What is Low Production of Parathyroid Hormone?
The parathyroid glands, which are located on the sides of the front of your dog’s throat (near the thyroid glands), are important in regulating the level of calcium in the blood. If your dog has hypoparathyroidism the level of calcium decreases (hypocalcemia) which is a dangerous condition if not treated. Just as with people, your dog needs calcium in his blood for more than just strong bones. It is also needed to build muscle, assists in nerve transmissions, and it is even needed for your dog’s heart to beat correctly. Hypocalcemia is a serious disorder that can be a life-threatening emergency if not treated because, as previously mentioned, calcium is necessary for nerve transmission and heart contractions. German shepherds, Terriers, Retrievers, and Schnauzers are most often found to have hypoparathyroidism and it is also most common in dogs between five and 15 years old.
Low production of parathyroid hormone, or hypoparathyroidism, is a metabolic condition in which your dog’s parathyroid hormone (PTH) is abnormally low. Hypoparathyroidism can be a primary disease or a secondary disorder caused by one of several different diseases, infection, or injury. Primary hypoparathyroidism is not common and is almost always caused by lymphocytic parathyroiditis. Although the disorder can be serious if left untreated, the treatment is simple and effective. With secondary hypoparathyroidism, the treatment and prognosis depends on the underlying condition. Any age and breed can have hypoparathyroidism, but there is a breed and age predisposition.
Symptoms of Low Production of Parathyroid Hormone in Dogs
With primary hypoparathyroidism you may not notice any symptoms until the disorder has been present long enough to cause hypocalcemia. The most common signs of hypocalcemia are:
- Appetite loss
- Rubbing head against walls or objects
- High body temperature
- Heavy breathing
- Muscle twitches
- Abnormal walk
Symptoms of secondary hypoparathyroidism depend on the underlying cause of the condition, but can include:
- Anxiety and restlessness
- Abdominal swelling
- Excessive panting
- Muscle tremors
- Increased urination and increased thirst
- Primary hypoparathyroidism is caused by lymphocytic parathyroiditis
- Secondary hypoparathyroidism is caused by an underlying disorder
Causes of Low Production of Parathyroid Hormone in Dogs
Primary hypoparathyroidism is caused by an immune related disorder called lymphocytic parathyroiditis, which is a condition caused by chronic hypercalcemia. In this condition, the tissue in the glands is replaced by lymphocytes (groups of white blood cells). Secondary hypoparathyroidism can be caused by many conditions including:
- Chemotherapy or damage to the glands from cancer treatment
Diagnosis of Low Production of Parathyroid Hormone in Dogs
The veterinarian will do a complete and thorough physical exam, which will include your dog’s weight, blood pressure, temperature, pulse rate, and respirations. During the exam, he will pay special attention to the glands on the underside of your dog’s neck. Be sure to tell the veterinarian all of the symptoms you have seen and how long they have been going on as well as your dog’s medical history.
Next, the veterinarian will do a urinalysis, a blood chemistry panel (including calcium levels), complete blood count (CBC), and a PTH concentration measurement. The veterinarian will also get radiograph (x-ray) views of your dog’s throat to rule out tumors and damage to the thyroid, thyroid glands, or parathyroid glands.
Treatment of Low Production of Parathyroid Hormone in Dogs
If your dog’s calcium level is low enough to cause the symptoms that brought you there, hospitalization will be in order in order to allow for a slow influx of IV fluids and calcium. Increasing the level of calcium is the only effective treatment to raise the calcium level and it is essential to introduce the calcium with vitamin D slowly to decrease the chances of heart irregularities (beating too fast) or heart attack from a sudden flood of calcium.
If the hypoparathyroidism is found during a routine examination, and the level is not lower than 6mg/dl, your veterinarian will give your dog oral calcium supplements at a high level (about 25 to 45 ng/kg/day) for several days and then 5 to 25 ng/kg/day divided into two doses every day for life. Vitamin D will also be given orally at a high dose (4,500 to 6,500 U/kg/day) for several days and then 1,000 to 2,500 U/kg daily for life.
Recovery of Low Production of Parathyroid Hormone in Dogs
Your dog’s outlook is excellent as long as you continue to give him the medication exactly as prescribed for a lifetime. This is a chronic condition that is not curable, so if you stop giving your dog the medication, the level of calcium will drop just as before. You will also have to bring your dog to the veterinarian every three or four months to get the calcium level checked. The veterinarian may have to adjust the amount of medication your dog needs depending on his age and health.