equine stress (williams)
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Welcome to this live web presentation featuring:
Webcast Expert:Dr. Carey WilliamsRutgers University
Please note: This presentation is intended for users with high-speed internet connections. Unfortunately, we cannot offer support for dial-up users at this time.
Contact [email protected](517) 353-3123
Question Facilitator:Dr. Camie HeleskiMichigan State University
Introduction• Types of Stress:
• Physical
• Psychological
• Causes of Stress:• Temperature
• Transport
• Oxidation
• Effects of Stress:• Ulcers
• Tying-up
• Summary
What is Stress?• The body’s response to anything that it considers
threatening• Types of stress:
– Physical• Based on physical makeup• Ability to respond to changes in diet, injury, etc.
– Psychological• Based on horses personality• Its perception to life
Causes of Stress• Traveling
• Showing
• Irregular feedings
• Change in other routines
• Poor nutrition
• Poor nutrition• Environmental toxins• Social environment• Variations in climate• Illness
Basic Stress Response1. Change in behavior
– Moving away from stimulus, swishing tail, tightening of muscles, bucking, etc.
2. Sympathetic nervous system is activated– Triggers “Fight or Flight”– Involuntary action of intestines, glands and heart
3. Neuroendocrine system is activated– Increase in energy utilization
Dealing With Stress• Depends on the
personality of the horse
• Demonstrative Confident = lets you know it!– Bucks, kicks, bites,
curious, mouthy, troublemaker
• Demonstrative Fearful = worries about everything!– Shies the first time,
needs time to relax
Dealing with Stress• Passive Confident =
what’s everyone worried about?
– Not normally stressed,
internalizes stress,
shows little change
• Passive Fearful = wants
to please!– Seems willing, tight muscles
and lips, won’t show fear
until pushed over the limit
Heat Stress
• Heat production will increase up to 50 % during exercise
• Normal response to heat stress:
– sweating rate (abnormal = anhidrosis)
– Blood moves to capillaries under the skin
– respiratory rate
Signs of Heat Stress• No sweating (Anhidrosis)
– Skin will be hot and dry– Horse lacks major cooling system - evaporation
• Rapid HR– 50 + at rest
• Rapid breathing– 20 + at rest
• High rectal temperature– 104 ° F
Treating Heat Stress• Move to a shady area• Provide fans, wind or other ventilation• Spray legs with cold water• Allow to drink small amounts of cold water
frequently• Provide electrolytes
Treating Heat Stress• If severe:
– Vet will give cold water enemas– Treat for dehydration
• Skin pinch test• Mucous membranes
• Once overheated they are more likely to
overheat again
Preventing Heat Stress
• Provide regular electrolytes in hot weather
• the amount of grain and the forage
• fat in the diet
• Properly cool down after exercise
• Provide plenty of ventilation
Cold Stress• Horses fight cold weather by using more energy to stay warm
• You would have to supply 2 lb of feed for each 10 degree F
below critical temp – In order to replace the energy lost during thermoregulation
• Know your horse is loosing too much heat if snow melts on
his back instead of accumulating
Dealing with Cold Stress• Precondition horse for COLD WEATHER
• Feed free choice grass hay
• Provide shelter from wind, rain and cold
• Blanket horses not ‘allowed’ in shelters
Why Do Horses Get Transport Stress?
• Physical factors: – Unnatural sense of confinement
– Withholding food and/or water
– Noise and vibration of a moving vehicle
– Balancing and bouncing during the ride
– Poor ventilation
– Presence of exhaust, dust, molds, manure, and urine
Why Do Horses Get Transport Stress?• Psychological factors:
– Separation from the herd
– Exposure to strange animals and environment
• Climatic factors: – High internal temperature
and humidity
• Health factors:– Dehydration and fatigue
Transport Stress• Shipping Fever – respiratory disease during or shortly after a
trip– Primary factor is a suppression of the immune system due to stress
of the trip
• Transport stress can also cause:
– fluid intake, loss of appetite, hypocalcemia or hypomagnesemia,
weight loss, dust inhalation and coughing, diarrhea, colic, and tying-
up
Effects of Transport Stress• Studies have investigated:
– Horse orientation, design of the suspension and ventilation, quality of the transport environment, amount of stress
– levels of Cortisol (stress hormone)
– heart rate variability (HRV)– Weight loss of ~ 6 % during a 24 hr haul
• Recovered ½ of weight lost over the 24 hr recovery
– Muscle enzymes (CK & AST) after a 24 hr haul
Decrease Transport Stress• Keep total travel time under 12 h
– If not plan over night stops
• Stop every 3 to 4 hrs – Offer water every 6 to 8 hrs
• Clean the trailer thoroughly after each use
• Leave your horse’s head untied, or loosely tied– This way they can lower his head to cough
Decrease Transport Stress• Give your horse a few days to
recover– Record daily rectal temperatures
• Provide things the horse is used to– I.e. usual hay, feed, water,
bedding, etc.
• Leave a window or vent open– Horses are much
more tolerant of cold than we are
Decrease Transport Stress• Dietary adjustments necessary?– Bran mashes not necessary
– Vitamin C to increase immune system
• Vaccinate your horses against respiratory disease at least 2 weeks before – Don’t ship a sick horse
• Allow extra time incase of an emergency
Exercise
Reproduction
Rapid Growth
UV Rays
Other Stresses
Poor Nutrition
Inflammation
Environmental Toxins
Bacterial Infection
Viral Infection
Protozoa
What Causes Oxidative
Stress?
Oxidative Metabolism• ROS are intermediates formed during
metabolism of oxygen O2
• HO•
H2O2
O2 + 4 e- + 4 H+ 2 H2O
Reactive Oxygen Species• Harmful effects:– Degrade proteins, DNA and PUFAs– Cell environment is compromised
• Include:– Hydrogen peroxide (H2O2)
– Singlet oxygen (1O2)– Free radicals
Oxidative Damage*OH H2O
Antioxidant Mechanisms
CC
C
*OH
H2O*OH H2O
E E E
E E
Antioxidant Action
Stable Chemical
Oxidation
Free Radicals
Stable Chemicals
Antioxidant
Antioxidants• Antioxidant supplements:
– Vitamin E (most common)
– Vitamin C
– Beta-Carotene
– Glutathione
– Lipoic Acid
– Selenium
– Cysteine
adapted from Sen and Packer, 2000
Antioxidant Interaction
Vit E
Vit E•
GSH
GSSG
DHAA
Vit C
DHLA
LA
2 Cys
Cystine
+
Antioxidant Supplementation• May be needed for:– Growth– Reproduction– Transport– Strenuous exercise– Illness – Any other stresses
• Avoid over-supplementation• Mixtures work best
Are you giving your horse an ulcer?• Ulcers affect:– 80-90 % of all race horses– 60 % of all performance horses– 30-40 % of all dressage horses
Equine Ulcers
• Horses secrete stomach acid even when not eating– Only ½ of stomach can handle acid
– When a horse grazes all day the roughage absorbs acid
– Saliva produced also neutralizes acid
– Grain increases ‘gastrin’, which stimulates acid secretion
Causes of Ulcers• Main causes of ulcers:
1. Changes in eating behavior
2. Changes in training intensity
• Horses that are used to being outside can develop ulcers in 1 week after being kept inside– Could be as early as 24 hours
Signs of Ulcers• Change in attitude• Poor appetite• Colic• Decreased performance• Decrease in body condition• Weight loss• Dull or sour attitude
• Prevent ulcers by preventing stress!– Also limit the use of Bute
Exertional Rhabdomyolysis
• Tying-up/Azoturia/Monday Morning Sickness
• Muscle pain associated with exercise
• Sporadic and chronic forms
• Different causes among breeds and types of
horses
• Leads to poor performance and may end career
Recurrent ER
• Primarily affects Thoroughbreds– but may occur in Standardbreds and Arabians
• Nervous 2 yr old TB fillies most severely affected
• May increase in severity as fitness increases
• Stress often creates and/or induces episode
• Elevations of CK and AST intermittent
• Hereditary condition
Clinical Signs
Managing the Episode• Move into box stall initially for up to 24 hrs
• Call your veterinarian
• Blanket horse if weather is cool or hose horse to remove
sweat if weather is warm
• Check for dehydration
• Small frequent sips of water when horse is hot– Free access to water when horse is cool
Minimizing Stress• Keep horses turned out if at all possible
– If not possible, feed ad libitum hay
• Stick to a routine– If you need to make changes, do so slowly
• When traveling take items that are familiar – I.e. own hay, water, grain, etc.
• Avoid riding in extreme conditions
• Feed a well balanced diet
Minimizing Stress• Maintain a good health program
• Provide a pleasant environment
• Provide regular varied exercise
• Allow for play time
• Prevent boredom
• Allow your horse social activity
• Keep yourself happy and healthy!
What’s in Those Calming Aids?• Supplements have been designed to ‘decrease stress’ or ‘calm
a nervous horse’• Thiamin, Magnesium, and Taurine combined with other B-
complex vitamins • Tryptophan, insitol, riboflavin, niacin, pantothenic acid, B12
• Little research• Lots of testimonials
Better horse care through research & education
Equine Science CenterThank You!
Carey Williams, Ph.D.Equine Extension Specialist
www.esc.rutgers.edu
Thank you for attending this live web presentation!
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Contact [email protected](517) 353-3123