Objective—To determine the disposition of orally
administered cefpodoxime proxetil in foals and adult
horses and measure the minimum inhibitory concentrations
(MICs) of the drug against common bacterial
pathogens of horses.
Animals—6 healthy adult horses and 6 healthy foals
at 7 to 14 days of age and again at 3 to 4 months of
Procedure—A single dose of cefpodoxime proxetil
oral suspension was administered (10 mg/kg) to each
horse by use of a nasogastric tube. In 7- to 14-day-old
foals, 5 additional doses were administered intragastrically
at 12-hour intervals. The MIC of cefpodoxime
for each of 173 bacterial isolates was determined by
use of a commercially available test.
Results—In 7- to 14-day-old foals, mean ± SD time to
peak serum concentration (Tmax) was 1.7 ± 0.7 hours,
maximum serum concentration (Cmax) was 0.81 ±
0.22 µg/mL, and elimination half-life (harmonic mean)
was 7.2 hours. Disposition of cefpodoxime in 3- to 4-month-old foals was not significantly different from
that of neonates. Adult horses had significantly higher
Cmax and significantly lower Tmax, compared with
values for foals. The MIC of cefpodoxime required to
inhibit growth of 90% of isolates for Salmonella enterica,
Escherichia coli, Pasteurella spp, Klebsiella spp,
and β-hemolytic streptococci was 0.38, 1.00, 0.16,
0.19, and 0.09 µg/mL, respectively.
Conclusions and Clinical Relevance—Oral administration
at a dosage of 10 mg/kg every 6 to 12 hours
would appear appropriate for the treatment of equine
neonates with bacterial infections. (Am J Vet Res 2005;66:30–35)
Case Description—A 19-year-old Thoroughbred mare was evaluated at 265 days of gestation with a markedly distended abdomen and edema of the ventral portion of the abdomen.
Clinical Findings—The uterus was distended over the pelvic rim, making transrectal palpation of the fetus impossible. Transabdominal ultrasonography revealed excessive amounts of fetal fluid. Results of analysis of fluid obtained via amnio- and allantocentesis confirmed that the amniotic cavity was large.
Treatment and Outcome—The mare was monitored for signs of weakness of the prepubic tendon and abdominal wall. The fetus and placenta were monitored for signs of stress and pending abortion. Flunixin meglumine and altrenogest were administered to the mare. Parturition was attended and occurred at 321 days' gestation. Postpartum complications in the mare included hypovolemic shock and cardiac arrhythmias. Both conditions were treated, and the mare recovered. The foal was considered small, had bilateral angular limb deformities, and was unable to nurse. The foal was given plasma for failure of passive transfer of immunity. Ten months later, the foal underwent procedures to correct limb deformities.
Conclusions and Clinical Relevance—Hydrops conditions are rare in horses, with hydrops allantois occurring more frequently than hydrops amnion; reportedly result in fetal or neonatal death; and may result in death of or injury to the mare. Close monitoring of maternal and fetal health in combination with supportive treatment of the mare can result in the safe progression of a hydrops pregnancy and the birth of a live foal.