equine stress (williams)

Welcome to this live web presentation featuring:

Webcast Expert:Dr. Carey WilliamsRutgers University

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Contact us!info@myhorseuniversity.comwww.myhorseuniversity.com(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

cwilliams@aesop.rutgers.edu

www.esc.rutgers.edu

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