Page 160 - WSAVA2017
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An Urban Experience
L. Urdes1
1University of Agricultural Sciences and Veterinary Medicine of Bucharest, Basic Sciences in Animal Husbandry and Food Industry, Bucharest, Romania
Laura D. Urdes DVM PhD PgDip CertAqV
Assistant Prof., Basic Sciences in Animal Husbandry and Food Industry Faculty of Engineering & Administration of Animal Products, University of Agricultural Sciences and Veterinary Medicine of Bucharest, Romania
Pain is a clinical expression of tissue damage. Pain management comprises the set of control measures deployed to ease the suffering and to improve the
quality of life. To control pain, there are available non- pharmacological, i.e. physical and psychological means, and pharmacological (chemical analgesics, sedatives and anaesthetics) approaches. Pain relief in fish, however, implies use of chemical analgesics and anaesthetics and, in very limited instances, physical treatment, e.g. gradual cooling of water.
The presentation will provide an overview of analgesic and anaesthetic agents that have been tested in fish, also highlighting the existing gaps in knowledge in this field. Firstly, comprehension of existing necessity and difficulties in applying pain management in fish might be required for a better understanding of the subject matter. Why veterinary practitioners should consider learning about, and applying pain management procedures also in fish?
Fish are companion animals, experimental models and livestock. For many practical reasons, fish are now in the top most popular pets. According to PetfoodIndustry. com, in the U.K., fish demand has increased by 17% over the last three years, with 12 million pet fish living indoors and another 18 million currently living in garden ponds. Ornamental fish are also increasingly being used in experimental research for a variety of reasons, such as the high degree of genetic homology between fish and humans, and the need for alternatives to mammal use in experimental settings. A relevant example is
the use of zebrafish (Danio rerio) as an in vivo model for the study of vertebrate development, neurological
disease mechanisms and preclinical drug screening. Nonetheless, fish are livestock farmed for food and/
or breeding purposes. Consequently, as surgery and other potential painful procedures are becoming more common in fish, the use of analgesics and anaesthetics has become a common requirement in aquatic veterinary practices and fishery farms, to help improve fish welfare and minimize the pain associated with the procedures.
Drugs designed to relief pain and discomfort in
fish are analgetics, whereas to induce insensitivity, unconsciousness and sleep, anaesthetics are used. Anaesthetics are also used as the first step of euthanasia in fish. However, both analgesia and anaesthesia in fish are areas where relatively little in terms of clinical data is known or formally reported. The factors acknowledged as impeding pain management practice in fish as successful as in terrestrial vertebrates are the width of range of species, which makes generalization across species very problematic; analgesic agents tested on fish, as well as licensed anaesthetic products for fish
are very limited; the ability to monitor depth of fish anaesthesia is restricted to a few specialist research groups globally 1. Additionally, the use of pre-anaesthetic (sedation) protocols in fish, in combination with one or more adequate anaesthetics - which ensure avoidance of aversive reactions to anaesthetics in other species, seems not to be yet available in fish.
The choice of the correct methodology of administration of analgesic and anaesthetic agents should take into account three groups of variables: i.) species-related characteristics, such as fish species, strain, body weight and physiological stress, ii.) environmental conditions, such as water temperature and pH, and iii.) agent- related characteristics, such as chemical composition, pharmacological properties, exposure duration and drug concentration. Generally, in small to medium sized fish, anaesthetics are administered dissolved into the water where fishes are held (equivalent to inhalation anaesthesia in mammals) or introduced, i.e. immersion of fish into a water tank containing anaesthetic. Administration of anaesthetics via injection is restricted only to large fish species, of over 10 kg. In the case
of anaesthesia, monitoring depth of the process by visual assessment and interpretation of ventilation rates (opercular ventilation rates), posture (body movement and equilibrium) and reflex response to stimuli (e.g. tail or fin pinch) are standard practice in fish.

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