Page 28 - Demo

Toxins - careful historical informationand a farm visit may be helpful in determining these conditions:%u2022 Moldy Corn Poisoning%u2022 Organophosphate insecticides%u2022 Lead%u2022 Arsenic%u2022 Strychnine toxicosis can cause cerebral lesions.%u2022 Russian knapweed or yellow star thistle causes nigropallidal encephalomalacia.This disease occurs in late summer and fallin horses on overgrazed pastures in thewestern U. S. Impaired prehension and mastication, facial muscle hypertonicity, anddysphagia are commonly seen in horseswith acute toxicosis. These horses may beable to swallow but cannot prehend or chewfeed. Seizures, head pressing, incoordination, and falling down may also be seen.Tumors can cause brain disease, and pituitary adenoma is the most commontumor in the horse. It occurs most often inthose over 18 years of age. Polydypsia,polyuria, hirsutism, a pot-bellied appearance, hyperglycemia and glucosuria arecommon. Pituitary tumors may rarely induce blindness and depression as a resultof pressure on the optic nerve and brainstem. In addition, meningiomas andependymomas have been identified inhorses showing signs of circling, blindnessand depression.Congenital malformations such as hydrocephalus rarely occur in young horses.A foal with an open fontanelle who showsprogressive depression, ataxia and weakness can have congenital hydrocephalus.Cranial trauma can occur from horsesfalling over backward and striking thepoll, colliding with obstacles and beingkicked by other horses. Skull fractures involving the mandible, maxilla, incisive,frontal, parietal and basisphenoid bonescan lead to cerebral, brain stem and cerebellar signs. Trauma usually results incerebral edema, which causes a redistribution of brain tissue in the rigid calvarium. Death can occur from depression ofthe respiratory and cardiac centers in thebrain stem. Cerebral trauma may result inmild weakness but does not usually causeataxia unless severe. A common manifestation of head trauma is blindness whichmay be acute or progressive in onset.Treatment centers around preventingedema: glucocorticoids (dexamethasome)and diuretics are rationale treatment.Brainstem Disease:Trauma occurs frequently in horses andoften without evidence of fractures is notuncommon. Basisphenoid basioccipitalbone fractures occur when horses fall overbackward and strike their poll, causingdamage to the medulla and pons. Headtilt, ptosis, hemorrhage from the externalear canal and leakage of cerebrospinalfluid from the nostril and ear may be seen.Intention tremors may be seen if the cerebellum is involved. Prognosis is guarded;horses may progress to recumbency anddeath, probably from respiratory failure.Horses that recover may have a residualhead tilt and circling but may be salvagedfor breeding. Treatment centers aroundpreventing edema: glucocorticoids (dexamethasome) and diuretics are rationaletreatment.multifoCal Diseases: Dementia anD ataxia togetherDementia, cranial nerve signs, ataxiaand weakness in one or several limbs in anunequal distribution are problems thatcannot be localized to a single focus andthus are considered diffuse or multifocal.Subtle differences in the clinical problemsexist between these conditions, whichmay help in their differentiation:%u2022 Polyneuritis equi: This is the newerterm for cauda equina neuritis and preferred because of the frequent involvement of other peripheral nerves those ofthe cauda equina. Progressive symmetricweakness of the rear limbs, analgesia ofthe tail, anus, and perineum and cranialnerve signs may suggest polyneuritisequi. Fecal incontinence, paraphimosis,urine scalding and bacterial cystitis mayalso be observed. The owner may mistakebilateral gluteal muscle atrophy and facialmuscle atrophy for weight loss. The causeof polyneuritis equi is unknown, but bacterial, viral and immune-mediated mechanisms have been proposed. Antimyelinantibodies have been detected in somecases.%u2022 EPM: Progressive asymmetric ataxia,weakness, muscle atrophy and cranialnerve signs suggest EPM. This diseaseusually occurs in horses of racing and performance age. Obscure hindlimb lameness, lateral digital extensor tenectomyand medial patellar desmotomy are oftenpart of the history. Sarcocystis neurona isthought to be the causative agent. Theseprotozoal organisms randomly invade thegray and white matter of the spinal cord,resulting in multifocal upper- and lowermotor neuron disease.%u2022 Viral Encephalotides: Often knowledge of the diseases that occur locally, clinical course and history can lead you to alikely diagnosis.%u2022 EEE, WEE, VEE: Rapid onset of fever,depression and ataxia that progress to recubency during mosquito season.%u2022 West Nile Virus: Variable fever withhyperesthesia to touching during mosquito season.%u2022 Equine herpesvirus (EHV) 1: Acuteonset and rapidly stabilizing (within 24-48hours) symmetric ataxia, bladder atony,urinary incontinence and hypotonus ofthe tail and anus with or without cranialnerve signs suggest EHV 1 encephalomyelitis. This condition mayoccur 7-10 days after an outbreak of respiratory disease or abortion. EHV 1 causesvasculitis and thrombosis, which lead toinfarction and necrosis of the nervous tissue. The vasculitis is thought to be an immunocomplex disease.28 Arizona Horse Connection June, 2026TWIN ACRES EQUESTRIAN CAMP 602-309-89536407 E. Cactus Rd. %u2022 Scottsdale, AZ 852548 Weeks - May 26 - July 16Tuesdays & Thursdays6 :00 AM - 10:30 AMAlso...%u2022 Bareback Week%u2022 Western Week%u2022 Horse Show Week%u2022 Dressage WeekAnd More!SESSIONS INCLUDE:%u2022 Hands-On Horse Care%u2022 Daily Riding Lessons%u2022 All Aspects Of Horse Care%u2022 Guest Speakers & DemonstrationsAnd more exciting & educational activities!