Use of computed tomography and magnetic resonance imaging to assess a case of spinal injury in a Showa koi Cyprinus carpio.

OBJECTIVE: A privately owned, 4-year-old female Showa koi (ornamental variant of Common Carp Cyprinus carpio) was presented for erratic swimming, air gasping, water spitting, and abnormal orientation in the water column. Initial physical examination revealed an obese patient with no external abnormalities except a small plaque localized to filaments on a right gill hemibranch. METHODS: The fish was anesthetized using AQUI-S 20E (10% eugenol solution) at 50 mg/L to facilitate diagnostic evaluation. Biopsy of the gill lesion yielded no significant findings. Whole-body computed tomography confirmed an excess of adipose tissue and mild scoliosis, with narrowing of the 10th-11th intervertebral space. A weight loss plan and need for repeat assessment were recommended. RESULT: The patient's original abnormal behaviors resolved over the following weeks, but it subsequently became hyporexic and depressed. Full-body magnetic resonance imaging (MRI) showed extensive alteration of vertebral centra, with multifocal compression of the spinal cord. Due to the patient's declining clinical condition and the grave prognosis based on MRI findings, the patient was humanely euthanized. CONCLUSION: Postmortem examination showed severe transmural myelomalacia associated with a vertebral subluxation. This case demonstrates the practical application of advanced cross-sectional imaging that has not been commonly afforded to fish or other lower vertebrates.

Retrospective study on the incidence of cats and dogs' spinal injuries by computed tomographic scan. Part II: Thoracolumbar and lumbosacral / Estudo retrospectivo sobre incidência de injúrias em coluna vertebral de cães e gatos por meio de exame tomográfico. Parte II: Toracolombar e Lombossacral

For vertebromedullary injuries, epidemiological knowledge is essential to guide the choice of the most effective diagnostic method. The objective of this retrospective study was to describe the epidemiological profile of animals and thoracolumbar and lumbosacral spine lesions diagnosed by computed tomography scan. A compilation of CT scan reports for the aforementioned regions performed in a comercial diagnostic center from 04/01/2017 to 04/30/2020, contrasted and non-contrasted, from routine, was performed in order to list the most common lesions and their locations, as well as the species, breeds and ages most affected. There were 1164 CT scans performed in the period evaluated, all of them in dogs, 57,56% (n=670) for the spine, with 89,7% reports accessed (n=601), where the regions mentioned here added up to 73,05% studies (n=439). In both regions, male French Bulldog dogs had the most injuries. For the thoracolumbar region, disk mineralization, followed by extrusion, were the most frequent injuries, while the site was T12-13 and the mean age 6,5±3,63 years old. In the lumbosacral, disk protrusion was most frequent, the most affected site was L7-S1 and age 6,65±3,79 years. It was concluded that the spine is the main target of CT scans, and that lesions related to the intervertebral disk were the main ones identified, with chondrodystrophic animals being more predisposed to injury.

Para lesões vertebromedulares é indispensável o conhecimento epidemiológico para direcionar a escolha do método diagnóstico mais eficaz. O objetivo desse estudo retrospectivo foi descrever o perfil epidemiológico dos animais e das lesões em coluna vertebral toracolombar e lombossacral diagnosticadas através de exame tomográfico. Realizou-se a compilação de laudos de tomografias computadorizadas para as referidas regiões realizadas em centro diagnóstico comercial, entre 01/04/2017 a 30/04/2020, contrastadas e não-contrastadas, provenientes da rotina, a fim de relacionar as lesões e seus locais de ocorrência, bem como a espécie, raças e idades mais comuns. Foram realizados 1164 exames tomográficos no período avaliado, sendo 57,56% (n=670) para a coluna, com 89,7% laudos acessados (n=601), nos quais as regiões toracolombar e lombossacral somaram 73,05% dos estudos (n=439). Em ambas as regiões, os cães Bulldog Francês machos foram os que mais apresentaram lesões. Para a região toracolombar, a mineralização de disco, seguida pela extrusão, foram as lesões mais frequentes, enquanto o local foi T12-13 e a média de idade 6,5±3,63 anos. Na lombossacral, a protusão de disco foi mais frequente, o local mais afetado foi L7-S1 e idade de 6,65±3,79 anos. Concluiu-se que a coluna vertebral é o principal alvo de tomografias, e que as lesões relacionadas ao disco intervertebral foram as principais identificadas, sendo os animais condrodistróficos mais predispostos a lesões.

Clinical reasoning in feline spinal disease: which combination of clinical information is useful?

OBJECTIVES: The aim of this study was to evaluate if a combination of discrete clinical characteristics can be used to identify the most likely differential diagnoses in cats with spinal disease. METHODS: Two hundred and twenty-one cats referred for further evaluation of spinal disease were included and categorised as follows: non-lymphoid neoplasia (n = 44); intervertebral disc disease (n = 42); fracture/luxation (n = 34); ischaemic myelopathy (n = 22); feline infectious peritonitis virus myelitis (n = 18); lymphoma (n = 16); thoracic vertebral canal stenosis (n = 11); acute non-compressive nucleus pulposus extrusion (n = 11); traumatic spinal cord contusion (n = 8); spinal arachnoid diverticula (n = 7); lumbosacral stenosis (n = 5); and spinal empyema (n = 3). Information retrieved from the medical records included signalment, clinical history and clinical presentation. Univariate analyses of variables (clinical history, breed, age, sex, general physical examination findings, onset, progression, spinal hyperaesthesia, asymmetry, ambulatory status and neuroanatomical location) were performed, and variables were retained in a multivariate logistic regression model if P <0.05. RESULTS: Multivariate logistic regression revealed that intervertebral disc disease most often occurred in middle-aged, purebred cats with a normal general physical examination and an acute onset of painful and progressive clinical signs. Ischaemic myelopathy occurred most often in older cats with a stable or improving, non-painful, lateralising, C6-T2 myelopathy. Spinal fracture/luxation occurred most often in younger cats and resulted most often in a peracute onset, painful, non-ambulatory neurological status. Concurrent systemic abnormalities or abnormal findings detected on general physical examination were significantly associated with feline infectious peritonitis virus myelitis, spinal lymphoma or spinal empyema. CONCLUSIONS AND RELEVANCE: This study suggests that using easily identifiable characteristics from the history and clinical examination can assist in obtaining a preliminary differential diagnosis when evaluating cats with spinal disease. This information could aid veterinary practitioners in clinical decision-making.

Clinical Findings, Treatments and Outcomes in Farm Animals with Vertebral Fractures or Luxations: 22 Cases (2006-2017).

OBJECTIVE: The aim of this study was to describe the signalment, clinical presentation, diagnostic findings, medical and surgical treatment and outcome of 22 farm animals diagnosed with a vertebral fracture or luxation. STUDY DESIGN: Medical records of 22 farm animals (7 goats, 6 alpacas, 5 cattle, 3 sheep and 1 deer) were reviewed for signalment, history, presenting clinical signs and neurological examination findings, clinicopathological results, diagnostic imaging, final diagnosis, medical and surgical management, clinical progression and outcome. RESULTS: Animals' age ranged from 1 day to 15 years. Neurological examination findings included decreased motor function (20/22), recumbency (14/22), altered mentation (13/22), cranial nerve deficits (4/22) and lack of nociception (3/22). Lesions were localized to the atlanto-occipital region (2/22), C1 to C5 (7/22), C6 to T2 (4/22), T3 to L3 (3/22), and L4 to S1 (6/22). Diagnoses included vertebral fracture only (4/22), luxation only (5/22) or both vertebral fracture and luxation (13/22). In five cases, no therapy was attempted, while 12 cases were treated medically and five cases were treated surgically. Surgical interventions included manual reduction (n = 1); arthrodesis (n = 2); laminectomy (n = 1); and laminectomy with pin fixation, cerclage wire and polymethylmethacrylate bridging (n = 1). Five of the 22 cases survived to hospital discharge; two of these were treated surgically. CONCLUSION: The cervical region was most commonly affected. Prognosis for these injuries in farm animals is guarded.

Frequência, caracterização e fatores associados à ocorrência de fraturas na coluna vertebral de suínos abatidos em Uberlândia - MG / Frequency, characterization and factors associated with occurrence of fractures in the vertebral column of swine in Uberlândia - MG

A ocorrência de fratura em coluna vertebral de suínos representa uma grande preocupação para a indústria pois resulta em condenação de partes da carcaça durante a toalete. Desse modo, o objetivo do trabalho foi avaliar fatores que influenciam a ocorrência destas fraturas em suínos abatidos em Uberlândia-MG. Foram coletadas informações sobre a origem dos animais, peso, conformidade da eletrocussão e localização da fratura de 745 suínos. Do total analisado, 274 (36,8%) apresentaram fratura, em sua maioria na posição medial (80,2%). Dentre os fatores analisados, o único que influenciou a ocorrência de fraturas vertebrais foi a origem dos animais (P<0,05). Conclui-se que a origem dos animais exerce influência sobre a ocorrência de fraturas de coluna em suínos e estudos subsequentes podem ajudar a justificar esta relação.

Primary stabilisation for tail avulsion in 15 cats.

OBJECTIVES: To evaluate the effects of a primary tail stabilisation technique in relieving pain and supporting nerve recovery in cats that have lost voluntary motor function and pain sensation in the tail without caudal nerve transection. MATERIALS AND METHODS: Retrospective review of medical records and preoperative diagnostic tests, including clinical examination results and tail radiographs of cats suffering from tail avulsion with loss of pain perception in the tail between 2009 and 2015. Cats with open tail fracture, tail wounds that necessitated an amputation or caudal nerve root transection were excluded. Tail reconstruction was performed, after surgical exploration, with two nylon sutures. RESULTS: Fifteen cats were included, all of which had lost voluntary motor function in the tail and 8 of 15 were urinary incontinent. After surgery, 11 cats recovered voluntary tail function and pain sensation within 14 to 90 days (mean 39 days). Five of the eight previously incontinent cats recovered urinary continence within a month of surgery. CLINICAL SIGNIFICANCE: The reported method of primary tail stabilisation is associated with recovery of lost function in the majority of cats presenting with tail avulsions, loss of pain sensation in the tail but without caudal nerve root transection. A comparison study is required to determine whether these results are superior to conservative management.

Accuracy of a patient-specific 3D printed drill guide for placement of cervical transpedicular screws.

OBJECTIVE: To develop a patient-specific 3-dimensional (3D) printed drill guide for placement of cervical transpedicular screws and to assess its accuracy. STUDY DESIGN: Prospective case-series. SAMPLE POPULATION: Thirty-two cervical pedicle screws (CPS) placed in 3 large breed dogs. METHODS: Computed tomographic (CT) data of the cervical vertebrae were exported to a medical image processing software and 3D virtual vertebral models were created for each vertebra. These models were processed in a computer aided design (CAD) software to determine the optimal trajectory and size of the CPS. Virtual drill guides were created for each patient, 3D-printed, and used intraoperatively. Locking titanium screw heads were bonded with polymethylmethacrylate cement to stabilize affected vertebral segments. Postoperative CT was used to assess the radiological accuracy of CPS placement in each dog. For each screw, CAD files were analyzed to determine a screw-diameter-to-pedicle-width-ratio (SDPWR) at the narrowest point of the pedicle. RESULTS: A total of 32 CPS were placed, measuring 3.5 mm (n = 20), 2.7 mm (n = 11), and 2.4 mm (n = 1) in diameter. The majority (29/32) of these screws were placed without evidence of vertebral canal breach (grade 0), whereas a vertebral canal breach <2 mm (grade 1) was detected in 3/32 screws. This outcome was achieved despite a mean SDPWR of 0.75 (range 0.58-0.93). CONCLUSION: The use of a 3D-printed patient-specific drill guide permitted accurate placement of 32 bicortical pedicle screws in the caudal cervical vertebrae of 3 dogs. This technique may improve clinical outcome through superior biomechanical properties of screws, reduced surgical time, and reduced morbidity. These results warrant evaluation of patient outcome in a larger population.

MEDICAL MANAGEMENT OF COELOMIC DISTENTION, ABNORMAL SWIMMING, SUBSTRATE RETENTION, AND HEMATOLOGIC CHANGES IN A REEF MANTA RAY (MANTA ALFREDI).

An adult, female, reef manta ray (Manta alfredi) was evaluated for abnormal swimming and coelomic distention after colliding with a floating dock in an exhibit. Initial clinical signs included abnormal posture and swimming. Clinical signs progressed to include muscle wasting, poor body condition, and coelomic distention. Further diagnostics revealed excessive exhibit substrate within the gastrointestinal tract, gastric ulcers, free coelomic fluid, possible spinal lesion, possible uterine abnormality, and hematologic changes. The ray was treated with repeated gastroscopic examinations to remove substrate from the stomach. Psyllium and mineral oil were administered in gel food to assist with passage of substrate through the gastrointestinal tract. Gastric ulcers were treated with sucralfate. Vitamin B complex, iron dextran, and Yunnan Paiyao were used to treat the anemia. Amikacin and sulfadimethoxine-ormetoprim were administered for suspected bacterial and coccidial infections, respectively. Over the course of 11 mo the ray returned to normal health.

Usefulness of multidetector computed tomography in the evaluation of spinal neuro-musculoskeletal injuries.

Spinal trauma is commonly diagnosed in small animal practice. Although the first approach to the patient with spinal trauma includes survey spinal radiographs, an accurate evaluation of the injury often requires advanced imaging. Multidetector computed tomography has revolutionized computed tomography technology, providing near-isotropic volumetric representation of the complete body with exquisite anatomical detail in a brief scan time. This review aims to discuss the technical background, indications, and limitations of multidetector computed tomography in the assessment of spinal trauma with particular reference to skeletal, muscular and nervous spinal components.

Observações clinicocirúrgicas em fraturas e luxações vertebrais toracolombares em cães / Clinical and surgical observations in thoracolumbar spinal fractures and luxations in dogs

Objetivou-se avaliar as implicações e os resultados obtidos frente aos tratamentos conservativo e cirúrgico em 37 cães sem distinção de sexo, raça ou idade, que apresentaram fraturas e luxações vertebrais (FLV) toracolombares. Cada paciente passou por anamnese, seguida por exames clínico, neurológico e radiográficos para se obter o diagnóstico neuroanatômico e a severidade da lesão. Os cães foram submetidos ao tratamento conservativo ou cirúrgico de acordo com as características de cada caso. Dos 37 animais deste estudo, 37,7% tinham percepção de dor profunda (PDP) intacta. Vinte animais foram submetidos ao tratamento conservativo, 14 ao tratamento cirúrgico e três animais faleceram antes do tratamento. Dos animais que mantiveram a PDP intacta, a taxa de recuperação foi de 100%, com tempo de recuperação total variando de sete a 75 dias, ao passo que, dos animais que perderam a PDP, nenhum recuperou a deambulação voluntária. Dos 14 animais operados, 42,8% apresentaram alterações vertebrais não visibilizadas ao exame radiográfico convencional, sendo necessária mudança na técnica cirúrgica planejada em 14,2% desses casos. Nos animais que mantiveram a PDP, não houve diferença significante nas taxas nem no tempo de recuperação da deambulação voluntária, independentemente do tipo de tratamento. Entretanto, houve diferença altamente significante entre os graus que mantiveram a PDP intacta com os animais que perderam a percepção de dor profunda em relação à taxa de recuperação. A taxa de eutanásia foi menor que em outros trabalhos descritos na literatura. Dos animais sem PDP submetidos ao tratamento conservativo ou cirúrgico, 31,25% readquiriram a capacidade de caminhar sem recuperar a PDP, sendo essa deambulação involuntária atribuída ao caminhar espinal.

Our aim of this paper was to study the implications and results associated with conservative and surgical treatment of dogs with thoracolumbar Vertebral fractures and luxations (VFL) so that the information obtained can be used to obtain guidelines that lead to greater recovery rates. For such, 37 dogs presenting VFL were examined, without distinction of sex, breed, or age. Each patient had detailed history obtained, followed by clinical, neurologic and radiographic exams for obtaining neuroanatomic location and severity of the nervous and vertebral lesions. The dogs were submitted to conservative or surgical treatment according to each case. Deep pain perception (DPP) was intact in 37.7% of the 37 dogs in this study. Twenty dogs received conservative treatment, 14 underwent surgery and three dogs died before treatment. Of the dogs with intact DPP, 100% recovered, with a recovery time varying between seven and 75 days, while none of the dogs that lost DPP recovered voluntary motion. Of the 14 dogs submitted to surgery, 42.8% had vertebral lesions that weren't detected using conventional radiography, which demonstrates the low sensitivity of this exam, and led to a need for a change in the planned surgical technique in 14.2% of these cases. In dogs with intact DPP there was no significant difference in time or rate of recovery of voluntary motion, regardless of the treatment method. However, there was a highly significant difference between the dogs which retained and lost DPP regarding recovery rates. The percentage of euthanasia was less than in other reports, probably due to the greater awareness and protectiveness of owners nowadays. Of the dogs without DPP treated either surgically or conservatively, 31.25% recovered ambulation without recovery of DPP, characterizing this ambulation as involuntary, attributed to spinal walk.

SUSCEPTIBILITY ARTIFACTS ON T2*-WEIGHTED MAGNETIC RESONANCE IMAGING OF THE CANINE AND FELINE SPINE.

The T2*-weighted gradient recalled echo sequence is a sensitive means to detect blood degradation products. While not a routine sequence in magnetic resonance imaging of the spine in small animals, it can provide additional valuable information in select cases. The goal of this retrospective, cross-sectional study was to describe findings when acquiring this sequence during magnetic resonance imaging examination of the spine in small animals. The University of Tennessee's veterinary radiology database was searched for dogs and cats that underwent magnetic resonance imaging for suspect spinal disease in which a T2*-weighted gradient recalled echo sequence was acquired and susceptibility artifact was identified. The following information was recorded: signalment, clinical signs, location and appearance of susceptibility artifact, and final diagnosis. Thirty-nine cases were included in the study. Extradural susceptibility artifacts were observed in cases of intervertebral disc herniation with or without associated hemorrhage (n = 28), extradural hemorrhage associated with spinal trauma (n = 2), hemophilia (n = 1), and in a cystic extradural mass (n = 1). Remaining lesions displaying susceptibility artifact were intramedullary and included presumptive acute noncompressive nucleus pulposus extrusion (n = 2), hematoma (n = 1), hemangiosarcoma metastasis (n = 1), intramedullary disc extrusion (n = 1), presumptive meningomyelitis (n = 1), and a mass of undetermined etiology (n = 1). Inclusion of a T2*-weighted gradient recalled echo sequence may be helpful in spinal magnetic resonance imaging when standard imaging sequences are ambiguous or intramedullary lesions are observed.

MR cisternography/myelography of post-traumatic spinal CSF fistulae and meningeal lesions in small animals.

BACKGROUND: The diagnosis of post-traumatic spinal cerebrospinal fluid (CSF) fistulae due to dural tears or lesions remains a challenge. Thus far, CT myelography is the standard test used to diagnose these complications. PURPOSE: To evaluate the diagnostic ability of gadolinium-enhanced MR cisternography/myelography (intrathecal gadopentate dimeglumine or Gd-DTPA) in small animals that had experienced accidental spinal trauma. MATERIAL AND METHODS: Four dogs and one cat suffered traumatic accidents resulting in neurological deficits underwent spinal MRI with intrathecal Gd-DTPA after routine plain films and MR images. RESULTS: T2-weighted SE images showed high water content in the epidural space or in the surroundings of the vertebrae in four animals. MR myelography revealed CSF leakage in all of them. In two animals CSF leaks were observed exuding from the spinal canal and tracking towards adjacent loose fat and interfascial planes. In two other animals Gd-DTPA extravasation was diffusely collected in paraspinal tissues around the vertebral arch. In the fifth animal a focal pseudomeningocele was observed adjacent to the traumatized region. CONCLUSION: Intrathecal administration of Gd-DTPA is an effective method to reveal and confirm post-traumatic spinal CSF fistulae or other dural lesions in animals with potential application in humans.

Angle of insertion and confirmation of angles measured after in vitro implantation during laminar vertebral stabilization in vertebral columns obtained from canine cadavers.

OBJECTIVE: To determine angles of insertion for laminar vertebral fixation of L1 and L2 by use of a locking plate in dogs and to confirm screw placement by use of computed tomography (CT). SAMPLE: Vertebral specimens harvested from 8 canine cadavers. PROCEDURES: The point of insertion and minimum and maximum insertion angles for laminar and facet screws for laminar vertebral stabilization were determined by use of CT. A precontoured locking plate was then placed by use of 1 locking screw in the lamina of each lumbar vertebra and 1 nonlocking screw in the facet joint. The position and angle of the screws were examined by use of CT, and penetration into the vertebral canal was recorded. RESULTS: Mean ± SD insertion angles for L1 and L2 were 18 ± 4° and 21 ± 5° toward the vertebral canal and 11 ± 4.4° and 10 ± 3° in a dorsal direction, respectively. Insertion angles for the facet joint were between 24 ± 4° ventrally and 12 ± 2° dorsally. Insertion of the screw did not penetrate the vertebral canal for 23 of 24 (96%) screws. For 23 of 24 inserted screws, the previously determined angle was maintained and purchase of bone and cortices was satisfactory. CONCLUSIONS AND CLINICAL RELEVANCE: Placement of laminar and facet screws in canine vertebrae was possible and can be performed safely if angles of insertion determined pre-operatively via CT are maintained.

Head trauma in the cat: 2. assessment and management of traumatic brain injury.

PRACTICAL RELEVANCE: Feline trauma patients are commonly seen in general practice and frequently have sustained some degree of brain injury. CLINICAL CHALLENGES: Cats with traumatic brain injuries may have a variety of clinical signs, ranging from minor neurological deficits to life-threatening neurological impairment. Appropriate management depends on prompt and accurate patient assessment, and an understanding of the pathophysiology of brain injury. The most important consideration in managing these patients is maintenance of cerebral perfusion and oxygenation. For cats with severe head injury requiring decompressive surgery, early intervention is critical. EVIDENCE BASE: There is a limited clinical evidence base to support the treatment of traumatic brain injury in cats, despite its relative frequency in general practice. Appropriate therapy is, therefore, controversial in veterinary medicine and mostly based on experimental studies or human head trauma studies. This review, which sets out to describe the specific approach to diagnosis and management of traumatic brain injury in cats, draws on the current evidence, as far as it exists, as well as the authors' clinical experience.

Surgical procedures used for post-traumatic neurogenic bladder in a cat: report case / Procedimentos cirúrgicos utilizados no tratamento da bexiga neurogênica em um gato: relato de caso

A 1-year-old castrated crossbred male cat was referred to the Veterinary Teaching Hospital for evaluation of urinary retention associated with a subluxation at T12-T13 caused by a car accident. Urethral sphincter denervation by transection of hypogastric and pudendal nerves was performed to allow bladder emptying, but after three months post operation the cat had a urinary retention recurrence. Endoscopic urethral sphincterotomy was done resulting in urinary incontinence for four months.

Um gato de um ano de idade, macho, castrado, sem raça definida, foi encaminhado ao Hospital Veterinário Escola para avaliação de retenção urinária associada à subluxação nas vértebras T12-T13, que foi causada por um acidente automobilístico. Realizou-se a denervação do esfíncter uretral, por transecção dos nervos pudendo e hipogástrico, para permitir o esvaziamento da bexiga, porém três meses após a cirurgia inicial o animal apresentou recorrência da retenção urinária. Esfincterotomia endoscópica uretral foi então realizada, resultando em incontinência urinária por quatro meses.

A preliminary investigation of the relationship between the "moment of resistance" of the canine spine, and the frequency of traumatic vertebral lesions at different spinal levels.

The aims of this work were to re-evaluate the moments of resistance (MoRs) of the vertebral column proposed by Slijper (1946) in the dog and to study the relationship between the MoRs and the frequency distribution of vertebral traumas in the same species. The spine (C2-L7) of four dogs was measured to obtain MoRs and subsequently scanned with a dual-energy X-ray absorptiometer (DXA). These findings were then analysed retrospectively the frequency distribution of canine vertebral fractures and luxations, diagnosed radiographically at a referral practice. The highest percentage of vertebral injuries affected the T9-L7 tract. This study confirmed that this segment was characterized by a rising trend of the MoR curves and presumably bore the major bending forces. The significant correlation between T9-L1 MoRs and DXA values supports the Slijper's hypothesis suggesting the posterior thoracic region as the weakest segment of the body-axis.

Vertebral fracture and luxation in small animals.

Vertebral fractures and luxations are prominent causes of pain and neurologic dysfunction in dogs and cats. The prognosis is variable, depending on the severity of the damage to the spinal cord and nerve roots, ranging from hopeless in cases with severed spinal cords to excellent for those with minimal injuries. The approach to diagnosis and treatment must include an awareness of the possibility of multiple injuries, and the risks of further injury during diagnostic procedures or during surgical interventions. With judicious interventions cases of vertebral fracture/luxation can be rewarding to treat, because many animals recover good function despite initially severe clinical signs.

Effect of various electric field strengths and current durations on stunning and spinal injuries of Atlantic herring.

The aim of this study was to evaluate the effect of electric field strength and current duration on wild-caught Atlantic herring Clupea harengus stunned with sinusoidal 50-Hz AC in seawater. The fish were exposed to electric field strengths ranging from 16 to 142 V/m and current durations from 1 to 12 s. We recorded the elapsed times between the point at which each fish became unconscious and the points at which it resumed normal behavioral functions. We also investigated injuries such as broken spinal columns and hematomas after the fish were filleted. The threshold electric field strength required to stun all of the fish to unconsciousness was 33 V/m for 1 s. The duration of the unconscious condition increased as both electric field strength and current duration increased. Of a total of 260 Atlantic herring, 60% had broken spinal columns. The proportion of fish with fractured spines was independent of field strength and duration, but the number of fractures per fish increased with field strength. We conclude that electrical stunning would promote the welfare of Atlantic herring that are landed alive but negatively affect fillet quality owing to hematomas associated with the fractures.