Young Addison's Whippet Fainting Episode? Possible heart issues?

[nbruesch]

Hello, My 3 year old male Whippet has had Addison's for the last year and a half.  He was originally on Percorten but was later switched to Florinef about 5 months ago.  About 2 weeks ago, he began vomiting and after bloodwork was presenting as having kidney failure.  We immediately switched back to Percorten and he was doing well!  Kidney values are back down and it no longer seems to be a kidney issue.  However, 2 days ago, after 3 runs chasing the ball at the park, he passed out and lost consciousness.  It was not hot that day and I was not pushing him hard.  He went from bringing the ball back one minute to laying down on his side, letting out a long moan and passing out for about 45 seconds.  Potassium, blood sugar, NA/K ratios were all within range.  Now, my vet hears a new mild heart murmur and an EKG test showing some irregular heartbeats (gallups?)  The vet as well as the coordinating University vet both do not think it's Addison's related but I was wondering if anyone here might have some further insight? Especially since he has just recently been through a roller coaster ride and he is so young.   Thank you so much!

[Jo CIMDA]

Hello and welcome

I am sorry your young whippet has Addison's and is not well at the moment.  It is good that the electrolytes are within normal limits and his Addison's is being well controlled.  Is he still on prednisolone? I presume he is and I therefore wonder if the cortisol levels (provided by prednisolone)  are inadequate especially in a stressful situation or an excitable situation when the demand for cortisol is greater than at rest.

The other consideration might be to test him for hypothyroidism.  A dog with Addison's' disease is genetically predisposed to other autoimmune diseases and as he has one endocrine disease it is reasonable to suspect another, and the most common endocrine disease seen in a dog with Addison's is hypoT.  So I would check out his thyroid  The best tests that are diagnostic are TT4, FT4 and TSH. Don't just do a TT4,  as vets are likely to do,  because if the TT4 is lower than usual then the other tests will have to be performed anyway so you may as well have all three tests done at the same time and this will give a picture of how the thyroid is functioning - or not.    Also, the TT4 is often lower due to a non-thyroidal illness so on its own it is not reliable.    HypoT causes the heart to beat slower than normal and this may be a consideration.

Another possibility is anaemia.  Again, because he is genetically predisposed to autoimmune disease, one should consider autoimmune haemolytic anaemia (AIHA). Because non-regenerative AIHA is a chronic anaemia, and it slowly progresses over a period of about 6 weeks before clinical signs start to show, the first sign you might see is when your dog gets excited or during exercise, he may suddenly collapse. This is because there are not sufficient red blood cells available within the circulation of the blood to take oxygen to the brain. So I would have a complete blood count and a thyroid test done. volume).

I hope you find out the cause of this collapse very soon.

Jo

[Jo CIMDA]

One more thing to consider. 

Has your boy had any recent vaccinations or spot-on treatments or other drugs or chemicals that may have triggered this problem?

Jo