Stringhalt to three years. Horses may be affected so severely that euthanasia is necessary. It is unknown how long it takes for clinical signs to develop after the exposure to the cause of the condition. The majority of horses affected by stringhalt are dependent upon pasture for nutrition. Removal of the horse from its original paddock containing low-quality pasture, weeds and native grasses, along with dietary control, was the most common and successful treatment. Lateral digital extensor tenectomy has also been used as a treatment by veterinarians with a success rate of just over 50%. Phenytoin has been used in the
Nervous system multicellular animals, but vary greatly in complexity. The only multicellular animals that have no nervous system at all are sponges, placozoans, and mesozoans, which have very simple body plans. The nervous systems of the radially symmetric organisms ctenophores (comb jellies) and cnidarians (which include anemones, hydras, corals and jellyfish) consist of a diffuse nerve net. All other animal species, with the exception of a few types of worm, have a nervous system containing a brain, a central cord (or two cords running in parallel), and nerves radiating from the brain and central cord. The size of the nervous system ranges