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EQUINE VETERINARY EDUCATION / AE / FEBRUARY 2018


monitor for recurrence of infection (Axon and Wilkins 2015). When long-term therapy is necessary, oral therapy with drugs selected based on culture and sensitivity can be used once the patient is stable. Septic foals should be monitored for signs of localised


infections. Periodic ultrasonographic evaluation of the chest and umbilicus should be performed. In any foal with fever and lameness, septic arthritis should be considered. Prompt treatment of septic arthritis is essential to recovery and ensuring athletic potential. Radiographs, ultrasound, joint fluid analysis and synovial fluid culture can direct therapy. Elevated synovial fluid cell count (>20 9 109/l), a predominance of neutrophils (>90%), and increased protein concentration (>40 g/l) all support a diagnosis of septic arthritis. Even with radiographs, early osseous infection can be difficult to identify, but lameness, oedema, heat and pain upon palpation should increase suspicion (Lester et al. 2009). Joint lavage and/or regional limb perfusion are recommended to treat septic arthritis.


Neonatal encephalopathy After sepsis, neonatal encephalopathy (NE) is one of the most common abnormalities of the foal. Clinical signs may be present immediately after birth or may be delayed 24–48 h. Signs of NE include loss of affinity for the dam, loss of suckle, increased sleepiness, abnormal vocalisation, and declining response to external stimulation. Increased stiffness, intermittent nystagmus, and forelimb marching may precede seizure activity (Axon and Wilkins 2015). Causes of this condition are multifactorial and were recently discussed in an in-depth review by Gold (2017). Proposed causes include hypoxic-ischaemic damage, reperfusion injury, dysregulation or persistence of neuropregnanes, and increased inflammatory mediators in the brain. NE is most easily treated in a hospital with sufficient personnel, rapid access to laboratory support including blood gas analysis, and the ability to provide supplemental oxygen. If referral is not possible, then treatment goals include control of seizures, supportive care, antioxidants and prophylactic antibiotic therapy (Table 4). Seizures can be controlled with either diazepam or midazolam. If seizures persist, then midazolam constant rate infusion or phenobarbital may be used. Caffeine is an effective respiratory stimulant in foals that develop hypercapnia and can be used in a field setting when ventilator support is not possible. Dimethyl sulfoxide has been advocated to decrease brain swelling, but its use is controversial as there are few data on its efficacy. Magnesium sulfate is another therapy thought to attenuate brain injury by inhibition of N-methyl-D-aspartate receptor- mediated neuronal injury (Axon and Wilkins 2015); however, recent analysis of outcome for low and high dose magnesium sulfate treatment of traumatic brain injury in man has been associated with worse outcomes (Tempkin et al. 2007). Allopurinol, thiamine, vitamin C and vitamin E have been advocated as neuroprotectants and antioxidants. There is limited data comparing outcomes with any of these neuroprotectants, and appropriate supportive therapy remains the primary determinate of outcome. There is increasing evidence that therapeutic hypothermia increases survival in human infants with hypoxic-ischaemic encephalopathy (Jacobs et al. 2013); however, there is not sufficient evidence on hypothermia in foals to warrant specific recommendations for treatment of NE other than to


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TABLE 4: Drugs used to treat foals with neonatal encephalopathy Drug


Dosage


Diazepam Midazolam


0.11–0.44 mg/kg bwt, i.v., repeat as needed


0.11–0.44 mg/kg bwt i.v. 0.4 mg/kg bwt i.v. as constant rate infusion


Phenobarbitone Loading dose: 10 mg/kg bwt in 30 ml sterile water, give slowly Maintenance dose: 5 mg/kg bwt i.v. q. 12 h slowly


Caffeine


Loading dose: 10 mg/kg bwt per os Maintenance dose: 3.0 mg/kg bwt per os, q. 24 h


Dimethyl sulfoxide 1.0 g/kg bwt as 20% solution i.v. Magnesium sulfate Loading dose: 50 mg/kg bwt as 1% solution slow i.v.


Allopurinol Thiamine


Ascorbic acid a-Tocopherol


Maintenance dose: 24 mg/kg bwt/h for 24 h 44 mg/kg bwt per os within 4 h of birth 1–20 mg/kg bwt q. 12 h i.m. 50–100 mg/kg bwt/day 500–1000 iu, per os, q. 24 h


avoid overzealous warming of foals that are hypotensive and may have cerebral injury. Effects of this condition are not limited to brain injury but


also include multisystemic effects with renal, gastrointestinal, and respiratory systems frequently involved. Good nursing care is essential to monitor and address any changes in systemic function, and clients should be made aware that athletic function appears good for foals that survive (Gold 2017). Evaluation for FPT is important since many affected foals may not have nursed effectively enough to ingest sufficient amounts of colostrum.


Meconium impaction Signs of meconium impaction may include restlessness, stretching of limbs, frequent attempts to defaecate or urinate, twisting of head and neck, and rolling onto the back. Foals attempting to defaecate will ‘tail flag’ with an arched back and hind legs camped under, in contrast to the flat back with hind legs stretched backward seen in foals attempting to urinate. Nursing is frequently disrupted, and the mare may begin to stream milk as the foal’s discomfort intensifies. Over time, abdominal distention will be evident, and urine may be seen dripping from the urachus. Appropriate antiseptic care of the umbilicus should be maintained; however, if the urachus becomes patent, prophylactic antibiotic therapy should be maintained until the urachus closes and frequent ultrasonographic monitoring should be performed to detect complications. Many farms administer enemas prophylactically to prevent constipation. Enemas with either a human sodium phosphate product or warm, soapy water (2–3 ml of liquid detergent to 500 ml water, given by gravity flow) may be used. If straining continues after the initial enema, the foal should be examined by a veterinarian before another enema is given. Repeated enemas may cause mucosal irritation and produce signs of straining even after the constipation has resolved and commercial phosphate enemas may cause phosphate toxicity with repeated use. A diagnosis of meconium impaction can often be confirmed with either a digital rectal examination, careful abdominal palpation, or abdominal ultrasonography to identify meconium. Foals that


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