Section:
Overview Hypercalcemia
refers to an abnormally high blood concentration of calcium. Blood
calcium concentrations are measured in milligrams (mg) per deciliter
(dl). One hundred milliliters equals one deciliter. Normal values for
blood calcium concentration vary slightly from one laboratory to
another but approximately 9.0 to 11.6 mg/dl is considered normal in
adult dogs. Normal blood calcium concentration can be slightly higher
in puppies less than six months of age. Blood calcium concentrations
above 13.0 mg/dl are abnormal and warrant diagnostic evaluation and
treatment.
Some relatively
common (and benign) situations can cause erroneously high blood calcium
concentrations to be reported by the laboratory depending on the
analyzer used. Examples include blood samples with high fat content
(lipemia) due, for example, to collection of blood soon after a meal or
release of hemoglobin from the red blood cells during processing of the
blood (hemolysis).
Certain
anticoagulants and detergents used to clean laboratory glassware also
may cause erroneously high blood calcium concentrations to be reported.
In these situations, the blood calcium concentration should be
determined again using a properly collected blood sample that is free
of lipemia and hemolysis.
Dehydration is a
common clinical situation that can result in mildly increased blood
calcium concentration. Blood calcium concentration should be
re-evaluated after the patient has been rehydrated by intravenous or
subcutaneous (under the skin) administration of fluids.
What
to Watch For
Loss of appetite
Increased urine
production
Vomiting
Weakness
Lethargy
Dehydration
Diagnosis A thorough
diagnostic evaluation of the dog is necessary if hypercalcemia persists
after correction of lipemia, hemolysis and dehydration, because high
blood calcium concentration can be a marker of some serious underlying
disease processes including several different types of cancer. Routine
laboratory testing provides information about the total concentration
of calcium in the blood. It also may be necessary, however, for your
veterinarian to have the laboratory measure the component of
blood calcium (ionized calcium). This component contributes to many of
the clinical symptoms and physiologic consequences of hypercalcemia.
The symptoms of
hypercalcemia are nonspecific. Diagnostic tests are needed to recognize
hypercalcemia and exclude other diseases causing similar symptoms.
Tests may include:
A complete
medical history and physical examination. The medical history will
include questions about changes in water consumption and urination,
change in appetite, weight loss, previous illnesses, medications being
given, and exposure to toxins such as vitamin D-containing rat poison,
vitamin D-containing topical ointments or toxic plants. Physical
examination may include palpation of the abdomen to evaluate for
enlargement of the liver or spleen, palpation of lymph nodes located
under the skin to detect enlargement, palpation of the anal sacs to
detect masses because one important cause of hypercalcemia is cancer of
anal sac glands, and listening to the chest with a stethoscope.
A complete blood
count (CBC) to evaluate red blood cell count and rule out anemia and
blood protein concentration
Serum
biochemistry tests to evaluate your dog's general health and determine
the effects of hypercalcemia on other body systems, especially the
kidneys
Urinalysis to
evaluate the effects of hypercalcemia on the ability of the kidneys to
concentrate urine
Blood ionized
calcium concentration to evaluate the biologically active form of
calcium
Treatment Treatment for
hypercalcemia is determined by the underlying cause and the severity of
your dog's hypercalcemia and its effects on kidney function. Emergency
treatment may be necessary when blood calcium concentration is very
high. This may include hospitalization for intravenous fluid therapy
and drug treatment.
Serious damage
to the kidneys and mineralization of soft tissues can occur if very
high blood calcium concentration is allowed to persist.
Home
Care and Prevention Administer any
medications prescribed by your veterinarian. Follow-up with your
veterinarian for physical examinations and repeated testing of blood
calcium concentration.
If the
underlying cause of hypercalcemia is not identified on initial
evaluation, or if your dog responds inadequately to treatment, further
diagnostic evaluation and treatment will be necessary.
Make sure your
dog has free access to ample amounts of fresh drinking water. Avoid
exposure of your dog to toxins known to cause hypercalcemia such as
vitamin D-containing rat poisons, topical ointments containing vitamin
D-like compounds like calcipotriene, and plants such as day-blooming
Jessamine (Cestrum diurnum), Solanum malacoxylon and Trisetum
flavescens.
Section:
Information In-depth Several serious
medical conditions can result in hypercalcemia. It is important to
identify the underlying cause of hypercalcemia in your dog so that
effective treatment can be instituted. Disorders that can cause
hypercalcemia include:
Lymphosarcoma, a
type of cancer
Chronic kidney
failure sometimes caused by hereditary kidney disease
Primary
hyperparathyroidism, which is overactivity of the parathyroid gland
usually due to a benign tumor called an adenoma
Hypoadrenocorticism,
also known as Addison's disease, which is a hormonal disorder caused by
insufficient production of steroid hormones by the adrenal glands
Apocrine gland
adenocarcinoma of anal sac, or a cancer of the glands of the anal sacs
Vitamin D
intoxication caused by consumption of vitamin D-containing rat poison
Vitamin D
intoxication caused by consumption of vitamin D-containing plants such
as day-blooming Jessamine (Cestrum diurnum)
Vitamin D
intoxication caused by consumption of topical ointments containing
calcipotriene used to treat psoriasis in people
Multiple
myeloma, which is a cancer of antibody-producing cells called plasma
cells
Other cancers
including squamous cell carcinoma, thyroid adenosarcoma, nasal
adenocarcinoma, mammary gland adenocarcinoma, and others
Acute kidney
failure
Granulomatous
diseases, which refer to a specific type of inflammation, such as
blastomycosis (fungal infection). In these diseases, inflammatory cells
(called macrophages) are thought to produce vitamin D-like chemicals.
Osteomyelitis,
bacterial infection of bone
Overactivity of
the parathyroid glands due to nutritional disturbances
Dehydration with
increased blood concentrations of albumin, a major protein of the blood
Hypercalcemia
can occur normally in young growing dogs.
Section:
Diagnosis In-depth Veterinary care
should include diagnostic tests and subsequent treatment
recommendations. Diagnostic tests must be performed to confirm the
cause of hypercalcemia and exclude other diseases. The following
diagnostic tests may be recommended:
A complete
history and physical examination. The history will include questions
about changes in water consumption, urination, appetite, and weight and
questions about reproductive status – whether your pet is sexually
intact or neutered. Your veterinarian will also ask about previous
illnesses, previous medications, exposure to rat poison or toxic
plants. Physical examination will include palpation of the abdomen to
evaluate for enlargement of the liver or spleen, palpation of the
peripheral lymph nodes lying under the skin in various locations, and
listening with a stethoscope to the chest to evaluate the heart and
lungs.
A complete blood
count (CBC), serum chemistry tests and urinalysis.An ionized calcium
blood test also may be useful because the free (or ionized) calcium in
the blood has important biological effects that contribute to the
damaging effects of hypercalcemia in the body.
Your
veterinarian may recommend additional diagnostic tests to exclude or
diagnose other conditions or to better understand the impact of
hypercalcemia. These tests insure optimal medical care and are selected
on a case-by-case basis. Examples include:
Microscopic
examination of lymph node samples collected by needle aspiration or
biopsy
Microscopic
examination of a bone marrow sample
Ionized calcium
blood test to evaluate the biologically form of calcium
Abdominal X-rays
to evaluate for liver or spleen enlargement
Chest X-rays to
evaluate for tumors or lymph node enlargement
Biopsy of any
tumor masses found during physical examination
Ultrasound
examination of the neck to evaluate the parathyroid glands and lymph
nodes
Ultrasound
examination of the chest to evaluate for tumors or enlarged lymph nodes
Ultrasound
examination of the abdomen to evaluate for enlargement of lymph nodes,
liver or spleen
X-rays of the
skeleton to evaluate for tumors
Measurement of
parathyroid hormone concentration in blood to evaluate for overactivity
of the parathyroid glands
Adrenocorticotropic
hormone (ACTH) stimulation test to evaluate the function of the adrenal
glands and exclude the possibility of hypoadrenocorticism or Addison's
disease
Measurement of
the blood concentration of a substance called parthyroid
hormone-related peptide (PTHrP) that serves as a marker of
hypercalcemia caused by cancer
Blood
concentration of vitamin D to evaluate for vitamin D intoxication
The decision to
perform some diagnostic tests will be made based on the likelihood of
specific disease processes. Your veterinarian will make these decisions
on the basis of your dog's medical history and physical examination
results. Some underlying disorders that may cause hypercalcemia and
prompt your veterinarian to run specific tests include:
Lymphosarcoma.
This malignancy is the most common cause of hypercalcemia in dogs and
diagnosis is based on a positive biopsy or cytology results obtained
from enlarged lymph nodes, liver, spleen, kidney or bone marrow. X-rays
of the chest and abdomen are often performed. Approximately 40 percent
of dogs with hypercalcemia caused by lymphosarcoma have a mass or
enlarged lymph nodes in the chest that can be identified on X-rays.
Hypoadrenocorticism.
Addison's disease may result in hypercalcemia in up to one-third of
affected dogs. The diagnosis is based on failure of the adrenal glands
to respond to stimulation by the hormone adrenocorticotropin (ACTH).
Kidney failure.
Affected dogs also typically have high blood concentrations of
phosphorus and waste products used to assess kidney function, including
blood urea nitrogen (BUN) and serum creatinine. The kidneys can be
damaged by persistent hypercalcemia, and sometimes it is difficult to
determine if the kidney disease caused the hypercalcemia or the
hypercalcemia caused the kidney disease.
Primary
hyperparathyroidism. Overactivity of the parathyroid gland can cause
marked hypercalcemia in dogs that may have no symptoms other than
increased water consumption and urination. Such dogs usually have low
or normal blood phosphorus concentrations, as opposed to those with
kidney failure and hypercalcemia. The serum concentration of ionized
calcium usually is high in affected dogs. A high serum parathyroid
hormone (PTH) concentration in a hypercalcemic dog supports a diagnosis
of primary hyperparathyroidism. Ultrasound examination may allow
identification of enlarged parathyroid glands. In normal dogs, the
parathyroid glands usually are not visible on ultrasound examination.
The parathyroid
hormone-related peptide (PTHrP) test may identify cancer as the
underlying cause of hypercalcemia.
Approximately 20
percent of dogs with multiple myeloma, which is cancer of the
antibody-producing plasma cells, have hypercalcemia, which may arise
from the bone destruction caused by these tumors. The diagnosis is made
by abnormal results of bone X-rays that appear as lucent or black areas
in the normally appearing bony structure, a very high concentration of
one specific blood protein (monoclonal gammopathy) identified on a
serum protein electrophoresis test, increased numbers of
antibody-producing plasma cells in the bone marrow, and fragments of
the antibody protein molecules in the urine (Bence Jones proteins).
Vitamin D
intoxication and hypercalcemia can be caused by consumption of vitamin
D-containing rat poisons, vitamin D-containing plants (Cestrum diurnum,
Solanum malacoxylon, Trisetum flavescens), or topical ointments
containing a vitamin D-like chemical called calcitpotriene. Diagnosis
is based on history of exposure. Blood concentration of vitamin D can
be measured if necessary.
Section:
Treatment In-depth Initial therapy
should be aimed at the diagnosis and treatment of the underlying cause
of the hypercalcemia. Treatment of hypercalcemia must be individualized
based on the severity of the condition and its underlying cause.
Moderate to
severe hypercalcemia is a medical emergency because hypercalcemia has
adverse effects on several organ systems, notably the kidneys, heart,
nervous system, and intestinal tract. The decision to begin aggressive
medical therapy is based on clinical symptoms, abnormalities of kidney
function, abnormalities on the electrocardiogram (ECG), and nervous
system abnormalities.
Symptomatic dogs
– those with increased water consumption and urination, loss of
appetite, and lethargy – that have calcium concentrations greater than
15 milligrams per deciliter (mg/dl) of blood require immediate
treatment. Such dogs are at risk for mineralization of their soft
tissues, including their kidneys.
Emergency
Treatment Intravenous
administration of fluids, usually physiologic salt solution,
facilitates the excretion of calcium in the urine.
Administration
of the diuretic drug [furosemide (Lasix®) also facilitates
excretion of sodium and calcium in the urine.
Cortisone-like
drugs (prednisone) can limit bone release of calcium, decrease
intestinal absorption of calcium, and increase excretion of calcium in
the urine. These drugs can have a direct toxic effect on some cancer
cells, specifically, malignant lymphocytes, and, if at all possible,
they should not be given until a definitive diagnosis has been made.
A new class of
drugs called diphosphonates can be given to decrease bone release of
calcium.
Many other drugs
(some with potentially serious adverse effects) may be required to
treat dogs with refractory hypercalcemia. Examples include mithramycin,
calcitonin, and ethylenediametetraacetic acid (EDTA).
Above all it is
crucial to treat the underlying disease process that is causing the
hypercalcemia.
Section:
Follow-up Optimal
treatment for your dog requires a definitive diagnosis and a
combination of home and professional veterinary care. Follow-up is
crucial and may include the following:
Administer any
veterinary prescribed medications.
Allow your dog
unlimited access to fresh clean water
Follow-up with
your veterinarian for examinations and repeated measurements of blood
calcium concentration.
Other
recommendations will be determined by the underlying cause of the
hypercalcemia.
Contact your
veterinarian immediately if you experience difficulty treating your dog.
This article has been provided
courtesy of PetPlace.com
(www.petplace.com), the
definitive online source for pet news, health,
and wellness information.
The above information is simply informational. It's intent is
not to replace the advice of a veterinarian nor to assist you in making
a diagnosis of your pet. Please consult with your own veterinarian for
confirmation of any diagnosis. Your pets life may depend on it.
