calculating the daily sodium requirements. A detailed discussion of parenteral
nutrition is beyond the scope of this lecture.
Getting it wrong
Too much sodium or fluid may lead to oedema, which can exacerbate organ
dysfunction and increase morbidity and mortality.
Too rapid sodium correction can lead to central pontine myelinolysis, which causes
irreversible neurological deficits. Sodium should be replaced at a rate no faster than
10mEq/day. This is particularly important in chronic hyponatraemia, such as occurs
in cases with chronic diarrhoea or renal failure, but is not always easy to achieve.
On the Farm
50 kg neonatal foal is in shock, now what?
• Give 1L bolus polyionic solution
• Re-assess
• Repeat first and second point 2-3 times if no improvement
• If foal still shocky – refer for intensive care and inopressor support
• If foal significantly improved, showing signs of adequate perfusion and
mentally alert, then calculate maintenance fluid plan.
• Calculate the daily fluid requirement and divide into bolus administrations
(every 3-6 hours), ideally not more than 1L per bolus. Remember to subtract
oral fluids.
What should I do if the foal cannot get up to nurse, but can tolerate oral fluids?
Consider whether referral is indicated
Place a small indwelling nasogastric tube in the distal oesophagus. The
author uses a small silicone tube (8mm) sutured to the nose.
Most foals with healthy intestinal tracts will to lerate 10% of it body weight in
milk or milk replacer divided into 2 hourly feedings (12 times per day).
E.g. 50kg foal: 50 x 0.1 = 5L milk; 5000ml / 12 = 417ml every 2 hours. The
author would typically start with 200ml, and increase the volume by 50ml
every 2 hours until the desired volume is reached.
Milk the mare out as often as possible to maintain milk supply (1-2 hourly).
Stop enteral feeding immediately if reflux, abdominal distention or colic
develops.
All enteral fluids must be administered via gravity and foals must be kept
standing or in sternal recumbency for 10 min after administration to prevent
aspiration.
Foals older than 30 days can be approached more like an adult.
References:
Constable PD: Clinical Assessment of Acid-Base Status: Comparison of the Henderson-Hasselbalch and Strong Ion
Approaches, Vet Clin Pathol 2000; 29:115-128
Flaminio, J. Electrolyte balance in horses. Proceedings of the Latin American Veterinary Conference, Lima Peru - 2008
George, Y.W.H. Easy way to understand Stewarts acid base. www.acidbase.org
Proceedings
of
the
South
African
Equine
Veterinary
Association
Congress
2016
216