VetInfo Digest
September 2006
Table of Contents:
E-mail communications
Chronic Diarrhea
Hyperadrenocorticism
Diabetes mellitus
Lick Granulomas and Psychogenic Alopecia
Raw Meat Diets
Heartworm Disease
Gorilla Glue
Once Daily Thyroid Supplementation
Urine Protein/Creatinine Ratio Prognostic Aid in Cats
MRSA
Long Term Carprofen (Rimadyl Rx) Use
This Month's Note:
I often worry about the expense of veterinary care when I am discussing options
that include truly specialized procedures with clients. I think to myself, "How
many people are going to go to a specialist and spend this kind of money on a
pet?" It is something that veterinarians are very prone to, as we tend to be a
little more objective about our patients than their owners. That is, of course,
until we are the owners. So last month I found myself scheduling an appointment
with a veterinary cardiologist to examine Henry, our new puppy, and being more
unhappy about the fact that I had to wait three weeks to see the cardiologist
than over the potential cost. It didn't faze me that the most likely cause of
his heart murmur will require referral from this cardiologist to a teaching
hospital at a veterinary school because the procedures for repair are very
specialized. Traveling to another state for this seems entirely reasonable to
me. Every time this happens with one of my own pets it makes me wonder why I
don't trust my clients to have the same feelings. I'm glad that I correspond
with many of you who feel this way about their pets. It encourages me to
continue to take the time to explain all the possible options to my clients even
though I am often going to have to settle for my second or third choice of
options for care.
This month I'm going to devote the issue of VetInfo to short tips and
information that you will hopefully find helpful. We have not been putting
answers to questions online for some time and that has resulted in newer
information not making it onto the web site.
I'm sorry that this month's issue of the VetInfo Digest is late. Tropical
depression Ernesto left us without power or phone service for several days,
making it a little difficult to get this issue out!
E-mail
For those of you that want to ask questions there is one important change that
you need to know about. We have recently had broadband satellite service
installed at our home and as a result one of my e-mail accounts, mervet@inna.net,
is difficult to send mail from. For this reason, I have been using mervet@vetinfo.com
for most of my correspondence with subscribers and this seems to be confusing
several of your spam filters. If you add mervet@vetinfo.com to your white list
it might help you receive mail from me in the future.
Chronic diarrhea
Chronic diarrhea is a fairly common problem in kittens. This can occur for a
number of reasons and it appears to occur in the absence of any identifiable
problem, as well. When chronic diarrhea is present it often interferes with the
absorption of cobalamin (Vitamin B12). This in turn makes it harder for the
intestine to function properly and perpetuates the diarrhea. After attending a
continuing education meeting at which Dr. Jorg Steiner present research on this
subject we began supplementing cobalamin in kittens with chronic diarrhea. It is
not a "cure all" but it is definitely a "cure some" and it seems to help some
even in many of the cases in which the diarrhea persists. This problem can occur
in dogs, as well, although it is a little less common. Cobalmin must be given by
injection to be properly absorbed but the injections are no harder to give than
insulin shots and most of our clients have been able to make these injections
themselves. Cobalamin is inexpensive, doesn't sting when it is injected and is a
water soluble vitamin, making it very safe to use. There doesn't seem to be much
of a downside to giving this therapy a try, even though it doesn't always help.
This is a URL for more detailed information on this treatment: http://www.cvm.tamu.edu/gilab/cobalamin.shtml
The dosage is usually 250ug/cat, which is usually 0.25cc and must be given
weekly for 6 weeks, then every 2 weeks for 6 weeks and then once a month. Dogs
usually require 500 to 1000ug ( 0.5 to 1cc) on the same schedule.
Hyperadrenocorticism (Cushing's Disease)
There is still some argument about the best screening test for Cushing's disease
but the majority opinion seems to be moving towards the low dose dexamethasone
suppression test (LDDS test). The reasoning is that a suppression test has a
more precise end point and is less likely to be misinterpreted.
Most endocrinologists seem to be moving towards the use of trilostane for the
treatment of pituitary dependent hyperadrenocorticism. This is still an
experimental drug in the United States but it is available from several sources
with the proper paper work. Trilostane is more expensive than mitotane, the
treatment that was formerly favored. There is less lab work to be monitored when
using it, though, so overall cost is probably the same.
Medical treatment for pituitary dependent hyperadrenocorticism may be replaced
by surgery over the next decade or so. For some time Utrecht University in the
Netherlands has had success with removal of the pituitary brain tumors that
cause most cases of Cushing's disease. Now Auburn University in the United
States offers this procedure and has success rates that match medical therapy.
The advantage of surgery is that it removes the true cause of the problem and
the patient recovers rather than being managed for life. As more facilities
become competent at this procedure it is likely that it will become the favored
treatment for many patients with Cushing's disease.
Diabetes Mellitus
Insulin therapy for diabetic pets has been complicated recently by the
withdrawal of several forms of insulin from the market and the addition of
several types of insulin to the market. As insulin technology changes in the
human market it will continue to affect the types of insulin available for pets.
Humalin Lente (Rx) and Humalin Ultralente (Rx) insulins have been removed from
the market. There is a new insulin product approved for pets, Vetsulin Rx, which
is a pork origin Lente insulin. It should be possible to transition to this
insulin from Humalin Lente without too much adjustment. I have preferred to use
insulins available through pharmacies in the past because this is generally
easier for my clients but if you are careful to make sure that you have insulin
on hand for vacations, weekends and other times you might not be able to get to
your veterinarian's for a refill, Vetsulin should be a good choice in insulin
therapy. PZI insulin is available to veterinarians and is also a good
alternative to Lente or Ultralente insulin for many patients. In the past this
has been the preferred insulin for cats by many internal medicine specialists
but currently the trend in cats seems to be moving towards using insulin
glargine.
Insulin glargine is used once a day when initiating therapy. Many cats can be
maintained on once daily insulin but many will still require twice daily insulin
therapy when using insulin glargine. This insulin seems to be released more
consistently than most other forms of insulin and this makes glargine insulin
more likely to work in feline patients who are difficult to regulate. This is
something to keep in mind if you are having problems regulating insulin dosage
for your cat.
To make things even more confusing, there are several other new insulins
approved for humans that may eventually be shown to have good usefulness in
pets. While these are not currently being used widely they may be useful in
certain dogs and cats.
Insulin lispro (Humalog Rx) and insulin aspart (Novolog Rx) are two very fast
acting insulins that begin to act even faster than regular insulin. They are
generally used in mixtures of short and long acting insulin to provide a fast
effect initially. This allows administration right before meals when insulin
needs are highest and then for the insulin levels to be maintained by the longer
acting component in the mixture. The combination allows closer regulation of
blood sugar levels over the course of the day. Due to the differences in eating
and activity patterns it is not clear whether these combinations will ultimately
be beneficial for pets. It is probably more likely they will be helpful in dogs
than in cats. A third product, insulin glulisine, which should be similar in
action, is also being developed. While these are not products that your vet is
likely to discuss with you in the course of the next year, they may be an option
even now for dogs who are difficult to regulate.
One thing to consider before going on a search for a better insulin product is
that most of the problems regulating insulin dosage are due to problems with
handling insulin or injection of insulin or in the control of diet and exercise
in diabetic pets. Whenever you are having problems regulating insulin dosage
review the way you are handling the insulin and talk to your vet about diet and
exercise recommendations.
If you have been reading the section of our web site pertaining to diabetes you
are probably aware that I am a strong advocate of home blood glucose monitoring
for dogs and cats. I think that this is the best way to get a good blood glucose
curve which is the best way to evaluate how well insulin is working. About half
of our clients are willing and able to monitor blood glucose using home blood
glucose monitors. While I strongly believe in blood glucose monitoring there are
two camps of veterinarians who don't believe that veterinary clients should be
monitoring their pets in this manner.
The first group of veterinarians who don't believe that clients should monitor
their pet's blood glucose just seem to think that it isn't an appropriate thing
to encourage clients to attempt to draw blood from their pets or are reluctant
to trust information obtained in this manner because they aren't sure of their
client's ability to obtain consistent glucose results. This group doesn't sway
my opinion much because I think motivated clients do a good job of blood glucose
monitoring.
The second group of veterinarians who are starting to discuss their opinion of
home glucose monitoring have very different concerns, though. They fear that
some clients become overzealous and actually stress their pets taking blood
glucose levels too frequently. They also point out that clients fall into a
pattern of spot checking glucose levels that may be confusing. In addition, many
clients do begin to assume the responsibility of alternating insulin dosage on
their own, which can be a bad thing if they do it before they really understand
the effects of insulin on their pet and how to make changes in insulin dosing.
It is important when using insulin not to get into a habit of constantly
changing the dosage in order to adjust glucose levels. This can be harder on a
pet than slightly high or slightly low insulin dosages over time. Finally, they
often point out the tendency of veterinary clients to fall into a behavioral
pattern that sometimes affects veterinarians - a reliance on technology over
observation of the patient. Veterinary clients who pay attention to their pets
frequently become so good at noticing subtle changes in their pets that indicate
a need to check on glucose levels. Things like water intake, activity, appetite
and general attitude are very important to monitor in diabetic patients. Even
some veterinary specialists are beginning to think that it may be more important
to just pay attention to a pet with diabetes and use the information you glean
from that to assess needs for changes in insulin dosing.
Often my clients do become so good at picking up on these subtle signs that they
do less and less blood glucose monitoring over time, even though they are quite
good at it. I have never worried too much about this but lately I have been
thinking about the objections to home glucose monitoring put forth by the group
of vets discussed in the last paragraph and I am thinking that there are a
couple of really important things to consider in their thoughts.
The first thing is that you shouldn't feel too bad if you can't draw blood from
your pet, or if you just don't want to. You can do a good job monitoring your
pet if you work with your vet to learn the signs that blood sugar is too high or
too low and what to do when you suspect problems. The second thing is that it is
important to weigh the need for accurate blood sugar levels against the stress
to the patient and to the veterinary client. If you feel that blood glucose
monitoring is too stressful for you or your pet, remember that does affect the
blood glucose levels, especially in cats. In this case, it really might be
better to rely on fructosamine levels drawn monthly at your vet's to assess long
term glucose levels and to monitor your pet closely for signs of low or high
glucose levels. Even though there isn't much question that home glucose
monitoring provides the best way to assess blood glucose levels when it can be
done without too much stress there are times when other alternatives work out
better in real life where stress can be a major problem.
Common Causes of Lick Granulomas in Dogs and "Psychogenic Alopecia" in cats
Two of the more frustrating conditions in veterinary medicine, lick granulomas
(or acral lick granulomas) and "psychogenic alopecia" in cats have different
patterns of disease but often have very similar origins. Lick granulomas are
sores, usually on the lower extremities, that are caused by licking of the skin.
Lick granulomas are frequently blamed on boredom, stress and behavioral
disorders. True psychogenic alopecia in cats is hair loss from self trauma for
no medically apparent reason. Unfortunately, no medically apparent reason often
is the result of not looking hard enough for a medical cause, at least according
to two recent reviews of this problem. In these studies it was possible to
identify a medical cause for the hair loss in 80 to 85% of cats, with really
diligent effort.
In dogs the most common medical causes for lick granulomas are atopy
(allergies), pain from undetected arthritis or bone disease, pressure sores
(especially the outside aspect of the rear legs), fungal infection, bacterial
infection and demodectic mange. All of these conditions are chronically
irritating and there probably is an element of stress or boredom that
contributes to the licking even when a medical cause is present. If you think
about it, you probably recognize that your aches and pains and allergies are
worse when you are stressed or bored, too.
When we treat lick granulomas, we try to identify a cause first. Much of the
time that isn't possible but usually we can eliminate demodecosis and often
yeast infections from the possibilities. If we suspect pain as an underlying
cause (obvious arthritis, old dog having trouble getting up) then we use pain
relievers. We find that we do a little better when we use a combination of a
non-steroidal anti-inflammatory and hydrocodone (a narcotic) than with either
drug alone. If we don't suspect pain we try long term antibiotic therapy even if
we can't really identify an infection. One or the other of these treatments will
often work, probably in excess of half the dogs we treat for lick granulomas. If
these treatments don't work we try corticosteroids to see if alleviating
allergies will help. It is possible to make a case for doing this therapies in
different orders but we think the lower side effects of pain relief and
antibiotics make them reasonable to try first. If we don't get a response after
corticosteroids then we begin to think about behavioral treatments, the myriad
of topical treatments available and finally all of the "old wives tale"
treatments we have heard of. This can be a frustrating condition but it is
usually possible to find something that works. In addition, it is reasonable not
to treat lick granulomas if no underlying cause can be found and the damage
being done if minor.
When we treat for suspected pyschogenic alopecia in cats we usually do try flea
control first, even if we aren't seeing a single flea. Cats with flea allergies
are extremely sensitive to flea bites and can generally use their rough tongue
to find and remove fleas that are bothering them -- but it is after the flea
bites them usually so allergic reactions to the flea bite continue for some
time. When flea control won't work, we then usually use corticosteroids next.
Cats seem a little less sensitive to the side effects of corticosteroids than
dogs and I think it is reasonable to use them on a trial basis. If we don't get
a response to corticosteroids we usually test for dermatophytosis (ringworm) and
may consider a skin biopsy to look for demodectic mange. Skin scrapings
sometimes work for this but our luck in finding demodecosis in cats by skin
scraping has been moderate, at best. If the hair loss is in the ventral
abdominal region only, we also try to rule out interstitial cystitis and bladder
stones. We have had several cat patients with these diseases who would lick all
the hair off their inquinal region, often in very neat square patterns. In older
cats hyperthyroidism can lead to self trauma. In rare instances anal sac
impaction will lead to hair loss around the base of the tail or even in the
inquinal region. Arthritis is not as common in cats but it does seem to incite
impulsive licking at times.
Raw meat diets and Salmonella infection
Many people seem to think that dogs and cats are innately resistant to
Salmonella and E. coli infections. Several studies over the years have shown
that pets are susceptible to both of these infections but that there may be some
truth to the fact they are more resistant than people, especially to E. coli
infections. However, there is no question that cats can get Salmonella
infections that cause disease and in a study published this May (Morley, et
al.), of 138 dogs in a greyhound kennel who were fed raw meat, 66% of the dogs
harbored Salmonella in their digestive tract based on fecal cultures. While I am
not an advocate of raw meat diets I understand that some people do truly believe
they offer some advantages. If so, it still remains necessary to think hard
about the risks versus the benefits of feeding a raw meat diet.
Heartworm disease
Just so that you can impress your neighbors with your cutting edge knowledge, or
perhaps because you miss the convenience of the long term injections for
heartworm control, there is a new product being developed in Australia and
undergoing clinical trials now that is a silicon and ivermectin implant that can
prevent heartworm infection for at least a year. Like all products in clinical
trials it is hard to say if this one will actually make it to market but for
those of you that found the ProHeart (tm) injections to be a good alternative to
monthly heartworm prevention tablets you may get the chance to have a similar
product again.
Gorilla Glue (tm)
I do not know why, but it appears that dogs (and possibly cats) like to eat
Gorilla Glue (tm). The glue is apparently not toxic but it swells up in the
stomach, filling it with a hard foam consistency that has to be removed
surgically. It would be a good idea to keep this glue out of reach of your pets
and to keep them away from any projects that where you intend to use Gorilla
Glue (tm).
Once Daily Thyroid supplement for Dogs
Leventa (tm), a liquid thyroxine supplement for hypothyroidism in dogs is made
for once daily administration. This product fills two niches that pet owners
claimed to want -- once daily dosing and a liquid form of thyroxine.
Urine Protein Levels as a Prognostic Aid for Cats with Chronic Kidney Disease
Chronic kidney disease, often still referred to as kidney failure, is a common
problem in older cats. One of the problems for veterinarians and veterinary
clients is the great variability in how cats with chronic kidney disease will
respond to treatment. A recent study in the May/June 2006 Journal of Veterinary
Internal Medicine (Syme, et al), shows a strong correlation between urine
protein levels and prognosis. In order to test protein levels with one sample it
was measured as the urine protein/creatinine ratio (UPC) since this gives an
indication of protein levels over time. A UPC of < 0.25 was a good prognostic
indicator and was this low in about half the cats in the study, despite the
presence of chronic kidney disease. A UPC of > 1.0 was a poor prognostic
indicator. While this finding may not change treatment options it may help some
cat owners understand why their cat is not responding to therapy as well as most
cats with kidney disease.
Methicillin Resistant Staphylococcus aureus infections of cats and dogs
Veterinarians have been lucky over the last decade or so in not having to deal
with methicillin resistant staphylocccus aureus (MRSA) infections very often. It
is likely that this situation will change over the next few years as MRSA
infections are being reported more commonly in pets. In most cases these
infections are thought to be contracted by the pet due to association with an
infected human but it also appears that pets can be a reservoir for the
infection in households and much more rarely a source of infection for
previously uninfected humans.
There are two forms of MRSA that are recognized in people, community acquired
MRSA and hospital acquired MRSA. In general, hospital acquired MRSA is much
worse and can lead to organ failure and death fairly rapidly, despite treatment,
in some patients. So far, the pet cases that have been reported appear to be the
community acquired form of MRSA.
Cats infected with MRSA may have difficult to treat abscesses or lymph node
swelling not explained by other diagnoses. Dogs have more of a tendency to have
inapparent infections affecting the nasal passages but can have severe abscesses
or other signs of an infectious process.
At the present time the main thing to remember about MRSA and pets is that they
are usually infected by a family member who has the disease but that it may be
difficult to clear it from the household without treating pets who are infected.
So if you or someone you have close contact with is diagnosed with MRSA and it
is hard to eliminate, you may want to be sure that a pet is not harboring the
Staph bacteria and keeping the infection going in the household. It is also
important to keep in mind that most Staph infections in dogs and cats are caused
by Staphococcus intermedius, so just the word "staph" should not set off alarm
bells immediately.
Long term use of carprofen (Rimadyl Rx)
There are a number of dogs who benefit from the use of non-steroidal
anti-inflammatory medications. Many of my clients worry about the use of these
medications, though. Some dogs have an idiosyncratic reactions to carprofen and
develop liver failure. This seems to be a rare event but it is still worrisome.
A recent study followed dogs for two months and found no changes in blood
chemistry or physical exam findings in dogs on carprofen. While it would be nice
to have a longer study this is a good start. Clinically we have not seen
problems in dogs on carprofen long term. We have had several patients who had
problems within the first week when using carprofen. It is our impression that
if short term problems do not occur it is not likely that problems will develop
with longer term use.
Thanks for Your Support
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Copyright 2006