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Israel Journal of Veterinary Medicine  Vol. 70 (1)  March 2015 3 Perioperative Equine Antibiotics Prophylaxis
REVIEW
Perioperative prophylaxis is one of the most common
reasons for antimicrobial drug administration. Its goal is
to decrease the likelihood of infection after exposure to
bacteria during the surgical period (1). Te use of periop-
erative prophylaxis has evolved greatly in the last 30 years.
Improvements in the timing of initial administration, the
appropriate choice of antibiotic agents, and shorter dura-
tions of administration, defne its value in reducing surgical
site infections while minimizing the risks for side efects (2).
On the other hand, inappropriate use results in unnecessary
costs, increased antimicrobial resistance, and development
of superinfections (3). Whereas much information is avail-
able in human medicine, objective scientifc studies which
evaluate the use of perioperative prophylaxis in veterinary
medicine are limited and more studies are warranted.
An American College of Veterinary Internal Medicine
(ACVIM) consensus statement on antimicrobial drug use in
veterinary medicine was issued several years ago (4). In rec-
ommendation I, it is stated that the committee believes that
prophylactic and metaphylactic use of antimicrobial drugs is
appropriate for control and prevention of infectious diseases
Perioperative Antibiotics Prophylaxis in Equine Surgical Colic
Patients – Are We Doing the Right Ting?
Steinman A.,* Kelmer, G. Tatz, A. and Berlin, D.
Koret School of Veterinary Medicine, Te Hebrew University of Jerusalem, Israel.
*
Corresponding Author: Dr. Amir Steinman, DVM., Ph.D., MHA Director, Hospital Koret School of Veterinary Medicine – Veterinary Teaching Hospital,
Te Robert H. Smith Faculty of Agriculture, Food and Environment, Te Hebrew University of Jerusalem, PO Box 12, Rehovot 76100, Israel. Email:
amirst@savion.huji.ac.il
ABSTRACT
Perioperative prophylaxis is one of the most common reasons for antimicrobial administration. Its goal is
to reduce postoperative infection at the surgical site, thereby reducing morbidity, mortality and treatment
costs. When perioperative prophylactic treatment is used, several issues should be decided upon, including
the drugs that are used, timing of frst administration, re-administration after 2 half-lives of the drug if
surgery is still ongoing and duration of treatment. Equine colic surgery is typically an emergency procedure,
classifed in the best circumstances as a clean-contaminated surgical procedure and carries a high rate of
surgical site infection as an important short term complication. Information regarding the compliance with
prophylaxis guidelines in veterinary medicine is limited and is often not detailed enough. Te duration of
prophylactic treatment is a more complicated topic due to the high rate of post-operative complications in
horses undergoing colic surgery. Guidelines for the judicious use of antimicrobial therapy recommend that
antimicrobials should be administered for the shortest efective period possible to prevent the development
of resistant pathogens. A recent study in surgical colic patients has shown no diference in the rate of incision
infection with the use of perioperative antimicrobial therapy for 72 hours and for 120 hours, resulting in
the conclusion that there is no beneft for the longer duration of prophylactic antimicrobial administration.
Clinician’s awareness for guidelines or standard protocols for antimicrobial drug use for equine patients
undergoing surgery for colic is important. Implementing such guidelines, which should be reviewed and
updated regularly, and reducing the amounts of perioperative antimicrobials that are being used are important
goals which we all should strive for in order to reduce the emergence of resistant strains of bacteria that
could afect our patients.
Review Article
Israel Journal of Veterinary Medicine  Vol. 70 (1)  March 2015 Steinman A. 4
in animals. However, it is also stated that its use should be
conservative and should emphasize drugs assigned to the
primary use category. It is also stated that it is not necessary
to use antimicrobial drugs in all surgical cases to prevent
infections, which is especially true for clean surgeries, as
opposed to clean-contaminated or contaminated procedures
(4). Clean surgical wounds have an infection rate less than
5%, so antimicrobial prophylaxis is generally not neces-
sary (3). Clean-contaminated wounds are those in which
contaminated areas of the body (eg. gastrointestinal system,
genitourinary system) are entered under controlled condi-
tions without unusual contamination (3). Colic surgery in
horses is typically an emergency procedure, classifed in
the best circumstances as a clean-contaminated surgical
procedure (4). Surgical site infection (SSI) is one of the
most common short-term complications in colic patients
and can occur in as many as 22-40% of all cases (5, 6, 7).
When using prophylactic antibiotics, several aspects
should be taken into accounts including the selection of ap-
propriate agent, the timing of the frst dose, re-administration
of antibiotics during surgery after 2 half-lives of the drug
have passed, and duration of treatment. Regarding the timing
of the frst dose, prophylactic antimicrobials must be pres-
ent in appropriate levels at the surgical site during the time
of contamination (3). In human patients, administration
of the frst dose of antibiotics more than two hours before
surgery or three hours after surgery resulted in six times
higher complication rate as opposed to patients that were
treated 0-2 hours before surgery (8). Current guidelines for
use in horses suggest that prophylactic antibiotics should be
administered, preferably intravenously, within one hour of
frst incision (9). As for re-administration during surgery, in
human patients undergoing colorectal surgery, the incidence
of infection was decreased in patients that were administered
repeated intraoperative dosing of antibiotics (10). Regarding
re-administration of antimicrobials in veterinary patients if
surgery is ongoing after 2 half-lives of the drug have passed,
prophylactic beta-lactam antimicrobial administration should
be repeated during surgery (3).
Information regarding the compliance with prophylaxis
guidelines in veterinary medicine is limited. In a study report-
ing on prophylactic antimicrobial use in horses undergoing
elective arthroscopy, only 6.3% received preoperative antibiot-
ics within 60 minutes of the frst incision (11). Although it
is recommended that a second dose should be administered
in colic surgeries if the surgery is ongoing after 2 half-lives
of the drug have passed in order to assure adequate levels for
the duration of surgery, intraoperative antibiotic administra-
tion did not occur in any horse, in that study (11). Tese
discrepancies can be partially explained by logistical reasons
but it was suggested by the authors that adhering to these
recommendations is preferable (11). In a recent study that in-
vestigated antimicrobial use in horses undergoing emergency
colic surgery, only 88 (11.6%) horses received the appropriate
preoperative dose within 60 minutes of the start of surgery
and only 8 horses (1.8%) were re-dosed correctly (1).
Te duration of prophylactic treatment is a more com-
plicated topic due to the high rate of post-operative com-
plications in horses undergoing colic surgery. Guidelines
for the judicious use of antimicrobial therapy recommend
that antimicrobials should be administered for the short-
est efective period possible to prevent the development
of resistant pathogens (4). Continued use of prophylactic
antimicrobials beyond the conclusion of surgery contributes
to the development of resistant bacteria, superinfections
and nosocomial infections (3). While in horses undergoing
elective arthroscopic surgery, most (66%) were treated for 24
hours or less (11), this is clearly not the common practice
in colic patients. In 2006, Santschi suggested that equine
surgeons should seriously consider reducing the duration
of prophylactic antimicrobial use in their patients (9). Due
to various reasons, among which is the high post-operative
complication rate, it is still common practice in many equine
hospitals to administer prophylactic antimicrobial therapy
for 5 days, postoperatively, mostly aiming to reduce inci-
sional complications (6, 12). Tis is also the current protocol
at the Koret School of Veterinary Medicine – Veterinary
Teaching Hospital (KSVM-VTH). In a recent study, the
use of perioperative antimicrobial therapy for 72 hours and
for 120 hours was compared, in order to evaluate its efect
on the development of postoperative incisional infections.
High post-operative incisional complication rate (42.2%)
was found, but no diferences were seen between the two
tested groups, resulting in the conclusion that there is no
beneft for the longer duration of prophylactic antimicrobial
administration (6). Te authors of that study suggested that
further studies are warranted to identify the minimum ef-
fective duration of antimicrobial therapy as it is possible
that even a shorter course of 1-2 days would be equally
benefcial (6).
Review Article
Israel Journal of Veterinary Medicine  Vol. 70 (1)  March 2015 5 Perioperative Equine Antibiotics Prophylaxis
Te last but not least decision when administering pro-
phylactic antimicrobial is the selection of appropriate agent.
As stated earlier, in the ACVIM consensus it is recommended
that prophylactic antimicrobial use should be conservative
and should emphasize drugs assigned to the primary use
category. Te most common antibiotic combination used in
adult colic patients is penicillin G and gentamicin (1) which
is in accordance with the ACVIM consensus. Tis is the stan-
dard antibiotic combination in the Royal Veterinary College
and at the Bell Equine Veterinary Clinic, both in the UK,
in colic patients (6). In a survey of 761 horses undergoing
emergency colic in the New Bolton Center of the University
of Pennsylvania, 89.3% were given potassium or procaine
penicillin G and gentamicin and very few were given other
drug combinations (1).
As stated earlier, inappropriate use of perioperative pro-
phylaxis results in unnecessary costs, increased antimicro-
bial resistance, and superinfections (3). We cannot conclude
inclusively, but it is possible that among other reasons, the
recent emergence of multi-drug resistant (MDR) bacteria in
the Large Animal Department of the KSVM-VTH is the re-
sult of such use of antimicrobials. During 2013 49% (27/55)
isolates from diferent body sites in hospitalized horses at
the KSVM-VTH were MDR (Berlin, personal communica-
tion). Multi-drug resistant bacteria are classifed as those that
are resistant to at least 3 groups of antimicrobials (13) and
included 6/12 Escherichia coli isolates, 4/7 Enterobacter iso-
lates, 7/8 Klebsiella isolates and 1/1 a Salmonella isolate which
further emphasizes the problem of nosocomial infection and
question the current prophylaxis antimicrobial use routine.
Methicillin resistant Staphylococcus aureus was also isolated
from both carrier horses and infected wounds during this
year. Strict guidelines for the use of prophylaxis antimicrobial
use in horses undergoing colic surgery is needed.
In a survey that was conducted little more than a de-
cade ago among diplomats of the American College of
Veterinary Surgeons, 28 of 32 respondents (88%) reported
that they were unaware of any written guidelines or stan-
dard protocols for antimicrobial drug use for equine patients
undergoing surgery for colic at their veterinary teaching
hospital (14). A decade later, in a survey among UK equine
surgeons, less than 1% of the practices had antimicrobial use
guidelines (15). Te authors emphasized the importance of
implementation of such guidelines in any institution where
antimicrobials are prescribed in order to maintain their
efectiveness (15). Implementing such guidelines, which
should be reviewed and updated regularly, and reducing the
amounts of perioperative antimicrobials that are being used
is an important goal which we all should strive for in order
to reduce the emergence of resistant strains of bacteria that
could afect our patients.
In conclusion, in horses undergoing colic surgery, it is
important to administer the frst dose of antibiotics, within
60 minutes of the frst incision. A second dose should be
administered if the surgery is ongoing after 2 half-lives of the
drug have passed. Prophylactic antimicrobial administration
should be limited to no more than 72 hours and further
studies are required to determine if even shorter duration
is accepted.
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