Equis ISSN 2398-2977

Epilepsy: foal

Synonym(s): Seizures

Contributor(s): Kristopher Hughes, Mary Rose Paradis

Introduction

  • Cause: seizures in foals can be attributed to several different etiologies including hypoglycemia, neonatal encephalopathy (neonatal maladjustment syndrome), bacterial meningitis, trauma, hepatic encephalopathy, electrolyte derangements, eg sodium/calcium/potassium, toxins, eg organophosphates/strychnine, viral encephalitis, inadvertent intracarotid injection and genetic/congenital problems, such as lavender foal syndrome, hydrocephalus, Arab foal epilepsy.
  • Signs: focal signs random chewing, licking, rapid eye movement, muscle fasciculations, apneustic breathing; generalized signs thrashing, paddling, opisthotonus, extensor rigidity and hyperthermia.
  • Diagnosis: clinical signs, CBC, IgG levels, blood gas analysis, serum chemistry, cerebral spinal fluid analysis, computed tomography (CT), magnetic resonance imaging (MRI).
  • Treatment: general therapy anticonvulsants; specific therapy dependent on etiology.
  • Prognosis: depends on cause.

Pathogenesis

Etiology

Predisposing factors

General
  • Failure to nurse.
  • Failure of transfer or maternal antibodies.
  • Dystocia.
  • Premature placental separation.

Specific

  • Egyptian Arabian breeding.
  • Sepsis.
  • Trauma.

Pathophysiology

  • Seizures begin with a focus of abnormal spontaneous depolarization of cerebral neurons, which results in sodium and potassium selectively moving across cell membranes and generation of excitatory post-synaptic potentials. If this activity involves large groups of neurons discharging and it exceeds the individuals seizure threshold of activity then a generalized seizure may result.
  • Extra-cranial causes of seizures hypoglycemia, hypoxia, hypernatremia/hyponatremia, hyperkalemia, hypocalcemia, hypomagnesemia.
  • Intracranial causes of seizure inflammation, malformation, injury, infectious (viral, bacterial).
  • Idiopathic epilepsy possible genetics.
  • Foals may have a lower seizure threshold due to cortical immaturity.

Diagnosis

This article is available in full to registered subscribers

Sign up now to purchase a 30 day trial, or Login

Treatment

This article is available in full to registered subscribers

Sign up now to purchase a 30 day trial, or Login

Prevention

This article is available in full to registered subscribers

Sign up now to purchase a 30 day trial, or Login

Outcomes

This article is available in full to registered subscribers

Sign up now to purchase a 30 day trial, or Login

Further Reading

Publications

Refereed papers

  • Recent references from PubMed and VetMedResource.
  • Chaffin M K, Walker M A, McArthur N Het al(1997)Magnetic resonance imaging of the brain of normal neonatal foals.Vet Radiol Ultrasound38(2), 102-111 PubMed.
  • Hess-Dudan F & Rossdale P D (1996)Neonatal maladjustment syndrome and other neurological signs in the newborn foal: Part 1.Equine Vet Educ8(1), 24 VetMedResource.
  • Ragle C A, Koblik P D, Pascoe J Ret al(1988)Computed tomographic evaluation of head trauma in a foal.Vet Radiol 29, 206 VetMedResource.
  • Morris D D, Rutkowski J & Lloyd K C K (1987)Therapy in two cases of neonatal foal septicaemia and meningitis with cefotaxime sodium. Equine Vet J19(2), 151 PubMed.
  • Mayhew I G (1982)Observations on vascular accidents in the central nervous system of neonatal foals.J Reprod Fertil Suppl32, 569 PubMed.

Other sources of information

  • Paradis M R (2006)Foal with Hypoxic Encephalopathy. In:Equine Neonatal Medicine: A Case Based Approach. Ed: Paradis M R. Philadelphia, Elsevier. pp 179-190.


ADDED