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Pet Doc
Pet Doc, Veterinarian
Category: Veterinary
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Experience:  Veterinarian - BVSc
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If a senior dog has a high level of calcium in their blood,what

Customer Question

If a senior dog has a high level of calcium in their blood,what should we be looking for as the cause?
Submitted: 6 years ago.
Category: Veterinary
Expert:  Pet Doc replied 6 years ago.
Hi there,

Thank you for your question regarding your 11 year old Lab boy who has hypercalcemia (high blood calcium). There are a range of possible causes for this elevation - some are nothing to worry about, whilst others would definitely be of concern.

If the level isn't much more than the upper limit of normal, then we often disregard this, as often the lab results can be a little out on the calcium reading. This would only be the case with a very very mild increase however. Other causes for a mild increase would be a dietary cause (i.e. feeding a diet very rich in calcium - like many bones for example).

One of the main concerns of hypercalcemia in an old dog like yours, it hypercalcemia of malignancy. Some tumors have a 'side effect' of causing other problems throughout the body. These are termed 'paraneoplastic syndromes'. There are a couple of tumors that can occur in older dogs that cause high blood calcium. One is a tumor called an apocrine gland adenocarcinoma of the anal gland. If this was the cause of the increased blood calcium, I would expect the anal gland to be enlarged and/or thickened. Your Vet should definitely palpate both anal glands and if there is swelling or enlargement here - then this is the likely cause. The other two tumors that can cause hypercalcemia are lymphoma and multiple myeloma. Hopefully your Vet has palpated all this boy's lymph nodes and hopefully the rest of the bloods results look ok.

I am assuming this boy's kidney enzymes were ok as well. If so then this pretty much rules out hypercalcemia as a result of kidney failure - another common cause for this problem. There is also a condition known as primary hyperparathyroidism which causes hypercalcemia. This is where the parathyroid gland (responsible for calcium in the body) becomes enlarged causing an excessive amount of the hormone the increases the calcium level in the blood to be released. To rule this out your Vet can check the serum PTH (parathyroid hormone) level.

Finally - a syndrome called Addison's disease (hypoadrenocorticism) can also cause hypercalcemia. Your Vet will likely know of this condition and usually we get other signs of this on the bloodwork and from symptoms. This would be less likely, but if your Vet was suspicious, they would need to carry out an ACTH stimulation test.

All of this may be a little confusing, but for a more thorough explanation of all of this - please go to:

This also runs through some of the less common causes of the problem.

Definitely get your Vet to palpate all lymph nodes as well as this boy's anal glands, as lymphoma or an anal sac tumor definitely needs to be ruled out asap.

I hope this helps and best of luck with this boy. Definitely follow up on this high calcium level. Hopefully it is nothing to worry about - but in an older boy it definitely pays to double check everything!

Just reply if I can give you any more help.

Thanks and please now click ACCEPT.

Kind Regards,

Dr M D Edwards
Customer: replied 6 years ago.
Thank you for your answer. His blood work also showed:
Low phosphorus(2.3)
High ph(7.5)
Everything else was normal range

The dog has a large softball size growth in his neck under his fur. All rumors were previously tested and came back as far. Itching his neck area is the only sympthon that he has displayed other than increased water intake and frequent urination.
Would it be worth exploring whether the neck tumor is interfering with the parathyroid glands?
Expert:  Pet Doc replied 6 years ago.
Hi again,

That calcium level IS high. With the phosphorus being low, it definitely would pay to ensure he doesn't have a parathyroid issue. The parathyroid may or may not be affected by this mass - but it is definitely worth checking the serum PTH level to help rule this out. Hopefully your Vet has already taken a fine needle aspirate biopsy or full incisional biopsy of the mass on his neck to make sure it isn't a large lymph node or adenocarcinoma of the thyroid or parathyroid. Definitely get this done as well if it hasn't been done already.

Best of luck following this up and I would be very interested to hear the final verdict if you don't mind letting me know in the coming days.

Kind Regards,

Dr Edwards
Pet Doc and other Veterinary Specialists are ready to help you
Customer: replied 6 years ago.
Just getting back to you. It is cancer. I have decided to go the natural route. I have changed his dog food as I was told that grain based foods feed cancer. I visited a holistic vet and came away with numerous prescriptions. She prescribed Cartrophen injections(weekly). It appears from online information that this medicine can accelerate cancer. It doesn't feel like a good fit. Do you know anything about Cartrophen?
Expert:  Pet Doc replied 6 years ago.
Hi again,

Sorry to hear about your boy's diagnosis. You correct in that cartrophen is actually contraindicated in dogs with cancer. Cartrophen is really good for joints and helps improve the blood flow to the joints, in turn helping remodelling of joint cartiledge. The only problem is that cartrophen can also increase blood flow to tumors as well. This is the reason we generally try to avoid it's use in dogs. More info can be found on the data sheet if the holistic Vet needs further info.

Your boy may be better off with anti inflammatory pain relief if deemed appropriate and ok for his current condition by your regular Veterinarian.

I hope this helps and good on you for double checking.

Kind Regards,

Dr Edwards
Customer: replied 6 years ago.

Thanks for the response. Cartrophen was actually administered on 10/1. I took him to a holistic clinic.Four days later he stopped eating completely and struggled to walk. On the 7th, I took him in for a second injection and acupuncture. He could not use his rear legs after this and needed assistance to leave the clinic. It was rapidly downhill after this. He would not eat or drink and could barely walk. He tried to throw up but couldn't. He could wag his tail. We put him down on Monday. Our regular vet was surprised at the deterioration. He believed he had at least 6 months.

After our vet expressed his surprise(he did not know that I had gone to the other clinic), I went online to read about Cartrophen. I was sickened to read that I was the cause of my dogs rapid demise.

Expert:  Pet Doc replied 6 years ago.
Oh - sorry to hear about your boy :-( It is hard to just blame Cartrophen for his rapid deterioration. I am not completely sure (and you would have to contact the company who makes the drug), but I imagine the effects on accelerating tumours would be more of a mid to long term effect rather than a very short term one as would have to have been the case for your boy. It sounds like he must have had quite an aggressive form of tumour - particularly with the high level of calcium.

All the same this must be very upsetting for you.


Dr Edwards