Feline Cryopreservation, May 8, 2013 Case Report

I wanted to write about my experience cryopreserving my cat, Marmalade. It was a technical and emotional challenge to accomplish. I feel that writing about it will help me to improve for next time, and will be able to be a tool for others wishing to do the same. I opted to perfuse my cat for a simple reason. I cannot yet afford to send her directly to CI.

As background, I have been involved in cryonics in the human realm for many years, and had always planned not only to cryopreserve myself, and family, but also pets. Marmalade is a 13 year old domestic short hair cat. She appeared to be in good health for most of her life. In February I began to notice increased lethargy and weight loss. It became apparent later that she was experiencing pain in her mouth when trying to eat. I took her to the vet where it was discovered she had a heart murmur. This made her a poor surgical candidate for dental surgery as it would require anaesthesia. I decided to take the chance because it was evident that she would die from starvation if her mouth wasn't tended to.  I discussed the possibility of cryopreserving her, with the vet, should the surgery go poorly. The vet was visibly uncomfortable with the prospect but allowed me to wait on site while she was operated on, in case there was a problem.

She underwent a 4 hour surgery on April 10 to remove a broken tooth. She was discharged home, then on April 11, she suddenly developed paralysis and pain in her right forepaw, pallor to the pads of her paw, and went into shock. This was evident by severe pain and agitation as well as tachycardia and pallor of her gums suggestive of poor cardiac output or hypotension. I rushed her back to the vet and she was seen within the hour. It was decided (a conclusion I had already made) that she had a thromboembolism of her paw, which cut off circulation to the distal half of her extremity. There was no pulse in that paw as assessed by ultrasound. The same vet, who I shall call Dr B, suggested euthanasia. I was ready to do that because I was so upset about what had happened, and concerned about the pain she was in. In retrospect I was nowhere near ready for the prospect of cryopreserving her. I had called Andy Zawacki at The Cryonics Institute. He was extremely kind and helpful. He overnight shipped me the glycerol that I would need to cryopreserve Marmalade. The concentrations he sent were approximately 500mL of 10 percent solution, 500mL of 40 percent and two bottles of 75 percent glycerol. The bottles each held approximately 1000mL. I was advised to start with the 10 percent, and then if I noticed edema, to stop and change directly to the 75 percent. When I tried to explain to the vet that what I was asking for was post mortem, she still seemed to have difficulty with the issue and suggested I could contact a taxidermist. Thankfully my sister was with me or I would have lost my mind on her. We took my cat, and went to another clinic, in Guelph, which is a city nearby that is the home to a veterinary college. I met Dr F here. He seemed open minded and very knowledgeable. I explained that I wanted to cryopreserve my cat and he was indeed open to the idea, but also, had some suggestions for saving her. She was started on Plavix which is an anticoagulant, and Buprenorphine, a potent narcotic analgesic. So she came home with me, alive, and stable.
To make a long story shorter, she had a few more challenges in the following weeks, which ended up requiring subcutaneous hydration and more veterinary visits. I agreed to take her to a veterinary cardiologist as it seemed that circulation had returned to her paw and she might recover.

We went to the specialist on May 2. A chest xray and echocardiogram were done. A neurologist consulted and looked at her paw, which seemed to be causing her more pain as the days went on. They diagnosed her with lung cancer. She had two large tumours that were likely throwing clots. She also had ischaemic cardiomyopathy- related likely to an unnoticed clot and nerve sheath tumours in her extremity that were causing her tremendous pain and immobility. I asked the specialist if she would help me with cryopreservation. Her reply was that she did not have an ethical problem with what I was asking but was too busy to help me. Marmalade was started on prednisone. I waited a few days to see if there was an improvement. There wasn't.

I started anxiously searching for a vet to help me perfuse her. The clinic in Guelph turned me down, stating legal liability. Dr B's partner, at the original clinic, who had shown some interest in helping me, was off on vacation. I even went as far as stopping at a local funeral home to ask if they would help me.  Mr B was helpful and curious about what I was proposing, but stated he could not work on animals in his mortuary. The positive takeaway here was that he was open to helping with human cases on the condition that we could demonstrate that he was not in violation of any laws, and that he was paid for his effort. We shook on it and I took his business card.

I returned to my original clinic, desperate and very sad. As it turned out, there was a new vet starting there that day. I met with her and explained what I wanted. She accepted my proposal without hesitation. She wanted a protocol to follow, though, from CI. Andy sent me information to give her.

On May 8, I gathered the needed equipment. I used a laundry basket sized Tupperware bin with a lid. The glycerol had been stored in the fridge, and I had a supply of bagged ice, tray ice and a blue gel pack in the freezer. I also had heparin. Andy informed me that likely 10 000 units of heparin would suffice for my cat's size. The act of putting my cat into the carrier to take her for this nearly broke my heart. I realize that I am writing excessively on this but I have a strong need to describe the entire experience, both as a method of grieving and to help others. There is a difference between talking about cryonics, and putting your beloved pet to death in the hopes that she may have a better future. I have advocated for cryonics for 17 years, and yet this was a very real, very painful threshold to cross. I also couldn't help but think of the fact that this week, I mailed the contracts to CI for my parents and sister.  The act of planning my cat's cryopreservation forced me to examine my 'faith' in science, and my commitment to this cause. Its no longer just an academic pursuit. The only relevant analogy that comes to mind is my recent experience with learning to scuba dive. In February while in Mexico, I tried a scuba lesson. The pool training was ok, but then we went by boat about a kilometre offshore. Here my instructor and I were dropped in the ocean and the boat left. I stared into the black rough sea and was certain my life was about to end. I have never reacted this way to anything in my life.  I tried for 15 minutes to control the intense fear reaction I had but could not- and asked to return to shore. This felt very similar.  As I was leaving the house with the cat, my mother got very upset and pleaded with me not to euthanize her. Her proclamation as I walked out the door was that I am not God. I kept walking.

We arrived at the vet at noon and were taken into an exam room. I said my goodbyes. The vet gave Marmalade an intramuscular shot of ketamine and something else I cannot recall, to sedate her. They started a 24g saline lock in her rear leg after shaving the skin. The vein was much more prominent than I anticipated.  She injected 10000 units of heparin. We waited two minutes for it to circulate then she euthanized her. It was very fast- about 20 seconds and she was in cardiac arrest. I quickly placed the gel pack under her head and icepacks on her body. Her neck was shaved. Using a scalpel, the vet cut into her neck to reveal her vessels. They were reluctant to enter through the chest as they didn't have a rib splitter. The anterior jugular vein was about 5mm in width and it was dark purple. The carotid artery was much deeper, and was whiter in colour, and seemed a bit smaller. The vein was probably engorged due to static blood. The artery was held with a hemostat, and then a 20g IV catheter was inserted- one into the artery pointed toward the head and the other into the vein pointed to the heart. We had cut the top off a 500mL bag of IV fluid, emptied it and poured in the 10 percent glycerol. It infused through a standard IV  line, first by gravity, then by an IV pump. 500cc/hr seemed to be the best rate as when I increased the speed, the fluid leaked out around the catheter. The catheter in the vein was connected to IV tubing that went straight down into a pail- with the end of the tube cut off.  After about 30 minutes, we noticed bloody fluid leaking from her nose  and some edema to her face. We stopped the 10 percent and switched to 75 percent. It was much thicker and more challenging to infuse. After about an hour of adjusting the rate, and position of the catheters, I was now aware that there wasn't a lot of blood in the outflow. On inspection, it seemed that a fair amount of the glycerol had leaked into the interstitial space. We tried to adjust the position of the catheter in the carotid artery but lost the grip. Andy later told me that once you lose the vessel its very difficult to get back as they do tend to shrink when exposed to the glycerol. We clamped the vessels. I am satisfied that her head did get a reasonable amount of glycerol anyways.

She made a long incision into her abdomen, in search of the aorta. We found it and the inferior vena cava. She catheterized the aorta with another 20g IV catheter and tried to flush it with saline. It was clotted. The vet made plans to try another location but I asked her to stop. We had perfused the brain, the ice was melting, and I was more concerned that her rectal temperature was 33.1C. I suspect her head was colder as most of the focus had been on perfusing her brain, but I did not know how to check it. By the way, the blue gel pack was inferior to the actual baggies of ice. It was pliable and soft, which is why I originally chose it, but it warmed up too quickly. She sutured the incisions and the vessels, I cleaned her up, then placed her in the ice, in the bin. We came home and I put her into the freezer. I am arranging to get a regular supply of dry ice, but for the next few days she will be at freezer temperatures wrapped in a towel, with ice covering her. When I have the necessary funds, I will arrange to ship her to CI.

In retrospect, I am glad I made this effort. I can't deny that I have doubts as to its success, but I have to base my thinking on positive results. Even if cryonics had not been an option, it was the right time to euthanize her. She was in a lot of pain. My hope is that the more effort I put into cryonics- in developing this industry, the better will be her chances as well as mine.