Again, I am so sorry for your recent loss of beloved Marie. I know that you loved and treasured her and that she was truly a child to you.
Reading over your information about how she rallied after her crash in September of 2008, I am amazed by how much love and tender care can really do to treat disease. Marie clearly fought as hard for her health as you did. Despite being told she had only 1 month to live at that time, she went on to live another 2 ½ years! This was due to her strength and your love and care.
You mentioned that in March, 2011 your vet diagnosed hyperthyroidism, for which he prescribed medication. I am sure that medication was methimazole. I understand that you suspect that this medication caused her kidney function to deteriorate. Methimazole is a very effective drug for controlling hyperthyroidism. It is not toxic to the kidneys, but it can cause kidney values to increase....let me explain how.
First, here is more about hyperthyroidism:
Now, in terms of how CRI and hyperthyroid disease inter-act in a cat, it is important to know that the hyperthyroid disease causes an increased heart rate. A normal resting heart rate in a cat might be about 150 beats per minute (bpm). In a hyperthyroid cat, that rate might be 250 to 350 bpm!
The increased heart rate will increase the amount of blood going through the kidneys in a 1 minute period. The blood is flowing faster with this increased heart rate, so the glomerular filtration rate (GFR) is increased.
Let's imagine a cat with CRF - suppose her kidneys are only working at 50%. So, they only remove 50% of the toxins they are meant to. In one minute, suppose 100mls of blood goes through her kidneys and this 100mls had 100 units of toxins.
So, she removes 50 units of toxins in one minute.
Now, let's imagine this little cat has hyperthyroid disease as well. Her heart rate doubles. Thus, in that one minute period, 200 mls of blood goes through her kidneys. This has 200 units of toxins, and her kidneys remove 100 units of it.
So, she removes 100 units of toxins in one minute.
As you can see, when she has hyperthyroidism, her glomerular filtration rate is increased, and thus she can remove more toxins from her blood stream in a given period of time.
This does NOT mean her kidneys are actually working any better. However, it will mean that on blood tests, her BUN and creatinine will actually drop as her thyroid disease becomes more pronounced.
Similarly, when we take this same patient and LOWER her T4 levels by treating her hyperthyroidism, we will drop her heart rate and thus drop her GFR and thus her BUN and creatinine (the measures of kidney function) will increase. We are not actually harming her kidneys with the thyroid treatment, we are just lowering her heart rate and thus her kidneys can't remove as much toxin in a given period of time.
So, you must wonder why on earth we would even consider treating a cat's thyroid condition as it could be argued that it is beneficial to her if she also has CRF.
Well, the reason is that high levels of T4 can cause other problems (heart problems, weight loss, vomiting and diarrhea in some patients).
So, when we treat a hyperthyroid cat who also has CRF, we do expect her BUN and creatinine to increase as she is treated. That is NOT because the medications are toxic to her kidneys. It is simply because the treatment will lower her GFR.
As you can see, the thyroid medication would not have caused damage to Marie's kidneys, though it can decrease GFR. It's always tough to treat these 2 problems concurrently as we have to find a balance between treating the thyroid without lowering the GFR to the point that the kidney problem becomes worse. Sometimes, we simply cannot treat the 2, especially if the CRF is advanced.
You also mentioned that Marie went blind, and was then treated for hypertension. This suggests that her loss of vision was due to high blood pressure causing retinal detachment.
Marie's high blood pressure would have been due to her CRF, not by stress. One of the kidneys' functions is to control blood pressure. As CRF progresses, the kidneys lose their ability to monitor blood pressure and it then increases. It was definitely NOT your absences that caused her hypertension. It was her kidneys! So, stop worrying that this was in any way your fault. It wasn't!
Acute blindness is often the first thing that people notice when their pet is suffering from high blood pressure. The retina at the back of the eye is very delicate. High blood pressure can cause it to become unattached to the eye, and thus it is not able to transmit the message that light is striking it to the optic nerve and on to the brain.
If caught early, and if the high blood pressure is brought back down to normal, the retina can reattach and vision can return. Obviously, you caught it very quickly as her vision did return!
Here is a link to more information:
So, the fact that Marie's kidney disease had progressed to the point where her blood pressure went up and caused retinal detachment tells me that her kidney problems were advancing. This was before you fed her fish. You then offered her fish, and kept her on that as she so enjoyed it. You did not cause her kidneys to worsen. Your incredible care and love kept her alive for more than 2 years beyond what her veterinarian ever expected! When her kidneys finally progressed to a point where they were no longer able to even control her blood pressure, she also reached a point where she was no longer wanting to eat her kidney food. CRF leads to loss of appetite, for a variety of reasons. It is this loss of appetite that leads to the demise of most of my kidney patients. They lose the will to eat, and thus the will to live. You battled that by offering Marie the foods most tempting to her, to lure her into eating and fighting to live.
So, not only was it not wrong to keep feeding her the fish at this point, I really believe it was a delight to her, and the only thing that gave her the will to live for the final days! As you said, at least she managed to enjoy all the fish she wanted during her last two weeks!
I really don't think that this hastened her demise. I think it delayed her demise as it gave her a pleasure to live for.
You worry that you left her alone too much on her final weekend. As I type, I have 3 cats and a dog around me. You know what every one of them is doing? They are sleeping! All of them! I know that Marie must have slept a lot in her final months. Even young, healthy cats do, and she was neither of those things. I am sure she slept while you were out, not being aware of the passage of time. Have you ever been really sick? When you are sick, you sleep. Time passes in strange ways, and days slip by so quickly. Marie surely slept while you were out, and was unaware of how many minutes or hours passed. I have no doubt that she knew she was loved. She slept while you were gone, she did not feel lonely or worried. She was secure in her home, in the surroundings where she felt at peace and was able to sleep. Don't berate yourself!
Finally, Bill, you knew it was time when she woke you in the night, meowing in pain. I know you did not want her to suffer. I know you loved her so much that you would rather suffer than let her suffer... and that led you to do the thing which was the most painful for you, but the kindest for her. You let her go. Letting her go, with no pain, no fear, no suffering was gentle for her. It has cut you so deeply and hurt you so sharply... but that pain is the pain YOU take on in order to stop HER pain. It is your burden that you bear in order that she has no further burdens to bear.
I wish I could take away your pain as you took away hers. I wish I could help you to stop hurting... but I cannot. You loved her and she is gone. That hurts deeply. I'm so sorry! Your bond with Chantal and Marie is not broken by their deaths. It is strong and they are waiting at the Rainbow Bridge for you.
Just this side of heaven is a place called Rainbow Bridge.
When an animal dies that has been especially close to someone here, that pet goes to Rainbow Bridge.
There are meadows and hills for all of our special friends so they can run and play together.
There is plenty of food, water and sunshine, and our friends are warm and comfortable.
All the animals who had been ill and old are restored to health and vigor; those who were hurt or maimed are made whole and strong again, just as we remember them in our dreams of days and times gone by.
The animals are happy and content, except for one small thing; they each miss someone very special to them, who had to be left behind.
They all run and play together, but the day comes when one suddenly stops and looks into the distance. His bright eyes are intent; His eager body quivers. Suddenly he begins to run from the group, flying over the green grass, his legs carrying him faster and faster.
You have been spotted, and when you and your special friend finally meet, you cling together in joyous reunion, never to be parted again. The happy kisses rain upon your face; your hands again caress the beloved head, and you look once more into the trusting eyes of your pet, so long gone from your life but never absent from your heart.
Then you cross Rainbow Bridge together....