Anesthesia in Cats

Isoflorine anesthesia

Question: I am a subscriber of VETINFO and enjoy it very much.

I have a question about the safety of isoflorine gas when used on cats, specifically a kitten of 4 months. I am currently fostering a 4-month-old litter of 4 kittens for a local humane society. I have had them since they were about 10 weeks old. At that time they were feral and very terrified of humans. My job was to socialize them and get them ready for adoption (healthy, friendly, etc.). Within a week they were starting to come around and have since turned into real love bugs that insist on sitting on your shoulder or lap .

On August 7, when they weighed at least 3 pounds each they got their spay/neuter surgery and all came through with flying colors except for one of the 3 females. When I picked them up I noticed she was having a harder time getting her bearings than the others but assumed she would 'sleep it off' and, knowing the vet uses only isoflorine except for truly feral cats that need some kind of sedation prior to anesthesia, I expected to see her back to normal by morning. However, when I got up at 4 AM to feed a litter of 1-week-old kittens I am also fostering, I realized she was in serious trouble: she could not stand, walk, turn her head without falling. Obviously, she could not get to the litter box, water bowl, or food dish. I immediately took her to the emergency hospital; the vets there did not know what was wrong with her though her blood glucose was a little low. When I picked her up at 8:30 to transfer her to the vet that had performed the surgery, she seemed a little better but we are talking tiny bits better. The surgery vet gave her a thorough exam and her diagnosis was one of 2 possibilities: a stroke caused by a clot from the surgery site or a reaction to the gas.

It has now been almost 3 weeks and she continues to make great strides toward a complete recovery, though she still has a little head bobbing and some side-to-side head stuff she does. My husband and I have decided to definitely keep her since she will need some special care, at least for awhile. In fact, we will probably keep all four and add them to our other 5 indoor rescues since we have just fallen in love with them and can't bear to part with any of them. There is something totally seductive about a feral that comes to trust and love us humans.

My question is - have you ever heard of this kind of reaction to isoflorine or do you have any thoughts on what could have happened.

Thanks,

Sara

Answer: Sara-

Isoflurane is one of the safest anesthetic gases but it can cause problems in some patients and lots of things can go wrong during anesthesia that don't have anything to do with the anesthetic agent being used. In addition, the usual practice in most cases is for an induction agent to be used prior to administration of the isoflurane and the induction agents can cause problems for some cats.

The most common induction agents in cats are combinations of ketamine, a short acting injectable anesthetic, sedatives and/or pain relievers. These medications often have variable effects on individual cats, with some cats tolerating the medications with no problems at all and others having more difficulty. Ketamine appears to cause hallucinations in some cats (known effect in people) and is less commonly associated with blindness or other side effects. It can cause rises in blood pressure that are significant enough to cause problems in some cats. It is considered to be a very safe anesthetic overall, but it is not completely safe. The sedatives and pain relievers used (there are several) also have the potential to cause side effects. These agents often allow the use of lower anesthetic doses and even with some side effects are generally viewed as an improvement in safety when compared to using higher dosages of more potent anesthetic agents that are necessary without premedication of anesthetic patients. Diazepam (Valium Rx) is sometimes used as a preanesthetic agent and a small number of cats react very adversely to this medication, although liver damage is the usual finding in these cases.

Isoflurane is quickly eliminated from the body and when it is gone, the pain relieving effect of anesthesia is gone, too. I think that pets who are more susceptible to pain or who have more painful surgeries and are not given additional pain relief medications may suffer from shock or have difficulty recovering from anethesia due to the effects of pain when isoflurane is used as the sole anesthetic agent. I am not at all sure that I am right about this, but I have long suspected that with isoflurane there are more problems with underdosing it than with overdosing it, as some patients seem to be immobilized well before they have really good pain relieving effect from isoflurane. The quick elimination and potential to use low dosages are good reasons to use isoflurane but they have to be balanced against the need for additional pain relief and the need to carefully monitor patients to be sure that they are receiving adequate anesthetic effect during the procedure and following it, to ensure that reactions to pain do not lead to more severe consequences.

Oxygen is administered along with the anesthetic agents and this can cause problems if the flow rates are too high or if there is insufficient oxygentation due to problems with the anethestic equipment or if the patient doesn't maintain an adequate respiratory rate and the anesthetist doesn't notice this (or there isn't an anesthetist and the surgeon misses it). There are occasionally problems with apnea (stopping breathing) during the recovery period and on a busy day this might be overlooked, as well. We had one of these in our clinic a couple of weeks ago and truthfully it was fortunate that we caught the problem in time to prevent any serious damage to the kitten we had just neutered, as we were busy enough that we could easily have missed it on a similar day at another time. I think that problems with delivery of oxygen are the most common causes of anesthetic problems and that these often occur when the equipment and monitoring all seem to be working well, which makes it hard to figure out what happened in retrospect.

In cats the possibility of hypertrophic cardiomyopathy ( a heart muscle defect) has to be considered whenever there is an adverse event during anesthesia. This can be very hard to diagnose in some cats since there may be no symptoms other than sudden death or unexplained complications during anesthesia or other stressful events. Watching carefully for signs of tiring more quickly than the other kittens, increased respiratory rate or just testing for this condition with ultrasound examination are both reasonable choices with the history of problems during anesthesia.

The good thing is that young cats have a lot of capacity to recover from most of the problemsthat occur with anesthesia and there is a good chance that your kitten will recover completely from this event over time. I hope she already has.

Mike Richards, DVM

10/12/2001

The stages of Anesthesia

Question: Dr. Mike,

Can you explain the stages of anesthesia?

Answer: J-

Anesthesia is sometimes divided into stages and some of the stages are further divided into planes.

Stage 1 anesthesia is the period between administration of an anesthetic and loss of consciousness. In people there is reported to be some disorientation prior to the loss of consciousness but in pets this is rarely obvious.

Stage 2 anesthesia is the period after loss of consciousness. In this stage there is sometimes uncontrolled movement, delirium, breath holding, irregular respiration, whining or howling and dilation of the pupils. This stage can be worrisome and most anesthetic protocols seek to keep this period as short as possible without endangering the patient.

Stage 3 anesthesia is the level at which surgery can be performed. The transition from Stage 2 to Stage three is usually denoted by the return of regular respiration, constriction of the pupils and the stopping of involuntary motion or vocalization by the patient. Stage 3 anesthesia is divided into four planes:

In Plane 1 Stage 3 anesthesia the patient still has blink reflexes and swallowing reflexes but has regular respiration with good chest motion. This stage would be considered "light" for surgical anesthesia.

In Plane 2 Stage 3 anesthesia the patient loses the blink reflexes, the pupils become fixed in one position (usually central) and respiration is still regular with good use of the chest muscles and diaphragm. This is the plane at which most veterinarians are comfortable performing surgery.

In Plane 3 Stage 3 anesthesia, the patient starts to lose the ability to use the chest muscles and abdominal muscles for respiratory efforts, so breathing becomes shallow and assisted ventilation is best when the patient must be maintained at or near this level in order to allow control of pain in surgeries that are unusually painful (such as extensive abdominal exploratories).

In Plane 4 Stage 3 anesthesia, the patient does not use the chest muscles and abdominal muscles at all, which means that all respiratory effort is produced by the diaphragm. This plane of anesthesia is very close to the point where the patient will stop breathing entirely and it should be avoided.

Stage 4 anesthesia is basically an anesthetic crisis. It is the time between respiratory arrest and death from circulatory collapse. Assisted ventilation is absolutely essential in this stage, as well as support for the circulatory system through IV fluid administration and medications to stimulate respiration and the cardiovascular system. Hopefully, this stage of anesthesia is never encountered in practice.

Mike Richards, DVM

6/27/2001

Anesthetic death in cat

Question: I am a new subscriber. I brought my most cherished cat in to have her teeth cleaned last Wednesday. She died, the vet said from a reaction to the valium he used as anesthetic. She was a very healthy 10 year old cat and I had done a CBC on her two weeks before to confirm she was healthy enough for this dental work. The vet said he used one-half the amount of valium he usually does because she went right under. Five minutes after the cleaning was completed he said she started foaming and turning blue. He said he tried resusitory drugs, intubating her and CPR. I am devastated. Have you ever heard of valium killing a cat? Is there a central agency to which vets must report adverse reactions to drugs? Although I realize nothing will bring my angel back to me, I feel as though I must get some answers. The vet also said approximately two animals die a year from anesthetic - that sounds like two too many to me. Thank you.

Rhoda

Answer: Rhoda-

Valium (Rx) is usually used in combination with other medications for anesthesia. It would be important to consider all of the medications used and to report this reaction to each drug company. Your veterinarian should be willing to do this. There is a central reporting number for veterinarians to report reactions, as well ( 888-FDA-Vets).

The first 12 years that I was in practice we had an anesthetic death rate of about 1 patient a year and our practice is a small practice. Then we made a change in anesthetic protocol, moving away from sodium thiamylal (Surital Rx) as our induction anesthetic (short acting anesthesia that allows placement of a breathing tube) and away from halothane as our primary anesthetic gas. We use diazepam (Valium Rx) and ketamine (Ketoset Rx) as our induction agent in dogs and ketamine and xylazine (Rompun Rx) as our induction agent in cats, if we do not use solely gas anesthesia. Since making these changes we have had one anesthetic death.

In a study published in the Journal of the American Animal Hospital Association by Dyson, et.al in the July/August 1998 issue veterinarians in the study group kept track of anesthetic procedures for six months and the medications used. The overall risk of death from anesthesia was reported to be 0.1 percent (1 in 1000). There was an increase in risk in cats when diazepam was used and when cats were intubated. It is likely that your cat was intubated for a teeth cleaning procedure, as well. Whether these risks will be the same in future similar studies is hard to say, since I could only find this one study with well documented information on anesthetic risk.

I have had some bad experiences with diazepam in cats. I have not had these experiences using it as an anesthetic agent, though. The reaction to diazepam most commonly reported in cats is liver damage, which usually shows up after using diazepam orally for a week or so. This is the reaction that we have experienced. We withdraw diazepam at the first sign of problems but even doing this we have had one cat come very very close to death when using this medication. We have not had a problem with single injections of diazepam and this has not been reported to be a problem, as oral diazepam has.

It is really hard to accept an anesthetic death for a routine procedure. This is not a pain that goes away quickly. Please remember that it is important to take care of dental problems and other disorders that place patients at risk of anesthetic complications. Overall, there are many more pets served well by the availability of anesthesia than patients who are harmed by it. That doesn't make it easier when your pet is the one who dies, though. It just helps to remember that you made the decision to proceed with anesthesia for good reasons.

If this raises more questions, please feel free to ask for more detail.

Mike Richards, DVM

7/31/1000

Effects of anesthesia and problems recovering after operation

Q: Dear Dr. Mike, I found you on the Internet late last night (I am sending you this from Spain) and subscribed immediately today in hopes that you can help. My question concerns side effects of anesthesia and problems recovering after the operation. My friend Claudia has a male cat named Woody. He went in for a castration on Saturday and arrived back to his home in pretty bad shape. He was trembling and couldn't walk. Sunday, Woody seemed much better, he was eating, going to the toilet and playing (although not too enthusiastically). It seemed that Woody was recovering fine but on Monday, it turned bad again. Woody could not walk well, he was sleeping most of the time but trembling and shivering and not eating. Claudia suspected as well that he could not see very well as he kept walking into the walls, she called the clinic and they said that it was ok that he just need to rest. Monday night - Tuesday early morning he started having convulsions and seizures. Claudia took him to the vets and they gave him something like valium (or maybe it was valium) to calm him down. They also put him an IV (sometime between Monday and Tuesday morning) which was removed by Tuesday afternoon. Tuesday during the day Woody tried to stand and to walk around and started to eat again but then Tuesday night he got worse, very lethargic and lying down and not reacting to sounds although his pupils were dilating so he had vision to a certain degree. The vets did blood tests and exams and said that his body was fine (only that there was a high white cell count due to the stress from the convulsions and seizures). Today, Woody is not eating and not walking and had several little attacks (convulsions or seizures), and was given valium and IV. The anesthesia used during his operation was a combination of ketamine and xylazine, Woody did not have any food prior to the operation as was instructed. The vet said that Woody is suffering from the side effects of the anesthesia (and that about 1 in 250 000 cats are affected) and that they had a case like this once before but the cat got better after 3 days. (with Woody, he was operated Sat. and now it is Wed.) We are all very upset and worried and don't know what to do or think. The vets say that we all have to wait some days to see if he gets better but it seems that they might not really know what is going on. This is why I am writing to you... I know it must be difficult because you cannot give Woody an exam yourself and have only to go on by my e mail... I am trying to remember all details.

Woody's history: he is around 8 months old, (no one knows for sure because he showed up at another friend's doorstep as a very young kitten maybe 6- 8 weeks old, we all looked around for the mother but there was none) black and white mixed , adopted by Claudia because the other friend was pregnant. Woody did not show his testicles for quite a while and then only ne came out. He was not given any hormones or medication for that because the vet said that the success rate was not so high and that maybe it was better to wait and see if it would come out by itself. Around a month and a half ago, the other one finally came out. They decided on castration because he is an indoor cat... Claudia also has another cat (female, around 2 years old). They are all vaccinated. Is Woody's problem's due to the anesthesia or is it something else and how can we help him? How do we know if he has epilepsy? Another person thought that maybe Woody was not put in the correct position after his operation and that caused brain damage and epilepsy? Should they check for something else? On the Internet, I only found questions concerning the immediate deaths of animals due to the anesthesia but did not find anything at all concerning something like this?! I have 2 cats (one boy , one girl) myself and they have been operated on at the same place by the same vet and both are fine. Sorry if this all is written down mumble jumble, I hope that you can understand what I tried to write as I am doing this in a hurry to send it to you as soon as possible. Thank you, Vicky

A: Vicky-

There are a number of possible problems that could combine with anesthesia to lead to the symptoms that have been seen in Woody. To make this as simple as possible, I will try to list them and then give you some idea about which ones are the most likely. I do not know the trade names for medications outside the United States, so there is a good chance that the trade names for medications mentioned may be different in Spain.

Ketamine will sometimes cause seizures in pets who are anesthetized with it. These are more common when ketamine is used alone than when it is used in combination with a sedative such as diazepam (Valium Rx) or xylazine (Rompun Rx). These seizures usually occur around the time of administration and it is unlikely that the continued problems are due to ketamine alone. Ketamine can cause increases in blood pressure which can be dangerous to pets with previous brain injuries that involved cerebral hemorrhage or edema in the recent past.

Xylazine will sometimes cause seizures, too, but usually in situations in which it is overdosed. This is not all that likely because most vets use small amounts of xylazine when it is used in combination with ketamine. I use xylazine and ketamine anesthesia in cats. I do this because it works well for our practice and because we have not had problems with this combination. However, there are veterinary anesthesiologists who consider xylazine to be dangerous to pets because it can cause severe reductions in blood pressure in some pets and almost always causes a short term rise in blood pressure followed by a period of low blood pressure. In some pets xylazine may cause enough hypotension to lead to cardiac arrythmias and this can lead to lack of oxygen reaching the brain -- which would could cause blindness, seizures and other central nervous system signs.

Lack of oxygen for long enough to affect the brain can lead to the symptoms seen in Woody. This can happen during surgery for a number of reasons. Shock from blood loss, a period in which the airway was blocked for any reason (vomiting during surgery when an endotracheal tube is not in place, kinking of an endotracheal tube, forgetting to turn on the oxygen when anesthetic gasses are used -- all sorts of possible problems). The most common sign of low oxygen to the brain during surgery is blindness. Seizures are also possible.

Sometimes, surgery just uncovers pre-existing problems. Cats with cardiomyopathy (weakness of the heart muscle), liver disease or kidney problems are susceptible to having severe reactions to anesthesia and that could potentially lead to the problems seen. This is less likely since blood work was normal. Cardiomyopathy will not show up in blood work, though. Sometimes portosystemic shunts (circulatory problems affecting the liver) will also not show up in lab work. Cats may appear to be normal prior to a major stress such as surgery when a liver shunt is present. Sometimes pets have low blood pressure for some reason and anesthesia just makes it worse. If the blood pressure falls to low enough levels the brain won't get enough oxygen.

At this point, there are some things that have to be done to ensure that Woody will live through this problem and have the best possible chance of a full recovery. The first thing that is important is supportive care -- making certain that he gets adequate fluids and that he is eating. If he is not drinking it may be necessary to continue to the IV therapy. If he is not eating it may be necessary to consider some form of assisted feeding --- such as feeding by hand or feeding through a stomach tube. Cats that do not eat for several days can develop hepatic lipidosis, which is a life-threatening illness. Seizure control is also important. Diazepam is frequently used for seizure control in cats, especially when it seems necessary on a short term basis.

There is a good chance that Woody can recover from this problem. Many cats will regain their sight completely and the seizures usually stop happening after several weeks to several months. Some cats do not recover, especially if they develop secondary complications such as hepatic lipidosis.

I think that it is unlikely that this is the onset of epilepsy that just suddenly occurred at this time. Cats are less prone to epilepsy than dogs and do not normally show blindness as a symptom of epilepsy.

The most likely cause of the problems seen is a period of time during surgery and anesthesia when oxygen was not making it to Woody's brain. This could have happened because of a pre-existing problem with Woody, a problem with his interaction with anesthesia or due to human error during the procedure.

Hope this helps some.

Mike Richards, DVM

5/20/99

Ketamine anesthesia

Q: Hello Dr. Mike,

We have three male Persian cats -- one shaded silver (2 years) and two shaded goldens (same litter, just over 1 year). Both goldens recently had their 1-year check-up and vaccines. While examining Ari, the larger of the two goldens (8-1/2 lbs.), our vet realized that his bite was unusually off. His bottom teeth seem to collide with his top teeth. When our vet touched his top teeth with her finger, his teeth moved quite a bit and there was visibly movement in his nose and eye areas. His gums bled and he was obviously distressed. The vet indicated that Ari would need to have two, possibly three, of his top teeth removed as soon as possible. He has been to the vet for regular check-ups this past year (vaccines, neutering) and his bite has always been fine. We recently noticed that he seemed to have an odd eating habit of pushing his food out of his bowl and eating off his food mat. Otherwise, he is in excellent health, otherwise -- thick shiny coat, clear eyes, normal appetite.

Our vet has assured us that Ari will be fine without a few of his front teeth, and so we have scheduled his surgery. However, the breeder of our shaded goldens has specified to us that under no circumstances should we permit Ketomine to be used if/when our cats need surgery. She indicated that she and other breeders have lost several cats while in surgery and the common thread seems to be that Ketomine was used.

I mentioned this to our vet (she uses a derivative of Ketomine for surgery) and she could find nothing in any literature that indicates why Ketomine should not be used, particularly on Persian cats. Can you provide us any information in this area?

I reminded my vet that Ari seemed to have a more difficult time recovering from being neutered (done when he was eight months old). He had the surgery done on a Friday at noon, and he did walk without wrobbling until the following Tuesday. He was listless and had little appetite for about one week following his surgery.

We want to do what is right for our little boy -- but, we don't want to hurt him! We would appreciate it if you would please email back ASAP with any information you may have concerning Ketomine and Persian cats.

Thank you.

Terri

A: Dear Terri-

If you are worried about ketamine anesthesia, it is reasonable to ask your vet not to use it. If your vet has isoflurane gas there is a good chance that your cat could be induced and maintained on this anesthetic for a procedure like dental extractions without too much difficulty.

We have used a combination of ketamine (Ketaset Rx) and xylazine (Rompun Rx) in our practice for over twenty years. We have had anesthetic deaths in cats in our practice but I do not remember one in which ketamine and xylazine were the sole agents used. We had several anesthetic deaths in cats while using sodium thiamylol as our induction agent and halothane gas for anesthetic maintenance. Despite this, there have been articles in the veterinary journals implicating ketamine in a number of anesthetic deaths. Ketamine is rarely used alone and it is difficult to keep track of all of the combinations of medications used with it, so I can not say for certain whether a particular combination of anesthetic agents is more likely to cause problems than another. Just that we have been lucky, so far, with the combination we use. The fact that we have isoflurane available to us allows us to use very low dosages of xylazine and fairly low doses of ketamine and that may contribute to the safety we have experience so far in our practice.

Ketamine causes hypertension during anesthetic recovery and it is possible that the detrimental effects attributed to ketamine may be due primarily to cases of undiagnosed cardiomyopathy in cats undergoing anesthetic procedures. These cats would be especially sensitive to hypertension and the increase in blood pressure induced by ketamine is supposed to be pretty significant in some cats.

If this theory is correct it may make sense that Persians are more sensitive to ketamine than other cat breeds since cardiomyopathy is supposed to be a problem in the breed. Another potential problem with Persians and ketamine is that many vets using ketamine anesthesia (included me when procedures are short) do not routinely intubate cats to provide a patent airway since they are not anticipating having to use gas anesthesia. In pets with short noses, both cats and dogs, intubation during any anesthetic procedure is best since these pets can develop airway obstructions much more easily than longer nosed pets. I think almost all vets do intubate pets when they are doing dental procedures other than very simple extractions, though.

In a pet in which there is noticeable looseness to the underlying bony structures it is a very good idea to run a pre-anesthetic blood panel to ensure that there is no problem with kidney disease or hyperparathyroidism leading to softness of the bone. This is never a bad idea prior to surgery as long as the cost of the panel isn't prohibitive for the pet owner.

I hope this helps. There is a very good chance that your vet can use an alternative anesthetic procedure. Different vets can have very different experiences with anesthetic protocols and experience with an anesthetic protocol can make a huge difference in the success rate using it -- so if your vet uses ketamine routinely and is having good success with it you may actually increase the risk by asking for an alternative medication, if there is not an alternative your vet is also very familiar with.

I hope this helps in your decision making.

Mike Richards, DVM

Pulmonary edema, anesthesia and cardiomyopathy

Q: please help me to understand exactly what has happened to our two male persians; In Feb.1998, our oldest male (age6) needed to be sedated for a dental cleaning,immediately after the procedure,our vet informed us "Sammy" developed acute pulmonary edema most likely caused from the anesthesia. Sammy was placed on oxygen therapy and given steroids I.V. After several days we were able to bring Sammy home although he was extremely short of breath and weak. Time passed and Sammy regained his appetite but remained short of breath and lethargic,our vet did not prescribe any medication for him but instructed us to avoid using any aerosol sprays around him. On June 23,1998 everyone was gone from our home except our daughter who called us at work and said Sammy was scratching on her bedroom door,when she opened the door Sammy was very short of breath and had "frothing pink fluid" draining from his mouth. She rushed him to the vet but he died en route and we have been devastated since. Our vet said he died from acute pulmonary edema.

On June 22,1998 our year and a half male "Spanky" developed pneumonia and he was placed on amoxi drops and sent home. On July 1,1998 Spanky had a follow up chest x-ray and EKG which revealed atelectasis,we started him on Lasix,that night Spanky developed rapid resp (80 per minute) At 5:30 A.M. he was in severe distress and I rushed him to the vet and he diagnosed him with pulmonary edema.Our vet administered I.V. steriods and placed Oxygen on Spanky but he showed no improvement.At 11:00 A.M. the vet recommended he euthanize Spanky since there was no improvement. I have buried two of my "children" within 9 days of each other and I keep thinking there was something more that could have been done to save them-such as preventive medicine using steroids,diuretics or cardiac meds.I have searched our home for any possible cause but there have been no major changes. Please help me determine the cause of their illness (they were unrelated cats)and tell me if there was anything which could have prevented their deaths.

Thank you

A: Dear Dobergal-

For a long time I have heard reports of episodes of pulmonary edema and/or heart failure following anesthesia in cats. There has been some concern among veterinarians over the potential for ketamine, a commonly used anesthetic agent, to cause episodes of pulmonary edema. No one seems to be certain why this occurs, nor how frequently. We use ketamine in our practice and have not had an anesthetic death in several years. Ketamine appears to cause hypertension during the recovery period in many cats. If the cat has pre-existing cardiomyopathy this could lead to a sudden worsening of the cardiomyopathy leading to pulmonary edema and death, if the cardiomyopathy can not be brought under control with medications. There is some possibility that this effect could occur even without cardiomyopathy being present. I have only seen reports of this condition in association with ketamine but it may occur with other anesthetic agents. Despite this risk, ketamine appears to be a lot safer than other injectable anesthetic agents in cats, especially when compared with barbituates.

Cardiomyopathy is the most common cause of pulmonary edema or in young male cats and this syndrome definitely can occur without anesthesia to facilitate it. Cardiomyopathy may produce a heart murmur but it can occur without any audible murmur or noticeable clinical signs. Murmurs associated with cardiomyopathy seem to be easiest to hear by placing the stethescope directly on the sternum of affected cats and this is not the place a lot of vets were taught to listen to pet's hearts so a vet who is following the protocol taught in their veterinary school may never listen there. With atelectasis it may be more likely that Spanky had pleural effusion (fluid collecting around the lungs) but this can occur with cardiomyopathy as well.

There are other possible causes of acute pulmonary edema and pleural effusion, including cancer, feline leukemia virus infection and heartworm disease. We just treated a patient who died from a thymus tumor even though she was only 1.5 years old. She had a great deal of fluid in her chest and we could not even control it well enough to allow us to proceed with a good diagnostic effort prior to her death.

We use high dosages of diuretics, withdrawal of fluid from the chest if the problem is pleural effusion rather than pulmonary edema, oxygen therapy and nitrogylcerine ointment sometimes to help control the fluid. Many times we succeed in getting cats stabilized. Sometimes this leads to long term control of the problem if cardiomyopathy is present. Sometimes it just prolongs a patient's life for a few hours or days. I wish we knew which cases were going to respond in advance but all we can do is try to treat and then wait to see what happens. It is very frustrating for us and even more frustrating for our clients.

It is extremely hard to lose two good friends in such a short period of time. You have my sympathy.

Mike Richards, DVM

Last edited 09/23/02