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Cattle heatstroke
Heatstroke occurs when a cattle is no longer able to evacuate the heat it produces and that it receives from the environment. Its internal temperature rises and the body becomes disrupted. The cow is particularly exposed: fermentation in th...
What is it?
Heatstroke occurs when a cattle is no longer able to evacuate the heat it produces and that it receives from the environment. Its internal temperature rises and the body becomes disrupted.
The cow is particularly exposed: fermentation in the rumen constantly produces heat, and a dairy cow in full production produces even more heat. She sweats badly and evacuates mainly through breathing, which explains the panting.
In Tunisia and throughout the Maghreb, this is a real and recurring issue every summer. Heat waves, hot winds and nights that no longer cool enough put the herd in difficulty for several days in a row.
Key point
A cattle that is panting heavily and refusing to move is in a life-threatening emergency. Every minute counts: put him in the shade, hose him down with cool water starting from the limbs, circulate the air and call the veterinarian immediately.
Commonly observed signs
These signs are neither exhaustive nor specific. Only a veterinarian can establish a diagnosis.
Related signs — each one links to its page:
Accelerated breathing, then panting with open mouth, tense neck, tongue sticking out in severe cases: this is the most reliable warning sign.
Profuse salivation, drooling.
The animal seeks shade, clumps together with others, stays upright instead of lying down to provide more surface area for the air.
Very increased water consumption, prolonged parking around the water trough.
Marked drop in appetite and rumination, drop in milk production.
Despondency, animal that no longer reacts, unsteady gait, refusal to move.
Signs of dehydration: sunken eyes, skin that remains wrinkled when pinched, dry nose.
In serious cases: tremors, lying animal that does not get up, then shock. This is a life-threatening emergency.
In pregnant cows, intense heat stress can result in abortions or smaller calves at birth.
When to consult without delay
This list does not replace veterinary advice. It gathers situations that justify a prompt consultation.
Causes and risk factors
High heat combined with high humidity: it's the combination of the two that counts, because humid air prevents heat from dissipating. A moderately warm but very humid day can be more dangerous than a very hot and dry day.
Direct exposure to the sun, with no shade available.
A lack of water, too hot water or insufficient drinkers.
Lack of air movement: closed building, poorly ventilated, or parking in a waiting area without traffic.
Handling during hot weather: sorting, transport, restraint, prolonged walking, waiting in direct sunlight.
High milk production, which increases the heat produced by the animal itself.
Nights that remain hot, preventing recovery: it is the accumulation over several days that pushes the animals over the edge.
Dairy cows in high production and cows at the end of gestation.
Overweight animals, animals with dark coats, animals with thick hair.
Sick, lame, or already weakened animals: an animal that cannot move toward shade or water is in danger.
Overcrowded buildings, poorly ventilated, sheet metal roofs without insulation.
Route without trees or shelter.
Few drinkers, poorly placed or exposed to the sun, which force animals to queue.
Transport in hot weather, trucks stopped in full sun.
High-potential European dairy breeds, less adapted to heat than local breeds.
Diagnosis and care
Diagnosis is the veterinarian's responsibility, based on clinical examination and laboratory tests. Care is decided case by case.
Reported heat stroke is an emergency: call the veterinarian and immediately start cooling the animal while waiting for their arrival.
Place the animal in the shade, away from direct sunlight, in a place where air circulates.
Sprinkle it with cool water, starting with the limbs and stomach before wetting the body, and always combine a movement of air: wetting without ventilation is not very effective.
Offer fresh water as much as you want, without forcing an animal that can no longer drink on its own.
Stop all manipulation, all movement and all unnecessary restraint: each effort still produces heat.
The veterinarian will assess the animal's temperature, state of dehydration and general condition, and will take care of cooling and rehydration.
Treatment
Gradual cooling is the top priority and must begin before the veterinarian arrives: shade, fresh water, ventilation.
The veterinarian implements appropriate rehydration, orally or by infusion depending on the severity, and corrects the imbalances in the body.
He can prescribe supportive treatments depending on the animal's condition and the complications observed.
The animal must remain calm, in the shade and in the immediate vicinity of water for several days: recovery is not immediate.
Do not administer anything on your own initiative. In particular, do not suddenly immerse the animal in ice water and do not force it to walk to shower: moving in the heat can worsen its condition.
Then monitor the other animals in the group: if there has been a case, the others are exposed to the same conditions.
Treatment depends on the cause and the animal's condition: it must be determined by a veterinarian. No self-medication.
Prevention
Shade first: trees, open sheds, mobile shelters, shade nets. Each animal must be able to get into the shade at the same time as the others, without competing for a place.
Fresh, clean water in plenty, with enough drinking points to avoid queues. Place the drinkers in the shade and clean them regularly: hot or dirty water is less drunk.
Air: open buildings, clear obstacles to air circulation, use ventilation when available. The combination of ventilation and sprinkling is much more effective than either of the two alone.
Avoid any handling during hot times: sorting, care, trimming, transport, walking to another route are done early in the morning or at the end of the day.
Never leave animals waiting in the sun, nor a loaded truck stopped in direct sunlight.
Adapt the diet: distribute at the coolest times, prevent the ration from heating up and spoiling at the trough, ensure that the animals do not compensate for the drop in intake with large, unbalanced meals.
Reduce density in buildings during periods of high heat.
Monitor the herd during the hottest hours and in the evening: counting animals that are panting is a simple way to measure whether the arrangements are sufficient.
Anticipate heat wave warnings: prepare shade, water and ventilation before, not during.
Possible complications
Shock and death of the animal in severe forms that are not treated.
Kidney damage due to prolonged dehydration.
Abortions and embryonic mortality, lasting drop in herd fertility: the effects on reproduction can still be measured several weeks after the episode.
Smaller, more fragile calves born to mothers who suffered heat stress at the end of gestation.
Fall in milk production which does not fully return to the previous level during the current lactation.
Increased acidosis and lameness: animals change the way they eat and stay upright longer.
Decreased immunity, with more mastitis and other infections in the weeks that follow.
When to see a veterinarian
An animal is panting with its mouth open, neck outstretched, tongue sticking out: it's an emergency, start cooling it and call the veterinarian.
He refuses to move, staggers or lies down without getting up.
He doesn't drink anymore even though it's very hot.
Several animals in the group breathe quickly and refuse to eat.
A pregnant cow shows signs of giving birth or shedding after an episode of extreme heat.
The herd's production collapses during a heat wave: it's time to review shade, water and ventilation with your veterinarian, without waiting for an accident.
Prognosis
An animal cooled early and properly rehydrated generally recovers well, but recovery of appetite and production takes several days.
A lying animal that no longer gets up is in a serious situation: the prognosis then depends on the speed of treatment.
At the herd level, the consequences on fertility and production extend well beyond the heat episode, which makes preparing for summer much more profitable than managing the crisis.
Frequently asked questions
At what temperature do my cows get into trouble?
There is no single threshold: it is the combination of heat and humidity that counts, as well as the level of production and the absence of night-time coolness. The best indicator remains observation: cows that pant, stand and crowd in the shade are already under heat stress.
Is watering the cows enough?
Wetting without ventilation is not very effective: it is evaporation that cools, and it needs air movement. The combination of sprinkling and ventilation, with shade and unlimited water, gives much better results.
Can I transport my animals in summer?
Yes, but early in the morning or at the end of the day, with rapid loading, a well-ventilated vehicle and never parking stationary in direct sunlight. A stationary truck very quickly becomes a heat trap, even for a short journey.
Why are my cows producing less even though none are sick?
Because heat stress acts well before heat stroke: animals eat less, ruminate less and spend energy dissipating heat. Production declines, as does fertility. This is the signal that we need to increase shade, water and ventilation.
Are local breeds less susceptible?
They generally tolerate heat better than high-potential European dairy breeds, but none are immune. A local cow deprived of shade and water during a heatwave remains in danger.
References
FAO — Organisation des Nations unies pour l'alimentation et l'agriculture
EFSA — Autorité européenne de sécurité des aliments
Content reviewed by the TunisieVet editorial team · Updated 09 August 2026
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