Page 1371 - Equine Clinical Medicine, Surgery and Reproduction, 2nd Edition

1346 CHAPTER 14

VetBooks.ir care is the key to treatment. Foals that have expe- Control of seizures
Diazepam (0.1–0.2 mg/kg i/v) is usually the first-
rienced a significant hypoxic injury are much more
difficult to treat and can require the highest level of
However, the drug accumulates in tissue and is not
intensive care, although many foals with NMS can choice drug for control of seizures in the short term.
be managed successfully on the farm. The main suitable for longer-term use. Midazolam by CRI
aims of treatment are to maintain hydration, provide (0.02–0.06 mg/kg/h) is an excellent choice when more
nutrition, prevent sepsis, encourage maternal bond- prolonged treatment (6–72 hours+) is required. This
ing and control seizures or other neurological signs. drug has the advantage that the rate can be adjusted
easily, and the medication can be discontinued with-
Cardiovascular support out a prolonged effect. Phenobarbitone (2–10 mg/kg
It is important to maintain adequate tissue per- by slow i/v infusion up to q8 h) reduces CNS excit-
fusion, which frequently involves the use of ability and can be used for control of frequent, more
appropriate fluid therapy to restore and maintain severe seizures. The major downside of phenobarbi-
circulating volume. Inotropes and vasopressors tone treatment is its prolonged effect and significant
may be necessary in more severe cases to maintain respiratory depression. Phenytoin is an alternative
blood pressure and tissue perfusion. (See Neonatal antiseizure drug that can be used in some instances.
sepsis, Cardiovascular support, p. 1339.)
Other treatments
Nutritional support Many other treatments have been proposed for the
Many foals with mild NMS will tolerate enteral treatment of NMS. The use of antioxidants such as
feeding but many have a poor suck reflex and conse- vitamins E, C and thiamine has been suggested to
quently should not be fed from a bottle. The use of help reduce oxidative damage, magnesium sulphate
a small indwelling nasogastric tube can allow small, to prevent cellular death and dimethylsulphoxide
frequent feeds. Enteral feeding should be monitored (DMSO), mannitol and dexamethasone to reduce
very closely because some foals will not tolerate large cerebral oedema. There is very minimal evidence to
volumes of milk; 10% of body weight is a good initial support any of their use. Broad-spectrum antimicro-
target and will provide maintenance fluid and energy bial therapy should be considered in these cases and
requirements. Foals with more severe disease will FTPI should be addressed if present.
not tolerate enteral feeding and in these parenteral
nutrition and small trophic feeds will be required. Reduction of progestagens
A full discussion of enteral and parenteral nutrition There is a great deal of interest in treatments to
is beyond the scope of this text. reduce progestagen concentrations in these foals
but at present it is too early to give any firm recom-
Respiratory support mendations. A technique called ‘squeeze-induced
Most recumbent or severely affected foals will somnolence’ or the ‘foal squeeze’ has been developed
benefit from respiratory support. This is gener- over the last few years to try to recreate the physical
ally possible using humidified intranasal oxygen at pressure of the birth process (Fig. 14.13). In some
2–15 litres/minute. Sternal positioning and encour- foals this leads to a dramatic and rapid improvement
aging mobility can also significantly improve lung in their clinical signs.
function. Arterial blood gas analysis can be useful
to monitor respiratory function. Foals with abnor- Nursing
mal central control of respiration will often develop High standards of nursing care and hygiene are
excessive hypercapnia (without hypoxaemia). In required. A quiet warm environment, if possible
these foals the use of respiratory stimulants such as close to the mare, is essential. Manual restraint
oral caffeine (10 mg/kg p/o, followed by 2.5 mg/kg on a padded bed to prevent self-inflicted trauma is
p/o q24 h) or doxapram constant rate infusion (CRI) important. For more severely affected individuals,
can reduce hypoventilation. encouragement to rise, move, regain the suck reflex,