Diuretic

A diuretic is a medication that promotes the excretion of fluid through the kidneys and increases urine production. It is used to remove excess water from the body and lower blood pressure. Diuretics are primarily prescribed for cardiovascular diseases, kidney diseases, and oedemas.

Function of Diuretics

Diuretics inhibit the reabsorption of water and salts (such as sodium) in the kidneys. As a result, more water is excreted via urine, and the fluid volume in the body decreases. This is relevant for conditions associated with fluid accumulation or high blood pressure:

• Reduction of oedemas: In heart or kidney problems, fluid accumulates in the tissues, leading to swelling. Diuretics flush out this excess fluid.
• Relief for the heart: In heart failure, the heart has to work against an increased fluid volume. Diuretics relieve the heart by reducing the volume and lowering blood pressure.
• Promotion of kidney function: In cases of impaired kidney function, diuretics support excretion and the breakdown of toxins.

Areas of Application for Diuretics

Diuretics are used in the following conditions:

1. Heart failure: The heart no longer works efficiently, and fluid accumulates in the body. Diuretics, especially furosemide, reduce the burden and remove excess fluid from the lungs, abdominal cavity, or limbs.
2. Pulmonary oedema: Fluid in the lungs makes breathing difficult. Diuretics break down this fluid and improve respiratory function.
3. Kidney diseases: In kidney failure, fluid and electrolytes cannot be removed sufficiently. Diuretics support the kidneys.
4. High blood pressure: Diuretics lower blood pressure by reducing fluid volume.
5. Liver diseases: In advanced liver diseases such as liver cirrhosis, fluid accumulates in the abdominal cavity (ascites). Diuretics reduce these accumulations.

Types of Diuretics

There are various types of diuretics, which are used depending on the condition and the state of the dog:

1. Loop diuretics (e.g. furosemide): Loop diuretics are the strongest diuretics and are used in heart failure or pulmonary oedemas. They act quickly and effectively by inhibiting the transport of sodium and water in the kidneys.
2. Thiazide diuretics (e.g. hydrochlorothiazide): Weaker than loop diuretics, they are used for long-term treatment of high blood pressure or mild oedemas.
3. Potassium-sparing diuretics (e.g. spironolactone): They retain potassium in the body while promoting the excretion of sodium and water. Often used in combination with other diuretics to prevent potassium loss.

Possible Side Effects of Diuretics

Diuretics can have side effects, especially with longer-term use or incorrect dosage:

1. Electrolyte imbalances: Diuretics disrupt the balance of electrolytes such as sodium and potassium. This can lead to weakness, lethargy, muscle cramps, or heart problems.
2. Dehydration: Since diuretics increase urine excretion, there is a risk of dehydration. Signs include: increased thirst, dry mucous membranes, and reduced skin elasticity.
3. Kidney strain: In dogs with pre-existing kidney damage, diuretics can put additional strain on the kidneys.
4. Weakness and fatigue: Since diuretics lower blood pressure, dogs may show weakness or fatigue.
5. Excessive urination: Diuretics lead to increased urination; the dog needs to go outside more frequently.

Precautions and Monitoring

Diuretics should only be administered under veterinary supervision. Important precautions:

• Regular monitoring: Dogs undergoing diuretic therapy should be regularly checked for electrolyte imbalances and kidney function.
• Monitor hydration: The dog should drink enough water to avoid dehydration.
• Long-term monitoring: With prolonged use, blood tests should be carried out to ensure that kidney function and electrolyte levels remain stable.