VetInfo Digest         June 2001

This Month:

An addition to last month's vets and vaccinations column

Grape and Raisin Toxicity in Dogs

Immediate Care of Newborn Puppies and Kittens

Alternatives to Glucocorticoids for Itch Control

Tick Control

This Month's Note:

My wife and I drive to a friend's house fairly frequently. There are several ways to get there and we often argue about which one is best. We know that one way is almost always faster, even though we drive away from our friends house at the onset of the drive, which always seems wrong. We know that another way is shortest, but it takes longer due to the nature of the roads. Finally, we know that there is a scenic route that definitely goes a little out of the way but is very pretty. What we never seem to agree on is what way is the BEST way any particular day.

Medicine is a lot like this. There is a goal that can be agreed on most of the time, but there are a lot of ways to get there. It is possible to choose a path that favors cost control, a path that favors patient comfort, a pathway that favors caution over cost or patient comfort. The right way is not always clear cut but must be decided on every trip. Just because one way to the goal works doesn't make it the only way to get there. The only really wrong answers are those that don't satisfy the goal in the long run. The rest may feel better or feel worse, depending on the perspectives of the veterinarian and the client but they aren't really right or wrong. They are just different paths to the same place.

An Addition to Last Month's Note On Vets and Vaccinations

Last month I wrote a little about the effect of changes in vaccination procedures affecting veterinary clinics. Some of our subscribers were worried about the personal effect this might have on my own practice. I am fortunate to have been in practice long enough to actually want to slow down a little at this time and to be financially able to do that. So for my practice, this is not a big concern. I do really worry about the profession as a whole, though.

New veterinary graduates have usually been in college seven to eight years and have accumulated a moderate to a great amount of debt during that time. They graduate into a profession in which the starting salaries hover around $40,000 per year and the average salaries for all vets are around $56,000 per year. And this includes a number of veterinarians in my position, who have been in practice a long time and make more than the average. The price of equipment continues to climb. When I started in small animal practice the X-ray machine was the most expensive piece of equipment that was available. Now, an X-ray machine costs about a fourth of the price of a good ultrasound machine and half the price of a surgical laser. Blood chemistry units are about the same price as an X-ray machine and good dental units are about half the cost of the X-ray machine. Granted, not all practices need all of these machines, but purchasing even one of them is a significant capital outlay that has to be recouped.

A recent survey was done in which pet owners were asked how much they were willing to spend on a pet before euthanasia became a serious option for them. The average figure was $652. There isn't a lot of room for advanced care in that dollar figure. I am worried that some of my younger colleagues are going to have significant problems supporting their practices without some drastic changes in veterinary medicine. On the other hand, the fact that a number of people have subscribed to our information service looking for information on advanced treatment options is a good sign that the surveys might not tell the whole story. I am also encouraged by the number of people who write whose vets are providing excellent care and trying hard to help their clients. I know that many of you are among the really good clients a practice needs to survive.

What can you do to help your vet and your pet?

Grape and Raisin Toxicity in Dogs

Recently, there was a letter in the AVMA Journal from Dr. Gwaltney-Brant and others at the ASPCA Animal Poison Control Center discussing grape and raisin poisoning in dogs. Apparently, grapes and raisins can be toxic to dogs when ingested in large quantities.

The grapes and raisins came from varied sources, including being eaten off the vine directly. The dogs exhibited gastrointestinal signs including vomiting and diarrhea and then signs of kidney failure with an onset of severe kidney signs starting about 24 hours after ingestion of the grapes or raisins. The amount of grapes eaten varied between 9oz. and 2 lbs., which worked out to be between 0.41 and 1.1 oz/kg of body weight. Two dogs died directly from the toxicity, three were euthanized due to poor response to treatment and five dogs lived. Due to the severity of the signs and the potential for death, the veterinarians as the poison control center advocate aggressive treatment for any dogs suggested of ingesting excessive amounts of grapes or raisins, including inducing vomiting, stomach lavage (stomach pumping) and administration of activated charcoal, followed by intravenous fluid therapy for at least 48 hours or as indicated based on the results of blood tests for kidney damage.


I have fed my dogs a few grapes every now and then for years, so I don't think there is a need to panic if a dog eats three or four grapes but if the whole bunch is missing from the table one day, it would be good to think about watching for any signs of a toxic reaction.

Immediate Care of Newborn Dogs and Cats

This year I found out that I have been taking care of neonatal puppies, and sometimes kittens, incorrectly, at least in part. Somewhere in my veterinary career I was taught to cup a newborn puppy or kitten in my hands and to swing it through a gentle but fast arc in order to try to clear its lungs. I happened to run across a discussion on the Veterinary Information Network (tm) about this procedure and the emergency specialists giving advice there felt that this procedure was potentially damaging to puppies and kittens due to the potential for causing brain damage (sort of like the shaken baby syndrome) and that it did not effectively remove the fluids and mucous from the respiratory tract, anyway. So I checked on this since I didn't really think that we had been harming puppies, even though we have had some who we could not revive after cesarean sections or even natural deliveries. There isn't a whole lot of information geared specifically to the care of newborn dogs and cats but there is some and there is also some general information that can be obtained from experiences with human infants that probably applies to pets, as well.

When doing a cesarean section, the first considerations are care if the mother and the choice of anesthetic for the procedure. Many times veterinary patients having birthing difficulties are in bad shape by the time they come to the veterinarian's office. They often have respiratory, cardiovascular and fluid balance complications that make anesthesia more of a risk. It is necessary to place one or more catheters to allow administration of intravenous fluids and to keep fluid therapy up during surgery. It is a good idea to assess whether there is food in the stomach with X-rays, if there is time. If there is food, it is necessary to use an anesthetic procedure that allows rapid intubation of an airway since the pressure from the kittens or puppies makes vomiting more likely. General anesthetic agents do cross the placenta and will cause sedation of the puppies or kittens in the uterus. For this reason, there is a growing tendency to use local anesthetics or regional anesthetic blocks such as spinal anesthesia techniques, in conjunction with a narcotic pain relief medication. Alternatively, anesthetic agents that are rapidly cleared from the body, such as propofol (Propoflo Rx) are a good choice. Use of inhalant anesthetics is acceptable (except perhaps for methoxyflurane) but an effort should be made to keep the dosage low and to use a local anesthetic and pain reliever to control some of the pain during the anesthetic procedure. It is important to remember to control postoperative pain, as well.

While surgery is being performed it is best if someone is preparing for the rapid arrival of a large number of kittens or puppies. It is helpful to know some things that are different about newborn kittens and puppies when compared to older puppies and kittens. The first thing is that newborns may not gasp for air if they are not getting adequate supplies of it. For some reason, newborns seem to lack this response and will just become lethargic and fade away if not stimulated to breathe.

It is necessary to keep puppies and kittens awake and aroused. We don't recommend swatting their bottoms for this, but it is a good idea to run them dry with a towel that has been warmed up just for this purpose and to suction their mouths gently with a bulb syringe like the kind sold with ear washing kits. If there is a clamp on the umbilical cord from a cesarean delivery it is important not to cause rough movements of the clamp as this can encourage the development of umbilical hernias.

Drying the puppies and kittens helps with the other problem that newborns have, which is an inability to stay warm. It is thought that failure to keep newborns warm enough is the major cause of neonatal death in kittens and puppies. The best temperature range for newborns is between 85 and 90 degrees Fahrenheit (28 to 32 degrees Celsius). Temperatures below this range will allow hypothermia to develop and temperatures above this range can sometimes decrease respiratory effort. It is necessary to have a spot ready for the puppies and kittens before they are born, especially when a cesarean section must be done. If the mother is with the newborns her body will provide a good source of heat but it is still a good idea to provide a small area that they can get to that it warm enough for them. It is not a good idea to keep the whole room at 90 degrees since that will upset the mother and can decrease her milk production, as well.

Puppies and kittens should have heartrates between 120 and 150 beats per minute and should attempt to breathe on their own within one minute of being delivered. If they do not breathe within this time resuscitative efforts should be made. It is OK to try to extend the newborn's head and then breathe gently into their nose at home. This is not as effective as using an oxygen mask placing an endotracheal tube and administering oxygen but at home it may be the best that you can do.

In veterinary clinics it is not unusual to try to stimulate respiration or reverse the effects of narcotic analgesic agents with medications. At the present time it appears to be the consensus of veterinary emergency medicine specialists that doxapram (Dopram Rx) is not every effective and most do not recommend its use any longer. Naloxone, a medication used to reverse the effect of narcotic agents in adult dogs is also of limited effectiveness in puppies. In situations in which narcotic agents were used to control pain in the whelping bitch and puppies seem to be very depressed it would hard to say that it should not be used, though. Oxygen therapy is probably the best medicine available at a veterinary clinic for newborns who are struggling in the first few minutes of life.

It helps a lot to think of the importance of the various things that you can do to stimulate a newborn and to develop a routine for helping them out. Immediately after birth it is best to dry puppies and kittens with a warm cloth, rubbing them gently to stimulate them. It is also helpful to suction any fluids from their mouth and nasal passages quickly, as well. While doing these things the newborn's heart should be evaluated by gently feeling for a strong heartbeat. Respiratory efforts should be monitored and the baby should attempt to breathe within the first minute. If this doesn't happen then an effort should be made to assist respiration, preferably by administration of oxygen but if that is not availabe then by very gently attempting mouth to mouth/nose resuscitation. Try to keep the newborn's neck extended to keep the resuscitation efforts from filling up the stomach instead of the lungs. If this does not produce quick results it may be helpful to compress the chest gently and rapidly for several compressions, although I can't really recall getting much benefit from this procedure. If that doesn't produce results really rapidly then it seems reasonable to try medical stimulation, even though it probably won't work, either.

Estimates of the average death loss in newborn puppies and kittens vary pretty widely in published studies but there is probably around a 5 to 10% death loss within the first few hours after birth. Having a plan to stimulate puppies and kittens who are not doing well at birth might make it possible to reduce this number, perhaps significantly.

Alternatives to Glucocorticoids for Itch Control

Itchiness, or pruritis, is a bigger problem in the summertime than it is in other months, even though we definitely have some patients who itch all year. We have seen a major change in the number of itchy pets and the patterns of itchiness in those pets over the last few years, though.

One of the biggest changes in veterinary medicine has been the arrival of flea control products that work extremely well. When I started in practice the standard flea control products were natural pyrethrins, carbamates and organophosphates. The pyrethrins were not very effective, even for the fleas and ticks that were on the pet at the time of application. Carbamate (Sevin Rx) was becoming less effective and organophosphates were good at killing the fleas on the pet but had no real residual effect. It was necessary to treat the pet, the house and whatever portion of the outside environment that the dog spent time in to control fleas. The difficulty kept most pet owners from succeeding at flea and tick control. The arrival of permethrin and other synthetic pyrethrin products upped the effectiveness of these products and insect growth-regulators also helped. But it was still very difficult to control fleas effectively with these products and it still is with the ones currently on the market, such as Defend Exspot (tm), BioSpot (tm), Hartz Control (tm) and others. When lufenuron (Program Rx) arrived, flea control improved but was still not really great. Finally, imidocloprid (Advantage Rx) and fipronil (Frontline Rx) were produced and good quality flea control really become practical for most veterinary clients. Selamectin (Revolution Rx) is also reported to be very effective for flea control. These three products provide continuous high quality flea control. A relative newcomer to the flea control market is nitenpyram (Capstar Rx), which kills virtually 100% of the fleas present on the pet at the time of administration, based on studies, but which has no residual effect. I suspect that this product would not be much better than the organophosphates were, except for safety, when used alone.

Prior to the time that good flea control was possible, at least twenty-five percent of our summer and fall days were spent treating itchy dogs and cats. At the present time, about ten percent of our office visits involve itchy pets. About half of these pets are owned by clients who won't use the new flea control products for one reason or another. The other half have some other cause for the itchiness. Being able to nearly eliminate flea bite sensitivity as a cause of itchiness has enabled us to use alternative medications to corticosteroids, such as prednisone, with more effectiveness. The first step when treating itchy pets is to use a good flea control or flea and tick control product and to ensure that there are no underlying conditions that can be treated to control the itching, such as bacterial infections or ringworm.

Our thinking on other diseases that cause itchiness has changed a lot, too. When fleas were present, I always assumed that they were the major cause of itchiness. Due to this, I was willing to accept that some disorders that were reported as non-pruritic (not itchy) weren't. Now I am convinced that there are some cats who are very itchy when they have ringworm or chiggers and that there are dogs who will chew incessantly due to bacterial skin infections. Other causes of itching, such as atopy (inhalant allergies), food allergies, parasitic mites still cause a lot of the cases of skin disease, of course.

Like many veterinary practices, we used more corticosteroids when flea control was not possible than we would have liked. The ability to control a major irritation has allowed us to explore the use of other medications for itch control and we seem to be having more success with medications such as antihistamines than we had in the past. In addition, there are some new choices in itch control medications that have helped some patients when it seemed important not to use corticosteroids for one reason or another and itching was not responsive to antihistamines.

There are a number of antihistamines on the market. Many of these have been used to treat itchiness in pets. There are conflicting studies over the relative effectiveness of the antihistamines and also over the percentage of pets that can be helped with these medications. I don't think that there is too much point in worrying over relative effectiveness at this time. We use the antihistamine whose dosage seems to work best for the size of the pet we are treating and then switch to others if the initial choice is ineffective.

I do think that it is important to have realistic expectations about the potential for the antihistamines to work. In some of the original studies the effectiveness of antihistamines for acceptable control of itching (to pet owners) was reported to be 10 to 20%. Early reports on clemastine showed effectiveness approaching 30%. This figure has risen in newer reports to as high as 40 to 50% client satisfaction and up to 30 to 40% for other antihistamines in dogs. I think that the change reflects the change in the causes of the itchiness and that it is worth trying antihistamines again if you tried them prior to the time that good flea control was available and were not satisfied at that time. The other thing that is reflected in these figures is that most veterinary dermatologists recommend trying several antihistamines at this time prior to giving up on them. Each antihistamine should be given at least ten to fourteen days for evaluation purposes and some vets recommend two to three weeks of use prior to giving up on an antihistamine. Antihistamines are thought to be more effective in cats but there are fewer choices for this species.

At the present time, the antihistamines which have been studied enough for suggested dosages to be published include the following medications:

Generic Name Brand Name Dog Dosage Cat Dosage
 
diphenhydramine Benedryl 2.2 mg/kg every 8 to 12 hours same dosage, increased risk of side effects
doxepin Sinequan 0.5 to 1mg/kg every 12 hours no published dosage
hydroxyzine Atarax 2.2mg/kg every 8 hours 10mg/cat every 12 hours
chlorpheniramine Chlortrimeton 0.2 to 0.8mg/kg every 8 hours 2mg per cat every 12 hours
amitriptyline Elavil 2.2 mg/kg 5mg/cat every 12 to 24 hours
trimeprazine tartrate Temeril 2.5 to 5mg/dog/every 8 hours no published dosage
clemastine Tavist 0.05 to 0.10mg/kg 0.34 to 0.68mg per cat once or twice daily

Antihistamines make some pets drowsy and vomiting is an occasional side effect at normal dosages. Tremoring, loss of balance, weakness or any other severe signs should be reported to your vet immediately and the medications discontinued. Amitriptyline has antihistamine effects but is also a tricyclic antidepressant, so it is possible that it's effects are due to both actions.

Essential fatty acid (EFA) supplementation has been shown to enhance the effects of antihistamines. There are a number of products that contain EFAs in varying amounts. A good way to evaluate these supplements is to look for the amount of eicosapentaenoic acid in the supplement. For best effect, it takes approximately 18mg/lb of body weight of eicosapentaenoic acid per day for both dogs and cats. These products seem to be very safe to use. If cost is not a significant factor in decision making they should probably be used for most itchy pets. These products can be expensive and when this is a major factor the benefit they provide may not be cost effective.

Pentoxifylline (Trental Rx) has been shown to be effective in reducing itchiness in dogs significantly but does not often totally control itchiness when used alone. It is dosed at 10 to 25mg/kg every eight hours. I am not aware of any studies that support the use of this medication for cats. Pentoxifylline can be used with antihistamines and essential fatty acids to enhance the effect of all three medications.

Misoprostil (Cytotec Rx) has been shown to control itchiness in dogs when used alone in 30 to 50% of dogs. It may also enhance the effects of antihistamines, leading to a better combined effect than when either medication is used alone. Some dogs will experience vomiting or diarrhea with administration of this medication. The recommended dosage is 3 to 6 ug/kg (this is micrograms per kilogram) every 8 hours.

It is important not to forget that immunotherapy works for many dogs and cats with atopy. This is the creation of specific injections that are based on testing to determine what a pet is allergic to and then developing injections from those tests that help a pet overcome its allergies. Immunotherapy works around 70% of the time, based on studies, to control itching from atopy in dogs and probably slightly less often in cats, although this is debatable. The biggest problem with immunotherapy is the delay in response to treatment. It takes several months in a best case scenario for a pet to begin to respond to the injections and much longer in some pets. Dermatologists usually recommend continuing the injections at least 18 months before giving up on them. Fortunately, once a diagnosis is made, it does not appear that the use of other medications to control itching has any major effect on the effectiveness of immunotherapy, including the use of antihistamines and glucocorticoids. So it is possible to control the immediate problems and hope for a long term reduction in itching with this approach to therapy.

For pets that do not respond to any of the above medications and for which corticosteroids can not be used or have not been effective, another alternative is cyclosporin (Sandimmune Rx). This is a very expensive medication and it has side effects in some patients that are just as worrisome as those associated with corticosteroids (bone marrow suppression, immune system suppression, kidney failure) but it is reported to be very effective in controlling itching in dogs with atopy and has been used in cats, as well. The dosage is approximately 5 to 10mg/kg per day but the dosage should be adjusted in each pet based on serum cyclosporin measurements. While it seems unlikely that this medication will ever be an early choice for use in itchy dogs it does have a place for patients that just don't respond to other medications.

Corticosteroids will continue to play a role in control of itching in dogs and cats due to the effectiveness of these medications for itch control. However, it is best to use the lowest possible dosages for the shortest possible time. Controlling fleas and having alternative medications helps to achieve this goal.

Tick Control

Ticks are different than fleas and the products that control fleas well do not always help with ticks. For this reason, it is important to determine if you have a tick problem and to make a strategy for dealing with it that is separate than flea control, in some cases.

Permethrin is a very effective tick killer and also repels ticks. Therefore, products such as Defend Exspot (tm), Hartz Control (tm) and Biospot (tm) are much more effective for tick control than for flea control. Our experience has been that these products only provide really good tick control for two or three weeks but that the labeling for Defend Exspot and possibly others does allow for application at two week intervals, if necessary.

Fipronil (Frontline or Frontline Topspot Rx) works well to control ticks for slightly less than thirty days, based on our experiences with it. This is good enough for most clients but we do have some who use Frontline once a month and a permethrin based product two weeks later and then once a month. This gives a rotating schedule of medications that provides very good tick control for the entire month.

Amitraz, which is included in the Preventic (tm) tick collars, is an effective tick killer and tick repellent product. The collars seem to work very well, which is a departure from the expectations we have always had with flea collars, which don't seem to work well at all. We are a little reluctant to sell Preventic collars to clients who have more than one dog or who have toddlers, though. The collars appear to taste good or be attractive to dogs (and sometimes young humans) and we have had several dogs who ate their companion dog's Preventic collar and exhibited definite signs of toxicity. While we have not had a death from this behavior I do think it is possible that one could occur and so we try not to sell Preventic collars when we think there is a risk of the collar being eaten. If a collar is ingested it usually causes sedation and balance problems resembling alcohol intoxication. Yohimbine is an antidote that works reasonably well for amitraz intoxication, so treatment is possible.

Selamectin (Revolution Rx) is approved for killing one type of tick. I have not used this product much but other vets have told me they weren't too impressed with selamectin's tick control properties. It is still early in the evaluation process but at this point I think that if ticks are a problem, it would be best to use a different product. It has been proven to be effective as a heartworm medication and the flea control properties of selamectin appear to be very good, as well.

Imidocloprid (Advantage Rx) and lufenuron (Program Rx) do not kill ticks. However, it is possible to use a tick control product in conjunction with these other medications if necessary. I am not sure that the program is still in effect, but the manufacturers of Advantage were giving away a permethrin based topical for tick control through veterinarians.


It is hard to keep track of all the products for flea and tick control. We still think that fipronil (Frontline products) is the best combination product for flea and tick control but there are times when it is better for an individual patient to use other products in combination. The most important thing is to remember that there are enough effective products market now that most pet owners can solve their flea and tick control problems.

My plan to catch up completely with email by the end of May has not worked out quite as well as I had hoped but I am continuing to work on the backlog and have been gaining on it. I appreciate everyone's patience while this process continues.

Thanks for Your Support!

If you send us e-mail, remember that Michal Justis answers the e-mail at vetinfo@vetinfo.com. E-mail sent to mervet@inna.net is answered by Dr. Michael Richards.

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The opinions expressed in this newsletter are those of Michael Richards, DVM., author.

Copyright 2001, TierCom, Inc.