Paralysis in horses refers to the loss of voluntary muscle function, which can result from a variety of neurological or musculoskeletal conditions. It can affect different parts of the horse's body and may be partial or complete. Causes of paralysis in horses include traumatic injuries, neurological disorders, infections, and toxicities. Common conditions associated with equine paralysis include equine protozoal myeloencephalitis (EPM), cervical vertebral stenotic myelopathy (CVSM), and botulism. Diagnosis and management of paralysis in horses require comprehensive veterinary evaluation, including neurological examinations and diagnostic imaging. This page compiles peer-reviewed research studies and scholarly articles that explore the causes, diagnostic approaches, and treatment options for paralysis in horses.
Traver DS, Moore JN, Thornburg LP, Johnson JH, Coffman JR.An aged gray stallion was examined because of fullminating posterior paresis, bladder paralysis, and perineal anesthesia. Lower motor neuron dysfunction was detected at the lumbosacral level of the spinal cord, and cerebrospinal fluid was yellow. After brief supportive treatment, the horse died. Necropsy revealed a single epidural melanoma at L5-6. The absence of cutaneous melanotic growth, absence of organ involvement, and extensive vertebral remodeling indicated the neoplasm to have been primary and to have been present for an extended period. Neurologic dysfunction was acute and progressive...
Hadlow WJ, Ward JK, Krinsky WL.Acute neurologic disease associated with intracranial migration of a first instar larva of a warble fly, Hypoderma bovis (Linnaeus), was observed in a 14-year-old Quarter Horse gelding in western Montana. The disease was characterized by incoordination of gait, circling to the left, head tilt to the right, partial paralysis of the right side of the face, and impaired vision in the right eye. Two and one-half hours after it was first noticed sick, the horse collapsed and was euthanized. Massive hemorrhage unaccompanied by necrosis or significant cellular response was present in the right side o...
Mayhew IG, deLahunta A, Whitlock RH, Geary JC.Five horses of mixed breeding and 1 zebra with symmetric tetraparesis and ataxia were studied. There were 2 females and 4 males. Signs of illness were first noticed from birth to 12 months of age. Clinical and pathologic studies were performed when the animals were 4 to 24 months old. Two of the horses were related. All of the subjects had diffuse degenerative myeloencephalopathy. The degeneration was most pronounced in thoracic segments of the spinal cord. Ventral and dorsolateral funiculi were most severely affected. Axonal swelling and abnormal neuronal cell bodies were seen in the gray mat...
Little PB, Thorsen J.Equine viral rhinopneumonitis type I virus was isolated from spinal cord and brain of a paraparetic horse with disseminated necrotizing myeloencephalitis. Necrotic arteriolitis,nonsuppurative necrotizing myeloencephalitis and Gasserian ganglioneuritis were present. On record were 12 more cases of horses with similar lesions. The horses had been ataxic or paretic for up to several weeks. A field survey indicated that 14 of 24 horses with acute myelitic signs developed them after recent exposure to respiratory disease.
Thorsen J, Little PB.A Standardbred mare became paralyzed shortly after showing signs of an upper respiratory infection. The mare was euthanized and equine herpesvirus type 1 was isolated from the brain and spinal cord.
Fitzgerald WE.Four cases of snakebite in horses are presented. Diagnosis was made on clinical signs in all, plus fang punctures in 2 cases. Tiger snake antivenene was used in the treatment of 2 patients and these recovered rapidly. Of the 2 in which antivenene was not used, 1 severely affected horse died. The clinical signs which were observed were those of progressive general paralysis and were entirely referable to the neurotoxic component of the venom.
Willoughby RA, MacDonald E, McSherry BJ, Brown G.Groups of young growing horses were fed toxic amounts of lead only, zinc only and the same amounts of lead and zinc together. Those fed Pb only developed pharyngeal and laryngeal paralysis ("roaring") whereas those fed Zn only and Pb and Zn together developed the same clinical syndrome which included swelling at the epiphyseal region of the long bones, stiffness and lameness. Anemia and decreased weight gains were most pronounced in animals fed Zn for the longest periods. Animals fed Pb only did not become anemic and weight loss did not occur until after there was an interference in swallowing...
Hartmann E, Baumgärtner W, Hungerland C.The present report describes the clinical and pathological findings of a one year old foal presented with paralysis of the hind legs. Macroscopically and histologically, a lymphosarcoma in the vertebral body and the adjacent epidural space of T 16, in the spleen and the mesenterial lymph nodes was observed. The adjacent spinal cord showed focal degenerative changes characterized by dilatation of myelin sheaths, swollen axons and few macrophages.
Bayly WM, Grant BD, Modransky PD.Arterial blood samples were collected during maximal exercise over 1.6 km in a thoroughbred horse with left laryngeal hemiplegia. Acid-base and blood gas measurements were performed on each sample and compared to the results from samples which were similarly collected 48 hours after laryngoplasty surgery was performed. Before surgery, the PaO2 was 53.2 mm Hg and the PaCO2 was 58.1 mm Hg after 1.6 km. After surgery, the corresponding results were 83.6 mm Hg (PaO2) and 39.0 mm Hg (PaCO2). There was no significant difference in the times taken for each gallop. The exercise intolerance associated ...
Sasaki N, Morita Y, Moriyama T, Yamada H.The purpose of this study was to evaluate the effect of the canine cranial cruciate ligament repair system on laryngeal hemiplegia in heavy draft horses. Twenty-four heavy draft horses diagnosed with grade 4 laryngeal hemiplegia were allocated to either the prosthetic laryngoplasty (PL) group (n=14) or a canine cranial cruciate ligament repair system (CCCLRS) group (n=10). Right to left angle quotients (RLQs) of abductions of the arytenoid cartilages were endoscopically evaluated before and after surgery. Post-operative RLQs in the CCCLRS group were significantly lower than those of the PL gro...
Firth EC.The signs observed in 6 cases of peripheral vestibular disease included incoordination, head tilt and nystagmus. The intensity of the signs varied greatly with duration of the disease, and in 3 cases facial paralysis was also present. Tympanosclerosis was demonstrable in all cases subject to radiology. Trauma was the causative factor in most cases. The causes of, and relationships between, vestibular dysfunction and concomitant facial paralysis are discussed. The exact etiology of the tympanosclerosis is unknown.
Harrison IW, Speirs VC, Braund KG, Steiss JE.Laryngeal hemiplegia was induced in 4 ponies via a left recurrent laryngeal neurectomy. Reinnervation of the denervated left cricoarytenoideus dorsalis muscle was then attempted using a muscle pedicle graft from the right cricoarytenoideus dorsalis muscle. In 3 ponies there was no return of abductor function and failure of graft survival. In the fourth pony there was return of abductor function along with survival of the muscle bridge, however, there was evidence of reinnervation across the neurectomy site. Muscle-to-muscle neurotization of the paralyzed equine larynx, utilizing the cricoaryte...
Fulton IC, Derksen FJ, Stick JA, Robinson NE, Walshaw R.The efficacy of a nerve muscle pedicle (NMP) graft in restoring upper airway function was evaluated in exercising horses with induced left laryngeal hemiplegia. The NMP graft was created from the first cervical nerve and the omohyoideus muscle and transplanted into the left cricoarytenoideus dorsalis muscle. Seven adult Standardbreds were trained to exercise on a treadmill inclined at 6.38 degrees. With the horses at rest and exercising at 4.2 and 7.0 m/s, the following variables were recorded: peak inspiratory and expiratory transupper airway pressures (defined as the pressure difference betw...
Gruys E, Beynen AC, Binkhorst GJ, van Dijk S, Koeman JP, Stolk P.The most important neurodegenerative diseases of the horse are reviewed. In addition to the literature, neurodegenerative diseases occurring in patients (horses, Mongolian Przewalski-horses, and two zebras) referred to the Utrecht Veterinary Faculty are mentioned. Neurodegenerative diseases described are: I. ataxia associated with: A/ static stenosis, B/ dynamic stenosis, C/ lesions at various locations in the central nervous system, D/ equine herpesvirus infections, E/ equine degenerative myelo-encephalopathy, or F/ cerebellar abiotrophy; II. equine motor neuron disease; III. grass sickness o...
Hadlow WJ, Ward JK, Krinsky WL.Acute neurologic disease associated with intracranial migration of a first instar larva of a warble fly, Hypoderma bovis (Linnaeus), was observed in a 14-year-old Quarter Horse gelding in western Montana. The disease was characterized by incoordination of gait, circling to the left, head tilt to the right, partial paralysis of the right side of the face, and impaired vision in the right eye. Two and one-half hours after it was first noticed sick, the horse collapsed and was euthanized. Massive hemorrhage unaccompanied by necrosis or significant cellular response was present in the right side o...
Firth EC.Low radial neurectomy in the left thoracic limb was performed in 4 mixed-breed weanling horses, with subsequent paralysis of the lateral and common digital extensor muscles. Weight bearing of the denervated and control limbs was discouraged by the use of special shoeing. Clinical signs of flexural deformity were not induced in the horses.
Yovich JV, LeCouteur RA, Stashak TS, Grandy JL, Whalen LR.Acute hemorrhagic myelopathy developed in the sixth cervical to the eighth thoracic spinal cord segments of a 1-year-old Quarter Horse colt that was castrated under general anesthesia while in dorsal recumbency. Clinical signs were consistent with severe transverse myelopathy caudal to the brachial enlargement and cranial to the lumbosacral enlargement of the spinal cord. Histologic examination of the spinal cord revealed hemorrhage in the gray matter, with multiple blood-filled clefts in otherwise normal neuropil. Hemodynamic changes in the spinal cord associated with anesthesia and dorsal re...
Hildebrand SV, Howitt GA.Cumulative vs single-bolus administration of pancuronium was studied in halothane-anesthetized ponies. Dosage levels were determined by giving small increments (0.01 to 0.04 mg/kg of body weight) until the desired relaxation occurred (0.125 +/- 0.038 mg/kg for 90% to 99% reduction of prerelaxant twitch height), then an additional 0.037 +/- 0.024 mg/kg for obliteration of twitch response. The dosage level defined by cumulative administration was then administered as a single bolus 2 more times, once on each of 2 days. Dosage requirements for the 2 methods correlated well. The difference in dura...
Valberg SJ, Baird JD.Pelvic limb movement disorders unrelated to lameness or proprioceptive ataxia have been described in horses for centuries. The two best described are Shivering and Stringhalt. Shivering is unique in that it is primarily apparent when horses are asked to walk backward, without affecting forward gaits until quite advanced. Horses exhibit abduction and either hyperflexion or marked hyperextension of one or both pelvic limbs when walking backward, resulting in a pause at the peak of the stride cycle and reluctance to move backward. Generally, Stringhalt differs from Shivering in that it produces c...
Berry S.Hemangiosarcoma in the spinal canal was diagnosed in a 25-year-old stallion showing progressive and symmetrical 4-limb ataxia, proprioceptive deficits, and weakness. On necropsy, an extradural mass consisting of spindle-shaped cells and numerous free erythrocytes was found at the level of C7-T1. Immunohistochemical staining confirmed a neoplasm of endothelial origin.
Bohanon TC, Beard WL, Robertson JT.Case records of 27 draft horses with laryngeal hemiplegia were reviewed. Twenty-one horses were treated by ventriculectomy with or without prosthetic laryngoplasty, and 17 owners were contacted to determine the results. Fifteen horses improved after surgery and were able to perform to the owners' expectations. Performance improved significantly and hospitalization was shorter after ventriculectomy alone. Results of this study indicate that the clinical signs of exercise intolerance and excessive inspiratory noise associated with left laryngeal hemiplegia in draft horses can be treated successf...
Jaeschke G, Rudolph R.The literature contains about 500 cases of equine leucosis, though the reports are deposited in a great number of journals and vary considerably concerning particular topics. During the last years there has been a remarkable increase of publications about this syndrome in the equine. The clinical leucosis key recommended by us has been confirmed in principle considering the latest literature. In about 70 individual symptoms which can be clinically observed in equine with leucosis 11 can be considered as main symptoms because of their frequency; they are again classified in primary (lymph node ...
Archer RM, Lindsay WA, Duncan ID.This study was designed to define a simple, unequivocal test for the evaluation of laryngeal function and the diagnosis of idiopathic laryngeal hemiplegia (ILH). ILH is a disorder that results from left recurrent laryngeal neuropathy and in which there is no movement of the left arytenoid cartilage and vocal fold. Laryngeal function was evaluated in seven horses using four techniques designed to stimulate laryngeal movements:-nasal occlusion, exercise, swallowing and administration of a respiratory stimulant. In addition, the effects of sedation and twitching on the endoscopic examination were...
Fitzgerald WE.Four cases of snakebite in horses are presented. Diagnosis was made on clinical signs in all, plus fang punctures in 2 cases. Tiger snake antivenene was used in the treatment of 2 patients and these recovered rapidly. Of the 2 in which antivenene was not used, 1 severely affected horse died. The clinical signs which were observed were those of progressive general paralysis and were entirely referable to the neurotoxic component of the venom.
De Jonge B, Dufourni A, Oosterlinck M, Chiers K.We report a 9-year-old Thoroughbred gelding that had sudden onset lameness of the right forelimb with episodes of lateral decubitus and generalized pain after completion of a normal training session. The clinical signs subsequently became less pronounced with only mild right forelimb lameness. However, after further orthopaedic examination, it developed severe, acute ataxia and paraplegia, the Schiff-Sherrington phenomenon and risus sardonicus. At necropsy, a partial duplication of the cervical spinal cord was identified, consistent with split spinal cord malformation type II or diplomyelia. H...
Hildebrand SV, Hill T, Holland M.To determine whether cholinesterase inhibition by an organophosphate would influence atracurium's neuromuscular blockade, six horses were anesthetized and paralyzed with atracurium (total of five injections per horse) on experimental Day 1, then were given trichlorfon (64 mg/kg per os) 6 days later. On Day 7, horses were anesthetized and paralyzed in the same manner as on experimental Day 1. Blood was taken to measure serum cholinesterase activity prior to anesthesia on Days 1 and 7. No significant difference was noted in atracurium's neuromuscular blocking activity between the 2 experimental ...
Tee SY, Feary DJ.A 9-year-old Miniature Horse gelding infested with ticks (Ixodes holocyclus) was presented with flaccid motor paralysis causing recumbency. Neurological examination and other diagnostic tests did not identify an alternative aetiology, leading to a presumptive diagnosis of tick paralysis. The gelding was treated with tick antiserum and intensive supportive care. He made a gradual recovery over the 48 h following presentation and was discharged without further complications. This case report describes in detail the clinical signs and successful treatment of a Miniature Horse with flaccid paral...
Hughes KJ, McGorum BC, Love S, Dixon PM.Six ponies and four horses with a mean (sd) age of 15.9 (6.0) years developed sudden-onset bilateral laryngeal paralysis (BLP) in association with hepatic dysfunction. Nine of them had been referred for the investigation of respiratory distress, and one pony had been referred for weight loss before BLP developed. Nine of the animals had clinicopathological evidence of liver disease, and nine had histological evidence of liver disease. All of the animals had one or more of the following: hepatic encephalopathy (in eight), hyperammonaemia (in six) and endoscopic evidence of BLP (in nine). Three ...
Sloet van Oldruitenborgh-Oosterbaan MM.Hyperkalaemic periodic paralysis(HYPP) is characterized by intermittent episodes of muscular tremor, weakness, and collapse, and is probably caused by abnormal electrolyte transport in the muscle cell membrane. During an episode of HYPP, most animals are severely hyperkalaemic. HYPP is a hereditary disease and occurs only in American Quarter horses or crossbreds. Because these horses are now being imported into the Netherlands, HYPP should be included in the differential diagnosis of horses showing signs of muscle tremor, paresis, or paralysis. The present article reviews the literature on HYP...
Grant RC, Basson PA, Kidd AB.A paralytic condition of farm stock in South West Africa, characterized by prominent neuronal and some mild extraneuronal pigmentation, is described. The distribution of the pigment, which was mainly located in the larger neurones of the brain and spinal cord, is given. Experimental evidence, obtained by feeding the plant, is presented that the condition is caused by Trachyandra laxa var. laxa. The histochemical features of the pigment proved to be compatible with a lipofuscin.
Church S.Three Quarter Horse stallions and 5 of their 11 tested progeny were diagnosed as affected with the inherited autosomal dominant defect hyperkalaemic periodic paralysis in Victoria in 1992. The diagnoses were based on the appearance of clinical signs and associated increased plasma potassium concentrations in response to oral potassium loading. All affected horses were descendants of the American Quarter Horse Impressive. Indirect evidence indicates that at least 3 other affected Quarter Horse stallions have stood or are standing at stud in Australia. The clinical details of the affected horses...
Meyer S, Ptok M.The term 'laryngeal neuropathy' (LN) has first been used in veterinary medicine to describe an idiopathic and typically exercise induced inspiratory noise in horses.Nowadays, the term is often used in relation with intermittent vocal cord pareses in humans. Some authors use the term 'irritable larynx syndrome' (ILS) in a similar context. This article reviews the state of knowledge regarding LN and ILS and discusses the somewhat confusing terminology.For this systematic review a selective literature research in PubMed has been carried out.35 articles were found, which report on LN in animals an...
Hay WP, Tulleners EP, Ducharme NG.An extralaryngeal approach to partial arytenoidectomy in the horse was developed by in vitro experiments on isolated larynges and then on intact equine cadavers. The goals of the approach were to preserve the laryngeal mucosa, eliminate the need for a laryngotomy or tracheotomy, and minimize postoperative complications. The new approach was evaluated in seven horses with normal upper respiratory tracts. Left laryngeal hemiplegia was surgically created, and, after a 30-day convalescence, left partial arytenoidectomy was performed using an extralaryngeal approach. The left-to-right hemilaryngeal...
Manohar M, Goetz TE, Nganwa D.Diaphragmatic O2 and lactate extraction were examined in seven healthy ponies during maximal exercise (ME) carried out without, as well as with, inspiratory resistive breathing. Arterial and diaphragmatic venous blood were sampled simultaneously at rest and at 30-s intervals during the 4 min of ME. Experiments were carried out before and after left laryngeal hemiplegia (LH) was produced. During ME, normal ponies exhibited hypocapnia, hemoconcentration, and a decrease in arterial PO2 (PaO2) with insignificant change in O2 saturation. In LH ponies, PaO2 and O2 saturation decreased well below tha...
Cramp P, Derksen FJ, Stick JA, de Feijter-Rupp H, Elvin NG, Hauptman J, Robinson NE.The nerve-muscle pedicle graft technique is a treatment for recurrent laryngeal neuropathy (RLN), but the optimal placement of the pedicles within the cricoarytenoideus dorsalis (CAD) muscle is unknown. Objective: The magnitude and direction of force placed on the muscular process of the left arytenoid cartilage affects the magnitude of laryngeal abduction. Methods: Five larynges were harvested from cadavers. Using increments of 0.98 N, a dead-weight force generator applied a force of 0-14.7 N for 1 min each to the left muscular process at 0, 10, 20, 30, 40, 50, 60 and 70 degrees angles. The r...
Sloet van Oldruitenborgh-Oosterbaan MM, Schipper FC, Goehring LS, Gremmels JF.In the course of several days most of the 40 riding-school horses turned out in paddocks developed ataxia of variable severity. Five of these horses showed severe ataxia and tremors, became paralyzed and were euthanized. Eleven privately-owned horses which were stabled on the same premises showed no clinical signs. The most likely diagnosis seemed to be the 'neurological form of EHV1', although the signs were not entirely typical. A few weeks later a second outbreak occurred among the riding-school horses and one of the privately-owned horses also showed signs of ataxia. In the meantime it had...
Dunlop CI, Hodgson DS, Watson JW, Gillespie JR, Steffey EP, Jackson AC.High frequency jet ventilation (HFJV) is a recently developed mode of ventilation that delivers small tidal volumes at frequencies greater than 60 cycles per min via an injection catheter to the animal's airway. The construction of a high frequency jet ventilator suitable for use in adult horses is described. The effectiveness of this ventilator in maintaining normal arterial blood-gas tension was evaluated in five healthy adult horses. The horses were anaesthetised with intravenous acetylpromazine, guaifenesin, and thiamylal, positioned in lateral recumbency and baseline measurements were mad...
