Why Your Veterinarian Goes Crazy for a Urine Sample from Your Pet

January 28, 2015

pet urine sampleWhile it is not unusual for a pet to have an accident in The Animal Medical Center waiting room or while standing on an examination table, my reaction to that accident may be considered unusual. As the embarrassed pet family is grabbing for a paper towel or a tissue to mop up, I blurt out “stop” so I can get a syringe to collect the urine for analysis in the laboratory.

18 Tests in One Tube
At The Animal Medical Center, a urinalysis tests 18 different parameters from just a teaspoon of urine. Some of the parameters are assessed visually, like color and clarity. A special dipstick measures six values simultaneously – especially important here are glucose and ketones – indicators of potential diabetes. The urine is spun in a centrifuge and the material that collects on the bottom of the test tube is specially stained and evaluated under the microscope. Finally, a drop or two of urine is placed on a refractometer, a device that measures the specific gravity and assesses how concentrated the urine is.

A Snapshot of Your Pet’s Health
The results from tests performed on that teaspoon of urine I have collected off the table or floor gives me a whole lot of information about your pet’s health. The finding of red and white blood cells and bacteria when the urine is evaluated under the microscope suggests a urinary tract infection. Observation of crystals in the urine is common and may not represent disease, but if your pet has bladder stones, the presence of crystals gives a hint as to the type of stones, and knowing the type of stone makes treatment more specific and successful. For example, the presence of ammonium biurate crystals in a dog with bladder stones suggests the presence of an abnormal liver blood vessel, and the presence of struvite crystals in a dog with a urinary tract infection and bladder stones suggests struvite stones. In addition to filtering the blood to remove waste products from the body, the kidneys help maintain the body’s water balance. Drink too much and they excrete the excess, drink too little and they hang on to every molecule of water they can. When the kidneys don’t work well, they lose the ability to dilute and concentrate the urine. Measurement of a urine specific gravity, part of a routine urine test, helps veterinarians assess the kidney’s ability to dilute and concentrate and is a partial measure of kidney health.

So much information from something you, the pet owner thought was just an accident. No wonder I am crazy about getting that urine sample from your pet.


Is Chronic Kidney Disease the Same as Chronic Renal Failure?

January 14, 2015

chronic renal failure chronic kidney disease

One of @amcny’s Twitter followers posted the question that is the title of this post. This person also asked, “Should the high end of the normal range of creatinine be 2.4?” These are very good questions, especially for cat families since cats are seven times more likely to have kidney disease than dogs. I am devoting this week’s blog to the answers.

Kidney Tests
A standard panel of blood tests includes measurement of blood urea nitrogen and creatinine. These tests are commonly used to evaluate kidney function, but the results can be abnormal with dehydration, intestinal bleeding and a high protein diet. When combined with a physical examination and an analysis of the pet’s urine, they become a more powerful assessment of how well the kidneys work.

For many years, when veterinarians discovered elevations in blood tests to measure kidney function, we talked with pet families about chronic renal failure or CRF, and before that we talked about chronic interstitial nephritis or CIN. Today we more commonly use the term chronic kidney disease or CKD. As time passed, the name has changed to more correctly reflect our understanding of the disease. Chronic interstitial nephritis comes from microscopic evaluation of a kidney biopsy, something most pets never have. Chronic renal failure was a confusing term to pet owners who were unfamiliar with the medical term for kidney – renal. Failure was a misnomer since the abnormal blood tests indicate decreased function, but not necessarily an absence of function or failure. Thus, renal became kidney and failure was swapped out for disease.

If There is Chronic, There is Also Acute
In medicine, if a disease has the modifier “chronic” you can bet there is also an ”acute” form of the same disease. Acute renal failure has a very abrupt onset in a decline of kidney function and is caused by a variety of disorders including leptospirosis, antifreeze ingestion and lily intoxication. Some pets with acute renal failure completely recover; others improve but continue to have chronic kidney disease and sadly, others don’t make it. The term chronic indicates a long term process that may or may not get worse, but one that, with treatment, can achieve a good quality of life.

Is 2.4 the High End of Normal Range for Creatinine?
Normal range is another term largely gone from the veterinary lexicon because normal depends on the age, sex and even breed of the dogs or cats used for comparison. Now we use the term “reference range or reference interval.” The upper end of the reference range is variable from lab to lab, based on testing methodology, equipment and the exact animals used to develop it. Perhaps more important than the exact reference range from the lab is what is normal for your pet, i.e. what was the creatinine last year and the year before and is the number trending upwards? When that happens, it suggests decreased kidney function and suggests more testing may be indicated.

Thank you to our Twitter follower for asking such important questions. If you are interested in more information about what blood tests tell your veterinarian about your pet’s health, read this recent blog on blood testsLearn more about feline kidney disease.


Adrenal Gland Yin and Yang

March 5, 2014

puppy-yinyangLast week was a big week for adrenal gland disorders at The Animal Medical Center. Not one, but three dogs were admitted by The Animal Medical Center’s 24-hour Emergency Service with a diagnosis of Addison’s disease, or hypoactivity of the adrenal gland. Additionally, I evaluated two of my patients for adrenal gland hyperactivity, or Cushing’s disease.

Small but Mighty
Adrenal glands are tiny organs, one sits atop of each kidney. The normal width of a dog’s adrenal gland is less than half an inch. In cats, adrenal glands are half that size. Small compared to the liver or kidneys, these glands are powerhouses pumping out an array of hormones critical to maintaining normal homeostasis. Because the adrenal glands produce so many different hormones, either condition hypo- or hyperactivity can cause a wide variety of serious clinical signs. The hormone most important in Cushing’s and Addison’s disease is cortisol.

Poodle Problem
Two of last week’s ER patients with Addison’s disease were poodles. This was no coincidence. Addison’s disease is inherited in the Standard Poodle and also the Portuguese Water Dog, Nova Scotia Duck Tolling Retriever and the Bearded Collie. Cats very rarely develop Addison’s disease. What is strange about the dogs at AMC is the diagnosis of Addison’s disease in three dogs in one week, since the prevalence of the disease in dogs is thought to be 0.6-0.28% of all dogs. Dogs with Addison’s disease have vague, nonspecific clinical signs such as vomiting and diarrhea. One reason your veterinarian performs blood tests when your dog has vomiting and diarrhea is to identify the characteristically low blood concentrations of sodium and chloride and the high concentration of potassium, classic for a diagnosis of Addison’s disease. The consequences of missing a diagnosis of Addison’s disease are dire. Dogs become progressively dehydrated and the potassium climbs to levels which can stop the heart from beating. The AMC ER has a machine which can test blood concentrations of sodium and potassium in minutes, speeding the diagnosis of Addison’s disease.

Too Much Water; Too Much Pressure
The adrenal glands of dogs with Cushing’s disease produce too much of the hormone cortisol, either because of an adrenal tumor or because the pituitary gland in the brain forgets to tell the adrenal glands to stop producing cortisol. The two patients I evaluated for Cushing’s disease had different medical problems. One dog had an increased amount of protein in her urine, high blood pressure, and an elevated liver test. All three disorders are known to occur as a result of Cushing’s disease. The other dog was drinking too much water and having accidents in the house — two more signs of Cushing’s disease. Neither dog had hair loss, but it is another common problem we see in dogs with an overactive adrenal gland. Cushing’s disease, like Addison’s disease, is rare in cats.

Giving and Taking Away
Treatment for these two opposite diseases is opposite! For Addison’s disease we give hormones, and for Cushing’s disease we take the hormones away by suppressing the adrenal glands. Dogs with Addison’s disease respond rapidly to either oral or injectable forms of the missing adrenal hormones. Treatment of dogs with Cushing’s disease takes a month or two, while oral medications are adjusted to individualize the dose for each dog.

Recognizing the Yin and Yang of Adrenal Gland Disease in Your Dog
Even though Cushing’s disease is more commonly seen than Addison’s disease, both diseases can be readily diagnosed with blood tests. Your veterinarian will suggest testing if your dog is showing the following signs:

Cushing’s Disease

  • Excessive drinking and urinating
  • Hair loss on the trunk
  • Elevated liver tests
  • High blood pressure
  • Protein in the urine
  • Pot-bellied appearance

Addison’s Disease

  • Waxing/waning vomiting and diarrhea
  • Poor appetite
  • Weight loss
  • Anemia
  • High blood potassium
  • Low blood sodium and chloride

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