Changes

A variety of foetal and maternal conditions are associated with NMS:  

A variety of foetal and maternal conditions are associated with NMS:  

'''Foetal factors''' include: '''twinning, meconium aspiration, sepsis, prematurity or dysmaturity and severe anaemia'''.

'''Foetal factors''' include: '''twinning, meconium aspiration, sepsis, prematurity or dysmaturity and severe [[:Category:Anaemia|anaemia]]'''.

'''Maternal factors''' include: conditions that cause '''hypotension or impaired tissue oxygenation''', maternal surgery or cesaerean section, '''dystocia''' and '''placental abnormalities''' (premature placental separation for example).

'''Maternal factors''' include: conditions that cause '''hypotension or impaired tissue oxygenation''', maternal surgery or cesaerean section, [[Dystocia - Horse|'''dystocia''']] and '''placental abnormalities''' (premature placental separation for example).

Initially, the foal responds to asphyxia by shunting blood away from non-vital organs (gut, kidney, bone..) to vital organs (brain, heart, adrenal glands). Continued asphyxia leads to cerebral ischemia. The brain's stores of glucose are depleted by anaerobic metabolism and glutamate uptake is impaired leading to accumulation and overstimulation of receptors.

Initially, the foal responds to asphyxia by shunting blood away from non-vital organs (gut, kidney, bone...) to vital organs (brain, heart, adrenal glands). Continued asphyxia leads to cerebral ischemia. The brain's stores of glucose are depleted by anaerobic metabolism and glutamate uptake is impaired leading to accumulation and overstimulation of receptors.

Free-radicals are produced which overwhelm the scavenging systems and lead to the release of neurotransmitters and inflammatory mediators.

Free-radicals are produced which overwhelm the scavenging systems and lead to the release of neurotransmitters and inflammatory mediators.

This goes on to affect all body systems leading to fluid and electrolyte derangements and abnormal acid-base due to central respiratory depression.

This goes on to affect all body systems leading to fluid and electrolyte derangements and abnormal acid-base due to central respiratory depression.

==Clinical signs==

==Clinical Signs==

Signs can be present at birth but usually develop over the first few hours of life.

Signs can be present at birth but usually develop over the first few hours of life. Initially, '''behaviour changes''' may be all that is apparent: '''depression''', wandering, loss of affinity for mare, head pressing. Other possible '''neurologic signs''' include: bruxism, hyperexcitability, '''extensor spasm of the limbs''', head, tail and '''convulsions''' alternating with a semicomatose state. Dysphagia, central blindness, head tilt and nystagmus have also been reported.

Initially, '''behaviour changes''' may be all that is apparent: '''depression''', wandering, loss of affinity for mare, head pressing.

Signs of '''trauma''' associated with seizure activity can also be apparent: traumatic [[blepharitis]], eyelid trauma, trauma to bony prominences.

Other possible '''neurologic signs''' include: bruxism, hyperexcitability, '''extensor spasm of the limbs''', head, tail and '''convulsions''' alternating with a semicomatose state. Dysphagia, central blindness, head tilt and nystagmus have also been reported.

'''Respiratory signs''' include varying degrees of '''tachypnoea and dyspnoea''' and erratic breathing patterns.

Signs of '''trauma''' associated with seizure activity can also be apparent: traumatic blepharitis, eyelid trauma, trauma to bony prominences

'''Cardiovascular signs''' present as '''tachycardia''', hypotension, or murmurs associated with valve dysfunction.

'''Respiratory signs''': varying degress of '''tachypnoea and dyspnoea''' and erratic breathing patterns.

'''Renal signs''', '''oliguria''' and peripheral oedema may occur if fluid therapy is not adjusted for decreased urine output.

'''Gastrointestinal signs''' such as ileus, poor feeding, loss of suckle reflex, colic, '''abdominal distension''', gastric reflux and '''diarrhoea''' can be present.

 

 

'''Gastrointestinal signs''': ileus, poor feeding, loss of suckle reflex, colic, '''abdominal distension''', gastric reflux and '''diarrhoea'''.

==Diagnosis==

==Diagnosis==

The '''clinical signs''' associated with the condition are usually sufficient to make the diagnosis.

The '''clinical signs''' associated with the condition are usually sufficient to make the diagnosis.

Because the signs of NMS are seen soon after birth, it is often associated with '''failure of passive transfer of antibodies''', which can lead to septicemia.  

Because the signs of NMS are seen soon after birth, it is often associated with [[Failure of Passive Transfer|'''failure of passive transfer of antibodies''']], which can lead to [[Septicaemia - Foal|septicemia]].  

 

There are no definitive blood chemistry or white blood cell abnormalities that aid in diagnosis, but these tests are helpful in eliminating other causes of the clinical signs. Other clinical syndromes that can present with similar signs and must be differentiated from NMS include '''hypoglycemia, electrolyte and acid-base derangements, septic meningitis, head trauma, cerebral bleeding, and congenital CNS defects'''.

There are no definitive blood chemistry or white blood cell abnormalities that aid in diagnosis, but these tests are helpful in eliminating other causes of the clinical signs. Other clinical syndromes that can present with similar signs and must be differentiated from NMS include '''hypoglycemia, electrolyte and acid-base derangements, septic meningitis, head trauma, cerebral bleeding, and congenital CNS defects'''.

'''Isotonic fluids with added glucose''' should be given intravenously, and urine output monitored to avoid overhydration.

'''Isotonic fluids with added glucose''' should be given intravenously, and urine output monitored to avoid overhydration.

'''Seizure control''' is imperative, and diazepam should be administered if needed, with long term control using phenobarbital.

'''[[Seizures|Seizure]] control''' is imperative, and diazepam should be administered if needed, with long term control using phenobarbital.

'''Respiratory support''' with flow-by oxygen, or positive-pressure ventilation if necessary.

'''Respiratory support''' with flow-by oxygen, or positive-pressure ventilation if necessary.

'''Renal dysfunction''' should be treated with dopamine infusions to increase renal blood flow and urine output.

'''Renal dysfunction''' should be treated with dopamine infusions to increase renal blood flow and urine output.

'''General supportive care''' includes: '''immunologic support''' with plasma infusions if the foal's IgG levels are below 800mg/dl. Antibiotic therapy should be considered because sepsis commonly accompanies ischemic bowel damage, and '''broad-spectrum antibiotics''' should be administered intravenously. '''Anti-ulcer medication''' such as ranitidine and sucralfate are recommended as gastric ulcers are a common complication.

'''General supportive care''' includes: '''immunologic support''' with plasma infusions if the foal's [[IgG]] levels are below 800mg/dl. Antibiotic therapy should be considered because sepsis commonly accompanies ischemic bowel damage, and '''broad-spectrum antibiotics''' should be administered intravenously. '''Anti-ulcer medication''' such as ranitidine and sucralfate are recommended as [[Gastric Ulceration - Horse|gastric ulcers]] are a common complication.

Prevention of further self-trauma by placing a '''padded head-collar''' and paying attention to '''corneal ulceration''' is vital.

Prevention of further self-trauma by placing a '''padded head-collar''' and paying attention to [[Corneal Ulcer - Horse|'''corneal ulceration''']] is vital.

==Prognosis==

==Prognosis==

Maggs, D. (2008) '''Slatter's fundamentals of veterinary ophthalmology''' ''Elsevier Health Sciences''

Maggs, D. (2008) '''Slatter's fundamentals of veterinary ophthalmology''' ''Elsevier Health Sciences''

[[Category:To Do - Helen]]

 

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[[Category:Alimentary Diseases - Horse]]

[[Category:Urological Diseases - Horse]]

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