Neonatal Foal Disease

Question 1

Question 2

1. What signifies beginning and end of stage 1?
2. What signifies beginning and end of stage 2?
3. What signifies beginning and end of stage 3?

Answer 2

Question 3

How long should each stage of the birth process last?

Answer 3

• How long should stage 1 last? → Minutes to about 5h or longer, How long should stage 2 last? → 15 - 30min
• How long should stage 3 last? → Less than 2 - 3h

Question 4

Risks associated with a prolonged stage 2

Answer 4

• The foal is at an increased risk of being exposed to hypoxaemia; during the birth process oxygen delivery to the foal can be compromised as the umbilical cord is frequently compressed but the foal is not yet able to breathe.
• Any period of hypoxia can predispose the foal to the development of perinatal asphyxia syndrome (PAS).

Question 5

What could an abnormally long stage 3 indicate?

Answer 5

• A prolonged stage 3 can indicate that the placenta is abnormal or that an abnormality of the pregnancy or the birth process has occurred
• infectious placentitis can predispose the foal to infection in the uterus and development of sepsis while any functional abnormalities of the placenta can compromise optimal oxygen delivery to the foal and predispose to the development of PAS.

Question 6

What is the normal length of gestation for a horse?

Answer 6

320-365 days

• The normal length of gestation for a horse is 11 months (320-365d). This varies significantly between mares although a lot of mares are very consistent with their individual gestational lengths.
• Gestational length is often not a good indicator of maturity of a foal: physical exam findings +/- radiographs to evaluate ossification of cuboidal bones are better.
• A mare that does not show any signs of an abnormal pregnancy should not be induced, even if gestational length is >330d.
• Although the gestational length for the described foal is short, it does not show any signs of prematurity. This could indicate that the intra-uterine development was accelerated for example due to a placentitis and associated inflammation in the placenta.

Question 7

How long should it take for a foal to sit sternal, stand and nurse?

Answer 7

• How long should it take for a foal to stand after birth? → 30min - 1.5h
• How long after birth should a foal have nursed for the first time? → 1h - 2h
• How long should it take for a foal to sit in a sternal position after birth? → 1min - 5min

Question 8

The foal has not nursed until 8h after birth. What does that tell you about the foal?

Answer 8

• The foal’s development has been very slow; it had trouble getting up and finding the teats which can indicate weakness due to sepsis or PAS.
• Other options are orthopaedic problems such as tendon contracture or congenital defects.
• The intestine becomes rapidly impermeable to IgG and this foal most likely has a degree of failure of passive transfer and will probably require plasma.

Question 9

Name five conditions that can affect the pregnant mare that could also affect the foal

Answer 9

Several conditions of the pregnant mare can have a significant impact on the foal’s in utero development:

• Bacterial placentitis
• Placental insufficiency
• Placental separation
• Body wall rupture
• Hydroallantois or hydroamnion
• Uterine torsion
• Colic
• Any systemic disease process (laminitis, infection, neoplasia..)
• Starvation

Question 10

PAS

(Perinatal Asphyxia Syndrome)

Answer 10

• (PAS; synonyms: hypoxic ischaemic encephalopathy HIE, neonatal encephalopathy NE, dummy foals, barkers..)
• Previously, PAS was thought to be secondary to a decreased oxygen delivery to vital organs including the brain before, during or shortly after birth. However, recent findings could indicate that an abnormal transition from intra uterine to extra uterine life (abnormally high progestagen concentrations persisting in the foal after birth) is either contributing to or responsible for the syndrome.
• These findings will need to be investigated further but could change our understanding and potentially treatment of PAS in the future.
• Manifestations vary greatly depending on the organ affected and the degree of organ dysfunction.
• CNS signs are often prominent and vary from mild depression to seizures and coma. Other organ manifestations include gastrointestinal damage (some forms of meconium retention, intolerance of oral feeding, diarrhoea, necrotic enteritis), renal dysfunction etc.

Question 11

Diagnosis and Treatment of PAS

Answer 11

• Diagnosis is based on clinical signs and treatment is symptomatic, supporting normal organ function.
• If treated appropriately, the prognosis to full recovery is good; permanent damage is rarely encountered.
• The foal described is very mildly affected but the owners need to monitor it very closely for any sign of deterioration which would indicate the immediate need for referral

Question 12

Sepsis

Answer 12

• Sepsis is defined as the presence of systemic inflammation (Systemic Inflammatory Response Syndrome or SIRS: presence of 2 of the following: hypothermia or fever, tachycardia, tachypnoea, leucopaenia or leucocytosis, increased band neutrophils) caused by an infectious process anywhere in the body. Infection can occur in utero or during or after parturition.
• The most common entrance site for bacteria are the gastrointestinal and respiratory tract, or, less commonly, umbilical infections.
• Bacteria can frequently be isolated either from the blood stream (bacteraemia) or other affected organ systems (lungs, joints, epiphysis, internal umbilical structures, CNS..).
• Clinical signs are very subtle in the foal and any compromised foal should be assumed to be septic until proven otherwise.

Question 13

Signs of Sepsis

Answer 13

• Signs may include: Hyperaemia of mucous membranes and coronary bands, petechiae visible in ears, oral mucous membranes or, in fillies, in the vulva, signs of uveitis such as fibrin or haemorrhage (hyphaema) in the anterior chamber.
• Body temperature can be low, normal or high.
• Joint swelling and lameness are highly suggestive of sepsis although it may take 3-5d to develop. Haematology often shows leucopaenia and neutropaenia, rarely leucocytosis and increased acute phase proteins
• acute phase proteins: shows inflammation (innate immunity). If high within 24 hour window after birth then likely happened in utero

Question 14

Diagnosis of SIRS and Prognosis

Answer 14

• Diagnosis is based on the presence of SIRS and identification of an infectious source, often a positive blood culture).
• Depending on the severity, foals frequently require intensive medical therapy in specialised neonatal intensive care units.
• Prognosis is good to guarded depending on the severity and willingness of the owner to pay for rather expensive therapy (£1500-6000 and up for intensive care).
• Survivors show little deficits in later life and can become successful athletes.

Question 15

findings that can indicate prematurity in foals

Answer 15

• Small size/low birth weight
• Silky hair coat
• Floppy ears
• Domed forehead
• Weakness
• Flexor tendon laxity
• Incomplete ossification of cuboidal bones (tarsal and carpal bones) evident on radiographs
• Respiratory distress due to surfactant deficiency

Question 16

How can you investigate whether a foal is septic and what other diagnostics should you pursue?

Answer 16

Is the foal septic?

• Complete blood count (CBC) and acute phase proteins (fibrinogen, serum amyloid A) should be obtained to evaluate for any signs of sepsis (leucopaenia or leucocytosis and increased acute phase proteins).
• Increased acute phase proteins shortly after birth indicate infection in utero. If infection has occurred intra or post partum it may take 24-48 before an increase is measurable.
• A blood culture could document bacteraemia and confirm sepsis; however, results would not be available until >48h. You cannot delay your initial treatment decision until then but results may be useful to guide your treatment later.
• Plasma IgG concentration should be measured to determine the degree of failure of passive transfer (FPT). FPT can be suspected in any foal that did not nurse in the first 6-8h of life.

Question 17

Septicemia and Bacteria Entering Blood Stream

Answer 17

• Once the bacteria have entered the blood stream, they can seed into other organ systems, causing localised infection.
• Joints (septic arthritis) are particularly commonly affected but signs often only become apparent after 3-14 days or even later.
• Infection of the umbilicus is also common (septic omphalitis: mainly infection of the internal umbilical structures; the umbilical vein and the umbilical arteries; can also be caused by ascending infection from umbilical stump)

Other organ systems include:

• Intestinal tract: Diarrhoea
• Lungs: Pneumonia
• CNS: Septic meningitis
• Kidneys: Pyelonephritis

Question 18

Treatment for the weak foal

Answer 18

• Administer 1-2L equine plasma IV to increase plasma IgG; re-measure IgG after 12-24h if only 1L has been given. The foal should be monitored very closely for any signs of worsening of its condition.
• Clinical and laboratory findings do not indicate sepsis at the moment but any foal with failure of passive transfer has an increased likelihood of developing an infection and early infection cannot be ruled out. Therefore treatment with systemic antimicrobials (broad spectrum: for example 3rd or 4th generation cephalopsorins) is probably justified.

The owner needs to carefully look for:

• Any sign of decreased nursing (distended udder of mare, milk on foals forehead indicating that it is standing under the udder but not nursing)
• Depression. The foal should consistently get brighter and more active as a mild episode of PAS is expected to resolve quickly. Any deterioration should be immediately reported to you.
• Failure to gain weight. Ideally, a foal should be weighed daily as failure to gain weight is a sensitive indicator of sepsis but few farms will have a suitable scale.
• The temperature should be taken several times daily. Fever or hypothermia should be reported to you.
• Any lameness should immediately be reported.
• If the foal shows the slightest sign of deterioration it should be immediately referred to a specialised hospital