What Is Anesthesia?
Anesthesia is defined as the loss of ability to feel pain. However, the term anesthesia is more commonly used to refer to a state of deep sedation or unconsciousness during which a patient is unable to feel pain.
Two forms of anesthesia are used in dogs. For some patients, local anesthesia is an option. This involves injecting the medication into a specific place in the skin (or applying it onto an area of the skin) to induce temporary localized numbness, allowing the veterinarian to perform a brief procedure.
The affected area can include the skin, underlying muscles, and nerves. The medication used for local anesthesia does not cause the patient to fall asleep; when deep sedation or unconsciousness is required, general anesthesia is a better option. Medications used for general anesthesia are available in many forms. Some are administered by injection, whereas other forms are inhaled through an anesthetic mask or breathing tube that is connected to an anesthesia machine.
When Is Anesthesia Used?
Anesthesia has many uses in dogs. Local anesthesia may be an option if your veterinarian needs to remove a small growth on your dog’s skin, perform a biopsy of a growth or an area of skin, use stitches to close a small cut or wound, or perform any type of minimally painful procedure during which unconsciousness is not required.
General anesthesia is used for more invasive types of surgeries or for procedures likely to be very painful. Examples include repairing a broken bone or performing surgery involving the abdominal or chest cavities.
Surgery is not the only time when anesthesia is recommended. Dogs generally require anesthesia or very heavy sedation before dental cleanings, dental x-rays, or complete dental examinations. Anesthesia is sometimes used for taking x-rays of other areas of the body, especially if the patient is painful and positioning for x-rays would result in more pain. General anesthesia tends to cause muscle relaxation, which has additional advantages when x-rays of the body are required.
Sometimes, local anesthesia and general anesthesia are used together for the same procedure. For example, some veterinarians use general anesthesia to place the patient into a state of unconsciousness, then inject a local anesthetic agent into the skin and underlying tissues where surgery will be performed. The numbing effect of the local anesthetic can reduce the amount of pain that the patient experiences when he or she eventually wakes up from general anesthesia.
How Is Anesthesia Performed?
Your veterinarian may recommend a pre-anesthetic evaluation before placing your pet under general anesthesia. This process is generally not necessary for local anesthesia. The pre-anesthetic evaluation may include a physical examination to ensure that your pet is healthy enough for anesthesia. Pre-anesthetic blood work may also be recommended to help identify medical problems that may increase the risks associated with surgery or anesthesia. Pre-anesthetic blood work can help identify medical conditions such as infection, anemia (a low number of red blood cells), low blood sugar, inadequate blood-clotting ability, liver disease, or kidney disease.
If your pet has any pre-existing medical issues, such as a heart problem, your veterinarian may recommend additional testing to determine if any precautions are recommended or if anesthesia should be postponed or cancelled due to health reasons.
Some practices perform the pre-anesthetic evaluation on the day of anesthesia. However, some veterinarians perform this testing a few days or weeks before the procedure is scheduled. This is a common practice before performing an elective surgical procedure such as a dental cleaning, spay surgery, or castration surgery.
Inducing and Maintaining General Anesthesia
The process of sedating a patient and preparing him or her for entering general anesthesia is called induction. Once induction is accomplished, the patient is maintained under general anesthesia until the procedure (surgery, x-rays, biopsy, dental cleaning, or other procedure) is completed and the patient is permitted to awaken.
Induction generally begins with administration of a sedative. This helps relax the patient so that the rest of the induction activities can proceed. During this time, an intravenous catheter may be placed to begin administration of intravenous fluids. Once the patient is relaxed, additional medications are given to induce a deeper level of sedation, leading to general anesthesia. If injectable anesthetic medication is used, this medication is continued until the patient is permitted to wake up. If inhalant anesthesia is chosen, a breathing tube is inserted into the patient’s main airway (or sometimes an anesthetic mask is placed over the mouth and nose) and connected to a machine that delivers a carefully calculated mixture of oxygen and inhalant anesthetic. The patient inhales this mixture until the procedure is completed and the patient is permitted to awaken.
Both methods of general anesthesia (injectable or inhaled) will safely keep your pet asleep and pain-free. Whichever method of anesthesia is chosen, your veterinarian will take every precaution to help ensure that your pet remains healthy and awakens safely from anesthesia. Veterinary technicians observe and monitor patients that are under general anesthesia. Additionally, monitoring equipment is generally used to constantly measure heart rate, breathing, oxygen use, and blood pressure.
When the procedure is completed, the anesthetic agent is discontinued and the patient is monitored until he or she is fully awake and recovered from anesthesia.
What Are the Benefits and Risks of Anesthesia?
Keeping patients pain-free during surgery is an important goal of anesthesia, but there are many other purposes for anesthesia. If a dog has an injury that is too painful to be examined while the dog is awake, anesthesia may be the best way to facilitate a thorough examination. Additional procedures, such as placing a splint or cast on a broken leg, taking x-rays of a painful injury, or cleaning and dressing a serious wound can frequently be accomplished more efficiently if the patient is under anesthesia.
Many dental procedures, including dental cleaning, extracting an infected or broken tooth, taking dental x-rays, or performing dental restoration, are generally not possible without anesthesia.
As with any medical procedure, anesthesia is not without its risks. Some patients may react negatively to the anesthetic medication or experience fluctuations in heart rate, breathing, or blood pressure. Your veterinarian is extensively trained in performing anesthesia, and your veterinary care team will take every possible precaution to help ensure that your pet awakens safely. Be sure to address any questions or concerns with your veterinarian.
What Is the Calcium Level?
Calcium is an important nutrient that the body needs to maintain many of its organs. Bones, the heart, intestines, and muscles are just a few of the organs that rely on a healthy blood calcium level in order to function properly. If the calcium level in the blood drops too low or goes up too high, serious illness can result.
The calcium level is an important part of a blood test known as a chemistry panel, so it is often evaluated during routine wellness checkups or pre-surgery screening in healthy pets. Because a variety of medical conditions can affect the calcium level, your veterinarian may recommend testing your pet’s calcium level if your pet has any of the following signs of illness:
How Is the Calcium Level Measured?
To test your pet’s calcium level, your veterinary team must obtain a small blood sample. This procedure is usually very quick; it may take only a few seconds if the patient is well behaved. For patients that are very frightened or not well behaved, your veterinary team may want to use a muzzle, towel, or other gentle restraint device. In some cases, such as in patients with very thick fur, it may be necessary to shave the hair from the area where blood will be drawn. The hair will grow back, and this is often a good way to find the vein quickly.
Some veterinary offices have in-house blood analysis equipment, so they can perform the test for the calcium level in the office and have results the same day. Other offices send blood samples to an outside laboratory for the test to be performed. If an outside laboratory is used, results are generally available within 1 to 2 days.
Because a recent meal changes the blood and may affect the calcium level, your veterinarian may recommend that your pet not receive any food for 12 hours before drawing blood to perform the test. In most cases, water can still be offered. Please let your veterinarian know if this temporary fast will be a problem for you or for your pet.
Be sure to tell your veterinarian about any medications or supplements your pet may be receiving, as some products can alter the calcium level in the blood.
What Does the Calcium Level Tell Your Veterinarian?
Supplementing a pet’s diet with too much calcium or administering certain medications (such as steroids) can affect the results of a calcium level test. However, an abnormal calcium level (whether too low or too high) can also indicate a serious medical problem. Because so many of the body’s organs depend on calcium or are involved in maintaining normal blood calcium levels, abnormalities in the blood calcium level can affect the body in a variety of ways. The following are a few conditions that can cause an abnormal calcium level:
If your pet has an abnormal calcium level, your veterinarian will combine that information with other vital information about your pet to decide if further diagnostic testing is recommended to investigate the abnormal result. Additional tests may include a urinalysis (a screening test to evaluate components in the urine), radiographs (“x-rays”), or additional blood testing.
Depending on your pet’s overall condition, your veterinarian may recommend medications or other management. If the blood calcium level is dangerously low or high, hospitalization may be recommended while the problem is being corrected through fluid therapy and medications.
Are There Risks Associated With Testing the Calcium Level?
There are very few risks associated with testing the calcium level. Drawing blood usually takes only a few seconds, and your veterinary team will take precautions to ensure that your pet is not injured during this procedure. Once blood is obtained, all further processing is performed at the veterinarian’s office or at a diagnostic laboratory, so there is no risk of harm to your pet.
CBC AND CHEMISTRY PROFILE
What Is a CBC and Chemistry Profile?
Blood testing is commonly used to help diagnose disease or pinpoint injury in animals. It can also help determine the state of your pet’s health during regular physical exam visits. Although a CBC or a chemistry profile can be performed separately, these tests are frequently done at the same time; when the results are interpreted together, they provide a good overview of many of the body’s functions. As with any other diagnostic test, results of a CBC and chemistry profile are not interpreted in a vacuum. Your veterinarian will combine this information with physical exam findings, medical history, and other information to assess your pet’s health status and determine if additional testing should be recommended.
Complete blood count (CBC)
The CBC can help determine many things about your pet, including whether he or she is dehydrated, anemic (having inadequate numbers of red blood cells), or dealing with an infection. The CBC measures the quantity and quality of red blood cells, white blood cells, and platelets. The CBC results may list abbreviations for the various tests included in a CBC:
The chemistry profile measures a variety of chemicals and enzymes (proteins that are involved in the body’s chemical reactions) in the blood to provide very general information about the status of organ health and function, especially of the liver, kidneys, and pancreas. The chemistry profile also shows the patient’s blood sugar level and the quantities of important electrolytes (molecules like sodium, calcium, and potassium) in the blood.
How Is a CBC and Chemistry Profile Performed?
To perform a CBC and chemistry profile, your veterinary team must first obtain a small blood sample from your pet. This procedure is usually very quick; it may take only a few seconds if the patient is well behaved. For patients that are very frightened or not well behaved, your veterinary team may want to use a muzzle, towel, or other gentle restraint device. In some cases, such as in patients with very thick fur, it may be necessary to shave the hair from the area where blood will be drawn. This is often a good way to find the vein quickly, and the hair will grow back.
Some veterinary offices have in-house blood analysis equipment, so they can perform a CBC and chemistry profile in the office and have results the same day. Other offices send blood samples to an outside laboratory for these tests to be performed. If an outside laboratory is used, results are generally available within 1 to 2 days.
Because a recent meal changes the blood and may affect the results of a chemistry profile, your veterinarian may recommend that your pet not receive any food for 8 to 12 hours before blood is drawn. In most cases, water can still be offered. Please let your veterinarian know if this temporary fast will be a problem for you or your pet.
Also, be sure to tell your veterinarian about any medications or supplements that your pet is receiving, as some products can alter the results of a chemistry profile.
What Is a CBC and Chemistry Profile Used For?
A CBC and chemistry profile is an important component of wellness blood work. Your veterinarian may recommend wellness blood work during your pet’s regular exams. Even if your pet is young and healthy, performing this testing periodically helps establish “normal” values for your pet. The next time blood work is performed, your veterinarian can compare the results with previous results to see if anything has changed. Depending on your pet’s age and health history, additional tests (such as thyroid testing or urinalysis) may also be recommended as part of wellness testing. For seniors or chronically ill pets, your veterinarian may recommend blood work more frequently. Wellness blood work screens for many medical conditions, including diabetes and kidney disease. In many cases, early diagnosis and management can improve quality of life and the long-term prognosis for pets with chronic illnesses.
When a pet presents with clinical signs indicating an illness, a CBC and chemistry profile is often performed very early during the diagnostic process. Even if results of this initial testing are all “normal,” this information can rule out a variety of medical conditions. If results of a CBC and chemistry profile are abnormal or inconclusive, your veterinarian may recommend additional testing to get closer to a diagnosis.
A CBC and chemistry profile is also part of routine blood work that is performed before a pet undergoes general anesthesia for a surgical procedure. If test results are abnormal, your veterinarian may recommend additional precautions to help ensure your pet’s safety during the procedure. Your veterinarian may also recommend postponing the procedure or choosing an alternative treatment option.
Performing a CBC and chemistry panel poses minimal risk for your pet, and in many cases, the information your veterinarian gains from this testing is invaluable.
BLOOD PRESSURE TEST
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.
A biopsy allows your veterinarian to determine the types of cells in a tissue sample.
What Is a Biopsy?
A biopsy is a surgical procedure in which a tissue sample is removed from the body and examined under a microscope. In some cases, only a small sample is removed for analysis. In other cases, several samples may be removed, or an entire growth may be removed and examined.
What Is a Biopsy Used For?
Dogs and cats commonly develop lumps and growths on their skin. Sometimes these lumps are cancerous, but in other cases, they are simply warts or other noncancerous (benign) growths. Examining a lump does not always give your veterinarian enough information to tell whether it is cancerous or not. A biopsy may be recommended to obtain more information about a suspicious lump.
A biopsy can also be used to diagnose a condition or determine the severity of a disease. For example, if an animal has liver disease, a sample of the liver can be removed (during a biopsy) and examined under a microscope to help determine the cause and extent of the liver damage.
How Is a Biopsy Performed?
Some form of anesthesia is generally required to perform a biopsy. Depending on several factors, including where the tissue sample(s) is/are located and how many areas need to be sampled, your veterinarian will decide whether to use local anesthesia, sedation, or general anesthesia. Local anesthesia usually involves injecting a medication in and around an area of the body to make it numb.
If local anesthesia is used, your pet will likely be awake during the biopsy. In contrast, if sedation or general anesthesia is used, the patient is heavily sedated or completely asleep during the procedure. Sometimes, if a growth is on the surface of the skin and is very small, your veterinarian may be able to perform a biopsy using local anesthesia. However, if the area to be biopsied is within the abdomen, for example, or if multiple areas will be biopsied, general anesthesia is usually recommended.
Your veterinarian has a few options when deciding how to perform a biopsy and how much tissue to remove. In an incisional biopsy, a small sample of tissue is removed from a larger mass. In an excisional biopsy, the entire growth is removed and submitted for biopsy.
Once the tissue is removed, your veterinarian will submit it to a diagnostic laboratory. There, a veterinary pathologist (a specialist at examining cells and tissue samples) will examine the tissue under a microscope to make a diagnosis. Results are generally available within several days.
What Are the Benefits and Risks of a Biopsy?
Biopsies are very important for helping to confirm a diagnosis. With many types of cancers, early diagnosis is helpful for determining the course of treatment and can help increase the chance of survival. Biopsies can also help to confirm causes of other conditions, including skin lesions as well as diseases of the kidneys, liver, or bone marrow.
Your veterinarian will take many precautions to help ensure that your pet is safe during the biopsy and fully recovers afterward. To help reduce the risk of complications associated with surgery or anesthesia, your veterinarian may give your pet a full physical examination and check your pet’s blood work before the biopsy.
Biopsies are very safe, routine procedures. The risks associated with a biopsy depend on several factors, including the overall health of the patient, the location of the area to be biopsied, and how many samples are taken. Be sure to discuss any questions or concerns with your veterinarian.
Dr. Carlson is an avid contributor to her blog, make sure you check out her articles!