Pathogenesis and lethal mechanism
The dairy cow baby in a muggy or hot environment can cause obvious congestion and congestion of blood vessels in the brain and meninges, thus causing brain edema. Besides, it can lead to pulmonary congestion and pulmonary edema, which can increase the burden of the heart and cause functional failure. In severe cases, it may even lead to death due to the simultaneous occurrence of pulmonary edema and heart failure.
The mechanism of heart failure.
Owing to the high body temperature and sweating in large quantities, the blood viscosity of dairy cows increases obviously, and the resistance of peripheral blood vessels increases, so that the pressure of aorta increases obviously. Only by forcing the heart to do more work, can the blood volume produced be the same as that under a normal blood pressure condition, otherwise the blood output of the heart can be reduced. If the arterial pressure keeps increasing, the myocardium will be in a state of intense contraction for a long time, and then gradually fatigue and pathological changes will occur, which will lead to the weakening of the pump function and eventually lead to heart failure.
The mechanism of pulmonary congestion and pulmonary edema.
Dairy cows of the cattle company are in a poorly ventilated and muggy environment, which makes the body in a state of heat stress and causes active pulmonary congestion. At the same time, due to the obvious weakening of myocardial contractility, obstruction of pulmonary venous reflux and reduction of cardiac output, a lot of blood stays and circulates in the lungs, thus increasing the static pressure of pulmonary capillaries and strengthening the lungs. The permeability of capillaries enables plasma to enter the lung media, alveoli and bronchus through the filtration of capillary walls, thus forming pulmonary edema, causing respiratory failure, affecting pulmonary ventilation, resulting in dyspnea of ventilation function, accompanied by paroxysmal cough, and often collapsed due to asphyxia and death.
Causes of disease
The summer climate is hot. Dairy cows exercise or graze for a long time. Their heads are exposed to direct sunlight for a long time, which leads to congestion of their brains, resulting in disorders of blood vessels, respiratory and motor central nervous system. Then they fall unconscious and cause heatstroke. If the cowshed environment is hot, the temperature is too high, and the heat dissipation or ventilation is poor, the feeding density is too high, and each other is crowded, it will lead to the accumulation of a large amount of heat in the body, and can not be timely distributed to the outside body, thus causing heatstroke.
The unreasonable feeding and management of dairy spotted cow, especially the unreasonable working and rest time in summer, long-term exercise or grazing, make their physique weak, too tired, sweating a lot, while not providing adequate drinking water and salt, make the body not get timely supplement, cause the body collapse, very prone to heatstroke.
Clinical symptoms
The disease usually occurs quickly, the cattle are depressed, dizzy, unstable gait, limb weakness, ataxia. Individual diseased cattle will suddenly fall to the ground and swim in their limbs. The body temperature of diseased cows increased significantly, especially those suffering from heatstroke. The body temperature of diseased cows could reach 41-44 C. The cow's nostrils are open, mouth opening, and foam-like saliva flowing out of the mouth, breathing rapidly, with frequent frequency and irregular rhythms.
Diseased cows reduce or stop urination. Heartbeat accelerated, more than 100 times per minute, palpitation hyperactivity, heart sound hyperactivity, then heart sound split or become muddy, heart sound low, weak pulse, vein first angry and then collapsed. The diseased cattle showed transient excitement, easy struggle, and restlessness. A few will quickly become a highly inhibited state, corneal, skin, anus reflex disappeared, tendon reflex hyperactivity. The pupil dilates at the beginning and shrinks at the later stage until it loses consciousness completely. In the endangered period, the diseased cattle sometimes fall to the ground in a pseudo-dead state, the skin reflex disappears, and the muscles stop trembling.
Only the heart sound can be used to judge whether they are dead or not. In the near-death period, the vein of the diseased cattle collapses, the body temperature drops rapidly, falls to the ground unable to stand, presents the coma shape, the convulsion, appears the asphyxia and the heart paralysis, causes the sudden death.
Diagnosis
According to the occurrence season of the disease, it is easy to diagnose whether the cows have been exposed to long-term hot sun or have a poor feeding environment, and what does cow eat, which is combined with the morbidity and clinical symptoms. However, we should pay attention to the diagnosis and treatment of related diseases or the complications caused by heatstroke.
Heatstroke treatment
If a cow is found to have heatstroke, it should be rescued immediately on the spot. First, the sick cow should be quickly moved to a ventilated, cool and spacious place. In the treatment of Heatstroke, the body temperature should be lowered as soon as possible. For this reason, the cattle rancher can place ice bags on the head and jugular groove of diseased cattle for a cold compress, or pour cold water directly.
Gradually, cold water should be sprayed all over the body. 10-20 ml.2.5% chlorpromazine solution was injected intramuscularly or intravenously into diseased cattle to protect the hypothalamus thermoregulation center, avoid excessive heat generation, promote vasodilation, increase heat dissipation, etc. It can also be used for intramuscular injection of 20-30 mL5% sodium Camphor Sulfonate Injection or 10-30 ml 10% sodium caffeine injection to stimulate the excitation of the respiratory center, increase ventilation volume and raise blood pressure.
Besides, some of the diseased Corrientes cattle can be treated with adjuvant therapy. When the sick cattle are agitated, a 100 mL ambroxol solution can be injected intravenously. The diseased cattle were intravenously injected with 5% glucose sodium chloride solution, 0.09% sodium chloride solution, or compound sodium chloride solution. The dosage was controlled at 1000-3000ml each time. It is used to supplement electrolyte solution and water, which can reduce body temperature, blood viscosity, promote blood circulation, help the body to discharge harmful substances and alleviate breathing difficulties. Intravenous injection of 500-1000mL 25% sorbitol solution or 20% mannitol solution can diuresis, relieve brain edema, reduce intracranial pressure, rescue diseased cattle in shock state, and inject 300-600 ml_ 50% glucose solution into diseased cattle.
To eliminate the autopoisoning of diseased cattle, 500-1000mL 5% sodium bicarbonate injection can be injected intravenously. During the recovery period of diseased cattle, 300-500 mL 10% sodium chloride solution, 200-300 mL 5% calcium chloride solution and 20-30 ml 10% sodium caffeine solution can be injected intravenously once a day, and an appropriate amount of artificial salt laxatives can be taken orally to clean up the gastrointestinal tract and improve water and salt metabolism.