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  Discussion on Resting tachypnea (40) and RR 100+ with moderate exercise-cushings related?
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Member:
obtunded

Posted on Sunday, Apr 8, 2012 - 12:20 am:

I have an 18 year old Morgan gelding that was diagnosed with cushings at the age of 11 by DMST following ligament injury. He also has Insulin Resistance.

I have elected to manage him conservatively with good husbandry, daily Chasteberry and Cinnamon for IR. He has a propensity for obesity.

He is "retired" now, but I have taken him on short walks in the saddle.

I have been concerned for some time that he he has a very high resting respiratory rate (40) with =i:e ratio, no adventitious sounds, and a fairly shallow breathing pattern. He is not febrile and shows no other overt signs of infection. He is de-wormed religiously.

With mild exercise, his respiratory rate rises to 100+ and he is inverted to his heart rate. His recovery to a "normal rate of 40" is delayed.

DO you have any ideas? Is their a metabolic component such as a ketoacidosis that could be the culprit?

He has many of the usual suspects in terms of cushings symptoms... fat distribution, chronic hoof issues (Separation, founder).

Where would my money be spent in terms of finding the most likely culprit?

Regards,

Ian
Member:
vickiann

Posted on Sunday, Apr 8, 2012 - 12:36 pm:

I don't have any answers about finding the "most likely culprit" but there are some professionals who believe such horses benefit from additional chromium and magnesium.

I have a 20-year old, 900 pound Arabian horse who has been diagnosed by two equine veterinarians as having metabolic issues.

At times he also has exhibited some unusual breathing issues, fatty pads, an episode of laminitis and a tendency to become overweight. His neck is only very slightly cresty.

He was put on one scoop daily of Thyro-L and that has done wonders for him.

Also, I carefully manage his weight and carbohydrate/sugar intake.

Your thoughts about Chasteberry and Cinnamon are of interest to me.

A friend of mine put a horse of hers on an herbal concoction after her first episode of laminitis and it seemed to really turn her around.
Moderator:
DrO

Posted on Sunday, Apr 8, 2012 - 3:13 pm:

Hello Ian,
Horses increase there respiratory rate mainly for 3 reasons:
1) Increasing CO2 levels in the blood and to a lesser extent decreasing O2 levels.
2) Increasing body temperature
3) Pain and/or excitement
There are some more rare causes like certain types of neurological diseases.

Certainly horses with Cushings with their very heavy hair coats can have problems in the spring with high body temperatures. Does he sweat when this happens? Have you taken his temperature during these times?

Your best money is first spent on a good physical exam by a experienced equine internal medicine guy followed by a set of chemistries and CBD which depending on the results of the exam might include evaluation of the metabolic/respiratory components of the blood's ph. Taking samples following exercise and comparing them while resting might also yield information.

We have more information on magnesium, chromium, and Chasteberry treatment for Cushings in the article on Cushings you may find interesting.
DrO
Member:
obtunded

Posted on Monday, Apr 16, 2012 - 1:04 am:

Lacking both the access to an Internal medicine vet and, frankly, the huge sums of money I would assume that go along with such an encounter, I have tried exploring this a bit further on my own.

I am "in the biz" you might say, at least with two-legged critters, and I was able to take some blood gas readings with an iStat.

Naturally, I would have preferred an arterial sample, but alas my talents don't extend to art punctures near the fetlock, thus I settled on a venous sample.

Here is what i cam up with.... I will also use a 5 year old in perfect health as a control...

18 year old horse...

pH 7.47
PC02 46.1
PO2 29
Base Excess 10
HCO3 34
Total CO2 35
SAO2 60 Actually, I guess this would be an SV02
Na 138
K 3.4
HCT 33
Hb 11.2
Serum Glucose 5.1 mmol/L

From my 5 year old control...

pH 7.46
PCO2 47.8
PO2 34
Base Excess 11
HCO3 34.5
Total CO2 36
SA02 68
Na 133
K 4.4
Hct 35
Hb 11.9
Serum Glucose 4.9 mmol/L

So... what this told me was "I really wish I had an art sample"

It raises a few questions... is the lower SA02 and PO2 a question of 02 extraction (being a venous sample)?

I would have expected a less basic pH, but as the control shows near identical values, I am not as concerned.

Obviously this is not an issue with anemia as hematocrit and hemoglobin appear unremarkable.

Again, bearing in mind these are venous samples, does anything jump out?

fwiw I was thinking exactly along the same lines in terms of respiratory physiology which is why I went the gas route.

Again, lung fields are clear - no adventitious sounds, and his inspiratory:expiratory ratio is equal.


Thoughts?

(Sorry, a CBC and Diff are going to be a bit tougher...)
Moderator:
DrO

Posted on Saturday, Apr 21, 2012 - 9:58 am:

Assuming proper sampling, handling, and testing I think it very odd that your horse has a respiratory pattern as you describe yet has a nearly identical CO2, HCO3, and base excess as your control horse. With increased ventilation should he not be blowing off more CO2 resulting in a respiratory alkalosis. I think your scenerio is suggestive of a problem with ventilation / perfusion in the lungs so the horse compensates with increased ventilation to keep blood values normal. Remember that your horse has normal values despite abnormal respiration.

I agree the O2 values of a venipuncture sample into a typical blood collection tube is probably without significance.
DrO
Member:
carylann

Posted on Sunday, Apr 22, 2012 - 9:38 am:

I also have a QH with cushings and experiences a increased respiratory rate with exercise. Initially no cough was noted, but now has shown an ocassional cough. I am treating for allergic respiratory/ early copd and has responded well. Just a thought. An equine respiratory specialist noted this can develop and may not show the usual cough.
Moderator:
DrO

Posted on Sunday, Apr 22, 2012 - 11:47 am:

Hello Caryl,
A bad case of COPD (RAD) would be a common cause of persistently elevated respiratory rates, due to the ventilation/perfusion mismatch created by bronchoconstriction, inflammatory exudate, and in the more advanced cases lung consolidation and emphysema. I would not expect the normal lung sounds Ian reports above. In my experience all of these horses have remarkable wheezies and crackles on auscultation.
DrO
Member:
paul303

Posted on Monday, Apr 23, 2012 - 12:07 am:

I have a 32 year old that I've been treating for Cushings since she was 23. Without Pergolide, I would have to put her down. With it, she functions well. She was retired from riding at 30...but we do still pony her for exercise. I would be terrified to stop the Pergolide. With it, she has no hoof issues, no fatty tissue issues, slight coat issues ( controlled by clipping ), and no excessive drinking or urination issues. She's basically a 32 yr. old horse with no major issues as long as she is on her 2mg Pergolide daily.
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