Panting and Excessive Panting in Dogs

Excessive panting in Alaskan Malamute

Question: Dr Mike,

I'm a VetInfo subscriber who has a 140lbs, neutered male Alaskan Malamute named Doc who's 8.5 years old. I guess my major heartfelt concern for him is that he is what I would call, excessively panting which seems to have started well over a year ago. He does also seem to salivate more than he used to. On average he pants about 170-230 times/minute (#pants in 6 seconds x 10). it's like he just finished a marathon. These are short rapid breaths he experiences even during bedtime. He does have difficulty going to sleep and it not only wakes him up several times a night but both my wife and me as well. Lately he seems to be having trouble controlling his bowels and has difficulties with his back legs (slow to sit).

I have discussed the panting at great length with my vet and have passed Doc through many tests. We have performed the following tests: ECG, chest X-rays, abdominal x-rays, cardiac ultrasound, abdominal ultrasound, endoscopy of his throat down most of his esophagus, basic blood chemistries, urinalysis, thyroid enzyme test (T4), ATCH, low dose dex. All his blood and urinalysis readings have been pretty much within the normal ranges except for the following: AMYL which has gone from 1474 U/L a year ago to around 667 now, CHOL 469mg/dl to 236, ALKP 249 U/L to 429 & ALT 134U/L to 366.

The end of his tail was starting to loose hair which prompted the vet to do the T4 test. It did reveal he had hypothyroidism. We then put him on Soloxine 1.2mg BID. This got his level to the top of normal range. Since this was at the top of the norm, we elected to drop his dosage to 0.4mg BID. This only moderately helped the panting and only for a short term. Consequently, we returned to 0.8mg BID a year later.

I don't know that he actually drinks more water than he used to but late last summer the vet was suspecting Cushing's disease. This prompted the additional blood work and the abdominal ultrasound. (by the way, the ultrasound was done by an Internal specialist - she was concerned about Cushing's because she thought the adrenal glands looked too large to her - 5cm I believe). The low dose dex test we ran twice with the second one 9 months later. The results from the 1st test are Pre 79nmol/L, 4hr 31 & 8hr 65 while the results from the 2nd test are Pre 92, 4hr 27 & 8hr 38. The ACTH test was done a few weeks before the first low dose dex a year ago with its results being: Pre 60, Post (2hr) 494.

The endocrinologist in Michigan who did the lab work on the dex tests said that the 8hr result was borderline and could be caused by stress and most likely not Cushing's. Because it was harmless (more or less) my vet and I tried Anipryl for two months with no improvement last August. I think the second test 9months later would seem to confirm that Cushing's is not the problem as the numbers don't indicate a progression of this condition.

I had his dental vet check his throat with a scope because 2 years earlier he had a non-cancerous growth in his throat and because when Doc breaths I can hear something rasping like someone who has a cold with flem. The endoscopy revealed nothing. The dental vet thinks the sound may be the excessive saliva draining into the back of his throat.

What do you think about canine hip dysplasia? His back end does on occasion go out from underneath him. Or perhaps it's just a bad case of arthritis. I know Northern breeds are tolerant of pain and we even tried a 2-week regimen of Rimadyl with no real progress (it didn't curb the panting). I'm starting to grab at straws here contemplating taking him to the Oklahoma State University Veterinarian College and have a CAT scan done or at least see an orthopedic specialist.

Any ideas would be appreciated here, as I'm pretty lost at this point. Thanks so much for your time and sorry for this being so long.

Sincerely, Steve

Answer: Steve-

I am a little confused by your note, but that may be because I don't have the normal values from Michigan State at home and have to rely on my memory.

I thought that the normal pre-dexamethasone resting cortisol level was usually between 15 and 115 nmol/L and that the 4 hour and 8 hour post-dexamethasone levels should be less than 30 nmol/L in order to assume adequate suppression. Since you have lab values outside these expected ranges in both tests, even though they are way out of line, I would have a hard time totally ruling out hyperadrenocorticism (HAC).

I thought that the ACTH response tests were the same for resting cortisol level and that the post ACTH response value should be less than 550 nmol/L. However, we draw the blood sample one hour after administration of Cortrosyn (Rx) and your vet might use ACTH gel, in which case the sample is supposed to be drawn at two hours.

Anyway, I would view the blood values as suspicious but not confirming hyperadrenocorticism. I think giving Anipryl (Rx) was reasonable and that the lack of response does make HAC less likely but still does not rule it out, since it only works in about 80% of dogs with pituitary dependent HAC. The ultrasonagrapher's impression of the adrenal gland size is also important and it does suggest a possibility of hyperadrenocorticism. Since Cushing's disease and administration of cortisones are two of the more likely causes of panting behavior, I thought it was worth going through that long explanation! I think it might be worth a visit to the vet school for another opinion on this, or possibly just asking your vet to call and see what their endocrinologist thinks.

A lot of pet owners with obese dogs complain about panting behavior and sometimes the panting is as bad as what you are seeing. It seems likely that 140 lbs. is at least overweight for a malamute but we have seen some really big malamutes in our practice, so I can't be sure of that. If he is overweight enough to be considered obese, though, it can cause this degree of panting all by itself. Weight loss would help his hips a lot, too. This is one of those things that people find hard to believe -- but our practice experience strongly indicates a high correlation between panting and being overweight, so please think about this possibility if Doc is overweight.

Pain can cause panting. Figuring out if there is pain and where the pain is can be pretty hard, but it is worth carefully looking for any other symptoms that might indicate chronic pain, such as lameness, weakness, tremoring, etc. If Rimadyl (Rx) didn't help, this seems somewhat less likely, too. The loss of control of bowel movements and weakness in the rear legs could indicate a problem with the caudal spine (lumbosacral instability, cauda equina syndrome) or possible degenerative myelopathy. I can't recall panting with degenerative myelopathy but I have definitely seen this sign with lumbosacral instability problems, as they can be very painful.

It is very hard for me to identify pulmonary diseases on X-rays, so I always think it is a possible problem even when I have taken X-rays. In addition, laryngeal paralysis sometimes causes panting, although it more commonly causes a roaring breathing sound, sensitivity to heat and even collapse on exertion.

As you can probably tell, I think you and your vets have done a good work-up and examined the obvious possibilities pretty thoroughly. For this reason, I tend to think that letting someone else see the records and the lab tests and review them, as well as getting a fresh look at Doc, would be a good idea. I'd vote for the vet school since they have specialists in radiology, ultrasonography, internal medicine, cardiology and orthopedics, too.

I wish I could help more with this problem.

Mike Richards, DVM 7/26/2000

Heavy panting and overweight

Question: Hi Dr. Mike,

I have a female spayed flat coated retriever that is approximately 2 years old. She is very large for her breed, but she is also about 10 pounds overweight and she weighs in at 90 pounds.

The problem: She breathes hard/pants all of the time and she is an indoor dog. The only time she doesn't pant is when she is in the middle of a hard sleep. We keep our house very cool and she has plenty of water available at all times. Is there any condition that can cause this excessive panting? We're really worried about her. Our other dogs don't do this, but they're not as large.

Her medical history is this: Like all of our dogs, she was a rescued dog - we found her running the streets and she had mange and intestinal worms at 3 months old and she has since been treated and recovered from all of that. I have had her blood tested thoroughly and the main thing they found wrong was hypothroidism, which I have started treating with USP Thyroid. She also has hip dysplasia, but we caught it early enough and are treating it with Glycoflex, Glucosamine and Ligaplex and it doesn't bother her. I also take her swimming in the pool twice a day to build up her legs.

Any ideas on conditions that can cause excessive panting? Or is it just an overweight thing? Or is it a "big dog" thing?

Thanks, Vanessa

Answer: Vanessa-

I would really question a diagnosis of hypothyroidism in a two year old patient. We have diagnosed this problem in pets this young, but I question it every time I am suspicious of it and every time lab values are suggestive of it. If this diagnosis was not made based on free T4 testing using an equilibrium dialysis technique or a combination of free T4 and canine TSH analysis, it would be a good idea to recheck this diagnosis at some time. This would be especially true if the panting showed up after the diagnosis (which doesn't sound like the case), because too much thyroid hormone could lead to panting. It is a good idea to check the T4 level when using thyroxin, just to be sure that hyperthyroidism is not occuring and to be sure that thyroxine supplement is adequate, as well.

Low T4 levels can be the result of any systemic illness, a condition referred to as "euthyroid sick syndrome". It is important to try to be sure that there is not another disorder present when the total T4 measurement is below normal levels but the free T4 measurement is normal.

I think that being overweight is a cause of panting, all by itself, though. We have several obese patients in our practice with this symptom and no discernible cause. I can't think of a thin patient we have had this complaint about except one that we were over supplementing with thyroxine, and the behavior stopped when we readjusted the dose. In a dog in your dog's age range I think that her weight is likely to be the main problem.

Weight also worsens arthritic pain, so it is a good idea to work hard to get her to lose weight, for both the panting and the hip dysplasia. I think we have some dogs in our practice who pant as a symptom of pain. It is hard to be certain of this, but it is my impression.

There are several diseases commonly associated with panting, especially hyperadrenocorticism (Cushing's disease) but this problem is also very unlikely in a two year old patient.

Your vet can help you design a weight control program, if you are unable to cause weight loss by cutting back some on her food and trying to get her to exercise a little more.

Mike Richards, DVM 7/14/2000

Panting and drinking a lot

Q: Our seven-year old Golden Retriever has started panting quite a bit during the last couple of months. He pants when he comes in from outdoors, but he may also start panting when he is just lying in the middle of the living room, and has had no recent exertion. He also drinks a lot of water. The change in the amount of water he drinks has been gradual, but I think he drinks more than he used to. He has also been unsually anxious to go out first thing in the morning during the past few months. We took him to our vet once, and he treated him with antibiotics for a hot spot. Our dog has stopped chewing the hot spot, but he is still panting. Could this be the sign of a more serious condition? Is drinking more water a sign of diabetes in dogs? What are the other symptoms of diabetes? Thanks for your help.

A: Panting excessively is a sign of Cushing's disease (hyperadrenocorticism), may show up with other hormonal diseases such as hypothyroidism, can occur with heart disease and is seen with conditions that result in lowering of the body's ability to carry oxygen -- but most of these are not long term problems. One example would be hemorrhage associated with hemangiosarcomas. We have seen a couple of these in which the owners recognized panting as the first clinical sign. There is usually an acute crisis shortly after that, though. Panting is commonly seen in dogs being treated with corticosteroids such as prednisone.

Drinking more water can be seen with Cushing's disease, kidney failure, diabetes mellitus (sugar diabetes), hypothyroidism, diabetes insipidus and several other conditions. Dogs being treated with corticosteroids also drink more water.

Diabetes usually results in increased hunger, at least early in the disease, and excessive drinking of water and urinating. After a while, there begin to be signs of poor nutrition, such as haircoat changes. Diarrhea is not uncommon with more advanced diabetes. Early cataract formation can occur. Increased susceptibility to disease and poor healing are additional signs.

You should schedule an examination of your dog by your vet soon. It is best to catch almost all the causes of increased drinking as early as possible.