Objective—To develop a high-speed, continuous-flow, automated plasmapheresis procedure for the high-volume harvest of equine plasma in accordance with current good manufacturing practice.
Animals—143 horses (predominantly draft breeds) between 3 and 10 years of age at the time of purchase.
Procedures—Adaptations were made to automated plasmapheresis instruments and sterile disposable collection sets, which allowed for dual-instrument, continuous-flow operation. Donor horses were connected to the apparatus via 2 catheters (1 inserted in each jugular vein). The instruments removed whole blood from donors, fractionated the blood, diverted plasma to collection bags, and simultaneously returned concentrated cells to the donors. Plasmapheresis was performed on donor horses at 14-day intervals with a maximum of 22 mL of plasma/kg of donor body weight harvested during each plasmapheresis procedure.
Results—During a 5-year period, 3,240 plasmapheresis procedures were performed and > 50,000 L of sterile equine plasma was harvested in accordance with current good manufacturing practice. Donors typically remained calm during the plasmapheresis procedures and tolerated the procedures well. The high-volume and frequent plasma harvest did not result in sustained hypoproteinemia in donor horses. Adverse events associated with the automated plasmapheresis technique were infrequent, and the recurrence of adverse events was minimized by making minor adjustments to the procedure.
Conclusions and Clinical Relevance—The automated plasmapheresis procedure described in this report can be used to safely harvest equine plasma or to perform therapeutic plasmapheresis in horses.
Objective—To determine the effects of intensive serial plasmapheresis on total plasma protein and total IgG concentrations in donor horses involved in a plasmapheresis program.
Animals—18 horses (13 mares and 5 geldings; 13 Belgians, 3 Percherons, 1 Standardbred, and 1 warmblood) ranging from 7 to 14 years of age (mean ± SD, 10 ± 3 years) and weighing 822 ± 128 kg.
Procedures—Horses from which 22 mL of plasma/kg of donor body weight was harvested at 14-day intervals for a minimum of 8 consecutive plasmapheresis donations were retrospectively selected for use in the evaluation. Automated plasmapheresis procedures were performed by use of 2 modified plasmapheresis instruments/donor horse. Plasma samples were obtained at each donation and used for determination of total protein and total IgG concentrations. Total plasma protein concentrations were determined via refractometry. A commercially available ELISA was used to determine total equine IgG concentrations.
Results—The 18 donor horses were used in 8 to 19 serial donations (mean ± SD, 13 ± 3 donations) during the study. Donor horses had significant decreases in both plasma protein and IgG concentrations over the study period.
Conclusions and Clinical Relevance—Serial plasmapheresis procedures caused significant decreases in both plasma protein and IgG concentrations in donor horses; however, decreases were not physiologically relevant. Performing plasmapheresis in horses in accordance with the evaluated automated plasmapheresis procedures did not result in a critical decrease in total plasma protein or total IgG concentrations.
Objective—To evaluate the pharmacokinetic-pharmacodynamic parameters of enrofloxacin and a low dose of amikacin administered via regional IV limb perfusion (RILP) in standing horses.
Animals—14 adult horses.
Procedures—Standing horses (7 horses/group) received either enrofloxacin (1.5 mg/kg) or amikacin (250 mg) via RILP (involving tourniquet application) in 1 forelimb. Samples of interstitial fluid (collected via implanted capillary ultrafiltration devices) from the bone marrow (BMIF) of the third metacarpal bone and overlying subcutaneous tissues (STIF), blood, and synovial fluid of the radiocarpal joint were collected prior to (time 0) and at intervals after tourniquet release for determination of drug concentrations. For pharmacokinetic-pharmacodynamic analyses, minimum inhibitory concentrations (MICs) of 16 μg/mL (amikacin) and 0.5 μg/mL (enrofloxacin) were applied.
Results—After RILP with enrofloxacin, 3 horses developed vasculitis. The highest synovial fluid concentrations of enrofloxacin and amikacin were detected at time 0; median values (range) were 13.22 μg/mL (0.254 to 167.9 μg/mL) and 26.2 μg/mL (5.78 to 50.0 μg/mL), respectively. Enrofloxacin concentrations exceeded MIC for approximately 24 hours in STIF and synovial fluid and for 36 hours in BMIF. After perfusion of amikacin, concentrations greater than the MIC were not detected in any samples. Effective therapeutic concentrations of enrofloxacin were attained in all samples.
Conclusions and Clinical Relevance—In horses with orthopedic infections, RILP of enrofloxacin (1.5 mg/kg) should be considered as a treatment option. However, care must be taken during administration. A dose of amikacin > 250 mg is recommended to attain effective tissue concentrations via RILP in standing horses.
Objective—To evaluate the cardiopulmonary and clinicopathologic
effects of rapid IV administration of
dimethyl sulfoxide (DMSO) in awake and halothaneanesthetized
Animals—6 adult horses.
Procedures—Horses received IV infusion of 5 L of a
balanced electrolyte solution with and without 1 g/kg
(0.45 g/lb) of 10% DMSO solution when they were
awake and anesthetized with halothane (4 treatments/
horse). Arterial and venous blood samples
were collected immediately before and at intervals
during or after fluid administration and analyzed for
blood gases and hematologic and serum biochemical
variables, respectively. Heart rate, respiratory rate,
and arterial blood pressure variables were recorded
prior to, during, and after fluid administration.
Results—After administration of fluid with or without
DMSO, changes in measured variables were detected
immediately, but most variables returned to baseline
values within 4 hours. One awake control horse
had signs of anxiety; agitation and tachycardia were
detected in 2 awake horses administered DMSO.
These clinical signs disappeared when the rate of
infusion was reduced. In anesthetized horses,
increased concentrations of WBCs and plasma fibrinogen
and serum creatine kinase activity persisted
for 24 hours, which was related to the stress of anesthesia
more than the effects of fluid administration.
Conclusions and Clinical Relevance—Infusion of
5 L of balanced electrolyte solution with or without
10% DMSO induced minimal changes in cardiopulmonary
function and clinicopathologic variables in
either awake or halothane-anesthetized horses.
Stress associated with anesthesia and recovery had a
greater influence on measured variables in anesthetized
horses than fluid administration. (J Am Vet Med Assoc 2004;225:560–566)
To develop a topical sildenafil hydrogel and evaluate its effect on wound healing in dogs.
6 purpose-bred, sexually intact, adult Beagles.
Hydrogels containing sildenafil citrate, N-methyl-2-pyrrolidone, propylene glycol, and poloxamer 407 were developed. Four excision wounds were created along the dorsum of the dogs. Each wound was treated for 21 days with a nonadherent bandage (C) or with a hydrogel containing 0% (G), 5% (5S), or 10% (10S) sildenafil. Daily bandage changes with wound imaging were performed. Biopsy specimens were collected 5 times.
Hydrogels were homogenous at room temperature and released > 90% of the sildenafil within 8 hours in vitro. Time to first granulation tissue was significantly shorter for the sildenafil groups (mean ± SD, 2.8 ± 0.8 days [5S and 10S]), compared with the control groups (5.2 ± 0.4 days [C] and 6.3 ± 1.4 days [G]). The G wounds had a 10% to 14% lower contraction rate, compared with the C, 5S, and 10S wounds. 5S wounds had a total wound area 0.7 ± 0.3 cm2 larger than 10S wounds. No significant differences were present when C wounds were compared with 5S and 10S wounds for total wound area, contraction, or epithelialization. Histologic acute inflammatory scores were higher for 5S and 10S wounds in the early and late stages of wound healing, with higher reparative scores on day 7. Neovascularization was higher for 10S wounds on day 7 and 14.
The topical sildenafil hydrogel promoted early granulation tissue, which may be beneficial for secondary wound closure in clinical settings.