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| Author(s): |
Sandra Satiko Kitamura
Total Authors: 1
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| Document type: | Master's Dissertation |
| Press: | São Paulo. |
| Institution: | Universidade de São Paulo (USP). Faculdade de Medicina Veterinária e Zootecnia (FMVZ/SBD) |
| Defense date: | 2002-07-30 |
| Examining board members: |
Enrico Lippi Ortolani;
Mauricio Garcia;
Marcia Mery Kogika
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| Advisor: | Enrico Lippi Ortolani |
| Abstract | |
To study the role of the kidneys and of alternative treatments for detoxifying ammonia four experiments were carried out in cattle and rats. Wistar rats (n=367) were used to compare eight treatments (O= urea-cycle amino acids; F= furosemide; H= saline solution, O+F; H+F; O+H; O+F+H; C=control) to reverse ammonia poisoning. Ammonium acetate solution was injected [ip] and 3 min later the treatments were injected through the same via. Higher survival rate and lower plasma ammonia levels were detected in rats treated with O+F+H (62.5%) and O+H (57%). Rats treated with O, H and F had higher urea serum, lower creatinine and less pronounced lung edema, respectively. To develop a practical model to induce ammonia poisoning through [iv] ammonium chloride infusion until the appearance of convulsion (NH4+Cl) 15 yearling steer were used. The clinical picture showed was identical to the natural poisoning. Higher blood levels of ammonia, urea, L-lactate, glucose, potassium and hematocrit and lower bicarbonate and blood pH were detected during the infusion. A metabolic acidosis occurred by the increase of L-lactate; the lower the blood pH, the higher the hipercalemia. The model was very practical, reliable, and highly reproducible; no side effects were seen. All steers survived after the poisoning. During the same trial the role of the kidney to excrete ammonium was studied as well as the relation of this excretion with the individual resistance to the poisoning. The higher the urine volume excreted during the infusion, the higher the volume of NH4+Cl infused to cause convulsion and the greater the amount of NH4+ excreted in the urine. The lower the blood and urine pH, the higher the urinary ammonium excretion rate. Some steers were dehydrated, but dehydration was not cause by diuresis. In conclusion, the kidneys have an important role in the excretion of ammonium in the ammonia poisoning cattle, the higher the diuresis throughout the induction, the more resistant the cattle is to the poisoning. Afterwards, the same poisoned steers were randomly distributed and treated for 3h with O+F+H, O+H or C (small amount of saline - iv). The two former treatments produced a pronounced clinical improvement, lowering the blood ammonium and L-lactate levels and urine pH and increasing the urinary volume and NH4+ excretion. The selected treatments were very effective for detoxifying ammonia in poisoned cattle. (AU) | |