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In a perfect world a vet or even an owner could look at an animal
and come up with an accurate diagnosis of whatever is troubling him
– maybe there would be one of those magical instruments that Dr
McCoy pointed at his patients in Star Trek that gave him an instant
diagnosis – even if the problem was new to then medical science.
In the real world many diseases present alike and yet their medical
management may be impaired if the wrong label is put on the
underlying disease. We often hear, "If only he could talk and
tell me what’s bothering him, I could help him." Even if he
could it’s doubtful our diagnostic ability would be significantly
increased. Most human doctors have this benefit, and yet, as often
as not are groping in the dark along with their veterinary
counterparts. Referred pain makes even saying where it hurts a
questionable exercise.
These thoughts have come home to me rather a lot of late. Those
who know me may have been bored this past year with the saga of my
daughter, Sarah’s, lame horse. OK, so Caliban isn’t a Beardie,
although the girls like to ride on his back, but his case
illustrates many of the points I wish to make. Having started the
last season’s show circuit in style, the best dressage score in
the show, a clear jumping round and offers from the dressage judge
and several others to buy him, we looked like having another good
year. Then one day Sarah said he didn’t feel right, the same the
next day, and the next day he looked like a non-believer trying to
cross the molten coals on tender feet. Everything seemed to hurt.
Cal being the biggest wimp about needles makes everyone wish to be
as conservative as possible about spending my money in finding the
cause of his problem. There is no heat in his feet, no pulses, no
sensitivity to hoof testers etc. Well, there are people who don’t
believe Lyme Disease exists in horses, but if you do he sure looked
like a good candidate. We’d also been pulling dog and deer ticks
off his anatomy in decent numbers. So we drew blood and did Western
Blot and ELISA tests for Lyme. They came back borderline and
equivocal, but it seemed a good place to start, so we treated him
for over three months with doxycycline for Lyme. Sarah rode him
lightly during that time, and while his improvement wasn’t
dramatic and wasn’t even smoothly progressive at the end of that
time he was serviceably sound again and he started back into work.
He did quite well for several weeks, and resumed jumping. Then he
was lame again. During the treatment for Lyme the lameness seemed to
settle in the front legs, sometimes shifting from one to the other.
We saw his toes point in on whichever leg was most painful;
sometimes it was both. Now he was consistently lame in his left
fore. A vet friend and I put our heads together, did flexion tests
and decided (nothing seemed to particularly help or increase the
lameness) he probably had torn a suspensory ligament in the back of
the leg. OK so normally we’d have used local anesthesia to
progressively numb the leg from the hoof on up until we knew where
he was lame, we figured we might block one joint and then it’d be
open season, so we thought the treatment for suspensory ligament
injuries won’t hurt him – 4 weeks to 4 months rest. We did let
him go out and be a horse in the pasture during his approximately 6
week lay up. He appeared sound throughout the period, and came back
seemingly raring to go. A few weeks later he was well enough, we
thought, to participate in a clinic. The instructor was not a good
choice. She thought she knew everything and wouldn’t listen to
Sarah when she explained how she warmed Cal up to spare his leg.
Result a horse that could barely hobble for the next three weeks
with someone on his back or not. Time to get serious, we loaded him
on the trailer and went to a new diagnostic centre in Acton
Massachusetts. Here we examined his whole body with digital infrared
thermal imaging (DITI). Popular in Europe this technique is just
reaching the US. It will be as applicable in dogs, I believe, as in
horses. DITI enables you to scan the whole body and see relative
areas of heat – which appear redder - and cold – which appears
bluer. The whole horse can be imaged in about 15 minutes. The most
notable things about Cal’s DITI was that he had intense heat in
his right neck, lesser heat on the left, centred in the region of
his 6th cervical vertebra. His front feet looked hot, I
thought the left more than the right, but when Mary Kahan, the vet
operating the equipment, reviewed the images later she felt this was
less significant. His legs above the hooves though were deep blue
and therefore stone cold. We continued with our exam. Cal was
feeling brave, and so was Mary, so we blocked his foot, and most of
his lameness disappeared. We X-rayed his foot. There were profound
changes in a little bone at the back of his foot called the
navicular sesamoid bone. Navicular disease is a popular diagnosis
for lameness in the horse, and one would have said Cal’s changes
were classic, except that nothing that looked like navicular disease
showed on his DITI. Also other bones in his foot and lower leg
seemed to be losing density. We ultra sounded his legs and his
suspensory ligaments looked fine – normal wear and tear only.
Finally we drew blood for further Lyme tests. Mary pointed out that
Cornell, despite the fact that at least 50% of vets don’t believe
horses get Lyme disease, use three times the dose of doxycycline to
treat the disease that we had used on Cal (results of these tests
are still pending.) So what did we conclude? Since she first saw
Cal, Mary has suspected he has Wobbler’s syndrome, a narrowing of
the spinal column so that there is pressure on the nerves. In Cal
this expressed itself as appearing to lose conscious awareness of
where his feet were, or even it seemed sometimes that he had feet at
all. Most of the time he was fine. The heat in his neck seems to
confirm this suspicion. The alternative explanation is that he was
abused or injured his neck at some time. We believe that the
narrowing of the space is also affecting the conduction of the
sympathetic nervous branch of the autonomic nervous system to
Cal’s front legs, especially the left one. The autonomic nervous
system controls functions in our bodies we don’t have under
conscious control - in this case, the flow of blood to the fore
legs. Diminution of the blood flow has resulted in loss of bone mass
and secondary navicular disease. We were able to show that when we
exercised Cal in hand the blood flow to his leg increased. Instead
of rest, exercise would help him get better. Of course exercise is
only part of his treatment, he is also fitted with special shoes to
relieve the pressure on the navicular bone, magnetic boots while
he’s inside to increase the flow of blood to the feet, and a
non-steroidal anti-inflammatory drug, which not only provides pain
relief but also increases blood flow. If he agrees to co-operate
he’ll also be acupunctured. This diagnosis is an uncommon one to
be sure, but it does underlie the importance of finding out what is
causing a problem rather than treating it empirically. OK so I
always want to know the outcome of cases. So far, 8 days after the
testing, Sarah is riding Cal again. He’s not completely sound, but
he is enjoying himself, and we hope he will be restored eventually
at least to where he was before this very bad year. I also don’t
discount that all this really started out with Lyme disease, and the
reduced work load then made the Wobbler’s more apparent. In
veterinary school we are always told to look for one disease or
problem to cover all the signs rather than multiple laundry lists of
causes. Another point to be made is that last spring Cal’s signs
were definitely very different than they are this winter. Often
owners ask why their vet missed a diagnosis. One very good reason is
because the animal they saw then isn’t the animal I am seeing now.
Another, when it comes to my behaviour patients, is because I have
taken the time to get extra training in my little niche of
veterinary medicine, and by seeing things more often I may be more
likely to pick something up than the general practitioner who gets a
very different case load. In Cal’s case, Mary and her husband Joe
have only had the DITI a month, and to diagnose Cal previously it
would have cost at least 10 times the cost of a DITI to get a soft
tissue and bone scan, not to mention filling the horse with
radioactive chemicals. Veterinary medicine is advancing by leaps and
bounds, where the use of CAT scans and MRIs in animals was most
unusual as little as 5 years ago, now it is becoming far more
common. Maybe we aren’t too far from Dr. McCoy’s little hand
held diagnostic tool.
Diagnosis can also be a problem with canine Lyme disease, and for
Beardies it may be especially problematical. Recently the veterinary
literature has contained a number of reports of mistaking Lyme
disease for systemic lupus erythematosus (SLE) and other autoimmune
diseases and vice versa. Diagnosis of SLE in Beardies seems to have
increased dramatically in recent years. SLE has been described as
the great imitator, but the same name could also be given to Lyme
and other tick borne diseases. SLE is an autoimmune disease in which
antibody-antigen complexes circulate in the blood and become lodged
in various tissues of the body; these can include the kidneys -
where they lodge in the glomeruli where the process of waste
filtration begins; the joints - leading to signs of polyarthritis;
the skin, subcutaneous fat and mucous membranes - where they can
cause ulcerative lesions (these will be felt as nodules under the
skin when the complexes invade subcutaneous fat – a condition
called panniculitis); or the brain - where abnormal behaviour or
neurological signs may result. A diagnosis of SLE relies upon two
major signs plus a positive titer on the antinuclear antibody (ANA)
blood test. While many consider the ANA test specific for SLE it can
also be positive with a number of infectious, inflammatory and
neoplastic diseases as well as a less common type of pemphigus (P.
erythematosus). Clearly too, the major signs associated with SLE are
not unique, glomerulonephritis can occur also in various infectious
diseases such as hepatitis, endocarditis, brucellosis, heartworm,
rickettsial diseases like ehrlichiosis or Rocky Mountain Spotted
Fever, Lyme disease, pyometra, leishmaniasis, trypanosomiasis,
chronic bacterial infections and septicemia; inflammatory diseases
such as pancreatitis, polyarthritis and prostatitis; endocrine
diseases like diabetes mellitus or Cushing’s disease or long term
administration of corticosteroids; as well as neoplastic, familial,
and idiopathic (unknown cause) cases. Joint pain can be seen in many
or single joints and be indistinguishable from osteoarthritis.
Certainly rickettsial diseases like ehrlichiosis and Rocky Mountain
Spotted Fever as well as Lyme disease are associated with similarly
painful joints. Dermatological conditions are not always
identifiable by cause, even with skin biopsy. Usually SLE is left
after everything else has been ruled out. Panniculitis can be caused
by a great many things, including trauma – including injection
sites; bacterial or fungal infection; degeneration; pancreatitis or
pancreatic carcinoma as well as SLE. If a needle aspirate contains
primarily lymphoplasma-histiocytic inflammatory cells it is
suggestive of SLE, but positive ANA and direct immunofluorescence
tests would be needed to confirm diagnosis. Brain lupus occurs in
about 40% of human patients. To date, I believe, the only case of
canine brain lupus reported in veterinary literature is my report on
the case of my Beardie, Tell. If a dog has SLE, treatment must be
directed towards suppressing the immune system and initial therapy
at least usually includes high doses of corticosteroids, like
prednisone or dexamethasone.
Cases of SLE can be further complicated because they are
frequently accompanied by other autoimmune diseases, like autoimmune
thyroiditis or immune mediated thrombocytopenia (ITP) and
occasionally immune mediated hemolytic anemia (IMHA – also known
as autoimmune hemolytic anemia AIHA). Thrombocytopenia is a
condition in which the number of platelets circulating in the
bloodstream has been reduced. Platelets are those little anuclear
cells in the blood that stick together to plug up tears in blood
vessel walls. While we are not aware of this, our internal blood
vessels are constantly springing small leaks, which the platelets
block off before we lose much blood. In ITP antibodies are formed
against the antigens on the platelets so that they are prematurely
removed from circulation, thereby reducing their numbers. The
designation ITP is also used to denote idiopathic thrombocytopenia,
which means a reduction in platelet numbers (thrombocytopenia) of
unknown cause. While that cause may be autoimmune it is not always
the case. Thrombocytopenia can have many causes, and it is
frequently seen in cases of Lyme disease as well as other tick borne
diseases such as the rickettsial diseases ehrlichiosis and Rocky
Mountain Spotted Fever.
Are we beginning to see a pattern here? A recent case report in a
veterinary journal told about a dog that had fallen down stairs.
This dog was found to have joint pain, a fever and was lethargic.
The dog had evidence of an infectious disease, and a moderate/high
titer for Lyme disease. He was negative for Ehrlichia canis
and Rocky Mountain Spotted Fever. The dog also had thrombocytopenia
and a positive ANA. Two positive signs for SLE with associated ITP,
if he had also had glomerulonephritis would the reporting vet have
assumed that to be the correct diagnosis? As it was he ran further
tests for other members of the Ehrlichia family. The dog was
negative for E. risticii and E. platys but had a very
high titer for E. equi. A bone marrow biopsy showed secondary
damage. E. equi is transmitted by deer ticks, as is Lyme
disease, E. canis by dog ticks. E. equi is often
transmitted with Lyme disease yet is rarely tested for routinely. I
have heard of many dogs, including Beardies, diagnosed with Lyme
disease that are also said to have ITP, although as in this case the
thrombocytopenia is likely to be secondary to the Lyme disease. The
reporting vet felt the Lyme disease was less important in this dog
than the ehrlichia. The excessive damage to the marrow suggested a
severe chronic form of the disease. The dog in the case report,
survived, but it took a very long time for the organism to clear his
body, and treatment was maintained for far long than most vets treat
either Lyme disease or Ehrlichia. If he had only had E. equi, and
had shown signs of kidney disease it is highly likely that this
diagnosis would have been missed. Perhaps a diagnosis of SLE and ITP
would have been made, even with the Lyme disease a seriously
considered rule out. Without antibiotic treatment the true cause of
his problems, which were considered minor throughout treatment,
would have been missed until he developed the ocular lesions,
seizures and coma seen as this disease progresses.
Getting an accurate diagnosis is rather like sleuthing out a
criminal case. Dead ends and red herrings abound. Often negative
findings are as significant as positive ones. Money is clearly a
factor. While most people’s immediate reaction is to "make
him better no matter what it costs," the cost can mount up
alarmingly quickly. Quality of life must also be considered along
side life itself. Sometimes time is against those trying to diagnose
the problem. Disease progresses too rapidly for a cure – in the
next column I’ll look at two of the most common causes of dog
poisoning, and we will see that unfortunately by the time owners
realize their dog has a problem, it may be too late to save him.
Other factors can enter into the picture. Sadly, in my field of
behaviour, tincture of time is often needed while the dog’s
behaviour is modified. Even where drugs are appropriate they may
take several weeks to reach therapeutic levels. If the problem is an
aggressive dog the owners may not be able to grant the dog the time
to find the right diagnosis. Other problems can be almost as
destructive and frustrating while a diagnosis is reached, and
therapy instituted. I think most vets enjoy the challenge of an
unusual or complex diagnosis; sadly we don’t always like the
outcome.
Good health to you and your Beardies.
Copyright © 2000 [ Linda Aronson DVM].
All rights reserved
A grateful thank you to Linda
Aronson for permission to use this article.
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