Our animal hospital is dedicated to providing pets with compassionate care. In offering cardiology services, we can better evaluate and treat heart and lung diseases, working towards improving both length and quality of life. Annual pet wellness exams and wellness screening enable our staff to detect early indicators of heart disease that could potentially save your pet’s life – just one more reason why an annual check-up is important for your pet’s well-being.
Diagnostic imaging is initially used when a disease or condition is suspected or has already been diagnosed, for example if we hear a heart murmur with the stethoscope or the ProBNP cardiac enzyme test is elevated. At this point, further testing will usually be recommended. If we need more information than chest x-rays can provide, we have a board-certified internist, Dr. Hattie Bortnowski, who visits our veterinary clinic regularly to perform echocardiograms (see explanation below). An echocardiogram allows us to determine the existence and severity of your pet's heart disease. After diagnosis, our veterinarians will discuss with you the best plan of action for your pet.
Possible indications of heart disease:
Coughing that lasts longer than three days.
Inability or refusal to sleep at night.
Shortness of breath, wheezing, or rapid breathing.
Sudden changes in pet behavior and an inclination to isolate themselves.
Sudden episodes of fainting, or unexplained collapses.
Swelling in the abdomen.
What do cardiology diagnostics involve?
There are several different diagnostic tests that we do routinely for patients with heart disease or suspected heart disease:
Blood Pressure – We routinely check our patients' blood pressures at pet wellness exams for senior cats; when heart, kidney or thyroid diseases exist; while pets are anesthetized or in intensive care, or in cases of shock or injury. High blood pressure is common in pets, as it is in people. Low blood pressure can be the result of some of the medications we use to treat heart and kidney diseases, or from anesthesia, shock, blood loss or any serious injury or illness.
Blood Tests – Blood tests for organ function, electrolytes such as sodium and potassium, thyroid level and heart muscle enzymes all are used to diagnose or monitor heart disease.
Digital X-rays – X-rays allow the veterinarian to examine the heart, lungs, and bones. An x-ray (or radiograph) may show enlargement of the heart, fluid build-up in the lungs or other signs of heart disease. X-rays can also be used to determine placement of pacemakers.
ECG – An ECG, sometimes called an EKG, allows us to monitor heart rate and rhythm. An abnormal heart rhythm is common in pets with cardiomyopathy, a serious form of heart disease. Heart enlargement, potassium deficiency and other abnormalities can also cause changes in the ECG.
Echocardiogram - an ultrasound of the heart, also called an "echo," lets the radiologist or cardiologist see a 3-dimensional image of the heart and its chambers. From this image, they can observe blood flow and whether the heart is contracting properly. Another name for ultrasound is a sonogram, because it uses sound waves to create an image. An echocardiogram, in which the sound waves are reflected off the heart, is a type of ultrasound study.
The ultrasound machine is one of the most widely used imaging tools in medicine, second only to radiographs (x-rays). It allows us to look at the insides of organs, such as the heart, liver or urinary bladder, without an incision. It is safe and economical, and has greatly reduced the need for contrast radiography. Unlike with x-rays, no dangerous ionizing radiation is produced by the ultrasound machine.
An ultrasound machine transmits sound waves at a much higher frequency than we can hear with our ears. The sound waves reflect back in greater or lesser amount depending on the density of the material they hit. The reflected sound waves that bounce back are picked up by a receiver. A computer analyzes the time delay and amplitude of the returning echo and forms an image on a screen. The depth of a structure producing an echo is determined by the amount of “round trip” time of the transmitted pulse of sound and the returning echo. Fluid and tissues reflect sound the best. Air or gas and bones prevent the transmission of the sound wave.
Pulses of sound and the images produced are updated approximately 30 times a second, so an ultrasound allows us to see an image of the heart contracting or a baby moving, just like viewing a movie that consists of thousands of individual images. A single image can be selected, stored and printed as a photograph, or the entire movie can be recorded on videotape or computer.
With the ultrasound machine we can measure the ability of the heart to contract, gauge the thickness of the bladder or intestinal walls, detect bladder stones, gallstones or fluid pockets, such as in the uterus with pregnancy or a cyst in a kidney. Guided by the ultrasound image, a doctor can direct a needle into a specific organ, a tumor or a nodule and obtain a tissue or fluid sample for analysis. This allows us to obtain small tissue samples from the liver, spleen or other organs without the need for invasive surgery.
Most pets will need to be shaved for an abdominal ultrasound procedure but often not for an echocardiogram. Air doesn’t transmit ultrasound waves, so the air trapped in the fur deflects the wave and makes the ultrasound ineffective. Gel is applied between the pet and the transducer, which transmits the sound waves and detects them bouncing back again, to further block out air between it and the patient. For pets that mind the clippers, sedation may be needed.
Depending on the pet and the procedure needed, performing the ultrasound exam itself may require sedation or anesthesia. Some pets find being restrained in one position for 15 minutes or more to be stressful or frightening. Because it isn't painful, however, most pets will tolerate it and don't need a sedative.
The cost of an echocardiogram is roughly $500. The ultrasound machine itself may cost as much as $100,000. The price of the echo will cover not only the doctor’s time but the cost of this expensive equipment and her travel expenses to get here.
Pulse Oximetry - Pulse oximeters are now the most commonly used instrument to monitor anesthesia in pets. Most people have seen these instruments on TV or in use in human hospitals. In people the sensor device slips over a finger. The sensor measures the heart rate and the oxygen saturation level of the blood – in other words, what percent of the red blood cells that carry oxygen to the body are saturated with it. A healthy person or pet has red blood cells that are over 95% saturated with oxygen. Decreased oxygen levels may be due to anemia, heart or lung disease, or a decreased respiratory or heart rate due to anesthesia, pain, shock or dehydration.
Pulse oximeters can detect pulse strength as well as rate – an indirect way to gauge the strength of the heart as it contracts and the patient’s blood pressure. Attachments to pulse oximeters can allow us to measure respiratory rate, blood carbon dioxide levels and core body temperature during anesthesia. Using this data we can adjust our therapy or anesthesia to keep the oxygen level and heart rate in the normal, healthy range.
The sensor device that picks up the oxygen level and heart rate reflects light off an artery. The artery must be close to the surface of the body. The sensor devices used in animals are different than the finger sensor used on people. The finger sensor sends light through the skin or, in darker skinned people, the fingernail. For pets we use a toe or hock clip that looks like a c-clamp. This picks up the heart rate and oxygen level from an artery located near the surface of the skin. With pets, too, dark skin decreases the ability of the sensor. If we can’t get a reading from a toe or hock area we use a tongue clip, which finds a vessel under the tongue, or a rectal sensor that uses an artery in the wall of the colon. Body temperature and respiratory rate are detected with a different sensor that is passed down the throat into the esophagus.
Anesthetic monitoring is the most common use of pulse oximetry in pets, because it is difficult to keep the sensors in place when a pet is moving around. however, it is also used to monitor critical patients with heart or respiratory disease and helps us to decide if a pet needs to be on oxygen. Pulse ox equipment has made anesthetizing pets safer than ever before because oxygen saturation is the most important statistic to watch when monitoring the status of the heart and lungs. Early detection of a problem allows for quick correction, before damage to the brain or tissues can occur. This is also true in the face of compromised heart or respiratory function.