Page 1362 - Equine Clinical Medicine, Surgery and Reproduction, 2nd Edition

The foal 1337

VetBooks.ir signs have regressed and the red cell picture starts to Prevention
Once a mare has been identified by blood typing or a
improve, limited periods of nursery paddock exercise
may be appropriate.
The prognosis for foals suffering from NI is usu- history of previous foals with NI, preventive strategies
can be used for subsequent pregnancies. It may be pos-
ally very good with appropriate treatment. Foals that sible to check the dam’s and sire’s blood type to assess
suffer from rapid haemolyis, and that have received the risk of developing NI. Alternatively, a blood sample
either a large quantity of antibodies or very anti- can be taken from the mare during the last 2–3 weeks
genic antibodies, are more likely to require multiple of gestation and titrated for antierythrocyte antibod-
transfusions. Multiple transfusions are associated ies. It is important not to take the sample too early,
with a poorer prognosis owing to the likelihood because antibody levels rise late, often peaking after
of liver failure caused by iron overload. The lifes- foaling. Once a potential case has been identified the
pan of transfused red blood cells is usually between foal must be prevented from suckling and given 500 ml
4 and 7 days, but this lifespan decreases with sub- of appropriate donor colostrum immediately after
sequent transfusions because of upregulation of the birth, then muzzled prior to udder-seeking behaviour.
foal’s immune system. Deferoxamine can be used The foal should then be bottle-fed a minimum of a
as an iron chelator to try to prevent iron overload, further 500 ml of colostrum and then milk replacer
although its efficacy is unclear. at the appropriate rate. The foal’s IgG levels should be
Kernicterus can also be a severe complication checked 18–24 hours post partum to ensure they are
of NI and is caused by marked hyperbilirubinae- adequate. The mare’s udder should be stripped fre-
mia. Bilirubin can become bound to the grey mat- quently following parturition and the IgG concentra-
ter cells of the brain and cause marked neurological tion monitored until it falls. The stripped milk should
dysfunction. Clinical signs include abnormal mus- be discarded. It is then considered safe to allow the foal
cle tone, opisthotonus and seizures, and it can be to suckle the mare provided it has been appropriately
fatal. Effective treatment for kernicterus is difficult. fed, because it is thought that feeding hastens closure of
Exchange transfusions can be given to remove excess the specialised absorptive mechanism in the foal’s small
levels of circulating bilirubin from the blood, but intestine. It is usually possible to let the foal return to
this is a specialist procedure. the mare within 24 hours of foaling.

PERINATAL/YOUNG FOAL CONDITIONS

NEONATAL SEPSIS by bacterial infection. Other factors can also trig-
ger SIRS, including viral or fungal infection, tissue
Definition/overview hypoxia or trauma.
Sepsis is a life-threatening condition in the neonatal Newborn foals are commonly exposed to a sig-
foal. It remains the leading cause of neonatal mor- nificant bacterial challenge shortly after birth. The
tality worldwide. Sepsis, if untreated, can rapidly foaling environment has a large bacterial population
progress to septic shock and multiorgan dysfunc- and mares frequently defecate during the foaling
tion in the neonate. Early aggressive intervention is process. A study examining sequential blood sam-
necessary to increase the likelihood of a favourable ples from healthy foals over the first few days of life
outcome. revealed that 57% were bacteraemic at one or more
time points. The foal’s immune response to these
Aetiology/pathophysiology bacterial pathogens is essential in preventing clinical
Systemic inflammatory response syndrome (SIRS) sepsis. FTPI has a major role in the pathophysiology
is the term used to describe the body’s response to of sepsis. Foals that do not receive colostrum have
upregulation of the immune system following an a reduced ability to fight infection, not only due to
inflammatory challenge. Sepsis is SIRS triggered the lack of specific antibodies, but due to a reduced