Clinical Vet. Advisor - The Horse D. Wilson [ 2012), konie - książki angielskie

[ Pobierz całość w formacie PDF ]
Abortion, Equine Infectious
3
Abortion, Equine Infectious
coinciding with the winter months;
however, no direct seasonal inluences
have been identiied.
• Leptospiral abortions are more preva­
lent in locations or seasons with heavy
rainfall and standing water.
ASSOCIATED CONDITIONS
AND DISORDERS
• Placentitis (ascending bacterial placen­
titis or nocardioform placentitis)
• Respiratory disease (EHV)
• Dystocia
• Retained fetal membranes
BASIC INFORMATION
DIAGNOSIS
DEFINITION
Pregnancy loss after placental develop­
ment around 40 to 45 days (may be more
correctly termed “stillbirth” in term preg­
nancies after 320 days). Causes include
bacterial, fungal, and viral organisms.
DIFFERENTIAL DIAGNOSIS
• Ascending bacterial placentitis:
Strep-
tococcus equi
subsp.
zooepidemicus
,
Escherichia coli
,
Pseudomonas aerugi-
nosa
,
Klebsiella pneumoniae
associ­
ated with placentitis, funisitis, and
fetal sepsis; the fetus may be fresh or
autolyzed.
• Nocardioform placentitis:
Crosiella
equi
,
Lentzea kentuckyensis
,
Amycola-
topsis
spp., and
Cellulosimicrobium
cellulans
cause chronic placentitis and
placental insuficiency without fetal
sepsis; foals may be born alive but
underdeveloped and emaciated.
• Leptospiral abortion:
Leptospira ken-
newick
(formerly
Leptospira pomona
),
Leptospira grippotyphosa
,
Leptospira
bratislava
(host adapted to equines);
associated with abortion of autolyzed
fetal tissue, mild diffuse placentitis,
and funisitis; the fetus may be icteric.
• Viral abortion: EHV, EAV, rarely EIA;
fetuses may be fresh (EHV) or auto­
lytic (EAV).
• Fungal abortion:
Aspergillus
spp.,
Mucor
spp.,
Candida
spp. associated
with placental insuficiency or fetal
infection;
Histoplasma
spp. are a rare
cause of abortion.
• Mare reproductive loss syndrome
results in fetal death and abortion or
mummiication early in pregnancy
(day 45–60) and rarely in late­term
abortion. The syndrome is associated
with ingestion of Eastern tent caterpil­
lars. The cetae (hairs) of tent caterpil­
lars are capable of penetrating the
intestinal tract and serving as vectors
for opportunistic intestinal organisms.
• Other infectious causes of abortion:
Taylorella equigenitalis
(contagious
equine metritis),
Neorickettsia risticii
(Potomac horse fever),
Salmonella
abortus equi
.
• Noninfectious causes of abortion:
Twin pregnancy, umbilical torsion,
fetal malformation.
EPIDEMIOLOGY
RISK FACTORS
Risk factors vary by inciting cause:
• Viral abortions, including equine
herpes virus (EHV) and equine arteri­
tis virus (EAV), may occur sporadically
or as “abortion storms.” Contact with
aborting animals and negative vaccine
status are important risk factors for
viral abortions.
• Environmental conditions, such as
standing water in pastures, and contact
with wildlife are known risk factors for
leptospiral abortions.
• Poor perineal conformation and
trauma to the reproductive tract may
be risk factors for bacterial or fungal
placentitis. Other sources of vaginal
or cervical contamination, including
iatrogenic contamination during repro­
ductive examination, may also repre­
sent risk factors.
CONTAGION AND ZOONOSIS
• Direct contact with infected, viremic
animals or with aborted tissue is the
primary mechanism of transmission
for viral diseases. Additionally, EAV
may be transmitted by aerosol across
short distances. Leptospiral organisms
may be transmitted in urine or via the
abortus; however, most leptospiral
abortions are sporadic. Bacterial abor­
tions are not known to be contagious.
• The zoonotic potential for equine viral
or bacterial abortiicants (or abortifa­
cients) is low; however, appropriate
personal protection should be used
when handling fetal or placental tissue
of aborted animals.
•
Leptospira
spp. are known to be zoo­
notic and cause human disease. Trans­
mission from horses to humans has
not been documented to the author’s
knowledge.
GEOGRAPHY AND SEASONALITY
• Viral abortions occur worldwide.
• Abortions caused by nocardioform
organisms are most commonly seen in
Kentucky but have also been reported
in Florida, Europe, and South Africa.
• Abortions are more common in mid to
late gestation (20–44 weeks), generally
CLINICAL PRESENTATION
DISEASE FORMS/SUBTYPES
• Bacterial
• Viral
• Fungal
HISTORY, CHIEF COMPLAINT
• Acute abortion or stillbirth
• Precocious mammary development
• Vulvar discharge
• Premature separation of fetal mem­
branes at birth
PHYSICAL EXAM FINDINGS
• Blood­tinged perineal area; protruding
membranes from vulvar area or in
vagina.
• Physical parameters of mares are gen­
erally within normal limits.
• The fetus may be fresh or autolyzed.
ETIOLOGY AND PATHOPHYSIOLOGY
• The pathophysiology of the disease is
poorly understood for most causative
organisms.
• Abortion may be associated with clin­
ical disease in the mare (EAV, EIA) or
in the absence of clinical disease.
• Ascending placentitis is generally
induced by opportunistic organisms
ascending from the vagina though the
cervix. The bacteria colonize the fetal
membranes and penetrate to the allan­
toic and amniotic luids, gaining access
to the foal either by fetal swallowing
and respiratory movements or by
umbilical penetration. Bacterial inva­
sion initiates a cascade of hormonal
and physical changes that precipitate
premature parturition. At the time of
parturition, the fetus may be prema­
ture, precociously mature, or septic.
• It has not been established how nocar­
dioform organisms reach the uterus,
but they are characteristically found at
the most ventral aspect of the uterus.
Nocardioform placentitis results in dis­
ruption of placental function and fetal
hypoxia but is not known to cause
fetal sepsis.
INITIAL DATABASE
• Complete blood count and chemistry
panel are usually normal but may be
indicated to determine other organ
involvement.
• Electrolyte content of milk may be
useful to predict timing to parturition
in mares with precocious mammary
development and milk production.
Abortion, Equine Infectious
Abscess, Perirectal
4
• A progesterone (estimating total pro­
gestagens) or estrogen assay may be
useful to predict timing to parturition
or severity of disease in some cases.
• Transrectal palpation and ultrasonog­
raphy should be performed to conirm
the presence of a fetus if premonitory
signs are noted or to conirm the com­
plete evacuation of the uterus in a
mare that presents after abortion.
• A thorough genital examination,
including a culture swab of the uterus
and a speculum examination of the
caudal genital tract, may guide post­
abortion treatment.
to evacuate retained fetal membranes
or fetal tissues or to enhance bacterial
clearance from the uterus.
• Antibiotic or antiinlammatory therapy
may be warranted based on examina­
tion indings.
• Infection does not result in protective
antibody formation for future pregnan­
cies in most cases (except EAV).
PEARLS &
CONSIDERATIONS
POSSIBLE COMPLICATIONS
• Dystocia
• Retained fetal membranes
• Retention of a dead fetus is a rare
complication but warrants examina­
tion. A retained fetus that is unde­
tected may result in mummiication or
maceration, which is associated with
metritis and severe maternal disease or
chronic infertility.
PREVENTION
• Vaccination of pregnant mares at 5, 7,
and 9 months of gestation prevents
abortion storms caused by EHV.
• Vaccination of at­risk horses reduces
the transmission of EAV.
• Pregnant animals should be separated
from young animals and competition
animals
ADVANCED OR CONFIRMATORY
TESTING
• Serologic tests for EHV, EAV,
Lepto-
spira
spp., and
Neorickettsia
on mater­
nal serum are available and may aid in
the diagnosis of etiology after abortion.
• Necropsy of the fetus and fetal mem­
branes represents the highest chance
of achieving a diagnosis.
to avoid
transmission of
disease.
RECOMMENDED MONITORING
• Mares and abortuses, including the
fetal membranes, should be examined
carefully at the time of abortion to
achieve an accurate diagnosis.
• Mares should receive regular nursing
care, including monitoring of the rectal
temperature to enhance diagnosis
of secondary complications, such as
retained fetal membranes and metritis.
• If clinically normal, mares should be
examined by transrectal ultrasonogra­
phy 5 to 8 days after abortion to
monitor uterine involution.
• A complete breeding soundness
examination may be warranted before
subsequent breeding attempts.
CLIENT EDUCATION
Although there are no known strategies
to prevent bacterial placentitis, client
education regarding the importance of
premonitory signs, including vaginal dis­
charge and precocious mammary devel­
opment, as well as routine diagnostic
ultrasonography of late­pregnant mares
may lead to a reduction in the incidence
of abortion.
TREATMENT
THERAPEUTIC GOAL(S)
• Maintaining pregnancy to term (if pre­
monitory signs are noted)
• Maximizing fertility of subsequent
breeding attempts
• Preventing transmission of contagious
organism to susceptible animals
SUGGESTED READING
Donahue JM, Williams NM: Emergent causes
of placentitis and abortion.
Vet Clin North
Am Equine
16(3):443, 2000.
Holyoak GR: Equine viral arteritis: current
status and prevention.
Theriogenology
70:
403–414, 2008.
Macpherson ML, Bailey CS; A clinical approach
to managing the mare with placentitis.
The-
riogenology
70:435–440, 2008.
Sebastian MM, Bernard WV, Riddle TW, et al:
Mare reproductive loss syndrome.
Vet
Pathol
45(5):710–722, 2008.
AUTHOR:
C. SCOTT BAILEY
EDITOR:
JUAN C. SAMPER
PROGNOSIS AND
OUTCOME
ACUTE GENERAL TREATMENT
• See “Parturition, Premature Signs of”
in this section for treatment of preg­
nant mares with suspected placentitis.
• Isolation of mares after abortion and
removal of fetal tissues and luids
from the presence of other pregnant
mares may reduce the risk of multiple
abortions.
• Large­volume uterine lavage (30–40 L
of nonsterile saline) may be warranted
• Prognosis for survival of the
mare is good.
• Prognosis for future fertility is good in
the absence of predisposing anatomic
conditions or secondary complications
(eg, dystocia with ensuing damage to
the reproductive tract, retained fetal
membranes).
 Abscess, Perirectal
BASIC INFORMATION
CLINICAL PRESENTATION
DISEASE FORMS/SUBTYPES
The ab­
scesses can be located anywhere circum­
ferentially around the rectum and anus.
HISTORY, CHIEF COMPLAINT
• Mild colic signs
• Depression
• Inappetence
• Decreased fecal output
• Tenesmus
• Dyschezia
• Dysuria
PHYSICAL EXAM FINDINGS
• Temperature is variable depending on
the severity of the lesion; it is often
elevated.
• Heart rate may be normal or may be
elevated.
• Mucous membranes are variable
depending on severity of compromise;
they are often pale pink and moist.
• Colic signs are variable.
ETIOLOGY AND PATHOPHYSIOLOGY
• Progression of anorectal lymphade­
nopathy
DEFINITION
Abscessation around the aboral rectum
and the anus
EPIDEMIOLOGY
RISK FACTORS
Anorectal lymphade­
nopathy can progress to abscessation.
Anorectal lymphadenopathy is more
common in horses 3 to 15 months of age.
 Abscess, Perirectal
Actinobacillosis
5
• Abscess drainage
• Laxative diet
• Antibiotics based on culture and
sensitivity
POSSIBLE COMPLICATIONS
• Peritonitis
• Endotoxemia
• Laminitis
• Adhesions
• Colic
• Stricture formation
• Jugular thrombophlebitis
• Recurrence of abscess
• Perianal istula
• Rectovaginal istula
• Rectal puncture
• Rectal tears, especially those in the
aboral nonperitoneal rectum
• Rectal inlammation
• Migration of an abscess after an intra­
muscular gluteal injection
ACUTE GENERAL TREATMENT
• Occasionally abscessed anorectal
lymph nodes in young horses can be
treated with antibiotics, antiinlamma­
tories, and laxative diets alone.
• Anorectal abscesses refractory to
medical management or those in older
horses
DIAGNOSIS
DIFFERENTIAL DIAGNOSIS
• Anorectal lymphadenopathy
• Small colon impaction
• Rectal tear
• Nonstrangulating small colon or rectal
obstruction
• Rectal neoplasia
• Rectal hematoma
• Urinary tract infection
frequently
require surgical
RECOMMENDED MONITORING
• Pain
• Fecal output and consistency and any
blood on feces
• Signs of endotoxemia
• Colic
drainage.
○
Perform caudal epidural anesthesia
with lidocaine (0.22 mg/kg)
○
Drain abscess
■
Lateral abscesses can be drained
lateral to the anus.
■
Dorsal abscesses can be drained
into the rectum.
■
Ventral abscesses can be drained
into the vagina in mares or
ventral to the anus in males.
○
Administer nonsteroidal antiinlam­
matory drugs (lunixin meglumine,
1.1 mg/kg).
○
Depending on the invasiveness
of surgery, consider administering
broad­spectrum antibiotics while
awaiting the results of culture and
sensitivity.
○
Feed a laxative diet and administer
mineral oil via nasogastric tube.
○
Occasionally, abscesses extend into
the abdominal cavity; these may
require exploratory celiotomy and
marsupialization or drainage into
the vagina or rectum.
PROGNOSIS AND
OUTCOME
INITIAL DATABASE
• Complete blood count: Leukopenia
and leukocytosis are common; occa­
sionally normal.
• Rectal evaluation: The irm abscess
may be palpated in the perianal area
or under the submucosa of the rectum.
• Ultrasonography: May see a well­cir­
cumscribed subcutaneous or submu­
cosal mass.
• Prognosis for abscesses
without abdominal involve­
ment is favorable.
• Abdominal involvement reduces the
prognosis as there is a higher risk of
complications.
SUGGESTED READING
Freeman D: Rectum and anus. In Auer JA,
Stick JA, editors:
Equine surgery
, ed 3. St
Louis, 2006, Saunders Elsevier, pp 479–491.
Magee AA, Ragle CA, Hines MT, et al: Ano­
rectal lymphadenopathy causing colic, peri­
toneal abscesses or both in ive young
horses.
J Am Vet Med Assoc
210:804–807,
1997.
Schumacher J: Disease of the small colon and
rectum. In Mair TS, Divers T, Ducharme N,
editors:
Manual of equine gastroenterology
.
St Louis, 2002, WB Saunders, pp 299–315.
AUTHOR:
CERI SHERLOCK
EDITORS:
TIM MAIR
and
CERI SHERLOCK
ADVANCED OR CONFIRMATORY
TESTING
• Perirectal abscess aspiration: This
can be performed percutaneously or
transrectally.
• Submit any aspirated luid for cytol­
ogy, culture, and sensitivity.
•
Escherichia coli
and
Streptococcus
equi
subsp.
zooepidemicus
are
commonly isolated.
CHRONIC TREATMENT
• Analgesia and antiinlammatories
• Antibiotics
• Laxative diet and mineral oil
• Lavage daily with dilute antiseptic
solution to open abscesses
TREATMENT
THERAPEUTIC GOAL(S)
• Systemic and local analgesia and
antiinlammatories
  [ Pobierz całość w formacie PDF ]

  • zanotowane.pl
  • doc.pisz.pl
  • pdf.pisz.pl
  • trzonowiec.htw.pl

    • Odnośniki