Hypocalcemia - Low blood calcium levels in Dogs

Low blood calcium levels (hypocalcemia), rapid decline lead to death in German Shepherd

Question: Dear Dr. Richards Last Monday our 6 1/2 year old German Shepherd Omar began feeling very lethargic. She lost her appetite and was continuously thirsty but wasn;t interested in doing anything else. Several trips to the vet indicated that her blood was normal i.e. white counts, etc but she had a low blood calcium level. Her urine was green in colour. A calcium injection was given to her on the Wed and she perked up but then her blood calcium dropped after a day. On Thursday her condition deteriorated and her heart rate and blood pressure dropped. She died on Thursday evening and we miss her terribly. We think that she had a growth on her parathyroid gland. She was apparently very healthy and happy until last Monday. What do you think?

Regards, Steve

Answer: Steve-

Low blood calcium levels (hypocalcemia) can be indicative of a number of conditions so there are other possibilities. In addition, calcium is one of the lab values that seems to have a high error rate in lab testing. Finally, calcium is bound to albumin (a form of protein) in the blood stream and if albumin levels are low, total calcium levels will be low but ionized calcium (the active form) are normal. In this case, the hypocalcemia is a false finding even though the lab is correctly reporting the measured calcium levels.

To correct for calcium levels to compensate for albumin levels, using a formula. One example of this is: Adjusted calcium = (Measured Calcium - albumin) + 4.

To give you some idea of how this works, if the calcium level is 6.5, but the albumin level is 1.4, then the adjusted calcium level is: (6.5 - 1.4) + 4 = 5.1 + 4= 9.1

The most common causes of protein levels falling low enough to cause low total calcium levels are intestinal disease in which protein is not absorbed or leaks back out of the intestines, glomerulonephritis in which protein leaks out of the kidneys and liver failure in which proteins aren't manufactured from amino acids by the liver. In German shepherds, protein losing enteropathies have to be considered as a possible cause of the symptoms seen in Omar.

Assuming that the calcium level was actually low, though, these are some of the possible diagnoses:

Hypoparathyroidism, acute pancreatitis, kidney failure in which no urine production is occurring, nutritional secondary hyperparathyroidism, and renal (kidney origin) secondary hyperparathyroidism, rapidly growing bone tumors (can also cause increases in calcium), deficiency of Vitamin D and thyroid gland tumors (sometimes produce calcitonin, a hormone that causes drops in calcium levels).

I would consider acute pancreatitis among the differential diagnoses in Omar's case, because it can lead to a sudden loss of appetite and then increased drinking and urinating if an intestinal obstruction or absorption of toxins from the GI tract occurs.

Hypoparathyroidism is also possible. When hypoparathyroidism occurs, the albumin level is usually normal, the blood urea nitrogen and creatinine are usually normal, lipase and amylase are usually normal (helps to rule out pancreatitis), phosphorous is usually increased, parathormone (requires special testing) is usually decreased and there is usually not a tumor of the parathyroid gland but a degenerative process, lymphocytic/plasmacytic atrophy, that is thought to be an immune mediated disorder. The clinical signs of hypoparathyroidism include seizures, muscle tremors, difficulty walking, excessive panting, sometimes increases in drinking and urinating and sometimes restlessness.

Primary hyperparathyroidism is often caused by cancer of the parathyroid glands but in this disorder there is usually an increase in calcium levels rather than a decrease. The symptoms are about the same as for hypoparathyroidism, though. These include seizures, loss of appetite, muscular weakness, apathy, stiff gait, shivering or tremoring and increased drinking and urinating that is probably at least partially due to the high blood calcium levels.

It is not really possible to tell you which of these conditions was most likely. I am not sure what to make of the urine color as a clinical sign. This may mean something that is escaping me at the present time, too. The only causes I know of for green urine are increases in bilirubin, which should have shown up in the blood work, too, and administration of methylene blue dye, which doesn't seem likely at all.

The most likely problems would seem to be low albumin levels from kidney disease or intestinal disease leading to low total calcium level, acute pancreatitis (usually the patient seems really sick with this illness) and hypoparathyroidism, but that is still a pretty long list, especially since some of the other problems are definitely possible, too.

I hope that this helps some in understanding the things that might have happened, though.

Mike Richards, DVM 8/20/2001

Last edited 01/30/05


Michael Richards, D.V.M. co-owns a small animal general veterinary practice in rural tidewater Virginia. Dr. Richards graduated from Iowa State University's College of Veterinary Medicine in 1979, and has been in private practice ever since. Dr. Richards has been the director of the PetCare Forum...