Although summertime brings many pleasant and enjoyable days, the heat of summer combined with seasonal changes can escalate horse health problems and cause misery for both horses and humans.
Horse splashing drinking water on a hot day
Horses should be offered fresh water frequently and have access to water at all times.
© 2008 by Louis New window.
Dehydration
The first and most important step in preventing dehydration is paying attention to each horse's consumption of water. Some horses can get by with five or six gallons of water a day, but since a three to four percent loss of body water will cause mild dehydration, most horses require a minimum of ten to twelve gallons of water per day.
In addition to water, the horse's body requires electrolytes for biochemical reactions within the body to get nutrients in and waste products out. Electrolytes are responsible for nerves functioning properly and muscles contracting properly. If a horse sweats out these electrolytes in too large amounts, balance is not maintained, and the horse's ability to endure is greatly compromised.
Many times, horses could do much better if handlers and owners paid attention to making sure electrolytes and fluids are balanced and at appropriate levels for the weather and the activity.
Never riding or exercising a horse to the point of exhaustion is another way of preventing dehydration. Forcing a horse to be active in hot, humid weather almost insures dehydration and electrolyte imbalance.
Wise timing of exercise by taking advantage of cool periods during the day and making sure the horse has time to drink and has access to salt during the activity will keep the horse safe from the consequences of prolonged periods of dehydration.
Check for signs of dehydration regularly and don't wait until a horse looks dehydrated to administer electrolytes. Learn to perform skin pinch and mucous membrane testing and how to listen for gastric sounds to help determine when a horse is becoming dehydrated.
Insect hypersensitivity
Summer sores, which may occur any time of the year, but become pronounced during warm months, originate when biting insects leave the larvae of stomach worms in their bite wounds. Two different types of stomach worms, Habronema muscae and Draschia megastoma, also known as Spurids are responsible for the larvae which the flies carry in their mouth parts.
When a fly feeds around a moist area, such as the mouth, the eyes, the prepuce, or a wound, the larvae are passed to the horse where they cause inflammation and open sores. The pus and moisture attract more flies, perpetuating the cycle of infection and irritation.
The larvae may also enter the gastrointestinal system and can cause gastric inflammation or ulcers if a number of larvae are present. In addition, they can migrate through the nose and end up in the lungs where they form cysts.
To protect against flies and insects, you may consider using a light fly sheet and fly mask, along with insect repellent. Be sure to check your horse regularly under their rug and fly mask to ensure they remain comfortable throughout the day.
Heat stress
orse's body becomes over heated either because of high temperatures or because of intense exercise under less than optimal conditions, it affects the horse's respiratory, vascular, nervous, and muscular systems and unless the horse is cooled down and lost fluids replaced, those systems will cease to function and the horse's body will shut down leading to severe damage or death.
Heat production can increase as much as 50% during intense exercise. The horse sweats to move more blood to the capillaries under the skin and breathing rate increases to release built-up heat. The horse's system may be unable to keep up with the mounting heat to the point that he becomes dehydrated.
Profuse sweating, rapid breathing, and rapid heart rate are indications that the horse is stressed and needs to be moved to a shady area, allowed to cool down, and given water to combat dehydration.
If the horse cannot be cooled down, the nervous and muscular systems will cease to function normally. When these systems stop functioning, heat stroke is inevitable unless measures are taken to cool the horse down and replace fluids lost because of sweating. If heat stroke is suspected, the veterinarian should be called immediately and steps taken to cool both the horse and the environment.
With a body that holds heat more efficiently than it disperses it, horses can acquire dangerously high body temperatures during Summer. A heat stressed horse will sweat profusely and, in extreme cases, they may stop sweating altogether.
Heat stress can also be recognised by panting, a dull demeanour or panicky behaviour. If your horse is heat stressed, cold water hose them, scrape it off and repeat. Keep them in the shade and offer them water. You may also use ice packs on their face and neck.
With no proven cure, horses with anhidrosis – the inability to sweat – must be managed carefully during Summer. An anhidrotic horse will be unable to cool themselves and may show signs of heat stress, such as those described above.
You may identify anhidrosis in your horse if they are dry when other horses are sweating or the temperature or level of activity would normally produce sweating. Horses with anhidrosis should be kept in a cooler environment and may require more stringent cooling methods during Summer.
Sunburn
Sunburn affects a horse in much the same way it affects a human. When a horse spends too much time unprotected in the sun, the skin becomes inflamed and the horse experiences pain, discomfort, drying and cracking of the skin, blistering, and possible loss of hair in the affected areas.
The face, especially the muzzle and around the eyes, gets quite badly sunburned when not protected. The correlation between sunburn and liver damage makes it important to check with a veterinarian in cases of severe sunburn.
Many white and grey horses can be affected the sun. As with humans, sunburnt skin will be red, tender and swollen. If the sunburn is severe, the skin may also crack, bleed or ooze fluid. Where possible, sunburn is best avoided.
Shield your horse’s skin from overexposure with a light rug and fly mask. Be mindful of vulnerable areas, like the muzzle, and use zinc if you don’t have a nose flap to cover it. If your horse is sunburnt, apply a thick emollient cream to the area.
Colic
“Colic” is a descriptive term, referring to a group of signs that indicate abdominal pain in the horse. Similar to the term “stomach ache” in humans, colic is a description, not a specific disease.
There are many causes of colic and the main ones in the summer months are due to the introduction of different feeds or hays and the amount of fast growing grasses after rain. This causes the bacteria in the intestinal system to have a field day and produce more gas after breaking down different feeds. This gas often builds up and is not released fast enough. When the intestines stretch, pain receptors are activated causing the common signs of colic like pawing at the ground, rolling and laying down etc.
Causes of colic related to the gastro-intestinal (GI) tract include flatulence (gas) – often related to a change in feed or water intake, stress, or weather, stomach ulcers, diarrhea caused by feed intolerance, bacterial or viral infection or parasites.
Summer weather often means horses spend more time grazing in pastures.This means horses eat off the ground and ingest sand particles, these particles can sink to the bottom of the intestine and cause irritation and/or obstruction resulting in colic.
Note: Updated article was first posted on EquiMed.com during summer of 2022
Press release by Equine Veterinary Services