Pain and injury Adroaldo J Zanella ANS 305

Pain and injury Adroaldo J. Zanella ANS 305

Introduction 4 Freedom from physical discomfort and pain 4 Freedom from injury and disease – Animal welfare codes/laws in many parts of the world.

Introduction 4 Animals are capable of an experience which they avoid, given the opportunity, and which can dominate their physiology and behavior in a similar way to the experience of pain in man (Flecknell & Molony, 1997)

Pain 4 Pain is a sensation which, without involving higher level brain processing such as that associated with fear, is very aversive.

Pain – Nociceptive neurons – Some degree of tissue injury – Protective motor reactions – Emotional responses – Learned avoidance behavior – Modify social or other behavior

Animal pain 4 Comparative anatomy, physiology and behavior indicates that animal pain is similar to that in humans (National Research Council, 1992, Short and van Poznak, 1992)

Recognition of animal pain 4 Anthropomorphism – Help to recognize acute pain – Fail to identify chronic pain

Chronic pain 4 Animals may be hyperalgesic to certain types of noxious stimuli !

Legislation 4 Laboratory animals – Extensive legislation in the USA and European countries (LASA, 1990; NRC, 1992; FELASA, 1994) 4 Farm animals – Some laws in Europe; limited discussion in the USA • Humane slaughter • Husbandry procedures

My work 4 Responses of piglets to castration – Stress hormones were higher for more than 24 post surgery in animals castrated with no anesthesia compared to control pigs (e. g. anesthesia) 4 Responses of foals to branding – Foals that were branded showed higher physiological responses to hoof trimming than non-branded controls

Assessment of pain 4 Behavior – Vocalization – Time budget – Posture – Food and water intake 4 Physiology – Glucocorticoids – Opioids

Stress axis Hypothalamus CRF Anterior Pituitary= ACTH ß-endorphin Adrenal: Cortex= Glucocorticoids Medulla= Catecholamines

Occurrence of pain 4 Wild animals: – Some hunting techniques – Pest control

Occurrence of pain 4 Farm animals: – Housing – Transportation – Slaughter techniques – Genetic selection – Injuries – Husbandry procedures – Training techniques (Tennessee Walker)

Occurrence of pain 4 Leg injuries, lameness, impaired locomotion: – Pigs: – Cattle – Sheep – Horses – Poultry – Turkey

Occurrence of pain 4 Husbandry procedures (without anesthesia): – Castration – De-horning – Tail-docking – De-beaking – Branding

Occurrence of pain 4 Companion animals – Genetic selection (hip displasia) – Injuries – Surgical procedures • Declawing • Debarking • Ears cropping

Occurrence of pain 4 Laboratory animals: – Experimental procedure – Genetic selection – Housing – Deliberately induced painful conditions

Failure to Alleviate Pain 4 Analgesic drugs are not used regularly by veterinarians (Townsend, 1987: 30 -50%; Dohoo & Dohoo, 1996: 49%).

Additional information 4 Recent textbooks are more informative 4 New compounds are available 4 Growing food safety concerns – Casualty slaughter 4 Controlled substances (how to handle) 4 Existence of legislation restricting the use of analgesics in food animals 4 Costs

The future 4 New compounds (UK): • Butorphanol, buprenorphine, flunixin, carprofen, ketoprofen, meloxicam 4 Work on laboratory animals may help farm animals 4 Public perception of farming procedures may accelerate the necessary changes 4 We should play an active role