Heat stress in animals

The disease often occurs in hot and sunny season. Excessive increase of body temperature leads to occurrence of this disease

1) Etiology
- When the temperature in animal houses, in the transporting wagons is too high , especially along with high humidity, animals can not transfer heat effectively leading to increased body temperature
As animals have to move from place to place, working in the environmental conditions of high temperature, lack of drinking water supply or the water is too hot for animals to drink, animals may take insufficient water.
- Fat animals that are more susceptibility to the diseases such as meat pigs, breeding pigs, meat chicken at the final stage, heat is badly eliminated so they are more susceptible to the disease
2) The pathogenesis
Body temperature that is higher than the tolerance of animals and severe dehydration are two main factors of heat stress.
Because of increased environmental temperature and increased body temperature, animals have to rise respiratory rate to eliminate heat leading to decreased levels of carbonic acid in the blood. The blood becomes alkaline, erythrocytes are broken causing stress so this disease is called heat stress.
In case of increased environmental temperature but lack of drinking water for animals, livestock body can not transfer heat, the body temperature rise beyond tolerance levels of the nervous system, the nervous system is stimulated in the early stages then some hours later will be inhibited, animals can not breathe leading to weak heartbeat and death (also known as heat shock)
3) Symptoms
The disease often occurs quite suddenly, possibly in many animals of a herd or just a few animals. Sick animals are more susceptible to this disease The symptoms often include :
-Heat stress :reduction of feed intake, increased respiratory rate, intense thirst, more susceptible to common diseases, reduced productivity, premature birth, abortion
- .Heat shock: - The first signs include fatigue, lying in one place, increased respiratory rate and shallow breathing
• Red skin in the whole body (visible on the white pig, mucosal congestion).
• High body temperature up to over 41^o C.
• very Rapid heartbeat( tachycardia), pulseless
These symptoms last from 30-60 minutes, if there is no cure and the environmental temperature is high, the condition will aggravate with the following manifestation:
The symptoms mentioned above may last from 30-60 minutes, if there is no measures of treatment and the environmental temperature is still high, the condition will aggravate with the following manifestation:dyspnea, very high respiratory rate, nose is expanding to breath
• weak heartbeat( bradycardia), pulseless due to concentrated blood .
• Pale mucosa .
•spasm of jaw muscles .
• In swine: vomiting.
• Paralysis, eventually convulsion of muscles, dilated pupils, coma and death.
• When death occurs Foam around the mouth sometimes with blood can be seen .
4) Prognosis
The disease is easy to be cured if it is detected early (heat stress), and properly treated If it is too severe the animal will die from circulatory obstacles, together with concentrated blood, congestion and edema in the lungs causing lack of oxygen status too seriously. Dehydration and lack of oxygen cause accumulation of intermediate products in the cells leading to systemic toxicity. Therefore, animals may die within a few hours or a few days after infection
5) Diagnosis
Heat stress should be distinguished from sunstroke. In sunstroke, sometimes body temperature is not too high, while in heat stress, neurological signs are not as apparent as that in suntroke .
6) Treatment
It is nescessary to reduce the body temperature of animals, quickly by placing them in well-ventilated place, pouring cold water on the head, then on the whole body, antipyretic drugs should be administered to promote heat elimination
Administration of PARAMAX-20% dissolved in drinking water (dosage is used per label direction)
Or MARNAGIN-C is injected (dosage is used per label direction)
.(HEAT ELIMINATION or ELECTROLYTE-GLUCO-K-C or ELECTROLYTE-ORESOL or MARPHASOL HERBAL are orally given
- Cool drinking water is provided for animals, at the same time conducting saline infusion into the veins or intraperitoneal ịnjection.
- cardiac and respiratory support by administation of Caffeine or camphora.
- or vitamin C is Injected at high dose (10-15 mg / kg body weight /once. twice a day.)
- Similar to the treatment of sunstroke, when the disease has subsided, sufficient water, drugs for cadiac and respiratory support and vitamins at high dose for several days are continued to be provided ,
- When the animals have recovered, digestible feed containing lots of water and rich in vitamins should be provided.
7) Prevention
-When building animal houses,two important factors should be paid attention to: temperature and ventilation. Less heat-absorbing materials should be used to make the roof, roof should be high, walls are of medium height, there shoud be door railing to increase ventilation. There should be proper distances between the ranges of animal houses. Shade trees around animal house can be planted.
- At very high environmental temperature, do not overfeed animals, bath animals with cool water, or spray aerosol, spray water onto the roof of the animal house and it is the most important to provide sufficient water for animals to drink.
- Density of animals raised in confinement should be moderate.
-The best way to transport animals when the weather is cool, the truck should run at a steady rate, the boot should have railing to increase ventilation. Do not stop too long on the way. If transport on far distance, choose a cool place, stop, for animals to take a light meal and drink sufficient water.