Nervous System of Dogs

Overview of Dog Nervous System

  • Brain Size and Weight

    • Average adult dog brain weight: ~50 g

    • Encephalization Quotient (EQ) for dogs: 1.0

  • Gyration Index (GI)

    • GI indicates brain surface area relative to cortical thickness

    • GI values vary across species; for carnivores, GI ranges from 1.5-2.0, and for primates, 1.3-3.0

  • Major Brain Divisions

    • Telencephalon: cerebral hemispheres, basal ganglia

    • Diencephalon: thalamus, hypothalamus

    • Mesencephalon: midbrain

    • Metencephalon: pons, cerebellum

    • Myelencephalon: medulla

  • Neural Development

    • Neural tube forms from ectoderm, developing into the central nervous system

    • The ventricular system plays a crucial role in cerebrospinal fluid (CSF) distribution

  • Histology of the Cerebral Cortex

    • Six layers of neurons are present in the cortex, facilitating synaptic communication

    • Neurons have extensive dendritic branching for synaptic connections

  • Spinal Cord Anatomy

    • Segment organization includes dorsal and ventral roots; sensory and motor information pathways

    • Dorsal horns: sensory input; Ventral horns: motor neuron output

  • Olfactory System

    • Highly developed in dogs (200 cm² olfactory epithelium)

    • Olfactory bulb processes odor information via glomeruli

  • Visual Pathways

    • Optic nerves convey visual information to the brain; some axons cross at the optic chiasm

    • Primary visual cortex receives input from the lateral geniculate nucleus (LGN)