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Welfare
• The concept of welfare has moved away from just providing feed, water, and a clean cage.
• We are now charged with providing for the psychological wellbeing of our animals.
• Why?• How?
– Behavioral tests– Biochemical analyses
Recognition of stress
• Behavioral signs– Changes in appetite– Changes in defecation or urination– Avoidance– Immobilization– Changes in activity level– Aggression– Stereopathies
Interpreting Results• Open Field Test
– Fearful mice tend to stay close to the wall for protection.
– Bolder mice explore the middle of the arena
• Movement can be interpreted as– Escape/avoidance– Exploration– Play
Recognition of Stress
• Biochemical measures– Changes within minutes
• SAMS: Increased plasma levels of NE and Epinephrine
• HPA: Increased plasma levels of ACTH and glucocorticoids
– Changes with prolonged stress• WBC count
– Plasma monocytes increase; don’t migrate– Plasma neutrophils increase but impaired phagocytosis– Decrease in B and T lymphocytes
Interpreting Results
• Biochemistry varies with – Circadian Rhythm:
– Social status:
– Sex:– Line or breed
T higher in dominant maleGC higher in subordinate male
NE is ♀ > ♂ & DE > E
Baseline glucocorticoids rise before 1st mealHigher at dusk in nocturnal animals Higher at dawn in diurnal animals
Biochemistry varies with Line and Sex
Mice at 8 weeks of ageFemale Male Female Male Units
WBC 3.24 2.86 3.48 2.62 103 cells/ulPercent Monocytes 0.80 0.90 0.70 1.40 %Percent Neutrophils 14.80 23.10 7.40 18.50 %B cells 53.43 51.06 56.13 57.80 %T cells 16.95 20.82 15.51 13.60 %
Information from the Jackson Laboratory website
Balb/cJ C57
Comparative Biochemistry
Example only—don’t memorize
What’s the take-home message?
Get baseline levels from the same line, sex, age, and social statusAnd take them from the same time of day and same cycle stage.
Interpreting Results
• Does NE increase more during breeding or transport?– Breeding
• Does corticosterone increase more during movement of home cage or seeing another rat decapitated?– Movement of the home cage
Stress vs Distress (Dr. Moberg)Normal Function
Altered biological function
Pre-pathological state
Pathology
Stimulus
Stimulus
Stimulus
Relief from stimulus Stress
Distress
Stress vs Distress, An ExampleNormal Function
Altered biological function
Pre-pathological state
Pathology
Stimulus
Stimulus
Stimulus
High ammonia levels
High ammonia levels
High ammonia levels
Loss of ciliated epithelium
Entry of bacteriaImmune system depression
Respiratory disease
StressSAMS
↑ NE and EpiHPA
↑ ACTH and GC
↑ Glucose levels in plasma ↑ O2 from lungs↑ circulation of glucose and O2
↑ Glucose levels in plasma
Winning male
Male mice fighting
All levels return to normal
DistressSubordinate male repeatedly attacked
Sensitization blocks negative feedback of glucocorticoids
Breakdown of fat and muscle for glucose
Body condition drops
Leukocytosis—Decreased immunityOpen to opportunistic infection
Breakpoint Stress
• Breakpoint stress—no longer able to respond or adapt to stress; no longer able to cope.
• Affected by– Severity– Predictability– Duration– Interval
The longer the stress goes on without a break for recovery, the more the body resources are depleted.
Habituation vs. sensitization
Breakpoint Stress
• Indicators– Change in weight or body condition– Change in organ weight and size
• Hypertrophy: • Hypotrophy:
– Suppressed reproduction– Gastric ulceration– Self-mutilation– Suppressed immune function disease
Adrenal gland and heartThymus gland and spleen
Individual Response
• Same conditions don’t lead to same response in all animals.
• Don’t rely on a single indicator to identify stress.
• Always get baseline levels
• Not all stress is bad.
Control of Variables• Housing
• Nutrition
• Health
• Genetics
• Cages designed for visibility, sanitation, and safety. Uniform bedding. Reduced exercise, little control over environment
• Nutritionally complete pellets; decreased labor. No foraging for food, increased obesity, decreased satiety
• Uniform health status; decreased exposure to disease. Naive or compromised immune system
• Uniform genetics. Deleterious genes may lead to problems with health or reproduction
Positives of Enrichment– Increases activity
• Decreases boredom• Decreases obesity• Increases species-specific behavior• Increases learning and memory
– Decreased anxiety• Gives a sense of control over
environment• Teaches coping strategies• Decreases aggression• Increases reproduction and
mothering• Decreases stereopathies
Negatives of Enrichment
• Cost • Variability in experiment• Reduced visibility • Risk of injury• Increased aggression
• Individual acceptance/preference unknown
Sources of Enrichment• Positive human interaction
– Positive vs negative attitudes
– Training of technicians– Prior training of animals
reduces stress of procedures
• Interaction with conspecifics– Group housing– Non-contact communication
Mouse Enrichment• Bedding & nesting material
– Mixture of Carefresh and Paperchip– Nestlets, Enviro-dri
• Plastic tunnels and houses– Bioserve– Watch for signs of aggression
• Plastic running wheels– Watch for aggression or obsessive behavior
• Paper tunnels and houses– Shepherd Shacks, paper towel tubes– Doesn’t elicit aggression
• Chew toys like small Nyla bones • Food treats
– Seeds (sunflower, safflower, pumpkin)– Cheerios – Seed blocks
Rat Enrichment• Bedding is needed but rats
don’t usually make large nests
• Plastic tunnels and houses– No sign of aggression
• Paper tunnels and houses• Chew toys like Nyla bones • Food treats
– Seeds (sunflower, safflower, pumpkin)
– Cheerios
Rabbit Enrichment• Chew toys—Nylabones, paper
tubes, hardwood blocks• Manipulatives/noise makers—
Shower curtain rings, Jingle balls, chains with washers hanging in cage.
• Food treats—Oat hay, fresh veggies (broccoli, parsley, cilantro, carrots) and fruit (apples).
• Tunnels, houses, and boxes• Split-level housing• Exercise runs or playpens