What Is a Blood Pressure Test?
A blood pressure test measures the pressure of blood against arterial walls as the blood is pumped through the body. As a general rule of thumb, blood pressure should not exceed about 160/100 mm Hg in dogs and cats. The first number is the systolic blood pressure, or the pressure when the heart contracts. The second reading is the diastolic blood pressure, which is lower because it is the pressure when the heart relaxes between contractions. Blood pressure is measured in millimeters of mercury (mm Hg).
Which Pets Should Have a Blood Pressure Test?
In most cases, a blood pressure test is performed to determine if your pet’s blood pressure is too high. When blood pressure is too high, bleeding may occur, which can damage internal organs. The organs that are most vulnerable to damage are the eyes, kidneys, heart, and brain. The most common sign of high blood pressure is sudden or gradual blindness. Blindness caused by high blood pressure may be reversible, if caught early. Other signs of high blood pressure include dilated pupils, disorientation, and, less commonly, seizures.
In dogs and cats, high blood pressure is typically caused by another disease or condition, such as:
Your veterinarian may recommend a blood pressure test if your pet shows signs of high blood pressure or has been diagnosed with a disease associated with high blood pressure. Because cats older than 10 years are at high risk for kidney disease and hyperthyroidism, veterinarians often recommend screening them for high blood pressure.
Pets that are critically ill or under general anesthesia are often monitored to ensure that their blood pressure doesn’t become too low. Maintaining normal blood pressure is important so that organs receive the oxygen necessary to maintain proper function.
How Is Blood Pressure Measured?
In most cases, a blood pressure test is noninvasive and painless for your pet and can be performed during a regular office visit. Anxiety and stress can raise your pet’s blood pressure, so the test should be done in a quiet, relaxed environment and should be performed several times to ensure the results are not influenced by stress.
With the most common technique, a blood pressure cuff is placed around one of the pet’s limbs or around the base of the tail. The cuff is inflated to a pressure above the systolic pressure, so it momentarily presses against the artery and stops the blood flow. The cuff is then slowly deflated, and a machine determines the systolic and diastolic blood pressures. This method is called the indirect method and is fairly accurate. The most accurate blood pressure measurement is accomplished by placing a catheter directly into an artery. This type of monitoring is more painful and typically only done for patients that are critically ill and/or under general anesthesia and need constant blood pressure monitoring.
How Is High Blood Pressure Treated?
Because high blood pressure is usually caused by another disease, identifying and treating that disease can help return blood pressure closer to normal.
Occasionally, additional medications that dilate the blood vessels are required to help reduce blood pressure. If your pet has been diagnosed with high blood pressure, a blood pressure test should be done every few months to make sure the condition is properly controlled.
What Are Bladder and Kidney Stones?
Bladder and kidney stones are hardened accumulations of minerals found in urine. Common minerals involved include struvite, calcium oxalate, and urate. Dogs and cats can develop stones anywhere in the urinary tract. Stones can form in many different shapes and sizes.
Certain breeds of animals may be more likely to form certain kinds of stones. Dalmatians, for example, are more likely to develop urate stones.
Stones can have sharp edges. They can irritate or become embedded in the lining of the bladder, causing the tissue to become thickened and inflamed. They can also form inside the kidneys.
Stones can cause serious problems when they lodge in the ureters (the thin tubes connecting each kidney to the bladder) or the urethra (the narrow tube that allows urine to flow from the bladder out of the body). When the normal flow of urine from the kidney to the bladder is obstructed, urine (and pressure) can build up in the kidney, potentially causing kidney infections or kidney failure.
If a stone obstructs the urethra, the pet is unable to urinate, and the urine builds up inside the urinary tract. This occurs more commonly in male pets because, compared with females, they have a longer and very narrow urethra. When pets are unable to urinate, it’s a medical emergency, and a veterinarian should see the pet immediately.
What Causes These Stones?
Stones are often caused by a change in the normal pH of the urine, making it too acidic (low pH) or too basic (high pH), or by diseases that alter the mineral balance in the body. Factors that can lead to the formation of stones include:
What Are the Signs of Bladder and Kidney Stones?
Most stones are found in the bladder. Pets with bladder stones may show no signs at all or may exhibit signs such as the following:
Signs of a possible urinary blockage include:
Pets with kidney stones may show no signs or may have persistent blood in the urine. If a blockage affects the kidneys, the pet may have pain near the middle of the spine (where the kidneys are located) or may drink and urinate more.
How Are Urinary Stones Diagnosed?
Some veterinarians may be able to feel stones in the bladder by applying gentle pressure with their hands. In most cases, an abdominal radiograph (x-ray) is required. Since some stones do not appear on regular radiographs, contrast medium (a sterile solution that appears bright on radiographs) may need to be injected into the urinary tract to help make the stones more visible. An abdominal ultrasound may also be helpful to visualize stones.
If the urethra is obstructed with a stone, the veterinarian will usually be able to feel a firm bladder, and the pet may have signs of pain.
Testing the urine is helpful to determine if a urinary tract infection is present and if the urinary pH is normal. Sometimes crystals may be found in the urine, which may provide a clue as to the type of stone involved. Still, the only way to identify the type of stone with certainty is to send sample stones to a laboratory for analysis. This is important because treatment will vary depending on the stone.
How Are Bladder and Kidney Stones Treated?
In pets with blockages, emergency surgery is usually required. If the pet is not blocked, some stones can be dissolved by feeding the pet a special diet. This food, available only through veterinarians, will help modify the urine pH and dissolve the stones.
Some types of stones cannot be dissolved by diet and must be removed from the bladder using other methods, including:
While kidney stones may be removed by surgery, this procedure may affect kidney function. Another alternative, which is usually only available at universities, is called extracorporeal shock wave lithotripsy. In this procedure, shock waves are used to break up stones in the kidneys and ureter so that they become small enough to pass in the urine.
Once stones are removed, they are generally submitted to a diagnostic laboratory so their type/composition can be determined. Once the stone composition has been determined by lab analysis, pets may need to be fed a special diet and/or given medication for the rest of their lives to help prevent recurrence.
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