Objective—To identify apoptosis in equine intestines
and determine whether apoptosis is associated with
gastrointestinal tract disease or a specific tissue layer
Animals—38 horses that underwent surgery or were
euthanatized for small or large intestine obstruction,
strangulation, or distension and 9 control horses
euthanatized for reasons other than gastrointestinal
tract disease or systemic disease.
Procedure—Specimens were collected at surgery
from intestine involved in the primary lesion and distant
to the primary lesion site or at necropsy from
several sites including the primary lesion site.
Histologic tissue sections were stained with H&E,
and apoptosis was detected by use of the terminal
deoxynucleotidyl transferase-mediated dUTP nick end
labeling technique. The number of apoptotic cells per
hpf was counted in the mucosa, circular muscle, longitudinal
muscle, and serosa.
Results—Apoptotic nuclei were seen in all layers of
intestine. An increased number of apoptotic cells was
found in the circular muscle of the intestine from horses
with simple obstruction, compared with strangulating
obstruction or healthy intestine. Intestine distant
from a primary strangulating lesion had higher numbers
of apoptotic cells than did intestine distant from
a simple obstructive lesion or intestine taken at the
site of a strangulating or simple obstructive lesion.
Conclusions and Clinical Relevance—Intestine
from horses with obstructing or strangulating lesions
in the small intestine and large colon had high numbers
of apoptotic cells possibly because of ischemic
cell injury and subsequent inflammation. Whether
substantial apoptosis affects intestinal function is not
yet known. (Am J Vet Res 2003;64:982–988)
Objective—To assess changes in systemic hydration,
concentrations of electrolytes in plasma, hydration of
colonic contents and feces, and gastrointestinal transit
in horses treated with IV fluid therapy or enteral
administration of magnesium sulfate (MgSO4), sodium
sulfate (NaSO4), water, or a balanced electrolyte
Animals—7 horses with fistulas in the right dorsal
Procedure—In a crossover design, horses alternately
received 1 of 6 treatments: no treatment (control); IV
fluid therapy with lactated Ringer's solution; or enteral
administration of MgSO4, Na2SO4, water, or a balanced
electrolyte solution via nasogastric intubation.
Physical examinations were performed and samples
of blood, RDC contents, and feces were collected
every 6 hours during the 48 hour-observation period.
Horses were muzzled for the initial 24 hours but had
access to water ad libitum. Horses had access to hay,
salt, and water ad libitum for the last 24 hours.
Results—Enteral administration of a balanced electrolyte
solution and Na2SO4 were the best treatments
for promoting hydration of RDC contents, followed by
water. Sodium sulfate was the best treatment for promoting
fecal hydration, followed by MgSO4 and the
balanced electrolyte solution. Sodium sulfate caused
hypocalcemia and hypernatremia, and water caused
Conclusions and Clinical Relevance—Enteral
administration of a balanced electrolyte solution promoted
hydration of RDC contents and may be useful
in horses with large colon impactions. Enteral administration
of either Na2SO4 or water may promote
hydration of RDC contents but can cause severe electrolyte
imbalances. (Am J Vet Res 2004;65:695–704)
Objective—To assess changes in systemic hydration,
concentrations of plasma electrolytes, hydration and
physical properties of colonic contents and feces, and
gastrointestinal transit in horses with access to large
amounts of grain.
Animals—6 horses with right dorsal colon (RDC) fistulas.
Procedure—In a crossover design, horses were alternately
fed 1 of 3 diets: orchard grass hay ad libitum
after being adapted to this diet for at least 5 days,
orchard grass hay ad libitum and 4.55 kg of grain
offered every 12 hours after being adapted to orchard
grass hay ad libitum for at least 5 days, or orchard grass
hay ad libitum and 4.55 kg of grain offered every 12
hours after being adapted to this diet for at least 5 days.
Physical examinations were performed and samples of
blood, colonic contents, and feces were collected
every 6 hours during a 48-hour observation period.
Results—Grain ingestion had several effects, including
changes in the concentrations of electrolytes in plasma;
RDC contents became more homogenous, dehydrated,
foamy, and less dense; RDC contents flowed
spontaneously when the cannula was opened; RDC
contents expanded when heated in an oven; and feces
became fetid and less formed. Horses did not have any
clinical signs of colic, endotoxemia, or laminitis.
Conclusions and Clinical Relevance—Changes
observed in the colonic contents and feces may be
explained by the large amounts of hydrolyzable carbohydrates
provided by grain. Access to large
amounts of grain may increase the risk of tympany
and displacement of the large intestine. ( Am J Vet Res 2004;65:687–694)
Objective—To determine effects of cyclophotocoagulation
via administration of 100 J with a neodymium:
yttrium aluminum garnet (Nd:YAG) laser on
corneal touch threshold (CTT), intraocular pressure
(IOP), aqueous tear production, and corneal nerve
morphology in eyes of dogs.
Procedure—Noncontact Nd:YAG laser was transsclerally
applied (10 applications; 25 W for 0.1 seconds for
each application to each of 4 quadrants) to the ciliary
body of the left eye of 15 dogs; the right eye was the
control eye. Corneal integrity, CTT, tear production as
measured by the Schirmer tear test (STT), and IOP were
evaluated for 14 days following laser treatment. On day
14, dogs were euthanatized, eyes harvested, and
corneas stained with gold chloride. Major nerve bundles
were analyzed by use of a drawing tube attached to a
light microscope, and maximum diameters were measured
by use of image analysis software.
Results—All laser-treated eyes had significantly higher
CTT values, compared with control eyes. Six of 15
laser-treated eyes developed ulcerative keratitis. On
most days, IOP was significantly lower in laser-treated
eyes in both morning and evening. Laser-treated
eyes had a significant decrease of approximately 1
nerve bundle/corneal quadrant. Values for STT or
nerve bundle diameters did not differ significantly.
Conclusion and Clinical Relevance—Administration
of 100 J with a Nd:YAG laser effectively
reduced IOP while increasing CTT and caused a significant
decrease in number, but not diameter, of
major corneal nerve bundles. Nerve damage and
corneal hypoesthesia are etiologic factors in ulcerative
keratitis following Nd:YAG cyclophotocoagulation.
(Am J Vet Res 2002;63:906–915)
Objective—To describe the anatomic features of the
pituitary gland region in horses via computed tomography
(CT) and determine the accuracy of CT for estimating
normal equine pituitary gland dimensions.
Animals—25 adult horses with no clinical signs of
Procedure—Transverse CT images and gross transverse
tissue sections were compared in 2 horses.
Contrast-enhanced CT of the pituitary gland region
was performed postmortem in 23 horses with 4 slice
thickness and interval settings (10-mm contiguous or
overlapping slices and 4-mm contiguous or overlapping
slices). Gross and CT estimates of pituitary gland
dimensions were compared via ANOVA. Accuracy of
CT estimates was calculated with gross pituitary
gland measurements as the known value.
Results—Pituitary glands were located between the
temporomandibular joints and had contrast enhancement.
Mean gross dimensions were length, 2.11 cm;
width, 2.16 cm; height, 0.98 cm; and volume, 2.66
cm3. Gross measurements and CT estimates of pituitary
gland length from 10-mm contiguous and overlapping
slices did not differ. Gross measurements and
CT estimates of pituitary gland width from 4-mm contiguous
and overlapping slices did not differ. Estimates
of height and volume from all CT techniques differed
from gross measurements. Accuracies for CT estimates
were length, 88 to 99%; width, 81 to 92%;
height, 58 to 71%; and volume, 43 to 55%.
Conclusions and Clinical Relevance—Accuracy of
estimates of pituitary gland dimension in horses varied
with CT scanning technique; via CT, estimates of
length and width of glands were more accurate than
estimates of height or volume. (Am J Vet Res 2003;64:1387–1394)
Objective—To evaluate the effect of frequent milkout
(FMO) on the outcome of experimentally induced
Escherichia coli mastitis in cows.
Design—Randomized complete block study.
Animals—16 Holstein dairy cows.
Procedure—Cows were randomly assigned to 1 of 4
groups and were either not infected and not treated
(NI-NT), experimentally infected with E coli and not
treated (EC-NT), not infected and FMO (NI-FMO), or
experimentally infected with E coli and FMO (EC-FMO).
The infected quarter in cows in FMO groups
was milked out every 4 hours from 16 to 36 hours and
every 6 hours from 36 to 84 hours after challenge,
with the aid of oxytocin administration. Somatic cell
counts (SCC); times to bacterial, clinical, and systemic
cures; and serum concentrations of α-lactalbumin
Results—Use of FMO did not appear to affect SCC.
For EC-NT and EC-FMO groups, mean bacterial cure
times were 203 and 159 hours, clinical cure times
were 276 and 360 hours, and systemic cure times
were 144 and 159 hours, respectively; these times
were not significantly different. Concentrations of
α-lactalbumin were significantly increased in the EC-NT
group at 12 hours and in the NI-FMO group at 36
and 60 hours after challenge, compared with values
of cows in other treatment groups.
Conclusions and Clinical Relevance—Compared
with results in control cows, FMO does not appear to
be an efficacious treatment for experimentally
induced moderate to severe E coli mastitis. (J Am Vet
Med Assoc 2003;222:63–66)
Objective—To compare induction and recovery characteristics and cardiopulmonary effects of isoflurane and sevoflurane in bald eagles.
Animals—17 healthy adult bald eagles.
Procedures—Anesthesia was induced with isoflurane or sevoflurane delivered in oxygen via a facemask in a crossover design with 4 weeks between treatments. Eagles were intubated, allowed to breathe spontaneously, and instrumented for cardiopulmonary measurements. Time to induction, extubation, and recovery, as well as smoothness of recovery, were recorded.
Results—Administration of sevoflurane resulted in a significantly quicker recovery, compared with isoflurane. Temperature, heart rate, and respiratory rate significantly decreased over time, whereas systolic (SAP), diastolic (DAP), and mean arterial blood pressure (MAP) significantly increased over time with each treatment. Temperature, heart rate, SAP, DAP, and MAP were significantly higher with isoflurane. Blood pH significantly decreased, whereas PaCO2 significantly increased over time with each treatment. Bicarbonate and total carbon dioxide concentrations significantly increased over time with each treatment; however, there was a significant time-treatment interaction. The PaO2 and arterial oxygen saturation increased over time with isoflurane and decreased over time with sevoflurane with a significant time-treatment interaction. Six eagles developed cardiac arrhythmias with isoflurane, as did 4 with sevoflurane anesthesia.
Conclusions and Clinical Relevance—Isoflurane and sevoflurane administration resulted in smooth, rapid induction of and recovery from anesthesia similar to other species. Isoflurane administration resulted in tachycardia, hypertension, and more arrhythmias, compared with sevoflurane. Sevoflurane was associated with fewer adverse effects and may be particularly beneficial in compromised bald eagles.
Objective—To assess the potential of adipose-derived nucleated cell (ADNC) fractions to improve tendon repair in horses with collagenase-induced tendinitis.
Procedures—Collagenase was used to induce tendinitis in the superficial digital flexor tendon of 1 forelimb in each horse. Four horses were treated by injection of autogenous ADNC fractions, and 4 control horses were injected with PBS solution. Healing was compared by weekly ultrasonographic evaluation. Horses were euthanatized at 6 weeks. Gross and histologic evaluation of tendon structure, fiber alignment, and collagen typing were used to define tendon architecture. Biochemical and molecular analyses of collagen, DNA, and proteoglycan and gene expression of collagen type I and type III, decorin, cartilage oligomeric matrix protein (COMP), and insulin-like growth factor-I were performed.
Results—Ultrasonography revealed no difference in rate or quality of repair between groups. Histologic evaluation revealed a significant improvement in tendon fiber architecture; reductions in vascularity, inflammatory cell infiltrate, and collagen type III formation; and improvements in tendon fiber density and alignment in ADNC-treated tendons. Repair sites did not differ in DNA, proteoglycan, or total collagen content. Gene expression of collagen type I and type III in treated and control tendons were similar. Gene expression of COMP was significantly increased in ADNC-injected tendons.
Conclusions and Clinical Relevance—ADNC injection improved tendon organization in treated tendons. Although biochemical and molecular differences were less profound, tendons appeared architecturally improved after ADNC injection, which was corroborated by improved tendon COMP expression. Use of ADNC in horses with tendinitis appears warranted.
Objective—To determine whether a limited sampling time method based on serum iohexol clearance (Cliohexol) would yield estimates of glomerular filtration rate (GFR) in clinically normal horses similar to those for plasma creatinine clearance (Clcreatinine).
Animals—10 clinically normal adult horses.
Procedures—A bolus of iohexol (150 mg/kg) was administered IV, and serum samples were obtained 5, 20, 40, 60, 120, 240, and 360 minutes after injection. Urinary clearance of exogenous creatinine was measured during three 20-minute periods. The GFR determined by use of serum Cliohexol and plasma Clcreatinine was compared with limits of agreement plots.
Results—Values obtained for plasma Clcreatinine ranged from 1.68 to 2.69 mL/min/kg (mean, 2.11 mL/min/kg). Mean serum Cliohexol was 2.38 mL/min/kg (range, 1.95 to 3.33 mL/min/kg). Limits of agreement plots indicated good agreement between the methods.
Conclusions and Clinical Relevance—Use of serum Cliohexol yielded estimates of GFR in clinically normal adult horses similar to those for plasma Clcreatinine. This study was the first step in the evaluation of the use of serum Cliohexol for estimating GFR in adult horses.
Objective—To compare the effects of 2 preoperative anti-inflammatory regimens on intraocular inflammation following phacoemulsification.
Design—Randomized controlled trial
Animals—21 dogs with immature cataracts.
Procedures—All dogs had cataract surgery via phacoemulsification, and most received prosthetic intraocular lenses. Dogs were randomly divided into 2 groups. Group A dogs were treated topically with prednisolone acetate for 7 days prior to surgery, whereas prednisolone acetate treatment commenced the evening prior to surgery in group B dogs. Postoperative care was identical for both groups. Blood-aqueous barrier breakdown was quantified by use of anterior chamber fluorophotometry, with fluorescein entry into the anterior chamber measured 2 and 9 days after surgery compared with baseline scans obtained prior to surgery. Ophthalmic examinations were performed before surgery and 1 day, 9 days, 3 weeks, 7 weeks, 3 months, and 6 months after surgery. A subjective inflammation score was established at each examination. Intraocular pressures were measured 4 and 8 hours after surgery and at each follow-up examination.
Results—There was no difference in the extent of blood-aqueous barrier disruption between the groups at 2 or 9 days after surgery. Subjective inflammation scores were also similar at most time points. Dogs in group A developed postoperative ocular hypertension at a higher frequency (60%) than did those in group B (18%).
Conclusions and Clinical Relevance—In dogs that underwent cataract surgery via phacoemulsification, a full week of topical prednisolone acetate treatment prior to surgery did not decrease postoperative inflammation, compared with commencement of topical prednisolone acetate treatment the evening prior to surgery, and was associated with a greater incidence of postoperative ocular hypertension.