CRF (Chronic Renal Failure) Treatment
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Treating Blood pressure problems in hyperthyroid cat with CRF
Question: My 16-year-old cat is hyperthyroid and CRF (early stages). At her last two check-ups, the vet has taken BP and the averages are from 172 to 179. She now has a heart murmur and a rapid heart rate. I think it is time to put her on BP medication, but the vet thinks that a BP of 200 would be the point to think medication. As the heart murmur and rapid heart rate are not likely to change without treatment, don't you think it might be wise to try a BP medication? If so, which one would you recommend?
Hyperthyroidism often induces a form of hypertrophic cardiomyopathy in cats. This can lead to increases in the heart rate and eventual congestive heart failure. Hypertension (high blood pressure) may also occur. At the present time, the medications most commonly used in cats with hyperthyroidism to counter these effects are propranolol ( Inderal Rx) and atenolol (Tenormin Rx). Propranolol is usually given every 8 to 12 hours at 2.5 to 5mg/kg. It should not be used when cats also have asthma. Usually atenolol is just given at a dosage of 6.25mg per cat, once or twice a day. The lower dosing frequency makes atenolol an attractive choice for many cat owners.
When we are treating chronic renal failure (CRF) without hyperthryoidism we like amlodipine (Norvasc Rx) and we have used this medication in several cats with both CRF and hyperthyroidism before. We have not run into discernible problems using amlodipine in hyperthyroid cats so it is another alternative. Enalapril (Enacard Rx) is also gaining in popularity. We have used this medication and it has been helpful in some patients. We still favor amlodipine at the present time, though.
If you have good control of the hyperthyroidism it may not be necessary to use propranolol or atenolol and you may wish to consider amlodipine. If you and your vet are having problems controlling heart rate or with arrhythmias associated with the hyperthyroidism then it would probably be better to use propranolol or atenolol. Strictly from the standpoint of high blood pressure related to chronic renal failure, the most common goal is to keep systolic blood pressure in the 150mmHg to 170mmHg range. The decision to use medications based on blood pressure is a little tricky, since it is not unusual to get occasional high systolic blood pressure readings based on the literature. I think that this might be the reason that the 200mmHg pressure is sometimes viewed as the point where blood pressure medications are necessary -- but I think this is really meant as a guideline for a single sample and that it is really best not to rely on single samples. If measurement of blood pressure is the only criteria being used it would be best to base the decision to use medications on the results of a series of blood pressure tests rather than one or two tests. On the other hand, there are a number of vets who feel that hypertensive agents are nearly always indicated in a patient with chronic renal failure and if this is the decision criteria then you may already have enough information to decide that anti-hypertensive agents are necessary.
If the blood pressure continues to be above 170mmHg when tested I think that it favors your view of the situation -- blood pressure medication should be considered.
I hope that this helps some.
Mike Richards, DVM 12/31/2001
CRF - Controlling Kidney Failure
Question: Dear Dr. Richards:
I have followed your vetinfo.com for some time and find it to be the most valuable site for any kind of information on cats.
We have some questions, but first, here is some history about our cat. Nukat is 18 yrs. old, looks like a Main Coon and Persian mix. She is an inside/outside cat, she stays close to the house in the daytime and comes in at night and sleeps on the bed.
One vet diagnosed her with CRF a little over three years ago. Her weight at that time was 12 lbs 8 ounces. We took her to another vet, who said she was okay, and we continued seeing this vet. In July 2000 her Bun was 31, Creat 1.7, Alt 72 (high) Albumin 3.3 (slightly high), Glucose 105, Calcium 9.7. Phosphate 5.0, PCV 36%, TP 7gldl. We didn't test for hyperthyroidism or potassium at that time. We took Nukat in for periodic check ups, shots, etc. Over the three years she was losing some weight, but other than that she was acting very normal.
In May 2001 Nukat had an infection in her mouth and did not eat very well. Her weight had dropped to 9 lbs. 2 ounces. We took her to our vet, her teeth looked bad and needed to be cleaned. We and our vet decided to postpone a decision on the teeth cleaning until the infection cleared up. We did bloodwork at that time. Results - Bun 44 (high) Creat. 2.6 (high), Albumin 3.7 (high), Alt 42, Calcium 9.8, Phosphate 4.6, T-Blirubin 0.1, Glucose 130, PCV 37%, WBC 8,305, TP 7.6 gldl. Our vet started out with Cefa drops (orally), and this didn't work, Nukat kept throwing up and had diarrhea. 10 days later the infection had not gone away. We swiitched to Amoxicillin (orally). That didn't work, she still kept throwing up and had diarrhea. So we started taking her in every other day to have shots. The vet also added Dexamethasone to the antibiotic. She tolerated that really well and started getting better.
The last part of May she broke off one of her upper canine teeth. The root was still left and, even though we were extremely afraid of the anesthesia, we had no choice but to get this taken care off. We had more bloodwork done before making our decision.. Results - Bun 43, Creat 2.2, Albumin 3.6, Alt 43, T-Bilirubin .0.5, Calcium 8.8, Phosphate 5.7, Potassium 4.4, T4 5.8, Glucose 115, TP 7.6 gldl.
These weren't the greatest results, but they were acceptable to us and our vet to go ahead with the dental work. He pulled several molars, pulled out the root of the canine tooth, pulled out the other upper canine tooth and cleaned her teeth. Most of the pulled teeth had resorption lesions. We continued to visit our vet every other day for the shots. Our vet reduced the Dexamethason dose to half after three weeks, and we finished up the treatment the middle of July. We continued giving her prednisone 5 mg per day orally, and she had no problem with that, no throwing up. The prednisone was supposed to overcome the diarrhea she has been having since she has been taking the antibiotics. After one week we went to every other day, then stopped the medication altogether. She still has loose stools off and on.
At our request, we took her to the vet for weekly checkups. Her gums were healing - just not very fast. She was eating okay, her weight went back up to 10 lbs 5 ounces, but she still had diarrhea and loose stools. We had more bloodwork done the end of July. Results - Bun 47, Creat. 2.8, Albumin 3.7, Alt 77, all high, T-Bilirubin 0.3, Calcium 9.1, Phosphate 6.8, Potassium 3.9 (low), sodium 161(high), T4 7.9, Glucose 88, PCV 34%, WBC 13,695.
By the first week of August, her gums still looked just a little inflamed, and because Nukat wasn't eating so well, our vet gave her a depo-medrol shot. We are also trying Tumil-K, but it is very difficult to even get her to take the smallest amount. This cat is fast when it comes to any kind of "at home" medicating. She has also started screeching in the evenings and at night, and once we get up or she sees us, she stops the loud howling and it turns into a mild meow. We know a lot of that night time howling can be caused by any of her illnesses. We don't suspect dementia, since her behavior is very normal, she is alert, her eyes are clear, she can see very well, her hearing is excellent and she is aware of everything that goes on around her, she does not ever seem lost when walking around.
The shot seemed to wear off after about 14 days, and our vet said to go back to an every other or third day prednisone pill as needed. The prednisone did not increase her appetite, and when we saw the vet last week, she weighed 9 lbs 5 ounces. We also explained that Nukat had started smacking her lips and moving her tongue in and out of her mouth licking her lips often. The vet looked in her mouth, and other than a small inflamed area around one of her molars, it looked pretty good.
Obviously the hyperthyroidism could account for the weight loss as well as the low intake of food. She had only been eating about 140 to 160 calories per day, and most of that was baby food. We also have read that, if the Bun goes to 75, most cats stop eating.
Our vet feels that her hyperthyroidism should not be treated for fear that it would worsen her kidney failure. We also suspect that her blood pressure is quite high. During the time she was treated with the antibiotics and the Dexamethasone, her heartbeat had been right around 160, very steady every time we took her in. The last four visits showed her heartbeat had increased to 180 and twice at 200. Our vet prescribed Winstrol 1mg 2x per day. She is more mellow and not yowling so much, but her appetite is not any better, it is actually worse. She is still quite active, moves around in the house, up and down the stairs, outside, up and down the stairs of our deck and in the back yard. So far we have not worked with subcutaneous liquids and Nukat is not dehydrated.
Here are our questions: Our Vet is certain that Nukat has high blood pressure along with her other ailments.. We don't quite know how to proceed from here.
Most of what we read about hyperthyroidism goes along with what our vet said, but what about the hypertension? Some articles say that hypertension exists because of the CRF, and it keeps the blood moving through the kidneys. Wouldn't that mean that, if the hypertension was under control, less blood would move through the kidneys and therefore the CRF would worsen?
Other articles say that hypertension should be treated to help prolong the CRF cat's life. But, since many vets don't have blood pressure machines, how would one really know how high the blood pressure is? Even with blood pressure machines it appears that being accurate is a problem. Wouldn't it be rather risky to either prescribe Enacard (for lower hypertension) or Norvasc (for higher hypertension)? Don't these medications have side effects?
Also, what is your opinion of high doses of Dexamethasone given to inhibit the release of hormones from the thyroid? Wouldn't that arrest or at least suppress hyperthyroidism? Could the doses Nukat received with her antibiotics also have been instrumental in showing her T4 at 5.8 in the first reading? If that were the case, wouldn't the side effects of the steroids be less problematic than the side effects of Tapazole, because of Nukat's CRF?
Some information actually shows that steroids mask hyperthyrodism, so could that mean that they help with the symptoms? Could that prolong a cat's life? Some information says that hyperthyroidism actually is beneficial for CRF cats. At this point, we are in a dilemma. If we treat the hyperthyroidism, and the CRF gets worse, that's not good. What do you think the downside would be in treating the hypertension?
There are a number of possible treatments that can be helpful in controlling some aspect of kidney failure. These include:
fluid administration, orally or subcutaneously potassium administration low phosphorous diets low to moderate protein diets calcitriol administration phophate binding agents such as aluminum hydroxide gel blood pressure medications, usually amlodipine or enalapril appetite stimulants gastrointestinal protectant agents such as famotidine or ranitidine kidney transplants
Choosing when to add treatments and how much "hassle factor" any individual cat can tolerate when adding medications is the tricky part of treating chronic renal failure in cats.
There are three methods of controlling hyperthyroidism -- medications (methimazole primarily), surgery and radioactive iodine therapy. There is sometimes a problem with sudden worsening of pre-existing kidney failure when hyperthyroidism is treated and this seems to be more of a problem with radioactive iodine therapy even though it is otherwise considered to be the best treatment option. With advance planning to compensate for kidney function changes, it is still considered to be the best treatment option even when kidney failure is present, by many vets.
The increased blood flow, appetite stimulation and weight loss associated with hyperthyroidism are good for the kidneys, but only to a degree. The appetite stimulation would probably always be good except that eventually many cats with hyperthyroidism have a decrease in appetite associated with thyrotoxicosis. Some vets really do think that it is best to treat with methimazole (Tapazole Rx) and to keep cats with kidney failure just barely hyperthyroid, to gain the beneficial effects while controlling the tendency for these effects to worsen to the point that they actually harm the kidneys. Overall, though, our experience has been that treating hyperthyroidism has helped with kidney failure over the long run more often than it has hurt in the short run. When to treat is a judgment call but I favor treating over not treating more often than not.
I think that it is best to treat for high blood pressure if there is any indication that it should be done, even in the absence of the ability to actually measure blood pressure. For the most part, there is less chance of doing harm with the medication than of hypertension harming the patient. Currently I still favor amlodipine (Norvasc Rx) but have used enalapril (Enacard Rx) in some patients with good success, too.
I am not familiar with high dose dexamethasone for hyperthyroidism but based on our overall experiences with this medication and other corticosteroids in these sort of circumstances I would expect it to have more side effects than other therapies. But this is just based on my experiences, not on reviewing the results of any studies or clinical trials.
Blood pressure and kidney function are closely intertwined. The kidneys do like to have a high blood flow and they control the hormones that increase blood pressure. However, the kidneys don't care if other organs are damaged by the high blood pressure and eventually they will be. When that happens, the entire body suffers, including the kidneys. It is necessary to protect the kidneys from themselves, sometimes. Over the long term, controlling blood pressure usually gives the best long term success.
There is no easy way to decide what the most beneficial path to controlling concurrent hyperthyroidism and kidney failure is. I really believe that it is best to try to control hyperthyroidism while doing everything possible to help the kidneys. If potassium is hard to administer orally it may be possible to administer it mixed with subcutanous fluids. Surprisingly, many cats who won't take pills easily don't mind fluid therapy much, even though it involves placing a needle under the skin to administer the fluids. Blood pressure medication is usually a good idea and we haven't seen problems using it while simultaneously treating the hyperthyroidism, although we do try to monitor patients carefully during this period. We have not yet seen the syndrome where radioactive iodine causes chronic renal failure to worsen but we have had at least two or three patients in which treatment greatly improved their condition. I don't think anyone can guarantee that outcome, but I do think that treating hyperthyroidism helps more often than it hurts.
I know this is a lot to think about. I hope that whatever choices you make they work out to be helpful for Nukat.
Mike Richards, DVM 9/28/2001
Placing long term catheter for Sub Q fluids - pros and cons
Question: Dear Dr. Richards:
Thank you for helping w/my cat problems. You have helped me sift through all of this tremendously. My vet has recently informed me about a catheter that just came out that can be left in for at least one year. Do you have any feedback on this? Since my cat Coco requires sub Q fluids daily my vet has recommended it. Thank you for taking the time to answer our questions. Lora
I am aware of the catheter that you are referring to. However, I am having a really hard time finding information on it. We just attended a seminar the first week in May at which the speaker, a urinary disease specialist, was asked if he had experience with these catheters and he was not even aware of them.
I can see where there would be a desire to have a port for administering subcutaneous fluids so that there was not a need to place a needle subcutaneously each time. Some of my patients do object strongly to the needle placement but most do not. I think I would avoid this use in patients who tolerated fluid therapy well already. The reason for this is that there is some potential to find out there are complications that didn't show up in initial studies for the FDA approval and there are probably cats whose objection to fluid therapy isn't the needle placement but the whole process of being held and of cold fluid running under the skin, which won't change much just because a needle isn't being used each time. However, I think I might be willing to try something like this for difficult patients, at least enough times to see if it helps.
That would be my thinking but it is just my thinking, not a report of experience with the catheters or based on any reports I have seen of their use. I wish I could be more helpful than that, but this is the best I can do at this time.
Mike Richards, DVM 5/18/2001
Use of lactulose in CRF cats
Question: Dr Richards,
I have been reading a great deal recently about the use of lactulose in CRF cats. I know it is useful for constipation, but it is also being used in smaller doses to bring BUN and creatinine numbers down. Do you know anything about this protocol and can continuous use of lactulose on a very low dosage for non-constipated cats be a problem? So many cat owners are crediting it for helping that I am seriously considering trying it. Anne
The theory behind using lactulose for chronic renal failure is that it may help to keep nitrogen in the digestive tract instead of allowing it to be absorbed/reabsorbed by the body, thus lowering the workload on the kidneys. This is just a theory, as far as I know, at the present time, because there have not been clinical trials to prove this occurs and/or to show any benefit from it. As long as the dosage of lactulose is controlled and kept below the level that diarrhea or vomiting occur, there is probably not much risk to this use and there may be another benefit. It is not uncommon for cats with chronic renal failure to have hard stools due to mild subclinical dehydration and lactulose would help to soften these stools and make the cats feel a little better. A low dose would probably work just as well for this use (like 1cc twice a day). We have a number of cats on lactulose at dosages varying between 1cc and 5cc two to three times a day for megacolon problems and some of these cats have been on the medication for years now, so I think it is a pretty safe medication as long as you adjust the dosage slowly to keep the stool soft without producing diarrhea.
There are a lot of therapies in veterinary medicine that are never validated through good clinical trials and so it is sometimes necessary just to try something and see if it works.
Hope this helps.
Mike Richards, DVM 1/23/2001
How important are blood pressure and urine checks on CRF cat?
Question: With a CRF and hyperthyroid cat, how important is it to do periodic urine tests and also check blood pressure? My vet does not have the equipment to do the blood pressure check and he also thinks that the urine testing is unnecessary at this point. Perhaps this is because it is somewhat difficult to get a urine sample? I have been told that I need to know how well my cat is concentrating her urine and also check for urinary infection.
Answer: Bob and Anne-
I don't have an in-clinic means of testing for high blood pressure in my practice, either. Due to this, we use anti-hypertensive agents based on our evaluation of the patient, which makes it a judgment call. I would feel bad about this approach except that the reason we haven't purchased a blood pressure monitor is that there still does not appear to be an easy and consistently accurate way to monitor blood pressure in cats. All of the available monitors that I am aware of have problems. When cats seem to lose their appetite, when blood flows into the syringe when we draw blood without putting pressure on the plunger, when visual problems occur or when we just have a strong feeling that it is necessary, we usually start an anti-hypertensive agent. At the present time I still favor amlodipine (Norvasc, Rx) but we have had some success using enalapril (Enacard Rx), as well. At some point, I am going to become convinced that one of the blood pressure monitors does work well enough to purchase it and then I suspect I'll want to check blood pressure at least a couple of times a year. I do respect veterinarians who have gone ahead and decided to try blood pressure monitoring and I think that it is possible to develop a technique that works to evaluate trends in blood pressure based on my conversations with vets that do this testing routinely. There is an equally strong case to be made for this approach, despite the problems inherent in the testing at this time.
We do a lot of urine analysis in our practice. In cats, we can get urine samples using cystocentesis, which is withdrawal of urine with a needle and syringe, in about 90% of our patients during office visits. We use a small gauge needle, usually 25 gauge, and place it through the body wall and into the bladder. The great majority of cats do not appear to notice that anything was done to them. I used to worry about puncturing the bladder doing this but we have not had a single problem in hundreds of patients that we have obtained urine from in this manner. Despite the fact that we routinely test urine when cats with renal failure come into the office, we do not schedule routine checkups for urinalysis very often. We tend to check urine when we are trying to establish the diagnosis, when we are trying to figure out if the kidney problems are the only problem, during yearly (sometimes every six months in older cats) routine exams and when we are faced with a patient who was doing well on medications and suddenly isn't.
If it is unclear whether kidney problems are present, urinalysis can be a very useful diagnostic tool. Sometimes it is necessary to differentiate between frequent urination that is the result of a bladder infection and frequent urination that is occurring because there is a kidney problem and urinalysis can be useful for this, too. If the diagnosis is already clear, due to blood work and if a bladder infection seems unlikely due to clinical signs, there is less need for a urinalysis.
Hope this helps clarify the situation.
Mike Richards, DVM 11/21/2000
CRF cat diet - what about Phosphorus?
Question: I have been reading that current research shows that it is the phosphorus in the diet that is a problem for a cat with chronic renal failure and not the protein. It is a real problem trying to help my cat maintain her weight (she also has hyperthyroidism) if I offer her low protein food that she doesn't really like. Anne
Controlling phosphorous does appear to be a major benefit of the diets that were designed originally to control protein levels and based on several studies, it does seem like controlling phosphorous levels by reducing them in the diet or using phosphate binders to prevent absorption from the digestive tract is very helpful in slowing the progression of kidney failure.
I think that it is more important that patients with kidney failure eat well and feel well than that they eat the diets we would like them to eat. Ideally, though, I'd like to have it both ways with the cat eating well from the selection of diets that are good for it. There are several, with Hills, Purina, Waltham and Iams all making low phosphorous, moderate protein content diets at this time.
When it is necessary to feed a cat what it wants to eat in order to get it to eat, phosphorous can still be controlled, in many cats, using phosphate binders. There are a number of these on the market and your vet can tell you which ones are available in your area. Currently, we have a compounding pharmacy in our neighborhood making aluminum hydroxide gel for us, since Amphogel (tm) has been hard to find, but there are other products.
Another alternative is supplementation of calcitriol to try to prevent secondary hyperparathyroidism (the problem associated with high phosphorous levels). This doesn't work as well after phosphorous levels are already high, though.
Mike Richards, DVM 11/6/2000
Epogen and CRF
Question: Dr. Richards,
Max, my 11 year old cat, was diagnosed with CRF in January. We were able to stabilize him with pepcid AC, metoclopramid, sub-qs, and calcitriol. He was doing very well for the last 6 weeks. We had taken him off of the sub-qs since he seemed to be doing well and the trips to the vet were causing stress and depression. Up until last Friday he was eating constantly and had gained some weight. Half of the time he would eat NF and half of the time Special Care (not for CFR but he likes it). His attitude and energy level was consistently very good.
On Friday he vomited when he woke up in the morning but seemed to be feeling good. Over the weekend he vomited 3 more times and Monday we went back to the vet. We are back on sub-qs and the blood test indicated that Max is anemic (19).
My vet suggested Epogen and he explained the high risk to using the drug. Have you used it and what has been your success rate? And would you recommend it.
At this point Max has maybe 3 months if I cannot get him to eat the right diet. Please share your thoughts on Epogen.
Thank you, mj
We usually refer patients to a neighboring practice which stocks Epogen, because it is expensive and we don't use enough of it to use a bottle before it goes out of date. We are fortunate that they are good about doing it for us. Our experiences have varied from very good to very bad, which I think is typical for this medication.
Epoetin alfa, which is the synthetic form of human erythropoietin in Epogen, causes some cats to produce antibodies against it. Unfortunately, these antibodies also attack the cat form of erythropoietin. This may cause the cat to be unable to produce red blood cells at all. Transfusions can be used on an "as necessary" basis to keep red blood cell levels in low normal ranges but this usually eventually leads to complications and is also expensive. I don't think that the risk has been accurately described but it is possible that as many as 30% of cats may form antibodies against erythropoietin, so the risk is significant.
It is supposed to be important to control high blood pressure prior to using Epogen. In some cases this seems to help with anemia, as well. It would be a good idea to check your cat's blood pressure or to just treat for high blood pressure since most cats with chronic renal failure do eventually develop hypertension.
We usually use an hematocrit of 15 as our point for deciding to use Epogen but many vets use any value below 20.
It might be easier to continue fluid therapy if you do it at home. Some vets are uncomfortable dispensing fluids, IV sets and the needles for this type of therapy but I think that the patient comfort factor outweighs these concerns and we often dispense fluids for home use.
Special Care (tm) diet is a particularly bad choice for a cat with chronic renal failure. It would be much better to feed Purina Cat Chow or a similar food that is close in taste to Special Care, if possible.
I wish that I tell you what to do but this is one of those situations in which you have to just make a decision and hope it is the right one, since there are risks associated with not treating cats and risk associated with treating them when severe anemia develops due to chronic renal failure.
Mike Richards, DVM 5/30/2000
Question: Dear Dr. Richards. apologies for the wrong cc no.only excuse is my 18 year old bunky was diag.with crf and in my hurry to get on line with you i messed up txs for your kind offer to e mail you before subscription approved.my question is:bunkys just diagnosed blood and urine panels are very high;creatinine 465 urea 357 in spite of this his demeaner is good and he is still eating and drinking well urination is high.at this point my vet has not discussed Sub Qs or any drug therapy and i would like to know if any of these procedures would help at this time.also wud it be appropriate to approach my vet re these matters seeing as how he chose not to broach these matters other than discussing dietry changes and to inform me that the outlook was not good.any advise at this time wud be greatly apprec many txs Don.
Unless I missed it, you didn't say whether Bunky was a dog or a cat.
The answer if Bunky is a dog is this: you need to talk to your vet about intravenous fluid therapy, especially if there is evidence of ongoing deterioration in Bunky's condition. Early aggressive treatment of renal failure in dogs is really pretty essential if they are going to have much of a chance with renal failure and they do not do as well as cats, even with aggressive care. Dogs seem to be helped by administration of enalapril (Enacard Rx, Vasotec Rx) based on the last three or four cases of renal disease in our practice.
If Bunky is a cat, there are many possible avenues for treatment and the prognosis is much better for long term control of the renal insufficiency. We usually use subcutaneous fluid therapy for the first few days, until the cat feels better and will eat well. In some cases it is necessary to start fluid therapy on a regular basis almost from the start of signs and in other cases, intermittent use when the cat doesn't feel well is sufficient. In a few cats, we catch the renal problems through lab work or some other way when there isn't inappetance or dehydration and in these cats we sometimes do just dietary management at first.
Many cats with renal failure have low potassium levels and most cats seem to feel better if potassium is supplemented. We are going to blood pressure control medications earlier now than we have in the past, as amlodipine (Norvasc Rx) really seems to make some of our patients feel a lot better. We use calcitriol frequently, as it also seems to make cats with renal failure feel better. When necessary, we use appetite stimulants, phosphate binders, gastrointestinal protectants such as famotidine (Pepcid AC Rx) and medications for secondary problems, like infections or anemia.
There really is a lot that can be done to make cats with renal insufficiency feel better and live longer. Let your vet know that you are really interested in providing the best possible care for Bunky.
If you need more information on any aspect of this treatment, please let me know.
Mike Richards, DVM 4/22/2000
CRF treatment options
Q: Thanks very much. I really appreciate the detail in your reply and I have been collecting my thoughts regarding some follow-up questions, namely:
(1) ACE Inhibitors: I have a copy of the The Pill Book Guide to Medication for Your Dog and Cat by Roby and Southam. They have some scary stuff in there about using Enalapril vis a vis inducing kidney failure. Do you know anything about benazepri? (This is the ACE inhibitor in common use in Germany with CRF cats and is used in the USA with humans until the name of Lotensin or Fortesin.) The internal medicine specialist that I have been using recently suggested that I consider ACE inhibitors as he heard about them at a vet conference he just went to. Thus Dr. J might be willing to help me use Benazepril. But given the lack of FDA approval, would I be better off just using Norvasc? In any event, what dosages and monitoring would you recommend?
Plus is there anyway to improve the quality of the blood pressure measurement with the doppler machine? The hospital I went to did nothing to reduce the stress of the experience. They forced the cat to lie down on a cold examining table, taped her up to get the wires to stay on and took three measurements in rapid succession. Any advice here, especially in how to convince the Dr. to let me hold the cat prone on my lap, etc.?
(2) Is Petinic the best choice for delivering the B vitamins and iron? If I want to reduce sodium levels to combat hypertension can I do anything more about diet since I am using Purina CNM NF for low phosphorus and protein?
(3) If I give the cat potassium citrate and her K level goes up (as we observed with a two week course of Tumil-K), is this dangerous? What dose of K citrate do you recommend and what kind of monitoring should I do while using it? Do I need a prescription or can I buy this in a health food store? Also, is it possible that there is enough K citrate in the Petinic to meet this dosage?
(4) Dr. J has been reluctant to recommend Calcitriol because of potential side effects. At the end of your email you suggested considering the use of this drug. Did you mean in Fluffy's case or in general as Fluffy's calcium level is 10.9 (high end of normal is 10.8)? Likewise on the amphogel, as her phosphorus is now down to 6 which is well within normal (2.4 to 8.3).
As you can see, this cat means a lot to me. I had to put another 18+ year old cat to sleep last January for cancer and this time I am trying to be a lot more informed and proactive. Thus I really appreciate all your feedback Susan
1) The dosage of benazepril for treatment of renal failure is 0.25mg/kg once or twice a day according to Dr. Brown from UGA. At the present time, there is still a lot of discussion among veterinary specialists on the Veterinary Information Network about whether it is better to use amlodipine (Norvasc Rx) or an ACE inhibitor. I do not know if there are advantages of one ACE inhibitor over another. There have been a small number of studies in pets on their effectiveness and different ACE inhibitors have been used. I do not know what the incidence of renal damage is in chronic heart failure patients treated with ACE inhibitors but if this problem has occurred in one of our patients, I missed it. We have had good luck with amlodipine, though. So I still usually prescribe it first. The hardest part of using it is dividing the tablets into fourths (they are really small).
1A) Practice is supposed to make the measurement of blood pressure using a Doppler machine more accurate. I don't know how much practice it takes, but at least once I am pretty sure I remember reading that it took as many as a hundred patients to really feel comfortable about reproducibility of the results. This is part of the reason that I think many veterinary practices haven't gotten into blood pressure measurement, yet. Our clinic is among the ones without this technology -- so I don't have enough experience to offer advice on the possibility of alternate ways of keeping a cat still enough for measurements.
2) I don't supplement vitamins very often and I tend to recommend PolyViSol pediatric vitamins because I was at a seminar in which the speaker said that it was about the same formulation as most of the pet vitamins --- but I'm not sure that is true. If Petinic isn't objectionable to Fluffy I think I'd stick with it. Purina's NF should be sufficient, though.
3)It is really hard to cause serious problems with potassium given orally but it is conceivable that problems could occur. If serum levels exceeded the high end of normal it is worthwhile to check plasma potassium levels as they often reflect the 'real' potassium level a little more accurately.
4)There is still a lot of disagreement about the value of calcitriol, too. We think that our patients on this seem to feel better but don't have much objective evidence of benefit to this medication. I think that the risk issue is real, but less of a problem than the study done by UGA would indicate, as they used fairly large increments in the dosage. Dr. Nagode (main promoter of calcitriol) says the phosphorous must be less than 6 and that hypercalcemia often seen in lab panels may not be reflective of the ionized calcium levels (so he recommends using ionized calcium and ionized phosphorous levels) but most practices have a hard time getting these values. If it is possible for your vet to check the ionized calcium level that may help in decision making, though.
We don't use phosphate binders until phosphorous levels get above 6, but with your cat's history it seems reasonable to continue them, especially since Fluffy has had higher values.
Hope this helps.
Mike Richards, DVM 8/30/99
Enalapril, amlopidine and benazepril for Hypertension with CRF
Q: I am a veterinary surgeon in Birmingham, England, and was recently brought a copy of your web site advocating enalapril for CRF by a cat's owner. Needless to say the cat has CRF. Could you give me some idea of the dose rate you use as neither I nor any of my colleagues have used this for CRF? Your web site was very interesting- I shall have to read it regularly from now on so I'm not caught off gaurd by well-informed clients in the future.
Many thanks C. H. BVMS,MRCVS England
A: Dr. H.
I did not check online to see what we had there prior to replying to this, but I thought it might be best to restate the information that I have seen on the use of enalapril, amlopidine and benazepril for control of systemic hypertension, intra-renal hypertension and proteinuria in cats. Since the damage from hypertension does seem to be part of the deterioration process seen with chronic renal failure in cats it makes sense that controlling hypertension would be helpful.
We have used amlopidine (Norvasc Rx, in the U.S.) at the dose of 0.625mg/cat for cats weighing less than 10 lbs and 1.25mg/cat for cats weighing more than 10 lbs. to control systemic hypertension for several years. I have been happy with this medication and feel that it has contributed to the well-being of many patients. Consequently, I have much more experience with amlopidine than with the ACE inhibitors.
Recently, the angiotensin converting enzyme inhibitors (ACE inhibitors) enalapril and benazepril have been reported to have beneficial effects in the treatment of renal failure, as well. Most of this information seems to be extrapolated from human medicine but there has been some mention of the use of these medications in the veterinary literature (Kirks Current Therapy XI has some information and there was an ACVIM abstract on the use of benazepril). I have seen several postings on the Veterinary Information Network (www.vin.com) pertaining to the use of ACE inhibitors. On VIN, the consensus appears to be that there may be some benefit to enalapril but that amlopidine is still considered to be the better medication for systemic hypertension. When it is possible to detect renal insufficiency early, enalapril may be better for early intervention as it is supposed to help control proteinuria and to provide more intra-renal hypertension relief than amlopidine, at least early on in chronic renal insufficiency. Enalapril is dosed at 0.1 to 0.15mg/lb of body weight in cats in the reports that I have seen on its use.
I was at a seminar talking to another vet and she said that her clinic had begun putting all cats with renal failure/renal insufficiency on enalapril and that they felt strongly that it was beneficial in delaying the deterioration associated with renal failure in cats. While this isn't scientifically validated information, it is supportive of the other information available.
At the same time that the hypertensive agents seem to be increasing in popularity, the vets at Ohio State University (Dr. Nagode, et al) are also strongly advocating calcitriol as beneficial to use early in chronic renal failure (also covered in Kirks XI). I am not sure which of these medications is actually best to use if only one is an option -- as might be the case in a cat that doesn't like to be pilled.
If this raises more questions than it answers, I'll be glad to try to clarify, With the caveat that I am just a general practitioner and not a specialist in any field of veterinary medicine!
Mike Richards, DVM 5/3/99
Q: Dr. Richards,
Thanks for the info on Feline CRF. I understand now what you mean about communicating to my Vet how aggressively I want to treat my cat's CRF. After an incidence of dehydration and my cat Bing's feeling rather crummy we had to put her on a day and a half of IV treatment to which she responded really well. After asking my Vet about the things you mentioned or that I've seen on the website, she is now on 3x a week SubQ fluids (200ml each time), a Potassium supplement and Amphogel as a phosphate binder.
In addition I remember reading about using Anabolic steroids for CRF cats (we also used them for humans (Deca) when I worked in a dialysis clinic). So I asked about it and so she's had a shot of Winstrol and is doing much better; her appetite and mood have picked up quite a bit. We've also decided to put her on Pro-Crit to deal with the anemia, 200u 3x per week starting Monday. For a 5lb. cat its only about $2.50 per dose. Even with the blood work to monitor the change in her crit over the next month or two, it's not exactly expensive. I'm just surprised more people don't do this. A few relatively simple things that are the difference between feeling crappy with CRF, having no appetite or energy, trouble moving muscles etc. and living a relatively normal comfortable life until the end. Again thanks a lot for all the info.
Just need to ask about two things:
Regarding using a steroid. Is Winstrol a good choice with a frequency of every two week injections? Does she ever even need to stop taking it; even after we help her anemia with the Epo and her appetite and energy are better, a steroid would probably help prevent muscle wasting. Should she cycle off it after a while onto another?
Secondly, we're using Amphogel as a Phosphate binder. Is this a good choice? Hopefully it doesn't also bind iron, which we've been supplementing and she needs for the Pro-Crit to work well.
Bing and I thank you for your help, Dennis
Stanazol (Winstrol Rx) has been recommended for use in renal failure because it may have a positive effect on red blood cell production and because it is reported to help increase appetite and sometimes general well being. I have used it sometimes in cats with renal failure and have seen no adverse effects in clinical use. This seems to be the experience of most vets I have talked to. I try to keep the total number of medications down with treating patients with chronic illnesses, when possible, so I don't routinely use Winstrol in all cases. It is one of the medications that just has to be used on the basis of perceived need. If you and your vet agree that it is beneficial there are not likely to be problems with continued use.
Amphogel (TM) is the phosphate binder that I see referred to most often in veterinary literature and among vets. It is easy to find and comes in a liquid formula so it is convenient to use in most cats. I have not seen any reference to it binding iron but it seems conceivable that it might. Many vets supplement B vitamins and iron in cats with chronic renal failure to counteract this worry and because it is assumed that these nutrients are necessary due to anemia. We don't usually do that but I can understand the worry.
Epogen (Rx) can cause the production of anti-erythropoietin antibodies in about 25 to 50% of cats (the exact percentage seems controversial) so it is recommended that its use be restricted to cats in serious anemia. Different vets have different opinions about the best time to start Epogen but the risk of reaction is going to be there no matter what so I haven't quite figured out whether it really matters when it is started.
I am glad that you are keeping Bing's comfort and quality of life in mind. That is the most important thing. He is lucky to have you caring for him.
Mike Richards, DVM 2/16/99Last edited 09/17/02
Michael Richards, D.V.M. co-owns a small animal general veterinary practice in rural tidewater Virginia. Dr. Richards graduated from Iowa State University's College of Veterinary Medicine in 1979, and has been in private practice ever since. Dr. Richards has been the director of the PetCare Forum...