most (15/18) survived. Conversely, the clinical condition of most of the other pigs worsened and most (14/16) died. Pigs exposed to PRCV when they were 2 or 4 days old also differed from all other pigs in that they had serum virus-neutralizing antibodies for PRCV and TGEV at the time of challenge exposure.

Conclusions

The PRCV can induce protective immunity to TGEV in neonatal pigs and such immunity develops at or about 6 days after exposure to PRCV. Moreover, protective immunity may be coincident with the appearance of virus-neutralizing antibody.

Clinical Relevance

Exposure to PRCV should enhance a TGE herd vaccination program.

Free access
in American Journal of Veterinary Research

Bacterial infection continues to be a major cause of morbidity and death in neonatal foals. 1–3 Neonatal foals are often subjected to extensive diagnostic evaluation and empirical systemic antimicrobial treatment because the prognosis for sepsis

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in American Journal of Veterinary Research

SUMMARY

The effect of age on the pharmacokinetics of chloramphenicol was determined after iv administration of chloramphenicol sodium succinate (25 mg/kg of body weight) to 6 foals at 1 day and 3, 7, 14, and 42 days of age. The disposition of chloramphenicol was best described, using a two-compartment open model in all foals at all ages evaluated. Significant age-related changes were observed in values for the major kinetic terms describing the disposition of chloramphenicol in foals; the greatest changes were observed between 1 day and 3 days of age.

The mean ± sd value for elimination rate constant (β) for chloramphenicol in 1-day-old foals (0.131 ± 0.06 h-1) was significantly (P < 0.005) lower than the value in 3-day-old foals (0.514 ± 0.156 h-1), and both values were significantly (P < 0.05) lower than values for β in 7-, 14-, and 42-day-old foals. With increasing age, the increase in the mean value for β resulted in decrease in the harmonic mean elimination half-time (t1/2β) for chloramphenicol, from 5.29 hours in 1-day-old foals to: 1.35 hours in 3-day-old foals; 0.61 hour in 7-day-old foals; 0.51 hour in 14-day-old foals; and 0.34 hour in 42-day-old foals. At 1, 3, and 7 days of age, values for t1/2β of chloramphenicol in a premature foal born after parturition was induced with oxytocin, were considerably longer than comparable t1/2β values for term foals born naturally.

The mean body clearance (ClB) of chloramphenicol in 1-day-old foals (2.25 ± 0.67 ml/min·kg of body weight) was significantly lower than values in: 3-day-old (6.23 ± 2.22 ml/min·kg; P < 0.05); 7-day-old (8.86 ± 1.90 ml/min·kg; P < 0.0005); 14-day-old (9.63 · 1.63 ml/min·kg; P < 0.0005); and 42-day-old (9.68 · 2.76 ml/min·kg; P < 0.0001) foals. In foals of all ages, ClB of chloramphenicol in the parturition-induced premature foal was lower than the mean value for term foals born naturally.

The volume of distribution (V′d[area]) of chloramphenicol decreased progressively with increasing age between day 1 and day 42, so that the mean value for 42-day-old foals (362 ± 163 ml/kg) was less than a third the mean value for 1-day-old foals (1,101 ± 284 ml/kg). The mean value for V′d(area) in 1-day-old foals was significantly greater than values for: 7-day-old (491 ± 158 ml/kg; P < 0.01); 14-day-old (426 ± 65 ml/kg; P < 0.005); and 42-day-old (362 ± 162; P < 0.0005) foals, and the mean value for V′d(area)on day 3 was significantly (P < 0.05) greater than the mean value for V′d(area) on days 7, 14, and 42.

Using dosage calculations based on mean values for the pharmacokinetic terms derived for each age group, it was predicted that to maintain plasma chloramphenicol concentration > 8 μg/ml, chloramphenicol sodium succinate (25 mg/kg) would have to be administered at dose intervals of 10, 3, 1.5, 1.5, and 1 hours in clinically normal foals 1 day and 3, 7, 14, and 42 days, of age, respectively. It was concluded that the marked changes in the disposition of chloramphenicol detectable during the first few days of life, the variation between individuals, the potentially major effect of prematurity, and the potential for compromised liver function in septicemic foals indicate that use of drugs, such as chloramphenicol, which rely heavily on hepatic metabolic processes for elimination, should be avoided whenever possible during the early neonatal period, unless plasma concentration is monitored.

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in American Journal of Veterinary Research
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Summary

Saline (0.9% NaCl) solution, flunixin meglumine (1.1 mg/kg), prednisolone sodium succinate (1.1 mg/ kg), U74389F (1.5 mg/kg), and dimethyl sulfoxide (0.5 g/kg) were each administered FV to 5 neonatal calves 15 minutes after the start of a 3-hour infusion of Escherichia coli lipopolysaccharide (lps; 2 µg/kg/hr). Four additional calves were given a 3-hour IV infusion of saline solution alone. Only flunixin significantly suppressed eicosanoid production and mitigated clinical signs associated with endotoxemia. Prednisolone provided partial protection against lps-induced hypotension and lacticemia. Pronounced hypoglycemia and lacticemia were observed in U74389F-treated calves; LPS-induced hypotension and hypoglycemia were marked in dimethyl sulfoxide-treated calves.

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in American Journal of Veterinary Research

SUMMARY

End-tidal carbon dioxide tension (Pet CO2 ) and arterial carbon dioxide tension (PaCO2 ) were determined and compared in isoflurane-anesthetized spontaneously breathing equine neonates. End-tidal carbon dioxide and PaCO2 values increased with respect to time. Difference between values of Pet CO2 and PaCO2 increased over time. End-tidal carbon dioxide tension was useful to predict changes in and was more closely correlated with PaCO2 early in the anesthetic period (T ≤ 60 minutes). The dead space volume to tidal volume (Vd/Vt) ratio increased with respect to time, indicating increase in physiologic dead space in isoflurane-anesthetized foals. The data indicate that the increased difference between widening of the Pet CO2 and PaCO2 values over time may have been attributable to hypoventilation and decreased pulmonary capillary perfusion of alveoli.

Free access
in American Journal of Veterinary Research