Seizures in a Foal
History. A 2-day-old Arab colt from an unobserved foaling displays lethargy and inability to rise, and he started to go into seizure in the last hour. The foal stood, but it took longer than normal.
The foal has been nursing, but the mare does not appear to have much milk; this is the mares first foal. The foal seems less active than normal foals and has become more lethargic as the day progressed. Finally, it seemed as though he would not stand, and he had a seizure while traveling to the clinic.Clinical Examination. The foal has a fever, and pulse and respiration are increased. Mucous membranes are darker red than normal, the membranes are dry (dehydration), and the capillary refill time is prolonged (poor perfusion). Auscultation reveals harsh lung sounds and crackles. The umbilicus is thickened and wet. There is petechiation (petechial hemorrhages) inside the ears and in the sclera. There appears to be signs of uveitis in the eyes. The foal is not responsive to manipulations and thrashes, although not in seizure, while being examined. The foal also lacks a suckle reflex.
Comment. Although many possibilities exist for the cause of seizures in this foal, the two most likely reasons are low glucose level (hypoglycemia) and infection (meningitis). The blood glucose level is high in this foal, so meningitis (inflammation of the meninges) with septicemia is most likely. This foal probably has become septic (blood-borne infection) based on the history and clinical signs, which support that he likely did not receive enough colostrum and may not be receiving
SECTION Il Neurophysiology
enough milk from the mare. Without adequate colostrum and nutrition» the foal’s immune system is more susceptible to infection. With the thickened umbilicus, harsh lung sounds, fever, petechiation, uveitis, and seizures, the signs are consistent with septicemia, which is manifesting in different regions of the body. The umbilicus could be infected (omphalophlebitis), the lung sounds are consistent with infection (pneumonia), and seizures are consistent with meningitis.
Complete blood count, chemistry, blood gases, and blood culture are warranted to determine the overall status of the foal. In many cases, these tests will be sufficient to make a diagnosis and determine treatment. In some cases, to make a definitive diagnosis, an atlanto-occipital (A∕O) CSF tap (which samples from the cisterna magna) is best because it is closest to the site of the lesion, compared with a lumbosacral tap. The tap also allows a culture to be submitted so that the foal can be treated with the most efficacious antibiotics. In performing the CSF tap, the foal can be sedated with diazepam (Valium). The CSF is submitted for protein, glucose, cytology, and culture. Typically, the protein level is high with meningitis, and cytology shows an increased number of leukocytes (neutrophils). There is always the potential for a false-negative result with the culture.
Treatment. Prognosis for a septic foal with seizures is poor, with many factors to consider. In regard to the meningitis, treatment consists of antibiotics, antiinflammatory agents, and anticonvulsants as needed. Seizures can cause hypoxia to the affected area, which can result in permanent damage. Besides meningitis, other problems include the umbilical infection, respiratory infection, and uveitis. With septicemia, other organs often become infected (joints, gastrointestinal tract, renal system). Additional concerns are potential renal insult caused by dehydration or complications associated with some antibiotics. Supportive care is another consideration. Managing a recumbent foal is challenging, not only for the reasons already listed, but also because of other factors, including additional infection, aspiration, and nutritional support.