The Importance of Blood Tests for Your Dog

Your six-month-old puppy is scheduled to be spayed tomorrow. When you call to confirm your appointment, and review the veterinarian’s estimate of charges with the receptionist, you learn that you could be charged extra for a blood panel. Is this necessary?

A young dog, at the veterinarian’s office for a spay or neuter surgery, should not be expected to have any health problems that would preclude anesthesia or surgery. However, veterinarians will tell you that there is one great reason to authorize the additional expense of a blood test at this time: the future. Your dog’s vigorous youth is the optimum time to establish a “baseline,” that is, a chemical picture of how she “looks” when she’s healthy. Results of these tests can be compared to those from tests taken in times of trouble to establish the extent of the deviations from her “normal.” Some veterinarians use this same rationale to request that you allow annual blood tests on your apparently healthy animal. This is undeniably a great opportunity to detect subtle signs of disease before your dog has an opportunity to display symptoms; early treatment of any disease helps prevent permanent damage.

Blood tests can give a veterinarian a wealth of information about the dog’s general health, and about the efficiency of his internal organs. Abnormal levels of certain chemicals in his blood serum can indicate disease even before symptoms are visible. After all, our doctors order blood work for us, sometimes several times a year.

Scenario One

  • Your five-year-old Golden Retriever seems sick. You’re observing him for any evidence of disease or injury. And yet, all you can really find is that Ralph seems “not himself.” A friend urges you to have Ralph’s blood tested . . . What for?

A dog who is “not quite right”
Blood tests are very valuable in cases where a dog isn’t displaying any overt signs of disease or injury, but still doesn’t seem quite like himself. A veterinarian attending to such a dog, would first conduct a thorough physical exam and take a complete history. However, there are numerous cases where a blood test and only a blood test would be able to reveal the source of his subtle malaise. For example, standard blood tests might show that his red blood cells were smaller than usual, his hemoglobin levels were low, and that he had an iron deficiency. These facts would suggest that the dog may have been losing small amounts of blood through his stools over a period of time. A radiograph of his digestive tract would be indicated, and the pictures could reveal an intestinal tumor that was responsible for the blood loss.

Chem screens can also detect complex problems with the endocrine system. The endocrine system is responsible for making gradual responses to environmental and internal stimuli, which are mediated by chemical substances (hormones) secreted by endocrine glands into the blood.

An experienced veterinary interpreter of the test results can read the hormonal responses that have been dropped into the blood system like clues to a crime. Thyroid dysfunction is the most frequently recognized endocrine disorder of the dog, followed by adrenal function disorders, Addison’s and Cushing’s syndromes (hypo- and hyper-adrenocorticism) which are very common in adult and aging dogs. Though these diseases may be detected early through routine periodic screenings and managed so as to improve quality of and prolong life, they are difficult to diagnose accurately without appropriate laboratory tests.

Other conditions commonly detected by blood work include hypercalcemia (too much blood calcium which could indicate possible tumor growth), and hypoglycemia (low blood sugar indicating diabetes). “Hypothyroidism is a common problem in aging dogs, so, starting at age seven, thyroid panels should be included in all dogs’ blood panels,” says Dr. Metzger. “Electrolytes tests are important too. For example, Addison’s syndrome (hypoadrenocortism) is frequently associated with severe hyponatremia (low sodium), but is frequently misdiagnosed by those who don’t run electrolyte panels.”

Scenario Two

  • Your Poodle is eight years old. She has bad breath and tartar-encrusted teeth, so you make plans to take her to a veterinarian to have her teeth cleaned. However, the doctor demands to perform a blood test before he will anesthetize her for a dental scaling. What’s that got to do with anything?

Pre-surgical tests
The middle-aged Poodle in need of dental work is another classic candidate for blood tests. Anesthetic drugs are processed by the liver and kidneys, which also remove the drugs from the body in a more or less predictable rate. However, if the dog’s liver and/or kidney function are impaired, normal usage of anesthetic drugs can have deadly consequences for the dog.

Just as with people, as your dog ages, her organs gradually become less efficient. Holistic veterinarians speculate that the plethora of toxins that modern dogs are exposed to (from flea-killing pesticides to preservatives in commercial dog foods) speeds up the degradation of these organs, rendering them ill-prepared for the major challenge of removing anesthetic from the bloodstream.

Results of a pre-surgical blood test, specifically focused on the values that reveal the efficiency of the liver and kidney, can help the veterinarian select the safest dose and type of anesthetic drug for your dog. Alternatively, in case of tests that reveal very poor organ function, the veterinarian may want to discuss the risks and benefits of the surgery with you, or may elect not to risk the surgery at all.

It’s impossible to say exactly when your dog’s organs are likely to start showing signs of compromised function. After all, what ages are considered “middle-aged” and “geriatric” differ widely from breed to breed.

Scenario Three

Geriatric dogs

  • Your 12-year-old Pointer no longer likes to go running with you, and when she does she’s exhausted and limping for days afterwards. At a recent health exam, your veterinarian asks about your 12-year-old Pointer’s activity level. You explain that the dog has begun to decline to join you on your daily jog, and chalk it up to the onset of his “old age.” But your veterinarian is alarmed, and asks to conduct blood tests. Isn’t it normal for an old dog to want some rest?

As for the 12-year-old Pointer who has decided to give up jogging? Most veterinarians would advise including a blood test in any elderly dog’s annual health examination. And a dog who has begun to “show his age” with stiffness, reluctance to exercise, or depression may actually be manifesting signs of disease, rather than “age.”

Once older dogs have their health problems diagnosed and treated, their owners are often surprised to discover them return to a level of activity they haven’t seen for years.

When a dog is considered a senior?
As a rule, a small dog breed such as a Chihuahua can live into their twenties while a giant breed, such as a Great Dane has an average life span of ten years. Within that broad outline, many factors come into play to determine an individual dog’s expected lifespan, such as his medical history, his genetics and the care he has received during his life. The best way to get information about your dog’s golden years is to talk to your veterinarian.

Geriatric health exams

Regularly scheduled veterinary examinations throughout his life are an important part of your dog’s health maintenance. As they age, these exams become more important, and don’t be surprised if your veterinarian suggests a general geriatric exam, including blood work, fecal exam and lab tests, every six months. These exams are the best defense in catching and delaying the onset or progress of diseases and for the early detection of problems such as organ failure and osteoarthritis.
When preparing for the geriatric health exam, make notes about any changes you’ve seen in your dog’s activities or behavior. It’s important to write it down so that you don’t forget to mention a critical change while at the veterinarian’s office. But don’t wait for the exam to talk to your veterinarian if you have questions or concerns about your senior dog’s health. What might seem like a small problem can quickly overwhelm the aged dog’s system.