Comparative approach to understanding traumatic injury in the immature, postnatal brain of domestic animals

Traumatic brain injury (TBI) is a frequent occurrence in veterinary medicine, but the mechanisms leading to brain damage after a head impact are incompletely understood, particularly in the postnatal immature and still developing nervous system. This paper reviews neurotrauma studies, largely in paediatric humans and experimental animal models, in order to outline the pathophysiological and biomechanical events likely to be operative in head trauma involving domestic animal species in the postnatal period, as there is almost no other information available in the veterinary literature. Predicting the outcome of TBI is particularly difficult at this developmental time, in large part because recovery is influenced by the stage of brain maturation and neuroplasticity. An important part of the clinical management of TBI is the differentiation of primary brain damage, which occurs at the moment of head impact and is largely refractory to treatment, from the cascade of secondary events, which evolve over time and are potentially preventable and amenable to therapeutic intervention. An understanding of the causes and consequences of secondary brain damage such as hypoxia-ischaemia, brain swelling, elevated intracranial pressure, and infection is critical to limiting the resulting brain injury.     

Traumatic brain injury: a review of pathophysiology and management

Objective – To review current information regarding the pathophysiology associated with traumatic brain injury (TBI), and to outline appropriate patient assessment, diagnostic, and therapeutic options. Etiology – TBI in veterinary patients can occur subsequent to trauma induced by motor vehicle accidents, falls, and crush injuries. Primary brain injury occurs at the time of initial impact as a result of direct mechanical damage. Secondary brain injury occurs in the minutes to days following the trauma as a result of systemic extracranial events and intracranial changes. Diagnosis – The initial diagnosis is often made based on history and physical examination. Assessment should focus on the cardiovascular and respiratory systems followed by a complete neurologic examination. Advanced imaging may be indicated in a patient that fails to respond to appropriate medical therapy. Therapy – Primary brain injury is beyond the control of the veterinarian. Therefore, treatment should focus on minimizing the incidence or impact of secondary brain injury. Because of a lack of prospective or retrospective clinical data, treatment recommendations for veterinary TBI patients are primarily based on human and experimental studies and personal experience. Therapeutic guidelines have been developed that center on maintaining adequate cerebral perfusion. Prognosis – Severe head trauma is associated with high mortality in humans and animals. However, dogs and cats have a remarkable ability to compensate for loss of cerebral tissue. It is therefore important not to reach hasty prognostic conclusions based on initial appearance. Many pets go on to have a functional outcome and recover from injury.     

Computed tomographic and magnetic resonance imaging of a coup contrecoup traumatic brain injury in a horse

A 3-year-old Thoroughbred mare found recumbent in the field was referred for further assessment with suspicion of a skull fracture. Neurological examination identified compulsive tight circling to the left, and hypermetria in all four limbs. The mare was obtunded, with a mild head tilt to the right, absent menace response of the right eye and decreased facial sensation on the right. Standing computed tomographic examination revealed a subtle depression fracture of the dorsal calvarium and moderate intra-axial midline shift consistent with a traumatic brain injury (TBI). Despite supportive treatment, the mare deteriorated and was subjected to euthanasia. Post-mortem high field magnetic resonance imaging revealed findings consistent with a small cerebral contusion adjacent to the fracture site, and moderate to severe ipsilateral cerebral oedema within the caudal cerebrum and rostral brainstem, consistent with a coup contrecoup TBI. Brainstem lesions indicate a poor prognosis and support the decision for euthanasia. This is the first report of the imaging findings of a coup contrecoup TBI in a horse.     

Animal models of traumatic brain injury: a review

OBJECTIVE: To review the main types of animal models of traumatic brain injury (TBI), their desirable characteristics and limitations, the major structural changes in the brain modelled, and special features of paediatric TBI modelling. CONCLUSION: Animal models have contributed substantially to our understanding of the mechanisms of TBI in humans, but many aspects of closed head injury remain to be elucidated and effective neuroprotective agents are few. Many of the advances in the pathogenesis of human TBI also have application in veterinary medicine and there is ample opportunity for veterinarians to contribute to the selection, development and characterisation of potential animal models of neurotrauma and other disorders and ensure that animal welfare standards are maintained.     

Brain damage in pigs produced by impact with a non-penetrating captive bolt pistol

OBJECTIVE: To assess the effect of impact with a nonpenetrating captive bolt pistol in pigs by studying the resulting traumatic brain injury (TBI) and to compare the pathological changes with those found previously in the brains of sheep using a similar experimental paradigm. PROCEDURE: The unrestrained heads of six, anaesthetised, 7- to 8-week-old, Large White pigs were impacted in the temporal region with a nonpenetrating captive bolt pistol. Four hours postimpact, brains were perfusion-fixed with 4% paraformaldehyde. Coronal sections from six levels along the brain were cut and stained with haematoxylin and eosin and immunohistochemically for amyloid precursor protein, a sensitive marker of axonal injury (AI) in the brain after trauma. RESULTS: TBI in pigs was characterised only by very mild AI, whereas AI in sheep after captive bolt impact to the same head region was much more severe and widely distributed and often associated with vascular damage such as contusions, subarachnoid and intraparenchymal haemorrhage. CONCLUSIONS: TBI in pigs was much less severe than in sheep after non-penetrating mechanical impact of similar magnitude, confirming the importance of interspecies differences in determining an appropriate physical method of euthanasia.     

Anesthetic management of the head trauma patient

Objective: To describe the optimal anesthetic management of patients with brain injury, with emphasis on the support of oxygen delivery to the brain, and the effects of anesthetic agents on cerebral perfusion. Data sources: Clinical and experimental studies from both the human and veterinary neuroanesthesia literature. Summary: The management of patients following primary traumatic brain injury (TBI) significantly impacts outcome. Outcome can be improved by strategies that improve oxygen delivery to the brain and prevent cerebral ischemia. Anesthetic agents have widely variable effects on the blood supply to the brain and, therefore, choice of anesthetic agent can influence neurological outcome. Although in the past, anesthetic agents have been selected for their neuroprotective properties, it is increasingly being recognized that the support of cerebral perfusion during anesthesia contributes more significantly to a positive outcome for these patients. Support of cardiorespiratory function is, therefore, highly important when anesthetizing patients with TBI. Conclusion: Choice of anesthetic agent is determined by the extent of brain injury and intracranial pressure (ICP) elevation. Factors that should be considered when anesthetizing head trauma patients include the effects of anesthetic agents on the cardiac and respiratory systems, their effects on cerebral blood flow (CBF), ICP, and possible neuroprotective benefits offered by certain agents.     

Anatomical and histologic pathology induced by cervical dislocation following blunt head trauma for on-farm euthanasia of poultry

The selection of an optimal method for on-farm euthanasia of poultry in cases of emergency killing is still under debate. The preferred approach would spare pain and suffering and would ensure proper stunning as well as rapid death. Here, the effects and pathological lesions induced by blunt trauma to the head followed by cervical dislocation were studied in chickens and turkeys of different weight groups of up to 20 kg. To allow for feasible on-farm execution, including birds heavier than 3 kg, a percussive blow to the head with subsequent manual or mechanical cervical dislocation using a nonpenetrating forceps was employed. Systematic macroscopic, radiographic, and histopathologic examinations were performed with special attention to anatomical structures essential for consciousness and vital functions. The 2 traumatic impacts resulted not only in massive subdural hematomas, cortical brain damage, dissecting vertebral bone fractures, and a disruption of the cervical spinal cord, but also severe lacerations of the medulla oblongata area of the brain stem. The lesions were suggestive of immediate loss of consciousness and indicative of immediate and irreversible loss of central regulation of breathing and heart function. Moreover, the results were largely independent of the weight class examined, indicating that from a pathology perspective the methods used may be suitable for humane euthanasia of poultry of up to 20 kg in live weight.     

"Reasonable cause"--an undefined legal term for the justification of the killing of equids

Killing of a vertebrate animal in Germany is allowed or not punishable only if a "reasonable cause" can be identified (Article 17 No. 1 TierSchG). A legal definition of the term "reasonable cause" does not exist. Currently the following definitions of the "reasonable cause" for the killing of equids are accepted: 1. Slaughter (in accordance with the equid pass and waiting periods) reasonable cause: Food production, initiated by the owner's desire. The requirements for slaughter of a sick animal or an emergency slaughter are defined through EU-legislations. 2. Euthanasia (in its original meaning) Reasonable cause: a) Compassion, initiated through medical indication b) scientific purposes (experimental animals) initiated through governmental authorization of a research request c) Epidemiological reasons initiated through veterinary legislative measures. According to the law for the protection of animals (TierSchG) "non curable pain or suffering" is a prerequisite for the killing of an animal because of a medical indication. Presuming an adequate knowledge base of the veterinarian this should leave enough room for an adequate medically reasoned decision. However, both a faulty veterinary explanation of a reasonable cause and an undue delay of the euthanasia (follow Article 17) can lead to an illegal punishable act (severe pain or suffering). Examples of veterinary medical indications for euthanasia will be presented. In addition, the question whether euthanasia can be considered as an alternative to treatment will be discussed. Finally, the more restrictive interpretations of the "reasonable cause" put forth by insurance companies will be explained. Future higher court decisions should lead to an adaptation of the insurance companies' interpretations of the "reasonable cause" to the outline presented above.     

Evaluation of brain damage resulting from penetrating and non-penetrating captive bolt stunning using lambs

OBJECTIVE: To compare the brain damage in sheep resulting from penetrating and non-penetrating captive bolt stunning. DESIGN: The unrestrained heads of anaesthetised lambs were impacted in the temporal region with penetrating and non-penetrating captive bolt pistols (humane stunners) using a constant charge. Two hours after head impact, brains were perfusion-fixed with 4% paraformaldehyde. Coronal sections were stained with haematoxylin and eosin and immunohistochemically for amyloid precursor protein, a sensitive marker of axonal and neuronal reaction in brains after trauma. Pathological changes in these brains were then quantified by morphometric analysis. RESULTS: The skull was fractured in 50% of lambs after a non-penetrating head impact and in all animals after a penetrating head wound. Impact contusions were present in 80% of lambs receiving a non-penetrating head injury and in all of those with a penetrating wound. Total contusion area was similar in both groups. Amyloid precursor protein-positive axons and neurons, and haemorrhage, were widely distributed in the brain after both head impact types, but there was no statistically significant difference between the two groups. Multifocal necrosis of the cerebellar granular layer was found in all lambs with non-penetrating head injury, but in none with a penetrating injury. CONCLUSIONS: The structural brain damage, a mixture of focal and diffuse injury, produced by penetrating and non-penetrating captive bolt pistols was overall similar and of sufficient severity to suggest that both types of weapon are acceptable for euthanasia.     

Attitudes to animal euthanasia do not correlate with acceptance of human euthanasia or suicide

Several reasons have been suggested for the elevated risk of suicide experienced by those in the veterinary profession. The current study aimed to investigate possible links between veterinarians' attitudes to 'convenience' or non-justified animal euthanasia and attitudes towards human euthanasia and suicide. Veterinary students and graduates had a negative attitude towards convenience animal euthanasia, but their attitudes changed over time (pre-clinical studies, clinical studies and recently graduated). A greater tolerance to euthanasia was displayed in the later years of study and post qualification - primarily by males. Attitudes towards both human euthanasia and suicide, however, remained stable over time and indicated on average a neutral stance. No correlations were found between attitudes to convenience euthanasia and either human euthanasia or suicide, suggesting a tolerance to convenience euthanasia of animals does not lead to desensitisation in valuing human life and a changed attitude to human euthanasia or suicide, or vice versa. Attitudes to human euthanasia and suicide were predictably correlated, perhaps suggesting an overarching attitude towards control over human death. The results of the current study throw into question the argument that it is the changes in attitudes to animal life that affect veterinarian's attitudes to human life and contribute to the high suicide rate.     

Vector-borne diseases in humans and animals: activities of the Swiss Tropical Institute and risks for Switzerland

The recent outbreak of anaplasmosis in a Swiss cattle herd triggered a discussion of the risk of vector-borne diseases in animals and humans in relation to climate changes and other factors. This overview presents the Swiss Tropical Institute's (STI) activities on vector-borne diseases (malaria, trypanosomosis, and leishmaniosis in humans and tick-borne diseases in livestock), describes the possible risks for humans and animals in Switzerland, and discusses options for action in the domains of public health, livestock production and companion animals. Switzerland is increasingly confronted with vector-borne diseases in humans and animals, but this is mainly due to an increase in imported cases. The emergence of a disease in one sector (human or veterinary medicine) may predict future trends in the other. A stronger intersectoral collaboration between public health and veterinary institutions at the federal and cantonal level is needed.     

Animals in schools

The keeping of animals in schools is discussed, with particular reference to aspects which are of relevance to the veterinary profession. Important considerations are the attitudes of teachers and others, numbers and species of animals, sources, animal care, legal considerations, breeding, culling and euthanasia and health hazards. The role of the veterinary surgeon in ensuring that animals are kept humanely, are of maximum value, and least danger to children is emphasized.     

Guidelines for zoo and aquarium veterinary medical programs and veterinary hospitals

These guidelines for veterinary medical care and veterinary hospitals are written to conform with the requirements of the Animal Welfare Act, which states that programs of disease prevention and parasite control, euthanasia, and adequate veterinary care shall be established and maintained under the supervision of a veterinarian. Ideally the zoo and aquarium should be providing the best possible veterinary medical care for the animals in their collections. Many of these animals are rare and endangered and the institutions should endeavor both to provide for the long term health and well being of these animals and to advance the field of non-domestic animal medicine. It is hoped that this publication will aid in this process.     

Extravasation reactions associated with the administration of pamidronate: 11 cases (2008–2013)

Pamidronate is a bisphosphonate drug widely utilized in veterinary oncologic practice for the palliation of malignant osteolysis. Pamidronate has not been previously reported to cause tissue injury upon extravasation in dogs. The medical records of 11 client‐owned dogs undergoing palliative treatment for primary bone tumors with known or suspected pamidronate extravasation reactions were reviewed. The majority of adverse events were low grade in nature, however in some cases, the reactions were severe and led to euthanasia in one instance. Time to complete resolution of lesions ranged from within several days to greater than one and a half months. Aside from the dog that was euthanized, no long‐term sequelae of extravasation were identified. Treatments employed to address the reactions varied widely. Pamidronate extravasation reaction appears to be an uncommon, but potentially serious complication of intravenous administration.     

兽用中药配方颗粒研究进展

近年来,中兽药在现代畜禽养殖、对抗动物疫病、调节改善动物免疫力方面都发挥了重要的作用,但是其在畜禽给药途径和生物利用度方面还存在一定不足。畜禽消化系统的不同导致给药方式必然存在不同,兽用中药配方颗粒使用方便,而且生物利用度高于中药散剂。目前尚无兽用中药配方颗粒的相关研究,本文对兽用中药配方颗粒的研究进展进行归纳总结,以期为兽用中药配方颗粒的开发利用提供依据。     

World veterinary manpower: comparative aspects.

The number of veterinarians in relation to livestock units, human population, milk and meat production and gross national product for 93 countries is presented. The structure of veterinary manpower is discussed and information on veterinary involvement with companion animals and public health is given. For 23 countries representing all the continents, the number of livestock units, human population and gross national product per veterinary school are presented.     

Retinal photoreceptor damage produced in guinea pigs by tunicamycin

Corynetoxins, members of the tunicamycin group of antibiotics, produce a severe and frequently fatal neurological disorder in ruminant livestock, and guinea pigs are a useful model to study the pathology and pathogenesis of this disease. The aim of this study was to determine whether tunicamycin produced ocular damage in this species, which could have pharmacotherapeutic and diagnostic value. Four 8-week-old guinea pigs were treated with tunicamycin, and two control animals were given the drug vehicle only. Guinea pigs were injected subcutaneously with 400 μg/kg of tunicamycin, in dimethyl sulphoxide, and killed 48 h post-injection. The eyes were then examined by light microscopy. Immunohistochemistry for rhodopsin was also performed. The principal pathological finding was marked retinal photoreceptor damage, which was characterised by disruption and disorganisation of rods, sometimes progressing to necrosis and separation of the outer segment. The cytoplasm of some rods was focally distended by accumulated, proteinaceous material. Rhodopsin immunopositivity in injured rods was markedly diminished and associated with shrinkage and shortening of the injured rod's outer segment. Ocular pathology, in the form of reproducible and extensive retinal photoreceptor damage, was found in guinea pigs given tunicamycin, extending the range of species found to be susceptible to this toxic injury. The guinea pig could prove to be a good animal model to test potential therapeutic interventions, and as brain lesions are often minimal and liver pathology non-specific in intoxicated ruminants, any spontaneously arising ophthalmic injury found in these species could be diagnostically useful.     

畜产品兽药残留及改进措施

畜禽养殖产业的快速发展也导致养殖中的疾病问题开始逐渐凸显,防治畜禽养殖中疾病兽药的使用量也不断提高,兽药的不规范使用易导致残留的情况,对于畜产品中兽药的残留问题受到广泛的关注。畜产品中兽药的残留会影响畜产品的质量,对消费者的机体健康带来负面影响,同时部分兽药的残留会导致生态环境的污染,进而影响人类健康。该文对畜禽养殖中畜产品兽药残留出现的原因,造成的危害及改进和防控措施进行论述。     

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.