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VetInfo Digest November 2004

Table of Contents:

Dealing with itchiness in pets

Legal Issues in Veterinary Medicine

Sugarless Candies Can Poison Dogs

This Month's Note:

Veterinary medicine is beginning to follow a trend in human medicine towards increased specialization. This trend is being driven by increased costs of some diagnostic and surgical equipment as well as the ever expanding amount of information available on specific problems such as dermatology or nephrology. As the information becomes more and more specific to a particular body system or particular group of animals it becomes harder and harder for general practitioners to keep up with all of it. In addition to the time and effort it is very hard to justify the cost of equipment that will be used infrequently. Specialization insures that expensive equipment dedicated to one purpose can still be used efficiently, as the specialist attracts cases from a number of general practices. Ultimately this process will improve the quality of diagnostic and therapeutic options for a number of conditions that affect pets. At the current, time, though, there are definitely areas of the country where specialization hasn't made significant inroads. In addition, there are specialties, such as behavioral medicine, where the number of board certified specialists is so few that there is no way they can meet the demand for services, even in their own practice regions.

Hopefully, as specialization becomes more common in veterinary medicine we won't go completely overboard and get to the point that sometimes seems to occur in human medicine where a different specialist is working on every body system but no one seems to be looking out for the entire patient's needs. Having specialists is a great boon for pets and pet owners who wish to provide the best possible care for their pets but it is still very necessary to have a good general practitioner who can help you make the best decisions about the overall care necessary to keep your pet healthy.

Dealing with Itchiness in Pets

I thought that it would be a good idea this month to update the information on itchiness in dogs and cats and to expand just a little on information previously presented on the web site and in the VetInfo Digest.

One of the most important concepts to understand about itchiness in dogs and cats is that the itchy feeling that the pet has is the cumulative result of everything affecting it that contributes to itching. Most pets can tolerate a certain level of itchiness without feeling the need to scratch or bite at themselves. Once that level of itchiness is exceeded, they may bite and scratch frantically. From a practical standpoint this means that some pets will tolerate low levels of fleas with no sign of problems or they may tolerate a food allergy with no visible symptoms -- but if they are tolerating the food allergy and then fleas are added they may become miserable quickly. This means that it is critical to control any and all sources of itchiness that occur in pets who are scratching or biting at themselves in an effort to push the itchiness level down below the threshold for scratching. In some cases when it isn't possible to eliminate one source of itchiness, such as an allergy to pollens, the pet can live with the allergy comfortably as long as no other source of itching is present.

There are many things that can be helpful in eliminating itchiness in pets. Looking at the following list and picking out as many of these things to do as seems possible for your pet may be the difference between dealing with chronic scratching, biting, hair loss and secondary bacterial or yeast infections and having a dog who looks and acts normal.

Without question, the first step in controlling itchiness in pets is to ensure that they are free of fleas. Nothing made a bigger dent in the number of itchy dogs and cats in our practice than the arrival of the first really good flea control products several years ago. These are the truly effective products for flea control:

1) Imidocloprid (Advantage Rx, Advantix Rx): There are two versions of this product, the original Advantage, which only controls fleas and the newer product Advantix, which aids in the control of ticks and is available for dogs only. Imidocloprid provides good flea control for about three weeks and the permethrin which is added to Advantix to control ticks works pretty well for 10 to 14 days. Imidocloprid can be washed off more easily than fipronil and this should be considered in pets who need frequent baths.

2) Fipronil (Frontline Spray Rx, Frontline Topspot Rx, Frontline Topspot Plus Rx): This product has three versions. The "Plus" is the addition of methoprene, an ingredient that can help prevent flea reproduction. The pricing of the Frontline products is a little peculiar and by examining it closely it is possible to purchase the least expensive version for an individual pet. The Frontline Spray will treat 180 pounds of body weight at the normal dosage and 90 pounds of body weight at the dosage advocated for long haired pets. This means that 1 bottle of spray is usually enough to treat a cat for an entire year -- for about the same price a one package of the Frontline Topspot that will last three months. The disadvantage is the fact that most cats don't like to be sprayed with anything -- but especially not with flea control products. Small dogs often can be treated for the entire flea season with one bottle of spray and most dogs are better about tolerating being sprayed than cats. Conversely, a bottle of spray might only treat a big dog once or twice and costs about the same as the large dog Topspot vials which will treat the dog 3 times. Fipronil is very effective for about 3 weeks and then the effect on fleas does diminish. It is resistant to being washed off the pet but very frequent bathing will diminish its usefulness. It is extremely important to follow the directions for the use of the spray. Applying an occasional light mist of Frontline Spray is not going to work to control fleas, you must use the correct dosage of 1 or 2 pumps of the sprayer per pound of body weight in order to get the full effect of the fipronil. The Frontline Topspot products take several hours to kill fleas so it isn't unusual to see live adult fleas on the pet while using these products until the fleas are controlled in the pet's environment so they are not available to jump onto the pet. This can be confusing to pet owners but you just have to give the product two or three months to clear out the fleas before deciding that it isn't working.

3) Selamectin (Revolution Rx) kills fleas, kills one type of tick, prevents heartworms and may also help in control of ear mites and sarcoptic mange. It is available for both dogs and cats. It is systemically absorbed so bathing after it has had a chance to be absorbed doesn't affect it much. It also produces its strongest effect in the first three weeks after it is applied. The efficacy of selamectin for heartworm prevention is estimated to be 90% based on recent studies. The failure rate for prevention of heartworms in the monthly oral tablet forms (ivermectin and milbemycin) is not known with certainty but is estimated to be about 99% at the present time.

4) Lufenuron (Program Rx, Sentinel Rx) is an oral tablet that must be given at meal times. It interferes with flea reproduction. If it is used consistently over time in pets confined to a controlled area, it will eliminate the flea population in that area. This process may take several months, though. Lufenuron can be combined with nitenpyram (Capstar Rx), also an oral tablet, which kills only adult fleas on the dog at the time the pill is administered. Typically the Capstar is given twice a week for the first 6 weeks or so when the two tablets are used together and then Program is continued long term. The combination can be very effective at controlling fleas.

With the advent of the flea products listed above there has been less need to treat the pet's environment to kill fleas there before they can attack the pet. Despite this it can be very helpful to kill the fleas in the house or yard, especially when first trying to get boom in the flea population in your pet's environment under control. It is absolutely essential that all pets in the household be treated with flea control products in order to get a flea problem completely under control. This is probably the most important reason for failure of flea control in our practice. Too many clients think they only need to control the fleas on the pet with flea allergies and that just doesn't work very well.

Fleas aren't the only insects whose bites can cause itchiness. Avoid mosquitos, biting flies and biting gnats as much as possible. It is OK to spray a pet with a pyrethrin based flea control product to repel mosquitos and flies while on a walk. Products such as Adams Flea and Tick Mist (tm) can be sprayed lightly on the pet prior to walks and is safe to use in combination with any of the flea products listed above.

While I haven't seen any scientific evidence for this, I am convinced that air conditioning during the hot months is the next best thing for pets with itchiness. Keeping the pet cool seems to limit the onset of secondary infections associated with causes of itching such as allergies and just seems to aid in the control of itchiness in general. The exception to this might be pets who are allergic to dust mites and therefore do better when they can be outside.

Dr. Keith Hnilica, a veterinary dermatologist at the University of Tennessee, has a good web site on ways to control itchiness in allergic dogs: www.utskinvet.org. On this site he advocates throwing out any dog bed over a year of age and washing all dog bedding every 7 days using hot water to kill dust mites, since they are a very common allergen for dogs. He also advocates keeping the pet away from cigarette smoke, strong perfumes (this isn't on his site but has mentioned it in continuing education lectures) and keeping the humidity in the house at 40% or less, if possible.

Bathing itchy pets, or even just running cool water over them for 10 minutes or so, can help to relieve itchiness for several hours to several days. Many of my clients are reluctant to bathe pets on a regular basis, fearing that it will cause more problems than it solves. Our experience strongly suggests otherwise. Pets who are bathed once or twice a week have fewer skin problems than pets who are bathed less frequently. For itchy pets the use of a soothing shampoo, such as an oatmeal shampoo, can be very helpful. If it is necessary to use an anti-bacterial or anti-yeast shampoo to control secondary infections or an antisebborheic shampoo to cut down on greasiness these can be followed with a soothing creme rinse. There are creme rinses with oatmeal or with ingredients like hydrocortisone or pramoxine to aid in itch control.

The use of antihistamines can help control itching in a small group of pets. Antihistamines seem to be effective about 10 to 15% of the time in controlling itchiness in pets. While this is a low rate of effectiveness these are over-the-counter products that are readily available and so it is worth trying them for 7 to 10 days to see if they will help. In cats the antihistamine of choice seems to be chlorpheniramine (Chlortrimeton tm, 2mg/cat every 12 hours) and in dogs the two that seem to work the most often in studies are diphenhydramine (Benedryl tm), 1mg/lb of body weight, and clemastine (Tavist tm) 0.02 to .04mg/lb of body weight .

Adding marine fish oil to the diet, or some other source of omega-n3 fatty acids, can also help in control of itchiness. The veterinary product most often recommended for this is 3V Capsules (tm) or 3V Caps Liquid Skin Formula (tm). Increasing the omega n3 fatty acids in the diet can control itchiness in dogs and cats about 10 to 15% of the time. Combining fatty acid supplementation with antihistamine therapy is supposed to provide an additive effect that makes it more likely the combination will work than either product alone.

If secondary infections do not seem to be present the next step up in itch control is the use of a triamcinilone spray (Genesis Spray tm) to control itchiness. If secondary infections are present it is better to treat them first and then to use the spray only if control of the secondary infections doesn't control the itchiness. Using Genesis spray is kind of a compromise between not using cortisones at all and using oral cortisones. It is not as effective as oral cortisones but it doesn't have as many side effect, either. The spray is surprisingly effective for some dogs but doesn't work well for all dogs. It is not approved for use in cats and we have not tried it in cats to see what the effect might be. It is plausible that it would work well, as some veterinary dermatologists feel that triamcinolone is the best corticosteroid to use orally in cats with skin disease.

Control of secondary infections is a critical issue in controlling chronic itchiness in dogs. Cats develop secondary infections from itchiness less commonly than dogs but when they do occur they need to be controlled, as well. By far the most common secondary infections in dogs with allergic or other itch producing disorders are bacterial infections from some form of Staphylococcus (Staph) bacteria. These can generally be controlled with antibiotics but it is essential that antibiotics be used long enough. The minimum recommended dosing period for antibiotics for skin disease is three weeks -- and it often takes 6 to 8 weeks or even several months to control skin infections completely. There are a few antibiotics that tend to work reliably for skin disease and it is reasonable for your vet to dispense an antibiotic without identifying the bacteria involved -- at least the first time that a skin infection occurs. If the response to antibiotics isn't as good as expected then it is better to try to obtain a culture from the skin to identify the bacteria and to allow sensitivity testing to see which antibiotics are most likely to kill it successfully.

Secondary yeast (Malassezia) skin infections are common in dogs and occur occasionally in cats. In dogs these infections produce a very characteristic thickening of the skin (elephant skin) that is almost diagnostic for yeast infection, although it does sometimes occur with hormonal diseases and once in a while due to bacterial skin infection. Still, if your pet has been itchy for some time and has thickened skin that is often gray to black colored it is important to think about the possiblity of a yeast infection. These can sometimes be treated with shampoos with yeast killing ingredients like chlorhexidine or ketaconazole but it is usually necessary to use oral ketaconazole to obtain control of long standing yeast infections. Treatment is usually only necessary for 30 days.

A few dogs who appear to have allergic skin disease actually have sarcoptic mange infestations. This mite is hard to find even when careful skin scrapings are done looking for it and it is frequently overlooked simply because it isn't considered as a potential cause of the itchiness. This is a particularly important consideration when multiple dogs in a household are itchy, even if only one has hair loss, enlarged lymph nodes or other signs that might be associated with mite infestation. Cats have a similar problem with demodectic mange going undiagnosed at times. If your pet isn't responding to treatment for itchiness it may be a good idea to ask your vet about treating for sarcoptic mange to rule it out or at least doing skin scrapings to try to make sure it isn't present.

Food allergies are not all that common in dogs and cats but they occur frequently enough that they have to be considered when a pet is itchy. Even in pets in which a food allergy can't be demonstrated there is often at least a partial response to diets intended for allergic dogs or dogs with sensitive skin or to using a home made diet that is high in polyunsaturated fatty acids (omega n3 fatty acids) and is made from a protein source not commonly found in dog foods such as fish or turkey. Cats will often respond well to the sensitive skin diets as well. In addition, we think that we sometimes see improvements in skin condition in cats who are eating the diets made to control hair balls.

Many dogs and a few cats with allergies develop ear infections or ear inflammation. In many cases the ear inflammation or infection is the first sign that allergies are present and in some cases the allergies never cause any other problems. This group of pets does best when the ears are consistently cared for. It is very helpful to use an ear cleaning product that has some astringent effect and which lowers the pH of the ear canal on a regular basis. EpiOtic (tm) is one such product that is popular among veterinary dermatologists but there are others that work pretty well, such as Tris8 (tm) or TrisEDTA (tm). Some vets like Novalsan Otic (tm) best because it is a little less irritating than these other cleansers but it doesn't seem to work quite as well, overall, in our clinic. We do keep it on hand for patients with sensitive ears, though.

Persistence in controlling all potential causes of itchiness is clearly helpful. Our patients who have owners who are willing to take all, or at least most of, the necessary steps to reduce itchiness tend to do much better over the course of their lives than pets whose owners wait to treat them for itchiness only after it has gotten out of hand -- even if they then work hard to control it until the itchiness stops before waiting for the cycle to start again.

Legal Issues In Veterinary Medicine

Every day that I practice someone asks me to break the law. Most of them don't realize they are making a request that is actually illegal but some of them do -- and they ask me to do it anyway. I have often wondered if stretching legal limits is just an ordinary part of some people's day. Of course, the flip side of this is that there are lots of times when I have to at least stretch the laws and in some cases break them, if I am going to be able to practice veterinary medicine effectively. The major difference to me is that if I choose to break a law in order to practice effectively then I am willing to defend that decision. If I do it because it is easier than telling a client "no" or because it is convenient but not necessary, I am less able to defend that decision if it becomes necessary to do so.

The most common request is for an antibiotic to treat a wound on a pet that we have not seen before or have not seen for a long time. Veterinarians are regulated by the Food and Drug Adminstration (FDA) just like human physicians. In order to dispense a substance that is limited to use on or by the order of a veterinarian we are supposed to have a doctor/patient/client relationship and to have enough knowledge of the patient to justify the use of the prescribed medication. It simply isn't possible to meet the test of a true doctor/patient relationship without actually seeing the patient, verifying the need for antibiotics and ensuring that the antibiotic is prescribed properly, including such things as having a current weight on the patient to ensure that dosing is accurate. If I do not meet these requirements then I am not meeting the legal requirements for my profession. Asking me to break the law because it is hard to come to the office for a visit or because it is costly to do so just isn't justified. My goal is to continue to practice veterinary medicine for another 20 years or so. I really do not wish to jeopardize that goal by giving clients medications for their pets without proper justification for doing so.

Another common argument at our front desk revolves around the dispensing of heartworm medications. If you read the package inserts for these products most of them call for doing heartworm examinations prior to dispensing the product and then at regular intervals based on the American Heartworm Society guidelines. In areas of high susceptibility to heartworm infection the recommendation is to test annually for heartworm disease even while using preventative medications. In areas in which the risk is lower the recommendation is to test every 2 to 3 years.

We use the every 2 year cycle in our practice because we feel that the risk of heartworm disease is moderate in our area. Many clients say something like "But I give the tablets every month, why do I have to pay for a heartworm test?" The simplistic answer is that you have to pay for the test because I insist on meeting the federal guidelines for dispensing the medication. The reality is that most veterinarians recognize that resistance to heartworm medications could begin to occur at any time. If we are not routinely screening for this possibility we will miss a lot of cases of heartworm when it first happens. This may not be enough reason to justify a heartworm test for some clients but it is necessary for the overall safety of dogs on these medications --- and the bottom line is that when we are asked by hospital inspectors if we are following the American Heartworm Society guidelines in dispensing these medications we can say yes.

The FDA does allow veterinary practitioners to make reasonable judgements about off-label use of medications. If you take the time to read the package inserts or direction sheets for many medications you are probably aware that the actual approved use for many medications doesn't come close to covering the actual use in real life situations. Lots of medications are approved for a single use in a single species but are used in multiple species and often for multiple uses not listed in the insert. I think that sometimes companies take advantage of this loophole in FDA requirements and deliberately get medications approved for dogs that are almost certainly going to be used in cats, just because dogs are more likely to do well in drug trials.

The catch for veterinarians is that off-label use of drugs places the responsibility for subsequent drug failures or drug interactions on the shoulders of the veterinarian rather than the drug company. Even though this is a risk, this is also the situation where most veterinarians recognize that they must take some risk in order to be able to practice effectively. If I stuck to medications approved for use in cats, I wouldn't have any way to treat a disturbing number of problems in cats. One glaring example is the lack of approved pain relief medications for cats.

Some veterinary products are approved by the Environmental Protection Agency (EPA) rather than the FDA. This group of products has even more restrictive labeling than the FDA products. It is actually illegal to use an EPA product in any manner inconsistent with its labeling. It is also illegal to take an EPA approved product out of its packaging and to sell it -- so things like breaking up packages of Advantage (tm) or Frontline Topspot (tm) to sell a single tube to a pet owner is actually illegal, unless the single tube is dispensed in the original packaging material, including all package inserts. Obviously, this means that only one client could receive all of the information , making it difficult to sell individual doses of these products without violating the law. This is also a concern when it comes to making recommendations for the use of EPA products to clients. It is pretty well known at this point that Advantage and Frontline begin to lose effectiveness about 3 weeks after application. A veterinarian who applies these products at 3 week intervals is violating federal law. It is less clear if instructing clients to apply the products more often constitutes breaking the law on the veterinarian's part but it would be illegal for the pet owner not to follow the directions -- it is just not very likely that the EPA would bother with trying to enforce their regulations at the consumer level.

To make matters even a little more confusing, vaccines are generally regulated by the United States Department of Agriculture (USDA). This is a boon to vaccine manufacturers because the USDA is pretty lax in its requirements for testing vaccinations and in regulating them, with a few exceptions. It is illegal for veterinarians or other retail outlets to break up a package containing multiple doses of vaccine and sell the individual vaccine doses. Like the EPA, the USDA wants the final consumer to have all of the package insert and package labeling information. Vaccine companies will often package some of their vaccine lines in single dose packages so that their vaccines can be sold in retail outlets or individually by veterinarians who wish to sell them directly to clients.

I am not sure what the situation is in every state, but Virginia has its own laws that regulate the use of veteirnary drugs, in addition to the federal laws. This isn't a major complication since the regulations usually follow similar guidelines to the federal ones but it serves to further reinforce the effort to ensure that when a veterinarian dispenses a medication there is a valid doctor/patient relationship. Most of the real enforcement of drug laws occurs at the state level, through veterinary hospital inspections and review of veterinary records during those inspections. We have been visited by undercover agents from the state on several occasions who have attempted to buy prescription medications, especially heartworm control medications, without a valid relationship with us. While enforcement efforts shouldn't be the main reason to be ethical they do serve to reinforce the need to follow the law when dispensing prescription medications.

Many veterinarians do chose to ignore some of these laws or regulations. The best explanation that I can come up for the difference relates to traffic laws. I tend to sit at a red light, even if it is in the middle of nowhere, until the light turns green. I have friends who think that I'm stupid for obeying the letter of the law in this situation when it is clear that it is safe to drive through the light after stopping and checking out the traffic. I have never gotten a ticket for running a red light, though. I know some veterinarians whose laxity in following drug laws have led to fines and even loss of their veterinary license with repeated episodes. Asking me to break drug dispensing laws might seem like a simple request to some of my clients and it is even possible to make a good case for doing this at times, but I really do want to continue to practice for some time and I'm just not a risk taker when it comes to that sort of thing.

Veterinarians have a lot less to worry about when it comes to liability for medical errors than human physicians but this has been changing some in recent years, as well. Large animal veterinarians have always had higher malpractice premiums than small animal vets because the veterinarians have traditionally only been able to be sued for the value of the animal. Some cattle and many horses are worth a great deal of money compared to the price of pets. In recent years there has been a trend towards allowing pet owners to sue veterinarians for damages suffered by the owner, such as the pain or grief caused by the loss of a pet. If pets are granted a status somewhere between property and human status in the eyes of the law, there may be increases in the amounts that clients can sue small animal veterinarians for and consequently increases in malpractice insurance rates.

The largest law suits against small animal veterinarians have related to injuries that pets have inflicted on their owners while they are at the veterinarian's office. It is the responsibility of the veterinarian to make sure that all diagnostic and treatment procedures are accomplished without risking injury to the client or the veterinarian's staff. Several lawsuits have been filed after a client's pet inflicted bite wound or other damage on the client during a veterinary office visit. At least one of these cases involved claims for damages to the client that exceeded one million dollars. These lawsuits are the reason that most veterinarians insist that a member of their staff restrain a pet during an examination and that pet owners or their children not try to comfort the pet during diagnostic or treatment procedures. Many pet owners find this hard to understand, since it is their pet. It may seem odd that a client who is injured by their own pet can sue the vet in the first place but it is the way that the liability laws work in this case. If your veterinarian insists on allowing his or her technician to restrain your pet during an examination you should allow this. It may be hard to do so but your vet can work more efficiently and pay better attention to your pet if the risk of a pet owner being bitten is minimized. In some cases your vet may even ask that you not pet or try to comfort your pet, especially when a procedure may involve discomfort or slight pain for your pet, such as cutting toenails or giving injections.

When you go to your vet, remember that you are seeing a licensed professional who must follow the rules, regulations and laws that pertain to the use of that license. Trying to talk your vet out of doing heartworm examinations or into dispensing medications without seeing your pet is simply asking your vet to break the law for your convenience.

Sugarless Candies May be Poisonous for Dogs

Sugarless candies can be toxic to pets. Candies containing xylitol have been recognized by the National Animal Poison Control Center to be a risk to pets. This information was first published in July 2004. This compound can cause liver damage and death in dogs susceptible to being poisoned with xylitol. If your dog ingests sugarless candy it would be best to contact the NAPCC (1-888-426-4435). It is possible your vet will not be familiar with this source of poisoning as this information is fairly new and candies have not usually been associated with poisonings in dogs if they did not contain chocolate as the major ingredient.

Thanksgiving Dinner Can Kill Your Pet

I can't remember a single year we have not treated a dog for pancreatitis or at least acute gastritis in the day or so following Thanksgiving. In addition, we have treated both dogs and cats who have ingested bones from the turkey carcass and developed esophageal or intestinal obstructions. I am not sure what it is about holidays that makes otherwise careful dog and cat owners forget about the need to protect their pets from dietary excesses but inevitably someone's pet comes to office sick from overeating or from eating turkey bones.

The biggest problem may be large celebrations of Thanksgiving where a large number of individuals give dogs a small treat --- adding up to a huge meal. It is best to keep pets safely out of reach of well meaning relatives and friends who just can't resist feeding them. Take the time to ensure that the turkey carcass is properly disposed of so that the cat and dog (or the neighbor's cat or dogs) can't get to it. Avoid feeding dogs large quantities of ham. A small amount is probably OK but being fed ham is a fairly common historical finding in dogs who have pancreatitis.

You can't expect your guests to be careful about feeding your pets. Pets are really good at convincing naive humans they are starving, even when their body shape obviously suggests otherwise. If you can't keep your pet away from the dinner table by putting them in another room or somewhere else that is safe, consider boarding them if you are planning a large Thanksgiving celebration at your house.

Our Thanks

Michal and I are grateful to the subscribers who have sent us donations over and above the subscription fee this year and in the years past. This year, in particular, donations have kept the site going. We have about 250 subscribers at any time (this varies from month to month) with a core support group of about 125 subscribers who have renewed steadily over the years. You have been the reason that we have been able to keep going and we are grateful for your support. I don't think that I could keep up with the questions from a larger group at the present time so we are not anxious to increase the number of subscribers, at least not quickly. Michal and I are glad to work on the site and to help people as much as we can but we're glad that we don't also have to bear the entire financial burden of keeping the site going. Thanks for your help!

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