HeadacheHeadache DisordersTension-Type HeadacheCluster HeadacheAcute DiseaseHematoma, Epidural, SpinalVascular HeadachesLameness, AnimalMigraine DisordersBrain Stem InfarctionsQuadriplegiaEncephalomyelitis, Acute DisseminatedDog DiseasesHeadache Disorders, SecondaryMagnetic Resonance ImagingFatal OutcomeTomography, X-Ray ComputedHematomaSpinal Cord DiseasesTreatment OutcomeAneurysm, DissectingFollow-Up StudiesAnti-Inflammatory AgentsTime FactorsRetrospective StudiesDogsDisease OutbreaksMigraine without AuraBrainSpinal Puncture