Caring for a Horse in Winter

Winter presents unique physiological and environmental challenges for horses. As a senior veterinary medical writer, I emphasize that successful winter management requires a proactive, evidence-based approach to shelter, nutrition, hydration, thermoregulation, and hoof health. This pillar article synthesizes guidelines from the American Association of Equine Practitioners (AAEP), the Merck Veterinary Manual, and Kentucky Equine Research (KER) to provide a comprehensive clinical framework for equine winter care.

Quick Q&A

Question: What is the most critical factor in caring for a horse in winter? Answer: Ensuring constant access to clean, unfrozen water is the single most critical factor. Horses decrease water intake in cold weather, which dramatically increases the risk of impaction colic and dehydration. Heated water buckets or tank heaters are strongly recommended by the AAEP.

Shelter: The Foundation of Winter Protection

Natural Shelter vs. Man-Made Structures

Horses are remarkably cold-tolerant due to their large body mass, fermentative hindgut, and thick winter coats. However, shelter from wind, precipitation, and ground moisture is non-negotiable. According to the AAEP, a three-sided run-in shed oriented away from prevailing winds is often superior to a fully enclosed barn, as it provides protection while maintaining essential ventilation.

Key shelter requirements:

• Minimum of 12 feet by 12 feet per horse (larger for group housing)
• Roof height sufficient to prevent snow accumulation and allow head clearance
• Dry, non-slip flooring (packed gravel or rubber mats over compacted base)
• Bedding: deep straw or shavings (at least 6 inches) to provide insulation from frozen ground

Ventilation and Respiratory Health

Stabling horses in tightly sealed barns during winter increases the risk of recurrent airway obstruction (RAO), also known as heaves. The Merck Veterinary Manual advises that ammonia from urine decomposition and airborne dust from hay are primary triggers. Ensure passive ridge vents or eave openings remain functional. If using blankets, remove them daily to inspect for moisture accumulation, which can promote skin infections and chilling.

Blanketing: A Clinical Decision

When to Blanket

Blanketing is not universally required. The horse's natural winter coat provides excellent insulation when dry and clean. The AAEP recommends blanketing only under specific circumstances:

• Body condition score (BCS) below 4/9: Thin horses lack subcutaneous fat and cannot thermoregulate effectively.
• Clipped or show coats: Horses clipped for competition lose their natural insulation.
• Extreme weather: Wind chill below -20°F (-29°C) or prolonged rain/sleet that wets the coat to the skin.
• Advanced age or illness: Geriatric horses or those with pituitary pars intermedia dysfunction (PPID, equine Cushing's disease) often have compromised thermoregulation.

Blanket Selection and Fit

A poorly fitted blanket can cause rubs, pressure sores, and restricted movement. Use the following clinical criteria:

• Weight: Medium weight (200-300 g fill) for most winter conditions; heavy weight (400+ g) only for extreme cold.
• Waterproof/breathable: Essential to prevent moisture trapping, which can lead to chilling and dermatitis.
• Neck cover: Optional but beneficial for horses with clipped necks or those in severe wind chill.
• Straps and closures: Leg straps should cross between hind legs to prevent shifting. Check daily for entanglement risk.

Important: Remove blankets at least every 24 hours to assess coat condition, skin health, and body temperature. A horse sweating under a blanket is at risk of hypothermia when the blanket is removed.

Water: The Critical Winter Nutrient

The Physiology of Winter Hydration

Horses require 5-10 gallons (19-38 liters) of water daily, with intake increasing in cold weather due to increased metabolic heat production. However, water temperature significantly affects consumption. Research cited by Kentucky Equine Research demonstrates that horses offered water at 45-65°F (7-18°C) drink 40% more than those offered near-freezing water.

Heated Water Systems

The AAEP strongly endorses heated water buckets or tank heaters as a preventive measure against impaction colic. Key considerations:

• Electrical safety: Use only grounded, outdoor-rated extension cords with GFCI (ground fault circuit interrupter) protection. Inspect cords daily for rodent damage.
• Placement: Elevate buckets to prevent freezing of the hose connection. For troughs, ensure the heater is fully submerged and thermostatically controlled.
• Alternative: Insulated bucket covers and floating tank heaters are acceptable if electrical heating is unavailable.

Monitoring Intake

In group housing, dominant horses may prevent subordinates from accessing water. Provide one water source per 3-4 horses, spaced at least 10 feet apart. Check water temperature and cleanliness twice daily. If a horse is observed not drinking for 12 hours, consult a veterinarian immediately.

Forage: The Engine of Winter Metabolism

Increased Caloric Demands

The horse's lower critical temperature (LCT) is the ambient temperature below which it must expend energy to maintain core body temperature. For a horse with a winter coat, the LCT is approximately 30°F (-1°C). Below this, the horse's maintenance energy requirement increases by 1% for each degree Fahrenheit below the LCT. Forage (hay) is the safest and most physiological way to meet these demands.

Hay Quality and Quantity

• Type: Grass hay (timothy, orchard grass, brome) is preferred for most horses. Alfalfa can be used for thin horses or those with high energy demands, but its high calcium content requires caution in horses with renal disease.
• Quantity: Increase hay by 25-50% during cold snaps. A 1,100 lb (500 kg) horse at maintenance requires 15-20 lbs (7-9 kg) of hay daily in moderate cold, increasing to 25-30 lbs (11-14 kg) in extreme cold.
• Feeding frequency: Divide into 3-4 feedings per day to maintain hindgut fermentation and heat production. Continuous access (free-choice hay) is ideal.

Soaking Hay

For horses with RAO or dental issues, soaking hay for 15-30 minutes reduces dust and sugar content. However, soaked hay must be fed immediately in winter to prevent freezing. Frozen hay can cause choke and colic.

Hoof Care: The Winter Challenge

Snow and Ice Accumulation

Snow and ice can pack into the hoof sole and frog, forming "snowballs" that cause lameness, slipping, and bruising. The AAEP recommends:

• Daily hoof picking: Remove packed snow and ice before turnout.
• Hoof packing: Apply petroleum jelly or commercial non-stick sprays to the sole to reduce adhesion.
• Boots: Use neoprene or rubber hoof boots with non-slip soles for horses turned out on icy surfaces.

Farrier Considerations

Winter does not eliminate the need for regular farrier care. The Merck Veterinary Manual advises trimming every 6-8 weeks year-round. Key winter-specific considerations:

• Shoeing: Full shoes with snow pads (rim pads with a thin layer of silicone) can prevent snow packing. Studs or borium (tungsten carbide) can be applied to shoes for traction on ice.
• Barefoot horses: May require more frequent trimming to prevent cracking from frozen, brittle hoof walls.
• Thrush prevention: Wet, muddy conditions increase the risk of thrush (Fusobacterium necrophorum infection). Apply a commercial thrush treatment (e.g., copper sulfate or iodine-based) weekly.

Laminitis Risk

While laminitis is more commonly associated with spring grass, winter laminitis can occur in horses with PPID or those fed high-starch concentrates. Monitor for digital pulses, heat in the hooves, and reluctance to move. If suspected, remove grain, provide deep bedding, and contact a veterinarian immediately.

Additional Winter Management Considerations

Body Condition Scoring

Assess BCS monthly using the Henneke 1-9 scale. A score of 5-6 is ideal for most horses entering winter. Horses scoring below 4 require dietary intervention (increased hay, fat supplementation) and veterinary evaluation for underlying disease.

Parasite Control

Winter is an opportune time for strategic deworming. The AAEP recommends a fecal egg count (FEC) in late fall to identify horses requiring treatment for encysted small strongyles. A single dose of moxidectin or a five-day course of fenbendazole (under veterinary guidance) can target these larvae.

Vaccination and Dental Care

Schedule annual vaccinations (e.g., Eastern/Western equine encephalomyelitis, West Nile virus, tetanus, rabies) in late fall to ensure immunity through winter. Dental floatation should also be performed before winter to maximize feed efficiency.

Regional Considerations

• North America: In northern US states and Canada, wind chill is the primary threat. Use windbreaks and consider full-body blankets for clipped horses. In southern states, wet cold (rain and temperatures near freezing) is more dangerous than dry cold.
• Europe: The FVE emphasizes the importance of ventilation in older stone barns. In the UK and Ireland, mud fever (pastern dermatitis) is a common winter issue; keep legs dry and apply barrier creams.
• Australia: In southern Australia (Victoria, Tasmania), winter brings cold rain and wind. Horses may require lightweight waterproof sheets. In northern Australia, winter is the dry season; focus on dust control and respiratory health.

Conclusion

Caring for a horse in winter requires a systematic approach that prioritizes hydration, forage, shelter, and hoof health. By following AAEP and Merck Veterinary Manual guidelines, owners can prevent the most common winter emergencies: impaction colic, hypothermia, and lameness. Regular veterinary check-ups, body condition scoring, and adaptive management are essential. Remember that each horse is an individual; age, health status, and coat condition dictate specific needs. When in doubt, consult your veterinarian or a board-certified equine specialist.

References

[1] American Association of Equine Practitioners. "Winter Care for Your Horse." AAEP.org. Accessed 2025. [2] Merck Veterinary Manual. "Management of Horses in Cold Weather." merckvetmanual.com. 2024. [3] Kentucky Equine Research. "Winter Water Intake and Colic Prevention." ker.com. 2023. [4] Henneke, D.R., et al. "Relationship between condition score, physical measurements and body fat percentage in mares." Equine Veterinary Journal, 15(4), 371-372, 1983. [5] Federation of Veterinarians of Europe. "Equine Welfare in Winter Housing." fve.org. 2022. [6] American Veterinary Medical Association. "Winter Pet Safety." avma.org. 2024. [7] Canadian Veterinary Medical Association. "Equine Winter Management Guidelines." cvma-acmv.org. 2023. [8] Australian Veterinary Association. "Horse Care in Cold Weather." ava.com.au. 2024.