Often clinically significant signs are detected during what is otherwise a routine check (see p. 75) and so the clinician will need to be properly prepared for any eventuality. Disease often progresses rapidly in foals and delays while treatment is obtained can be very harmful; a delay of 2–3 hours can change the prognosis from fair to hopeless. Detection of an abnormal foal should immediately trigger a chain of investigation and management that is conducive to the foal’s survival.

INITIAL EVALUATION OF THE SICK NEONATE

There is an urgent need to assess the severity of disease and a need to stabilize the foal as soon as is possible. This might need to be done during the completion of the clinical assessment or even before many of the diagnostic procedures can be performed. In many cases initial stabilization is essential prior to transport – transport can be highly stressful and this can add to the foal’s problems if suitable emergency measures are not taken. Seizures, respiratory distress, colic, bloating, unconsciousness, etc. must be dealt with immediately.

Failure to apply a full triage approach might easily result in failure even if the correct diagnosis is reached – the foal may be irretrievably sick or even dead!

TRIAGE

‘The medical screening of patients to determine their relative priority.’

Triage is a decision-making protocol that allows the identification of the foal that can be treated on farm as opposed to the foal that must be admitted to a specialist center if it is to survive. Nevertheless, there is no doubt that hospital care gives the best chances even in mildly affected foals. The advantages of moving the foal need to be balanced against the risks that this might entail both from a disease perspective and for the hospital itself. Nosocomial infections are often difficult to control even when full isolation facilities are available. Therefore, highly contagious infections or zoonotic diseases may need a different approach from non-contagious conditions. In any case, advice should be sought from a specialist center so that an informed plan can be made.

The objective of a good history and performing a clinical examination is to establish:

• a list of all the identifiable problems present

• a differential diagnosis list

• a diagnosis or likely diagnosis

• a prognosis

• a logical treatment plan to maximize the chances of a full recovery (including immediate stabilization medication)

• whether to leave the foal at the farm, admit it to the clinic or refer (see p. 455)

• whether further diagnostic tests are needed to eliminate some of the differential diagnoses or whether to monitor response to treatment

• any alteration in treatment regimen.

The initial assessment of the critically ill foal is usually limited to cardiorespiratory parameters (pulse and respiratory rate/quality, mucous membrane color) and the body temperature and mental status (demeanor and state of consciousness). Treatment at this stage is usually symptomatic (i.e. each prominent symptom is dealt with directly). Once the foal has been stabilized a detailed investigation may permit a definitive diagnosis and then specific treatment can be given. A logical triage approach is shown in Figure 8.1. For further details on clinical examination of the foal see page 82.

Figure 8.1 The triage approach to the sick foal.

Note:

• The process of deciding whether to refer the foal to a specialized center or not is discussed on page 455.

• Even at an early stage referral to a specialist center can be justified and certainly you will have to make a judgement on the amount of time and expertise that you can apply to the case and whether this is likely to be sufficient.

• Make the basic decision on the significance of congenital deformity or defect that is present.

EQUIPMENT REQUIRED FOR A FOAL INTENSIVE CARE UNIT

The foal intensive care unit is very expensive to run in terms of manpower in particular and practices should seriously consider the merit of such a facility unless all the requirements can be met and satisfied. Many facilities are built and then cannot be staffed adequately resulting in foals being left unattended for long periods of time. Under such circumstances it is often better to leave the foal in the care of owners – they will probably (with minimal tuition) manage much better than you will with inadequate backup and no supervision at a superb facility.

For an intensive care unit to be effective, all the required equipment should be ready and to hand as soon as the foal is admitted. Much of the required equipment is not itself highly specialized with one or two exceptions.

STAFF (24 HOUR) IS ESSENTIAL

In order to maintain a full intensive care program you will need to have three nurses and two veterinary surgeons available at all times. At least two lay personnel will be needed in addition. Intensive care needs someone in attendance at all times (and often actually sitting with the foal) (Fig. 8.2) to ensure temperature maintenance, catheter and nasal/gastric tube placement and suitable feeding regimens. Remember that the mare will also need looking after.

Figure 8.2 Twenty-four hour availability of veterinary surgeon.

BASIC REQUIREMENTS

Stabling

The size of the stable is important because mares may become disturbed in a closely confined area and may traumatize the foal.

Contact between the mare and foal may be needed or may not be allowed so a mobile division is required (Fig. 8.3). Some mares can become aggressive towards people when they appear to be permanently interfering with their foals. A mare that will not settle should be placed on the other side of a barrier (rather than removing her to another stall). Visual and olfactory contact must be possible at all times between mare and foal. Prolonged separation is harmful to both.

Figure 8.3 Stable separator.

Ideally have a temperature- and humidity-controlled environment. The ideal temperature varies between 20 and 25°C so heating/cooling/ventilation must be provided. Noise control is essential, as an excessively noisy facility is exhausting for mare, foal and attendants. Light control is also important; very bright to dim general lighting with suitable focus/operating lights should be available.

MORE SPECIALIZED REQUIREMENTS

Table 8.1 shows some of the more specialized equipment that is essential for a critical care unit.

Table 8.1

The equipment required for an effective neonatal intensive care unit (ICU) and sources

^a Heat pads can be extremely dangerous in critical foals and must not be placed in contract with the foal’s skin.

CRITICAL CARE

Critical care of the neonate is perhaps one of the most challenging areas for the equine clinician. It requires specialized knowledge, dedication and a genuine interest in the neonatal period.

Three levels of critical care have been described:

Level 1

This provides basic nursing care and is usually possible on the farm. It is suitable for mild to moderately ill foals in the short term. It should be possible to control the environment, and provide intermittent fluid therapy and oral nutrition. Level 1 care is well within the reach of all practitioners.

Level 2

This provides 24-hour attention for foals unable to nurse or stand. Level 2 care requires a level of commitment, time and finance which may be more appropriately provided at a referral center. It requires dedicated staff, full laboratory support and specialized equipment. To provide the best service to clients it is important to understand what care is available and how to maximize chances for a successful outcome if the foal is to be referred.

Level 3

This provides all the above plus positive pressure ventilation; costs are high and the prognosis is often grave. This is a specialized area that requires the full resources of a specialist hospital and specialist staffing.

A checklist of procedures provides a useful start but every case will be individual – there is no standard approach that is universally successful.

Note:

• Resuscitation after birth is described on page 71.

• APGAR scoring is useful especially in very young foals (see p. 69).

Critical care consists of four important components:

Specific critical care therapy

Following the initial assessment and clinical examination, it is essential at the start that the presence of any life-threatening problems or disease should be identified and treated immediately. Therefore the following is the usual order of priorities:

• seizure control – with anticonvulsants, corticosteroids, etc.

• respiratory support

• warmth

• nutritional requirements – IgG and other requirements

• hydration/fluid and electrolyte requirements (including circulatory support)

• sepsis assessment/antibiotics

anti-inflammatory drugs

antidiarrheals.

Further tests/reassessments are essential enabling changes in therapy to be made.

Nursing therapy

Continue to monitor rectal temperature. Heat-lamps and pads, rugs and leg bandages, etc., should be provided.

General nursing care includes being clean, washing hands and wearing gloves/overalls. Keep the foal dry and in a sternal position as much as possible.

Standard postfoaling routine treatments

These include, for example, treating the navel – dip in chlorhexidine (0.5%) solution q 8 hours for 24 hours.

Recording

Record everything!

SPECIFIC CRITICAL CARE THERAPY

Seizure control

Seizures are often encountered in prematurity and in septic, hypoxic, hypoglycemic and endotoxic conditions. In addition, cerebral edema is a significant feature of the neonatal hypoxic–ischemic disorder. Seizures are highly distressing and, because the seizure threshold in foals is relatively low, they can occur in many situations. Control of seizure activity is a basic aspect of intensive care and is often one of the first emergency measures required.

Seizures are very demanding on metabolic processes and, apart from the obvious dangers of self-inflicted trauma, hypoglycemia and dehydration are common.

Action

Seizures must be controlled immediately. The following can be used:

• Diazepam: this is useful in emergency situations but has only a short duration of action. The initial dose is 5–10 mg/50 kg (0.05–0.2 mg/kg) i.v. every 30 minutes as required. Usually 5 mg increments are administered to effect and to a maximum of 40 mg total.

• Detomidine (and butorphanol): this is a α₂-adrenoreceptor agonist which reduces the discharge rate of central and peripheral neurons, and decreases the CNS sympathetic output. A dose rate of 0.01 mg/kg i.v. is usually used (combined with 0.02 mg/kg butorphanol).

• Phenytoin: this acts by diminishing the spread and propagation of focal neural discharges. It has a relatively short half-life in the horse. A loading dose of 5–10 mg/kg i.v. can be given initially followed by a maintenance dose of 1–5 mg/kg i.v. q 6 hours. This is a useful drug in practice (many foals maintain their suck reflex) and it can be used orally for longer-term therapy.

• Phenobarbitone: this reduces the excitability of the CNS. An initial loading dose of 10–20 mg/kg diluted in 30 mL sterile water is used over 20 minutes. In some compromised foals the duration of action is considerably prolonged. The maintenance dose is 5–10 mg/kg either i.v. or p.o. q 8–12 hours. The maintenance dose rather than a loading dose may control the foal. The dose should gradually be tailed off. It should not be used in combination with phenytoin or cimetidine.

• Pentobarbitone: this produces cardiorespiratory depression. A dose rate of 2–10 mg/kg i.v. is recommended but it is wise to start at the lower end of the range and increase as necessary. It can be repeated every 3–6 hours if needed.

Note:

• Do not use acepromazine or xylazine as these can cause dangerous hypotension or depression.

• Acepromazine also lowers the seizure threshold, making seizures more likely.

Cerebral edema can be controlled by the following agents:

• Corticosteroids: their use in seizure control is controversial. Dexamethasone is used at a dose of 4 mg/50 kg foal q 12 hours i.v. or i.m. Methylprednisolone at 1–2 mg/kg i.v. can be used, or there have been reports of clinicians using a single high dose of 30 mg/kg i.v. – both are recommended within 6 hours of injury.

• DMSO: this acts as a cell protectant and diuretic, and has mild anti-inflammatory effects. It is given at a dose of 0.5 g/kg in 500 saline over 20 minutes.

• Mannitol: this is given at a dose rate of 0.25 g/kg as a 20% solution over 15–40 minutes i.v. (but be careful of hemolysis). It is contraindicated if CNS hemorrhage is suspected.

• Vitamin C: this is given at an arbitrary dose of 1000 mg total dose/50 kg foal i.v. q 12 hours.

Note: For more detail on seizure and cerebral edema therapy see page 168.

Respiratory support

It is very important to establish the state of asphyxia early on with the following:

• history

• clinical examination – heart rate, pulse quality and mucous membrane color, respiratory rate

• further tests:

blood gases (see p. 474)

100% oxygen test – administer intranasal or face mask 100% oxygen at 10 L/min for 5 minutes. A rise in P_aO₂ > 200 mmHg is the response in normal foals. A P_aO₂ < 160 mmHg indicates severe shunting and requires increased monitoring and a protracted illness

pulse oximetry

radiographs (see p. 382)

ultrasonography (see p. 379).

Even normal foals are often slightly hypoxemic in the first week of life and recumbency will reduce the blood oxygen by around 14 mmHg. Recumbent foals have a significantly lower blood oxygen partial pressure than this if maintained in lateral recumbency. Furthermore the dependent lung becomes less efficient as fluid and compression reduce the perfusion and gas exchange efficiency. The body position of the foal therefore has a considerable effect on lung function. Although normal foals can tolerate this well (usually because they are recumbent for short periods only), sick foals have much less ability to cope.

Sick foals and especially those with cardiopulmonary problems should be maintained in sternal recumbency as much as possible (Fig. 8.5). In any case even if sternal recumbency can be maintained the foal should be turned regularly (every 1, possibly 2, hours). Often the disturbance to the foal is less significant than loss of lung function, but if the foal finds it too stressful then do not fight it!