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VetInfo Digest May 2005

Table of Contents:

Optimal Preventative Care:

Diet

Vaccinations

Physical Exams

Spaying or Neutering

Routine Lab Work

Not so Routine Lab Work

This Month's Note:

I get a lot of letters asking what the optimum level of care is for some aspect of veterinary medicine. I generally try to avoid giving a specific answer for these questions, for the simple reason that no one really knows what the optimum level of care is for any individual pet. While I still don' think that I can really provide a simple answer to this question, we did have a discussion recently in our practice about what we would do if all financial restraints were removed from the decision making. Would we change our practices if we truly believed that each and every client truly wanted to do what we thought was best for their pet? Is it conceivable for us to provide more advanced medical care in many areas or is it better for us to direct clients to appropriate specialists on a routine basis? Could we afford to provide advanced diagnostic techniques such as magnetic resonance imaging (MRI) or color doppler ultrasonagraphy? In thinking about these things we came up with a list of things that we probably should do differently in our own practice, or at least wish we could do differently, and it seemed like it was an interesting enough topic to share our thoughts with you.

Feeding your pet

One of the areas related to health care that we have a poor ability to provide information about is diet. Most veterinarians are able to provide their clients with information on the basic nutritional requirements of pets and know how and when nutritional deficiencies cause disease. They also know that there are times when nutritional excesses cause disease or disability. However, there are no veterinarians who can tell you from a purely scientific basis what the optimum diet is for your pet. There is no one who knows this information, despite the relatively large number of people who tell you they do.

So what do we tell our clients about feeding their pets? We tell them that the major pet food companies appear to be making a sincere effort to make good foods. They have the financial incentive to do this. If a pet food manufacturer makes a food that your pet eats for its whole life it will eat more of the food the longer it lives. We also tell them that it is possible to make a diet at home that meets a pet' nutritional needs and if they prefer to make a diet, for any reason, it is fine to do so. We strongly suggest having the diet evaluated by a nutritionist to ensure that it is nutritionally complete. This analysis will probably cost between $100 and $200 but it is good insurance against making a diet that is deficient in some aspect. These are the best choices in our opinion. There are lots of alternatives and lots of smaller dog food companies that might make a better food for a particular pet but there is no way to tell for sure if this is the case.

Vaccinations

We have more information about vaccination now than we have had in the past. This has resulted in changes in vaccination recommendations over the last few years.

There is now, at least in cats, a definite "" for currently available vaccines. The best vaccines to use in cats are vaccines without adjuvents. These are irritating substances added to a vaccine to make the body' reaction to it more vigorous. It is evident that this inflammation is at least partially responsible for the production of vaccine associated cancers in cats. Merial (tm) has produced an entire line of cat vaccinations that do not contain adjuvents. These vaccines are all either recombinant or modified live vaccines which can produce adequate immunity without the use of adjuvents. The Merial Purevax (tm) rabies vaccine has to be given yearly, which is a disadvantage, but this is still better than giving an adjuvented vaccine every three years, at least based on the current thinking. An alternative to the injectable non-adjuvented vaccines are the intranasal vaccines. Since we know that panleukopenia vacccine provides very long term protection it is reasonable to use an intranasal vaccine that only has the rhinotracheitis and calicivirus components to avoid the whole problem of injection reactions in cats after the initial kitten series which includes the panleukopenia vaccine.

In our practice we do not currently follow this optimal recommendation. We have a hard time getting cat owners to agree to pay more for a yearly rabies vaccine than for one that lasts three years --- and then to pay for it every year instead of every three years. We do not use the intra-nasal vaccines on a routine basis because they cause many cats to have sneezing or slight runny noses and most of our clients are not happy about this when we use these vaccines routinely. We do use them for cats who have persistent signs of upper respiratory disease, anyway, and they seem to help alleviate this problem in a number of cats.

In dogs the interval between adult vaccinations should be three years, or more, as well. There is pretty good evidence that the core vaccines, distemper, parvovirus, adenovirus and parainfluenza provide protection for at least 7 years but there is some dispute about at least the parainfluenza component. Personally, at this point, if I was going to do what I really thought was optimum for vaccinations in dogs I would probably give the combined DA2PP vaccination as a puppy series, booster them a year later and then give them once more when the dog was 6 or 7 years old. I haven' actually made that decision in my own practice, primarily because an interval that long between vaccinations almost guarantees that many dog owners won' come in for the middle aged booster on a timely schedule. It is really what I believe will turn out to be the optimum vaccination schedule, though.

Physical examinations

Scheduling routine physical examination times is an important aspect of pet health. It can be hard to figure out what the best schedule for performing these examinations is, though. There is a trend at the current time to suggest twice yearly physical examinations in pets, on the theory that they age faster than humans. In thinking about an optimal schedule, though, I find that I think of this more in terms of the pet' needs than as something that should occur on a regular time schedule.

When pets are very young they should be examined more frequently. I think that examining kittens and puppies should ideally be done once every three to four weeks of age until they are about 4 months old. An examination should be done when the permanent teeth should be in place, approximately 6 months of age. It would be best in dogs to schedule an examination just prior to the end of the growth period, as well. This examination should include a good evaluation of the hips, knees and elbows, as this is the end of the time that some of the surgical procedures to alleviate problems with these joints can be performed. It is important not to miss this last chance to help a dog avoid problems with hip dysplasia or luxating patellas. This examination is less important in cats because they have fewer congenital orthopedic problems.

I think that it is best to check both dogs and cats at around 15 to 18 months of age. This is a time when vaccinations are often necessary and it is the time when many pets first show a tendency to be overweight. If this tendency is caught early and proper nutritional advice is followed it can help a great deal in avoiding problems associated with obesity.

I sometimes wonder if it is worthwhile to perform yearly physical examinations in young adult dogs and cats. The second through fifth years of age are usually pretty uneventful physiologically. Ultimately, though, these examinations often do prove to be important as things like allergies, ear infections, anal sac problems or tapeworms are often discovered during these examinations when pet owners have missed the condition. So even though most of my patients in these age ranges have normal physical examinations it is still important to check on them. These years are also the time that tartar accumulation begins and it is important to recognize this and deal with it, as well.

Spaying and Neutering

I think from a health standpoint it is best if female dogs are spayed. There are several reasons for this and there are both risks and benefits to consider. Spaying prior to the first heat period reduces the risk of mammary cancer later in life to less than 1% in female dogs, as compared to 25% for female dogs who have had 2 or more heat periods. Approximately 8% of female dogs will develop uterine infections (pyometra) during their life and this is a life threatening condition in dogs. Spayed female dogs are less prone to straying and are less likely to be injured in fights over breeding. On the other hand, spayed dogs have a higher tendency towards weight gain, there are risks associated with general anesthesia -- some dogs will die during the spay procedure due to these risks and urinary incontinence is likely to occur at younger ages in spayed female dogs than in unspayed female dogs. Overall the benefits outweigh the risks, in my opinion and therefore we recommend spaying female dogs as long as there are no plans for future breeding.

At the risk of seeming biased, neutering male dogs is more optional. There are some definite benefits to neutering male dogs. The major ones include less tendency to urine mark, less tendency to wander and to fight or exhibit other aggressive behaviors, lowering of the risk of prostate hypertrophy with age and eliminating testicular cancer. These benefits are not as clear cut as preventative measures as spaying is in female dogs, though. It is possible to obtain most of the these benefits at any time by neutering, so it may be reasonable to wait and see which problems develop and to make the decision to neuter or not based on whether any of these problems have occurred. One thing to keep in mind about waiting is that once dogs have established roaming behaviors it is hard to stop them from wandering. As in female dogs neutering carries an anesthetic risk and seems to promote weight gain. While I think that it is usually best to neuter males there is room to argue the other way.

Routine Laboratory Work

As long as there is a clear understanding of the meaning of the tests I think that it is best to test kittens for feline leukemia virus (FeLV) early in their life and to test for feline immunodeficiency virus (FIV) when they are 6 months or more of age. Routine testing for FeLVhas one major drawback that must be considered. When an FeLV test is negative it is very reliable. When an FeLV test is positive in a kitten with no apparent heatlh problems it has about a 50% chance of being accurate. Therefore, it is extremely important to recheck all positive test values with a more specific test in order to confirm the infection. This usually involves sending blood to a commercial reference laboratory or university rather than just using a different in-house test kit. If the initial screening test was done by a commercial lab using an ELISA technique it is still necessary to confirm the positive result.

Routine testing for FIV is more straightforward as long as one important fact is kept in mind. It is not possible to accurately test for FIV antibodies produced by the kitten until it is at least 6 months of age. Prior to that time it is possible that a positive test result could be due to antibodies still in the kitten' system from its mother or that the kitten is in the early stages of FIV and not yet producing antibodies against the virus on its own. Neither a positive or negative result can be trusted prior to 6 months of age.

In both kittens and puppies I think it would be a good idea to have a routine blood chemistry test and complete blood cell count done between 4 and 6 months of age to try to get a baseline value for the pet and to rule out hidden problems with the liver, kidney or other organs.

It is best to check fecal samples for intestinal parasites once a year. This is another thing that we do not routinely do in our practice despite a recognition that it is probably best. We routinely deworm kittens and puppies during the vaccination series and at yearly examinations (cats) or by routine administration of a heartworm prevention medication that also kills roundworms, hookworms and possibly whipworms (dogs). Despite this program we do occasionally have a pet who develops worm infestations that would go unrecognized without routine fecal examination unless clinical signs of illness developed. For optimum care it is best to have a fecal sample checked once or twice a year.

Heartworm prevention medications should be given to both dogs and cats in areas in which heartworm disease occurs. Heartworm prevention medications should be started at 6 weeks of age and given on a monthly basis during heartworm transmission season. In most areas of the country it is possible to use heartworm prevention medications for six months of the year, or less, but there are some advantages to using it all year in dogs, since most of the heartworm prevention medications also kill some species of intestinal worms. In cats Revolution (tm) heartworm prevention also provides protection against some species of intestinal worm and flea infestation. We use Revolution for outdoor cats pretty commonly in our practice in an effort to get both flea control and protection against heartworm infection.

Heartworm testing often seems to annoy my clients, who often protest, " give the medication once a month all year, why do we have to test for heartworms every two years (the standard in our practice)?" There are a number of reasons for routine testing, some of which benefit the individual patient and some of which benefit dogs as a whole. From the individual dog' standpoint it is necessary to catch any heartworm infections early in order to treat them with the least risk. There is a very significant difference between treating a dog with early heartworm disease and one with advanced heartworm disease. Heartworms can cause death before obvious clinical signs appear. We have had several patients who had conscientious owners who still managed to develop heartworm disease while on heartworm prevention medications. This can happen when the dog doesn' actually swallow the pill even though he seems to, when a pill is inadvertently missed despite real effort to ensure that it is given monthly or when a pill is vomited up after administration. From the standpoint of all dogs, it is reasonable to assume that at some point heartworms may become resistant to the preventative medications. If this does occur the only way to know early in the process, and thus protect the majority of dogs from the consequences or resistance, is if large numbers of dogs are being tested.

One recent example of this has already occurred, with recognition that selamectin (Revolution Rx) applied topically has only a 90% success rate at preventing heartworms in comparison to a 98 to 99% success rate with the oral monthly tablets. In our practice we think that the success rate of Revolution is higher than this and that the success rate of the pills appears to be higher than 99% but still slightly less than 100%.

It is not uncommon for veterinarians to avoid heartworm testing in cats. This is understandable because there really isn' a good test for heartworm disease in cats, yet. There are screening tests which work by detecting antibody to heartworms. These tests are good when negative but very unreliable when positive. The more definite tests used in dogs don' work as well in cats due to the low number of heartworms it takes to produce clinical symptoms of heartworm disease in cats. A cat can be very ill with a single worm and the tests for heartworm antigen (test for the heartworm itself, not antibodies produced in response to it) are not very accurate until there are more than 2 or 3 worms. In a situation in which we are looking for optimal care, it is still best to test cats for heartworm disease on a routine basis as long as the shortcomings of the in-house tests are recognized.

Non-congenital hypothyroidism begins to appear in dogs as early as three years of age. Therefore, it would be optimal to do a screening test for hypothyroidism yearly. The total T4 level could be used for screening purposes, although it is not a very good test to rule in or rule out hypothyroidism for treatment purposes. A total T4 value in the upper half of the normal range is very unlikely in a dog with hypothyroidism. A more accurate test for hypothyroidism is the free T4 test done by the equilibrium dialysis method, usually abbreviated fT4ed. This test is about 96% accurate in differentiating dogs with hypothyroidism from those who do not have this condition. It would be best to test for this disorder on a yearly basis starting at three years of age. There aren' too many veterinary clinics that routinely test for hypothyroidism in patients who have no obvious clinical signs of the disease but it is reasonable to do so when thinking about optimal care.

Cats develop kidney insufficiency syndromes much more commonly than dogs. There is a test for microalbuminemia that can detect a tendency towards kidney insufficiency long before other signs of the syndrome occur. This test is a reasonable test to consider for all cats and especially for long haired cats, given the tendency towards polycystic kidney disease in Persian and Persian mix cats. This is a urine test, which gives the added benefit of having urine to do routine screening procedures with.

Urinalysis is a very useful screening test for several disorders in both cats and dogs. It is the easiest way to find diabetes mellitus and it can give indications of bladder infection, kidney infection, kidney insufficiency or kidney failure, liver disease and other metabolic disorders. It would be easy to make a case for routine urinalysis as part of the yearly physical examination in both dogs and cats. Urine samples obtained by cystocentesis, or drawing urine directly from the bladder with a needle, provide the most accurate information but it would be reasonable for screening purposes to use " catch" urine. Most of our clients with dogs can get urine samples if we ask them to but it is a little harder to get urine from a cat. Fortunately, it is pretty easy to do cystocentesis in cats. Even though this test is often easy to perform one of the frustrating things about obtaining urine in this manner is that it is most difficult when it is also the most important. Urinary tract infections are best detected by urine culture using urine that is obtained by cystocentesis. Unfortunately, dogs and cat with urinary tract disease often try very hard to keep their bladders empty, which can make cystocentesis very difficult to perform. It is worth hospitalizing a patient or considering the use of anesthesia or sedation to allow careful needle placement when pets have persistent urinary tract infections and identification of the cause is important.

It would be optimal to take radiographs of the hips and elbows of many dog breeds early in life to rule in or rule out tendencies to develop hip dysplasia and elbow dysplasia. It can also be useful to have a chest radiograph of a young adult dog to compare to future radiographs that may be necessary to take for suspected diseases or disorders. Routine radiography is not a common practice in veterinary medicine but it really is optimal to have comparison X-rays when problems are suspected later in life.

Hyperthyroidism is common in cats as they age. This disorder is uncommon before cats reach 6 years of age and becomes more and more likely as they get older. I think that it would be best to do routine screening for increased T4 levels from about 9 years of age on in cats.

I have not been able to figure out an optimal schedule for routine blood chemistry panels and complete blood cell counts. Despite this, it is reasonable to pick some interval, perhaps even yearly, for these types of tests. It has been estimated that a yearly physical exam for a dog or cat is roughly equivalent to a physical exam every three to four years for person. If this is really true then it makes sense to check blood work at least every other physical exam.

One of the great difficulties in recommending routine laboratory testing is the potential for laboratory error. The normal values for laboratory tests are designed to incorporate the blood values of 95% of pets who appear to be normal on physical exam when the blood is drawn. This means that 1 in 20 pets who have no detectable sign of disease will have at least one value out of the normal range on any single test and that when a laboratory panel contains 20 test parameters it is somewhat likely that a normal pet could have one value outside the normal range. It is very important to remember that laboratory values that do not seem to match the patient' condition should be repeated to ensure accuracy. It is impossible to talk about optimum care without making a pitch for repeating laboratory tests before treating for conditions that don' seem likely or when contemplating life long treatment for a disorder such as hyperthyroidism or hypothyroidism based on the results of a single marginally abnormal value in a pet who doesn' have clear clinical signs of the disease being tested for. Of everything that we do that in our practice that isn' optimal, I suspect our reluctance to repeat expensive test procedures when the results are not clear cut may be the one thing that has the most impact on our patient' long term health. It is worth paying for laboratory work twice or even three times if that is what it takes to clear up confusion over the meaning of the test procedures.

Laboratory Tests to Rule Out Specific Diseases When Indicated

There are some diseases and disorders that are not common enough to warrant routine testing for every pet but which are still necessary to include in a review of optimal care. These problems occur frequently enough that they should at least be tested for when any clinical signs are present or when breed predilections indicate they may be more likely for a particular pet than for the average pet.

Vector borne diseases are infectious diseases that require an intermediary to transfer themselves from one dog or cat to another. Usually the transfer agent is an insect but there are some exceptions. There are a number of these diseases, including ehrlichiosis, borreliosis (Lyme disease), Rocky Mountain spotted fever and babesiosis. Over the last few years it has become apparent that these diseases are more common than previously estimated in veterinary medicine. Whenever a dog has vague non-specific signs of disease it is worth considering whether these diseases are present and testing for them. There are both in-house and more specific tests for several of these diseases and it is often necessary to do both types of testing to make a confirmed diagnosis.

Young dogs who simply don' grow well or have vague signs of illness intermittently without an obvious cause should be checked for hypoadrenocorticism (Addison' disease). This isn' a really common disease but it can be fatal and is relatively easy to treat when it has been properly identified. The screening test for Addison' disease is an electrolyte panel. In most cases the sodium/potassium ratio in the blood is much different than normal when Addison' disease is present. It is important to note that many routine chemistry panels run at veterinary hospitals do not include electrolyte levels.

Allergies are a common problem in both dogs and cats. Allergies can lead to severe skin disease, chronic gastrointestinal problems, asthma (mostly cats) or chronic bronchitis (mostly dogs). It is often possible to identify the specific things a pet is allergic to and to create a plan to avoid these things or to use allergy shots (hyposensitization) to try to control the allergies. There are several types of allergies but the ones that are easiest to test for are inhalant allergies (atopy) and food allergies.

Food allergies are uncommon enough that veterinarians are often reluctant to advise doing feeding trials to rule them in or out. There is no reliable way to tell if a food allergy is present other than a food trial. To accomplish a food trial it is necessary to feed a pet a special food that is made to avoid producing allergic reactions or to feed a diet that contains ingredients that a pet has never eaten before. It is best to feed these diets for 6 to 8 weeks.

Even though the basic concept of a food trial is easy to understand it is really very difficult to do a food trial in a " life" situation successfully. Even a small amount of forbidden food during a food trial will make it difficult to evaluate the results. In households with more than one pet or with young children it can be almost impossible to do a proper food trial at home due to the high probability that the pet will get into food that isn' allowed for the food trial. Veterinarians are often reluctant to suggest food trials due to these problems but they are the optimum in care for pets with persistent gastrointestinal problems or itchiness that doesn' seem to be due to other types of allergies.

Allergy testing is best done by skin testing. This is accomplished by shaving an area of skin and injecting small amounts of substances such as tree pollens or dust mite antigen that will cause a reaction in pets with allergies. This type of testing is best done by someone who does it very frequently so most of the time veterinarians will refer clients to a veterinary dermatologist for this type of testing. While skin testing still seems to be optimum there has been a lot of progress in blood testing for allergies and most dermatologists now consider it to be reasonable to do serologic testing for allergies, as long as some common sense is applied when interpreting the results. Many veterinarians are comfortable drawing blood for this type of testing and interpreting the results at this time. The laboratories that run these tests are very helpful in analyzing the results. It is best to test pets with allergies to see what they are allergic to so that the best possible plan for dealing with their particular allergies can be made.

We would probably do about ten times as much bacterial culturing and antibiotic sensitivity testing in our practice if we were always trying for optimal care. Dogs with persistent skin disease, persistent ear infections, bladder infections and several other conditions should probably have bacterial cultures done. Most veterinarians don' routinely do this type of testing, though. There are a number of reasons for this but the most important one is simply the cost of the testing and the fact that treatment is usually started well before the results of culture and sensitivity testing can be obtained. It is not uncommon for bacterial culturing to fail to provide a diagnosis even when bacteria are the cause of a problem. It is also not uncommon to pay for culture and sensitivity testing and then to get bacterial growth that is obviously not the cause of the disease that is occurring. These complications make vets very reluctant to add the cost of bacterial culture and sensitivity to the examination and treatment fees. Despite this, when bacterial culturing works it can provide invaluable information and it is optimal to include it whenever it is appropriate -- at least when the cost versus benefit ratio is not a huge concern.

Dental Care

There is no question that dental care for pets is not utilized to the extent that it should be. There are lots of reasons for this, including the difficulty in getting a pet to cooperate with oral examinations, tooth brushing and other aspects of dental care, expense and the need for anesthesia to perform a number of the dental procedures.

Ideally all dogs and cats would have their teeth brushed after every meal, or perhaps two or three times a day for those that snack all day. Very few pet owners have the time or inclination to brush their pet' teeth this frequently. Brushing once a day is good and brushing three times a week is thought to be effective enough to make it worthwhile. Brushing less frequently than this can still be helpful but is not very effective at preventing tartar formation. It is possible to make up for not brushing to some degree by using diets made to control tartar, which seem to work well in dogs and moderately well in cats. These diets are not the right answer for every pet, though. Some treats, such as rawhide chews, have been shown to be effective in limiting tartar formation. I haven' been too impressed with some of the other tartar control treats, though. Allowing dogs to chew on large real bones, such as beef " bones" is helpful in limiting tartar but can sometimes lead to broken teeth. I think of this as an even trade-off and so I do not advise allowing access to bones or limiting access to them.

Most dogs and cats would benefit from professional teeth cleaning on a yearly or every 6 month basis, starting at about one year of age. I think that this would be the standard recommendation in veterinary medicine except for the fact that most pets require anesthesia in order for the veterinarian or veterinary technician to do a good job of cleaning the teeth. The need for anesthesia introduces a risk to the dental cleansing procedure that really can' be overlooked. This is especially true for cats. I think that I have corresponded with more people whose cats had problems with anesthesia during teeth cleaning than during surgical procedures. Even with some risk of disability or death associated with the use of anesthetics it would still make sense from a risk/benefit ratio basis to do routine teeth cleaning procedures in a large number of cats and dogs. Inflammation and infection associated with periodontal disease can cause significant harm to other areas of the body in some cases and the pain associated with dental disease really seems to bother most pets who have periodontal disease.

The trick is to take the risk of using anesthetics as often as is really necessary without taking the risk unnecessarily. This generally means doing dental cleansing procedures less frequently than once every 6 to 12 months but much more frequently than they are actually done for most pets. There is no way to really give you an average that would cover all dogs but I suspect that the majority of dogs need teeth cleaning on some sort of regular schedule after they are two to three years of age. I cleaned one of our dog' teeth every 3 to 4 months for most of his adult life and I have cleaned my current 9 year old dog' teeth two or three times in her entire life, to give you some idea of the variability in the need for professional teeth cleaning in dogs.

At our practice, for cats, we take a completely different approach. Our approach to cats is not the mainstream approach and it is controversial among veterinary dentists. However, we attempt to clean every cat' teeth, if there is any need, during yearly physical examinations without using sedation or anesthesia. Most cats will tolerate removal of the tartar from the upper premolars and lower premolars without too much struggle and these are the primary problem teeth for tartar in cats. We know that we are not doing a complete and thorough teeth cleaning but we are able to do a reasonably good job of removing tartar in most cats. We believe, without any ability to scientifically prove it, that this yearly hand scaling of dental tartar reduces the incidence of feline odontoclastic lesions (FORLs) and limits the number of times we need to do a more thorough cleansing under anesthesia during a cat' lifetime. Sometimes the hand scaling isn' enough and we anesthetize the cat to do a more thorough tooth cleaning procedure. Overall, though, we think this approach is effective at minimizing the number of times cats must be anesthetized for teeth cleaning.

Using anesthesia to facilitate cleaning dog' and cat' teeth is a necessary evil. It can lead to the death of a pet. However, we know from experience that cleaning teeth can make a huge difference in a pet' health, well-being and even in its behavior. We really feel that when dental cleaning is necessary it is worth taking some risk for. Optimal care for pets has to include good dental care.

So Why Not Always Insist on Optimal Care?

I think that most of you recognize that if you followed these optimum recommendations strictly the expense of owning a pet, or certainly of owning more than one pet, could become prohibitive. This is why most veterinarians try hard to customize these types of recommendations to the needs of each individual pet and pet owner. Many of my clients would simply stop coming to me if I tried to provide the best possible preventative care for every pet. On the other hand, I suspect that most of the subscribers to our site are more involved with their pet' care than the average pet owner and I hope that having some idea of what a veterinarian might do if expenses were not part of the thought process might be useful to you.

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