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Canine Ehrlichiosis
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Canine Ehrlichiosis
Ehrlichiosis- Not just for German Shepherds
Canine Ehrlichiosis
Canine Rickettsiosis, Canine Hemorrhagic Fever,
Canine Typhus, Tracker Dog Disease
Roger Ross DVM
Affected Animals
Dogs, cats, and in rare instances, humans. German shepherds and Doberman
pinschers tend to be affected more severely by the disease.
Overview
Dogs get ehrlichiosis from the brown dog tick, which passes an Ehrlichia
organism into the bloodstream when it bites. There are three stages of
ehrlichiosis, each varying in severity. The acute stage, occurring several
weeks after infection and lasting for up to a month, can lead to fever and
disorders of the blood. The second stage, called the subclinical phase, has
no outward signs and can last for up to five years. If the infected dog's
immune system is unable to eliminate the Ehrlichia organism, the third and
most serious stage of infection, the chronic phase, will commence. Lameness,
neurological and ophthalmic disorders, kidney disease, and anemia and other
blood disorders can result. Chronic ehrlichiosis can be fatal.
Antibiotics, administered for an extended period of time, are effective
at eliminating the infection. Dogs with severe cases of chronic ehrlichiosis
cannot be cured, but supportive care and treatment of diseases secondary
to the infection, such as anemia, can help stabilize the dog.
Clinical Signs
The acute stage of the disease, occurring most often in the spring and
summer, begins one to three weeks after infection and lasts for two to
four weeks. Clinical signs include a fever, petechiae, bleeding disorders,
and vasculitis. There are no outward signs of the subclinical phase, which
can last for up to five years. Clinical signs of the chronic phase include
pale gums due to anemia, thrombocytopenia, vasculitis, lymphadenopathy,
respiratory dyspnea, coughing, polyuria, polydipsia, lameness, ophthalmic
diseases such as retinal hemorrhage and anterior uveitis, and neurological
disease.
Symptoms
Symptoms of the acute stage of disease include a fever, lesions within
the mucous membrane, bleeding disorders, and inflammation of the blood
vessels. The subclinical phase has no outward signs of disease. Signs of
the chronic stage of the disease can include pale gums due to anemia, inflammation
of the blood vessels, swollen lymph nodes, difficulty breathing, coughing,
kidney symptoms such as increased urination and increased drinking, lameness,
eye disorders, and neurological disease.
Description
Ehrlichiosis is a tick-borne disease of dogs that is caused by an organism
called Ehrlichia. There are several species of Ehrlichia, but the one that
most commonly affects dogs and causes the most severe clinical signs is
Ehrlichia canis. The brown dog tick, or Rhipicephalus sanguineous, that
passes the Ehrlichia to the dog is prevalent throughout most of the United
States, but most cases tend to occur in the Southwest and Gulf Coast regions
where there is a high concentration of the tick.
There are three stages of the Ehrlichia canis infection: acute, subclinical,
and chronic. Approximately one to three weeks following the infection,
clinical signs of the acute phase begin and typically last for two to four
weeks. The subclinical phase, which does not produce outward clinical signs,
lasts for up to five years. If the dog's immune system is unable to eliminate
the organism during this stage, the chronic phase will occur and may last
for years, depending on the severity of the infection. Dogs that are severely
affected can die from this disease.
Although people can get ehrlichiosis, dogs do not transmit the bacteria
to humans; rather, ticks pass on the Ehrlichia organism. Clinical signs of
human ehrlichiosis include fever, headache, eye pain, and gastrointestinal
upset.
Diagnosis
Diagnosis is achieved most commonly by serologic testing of the blood
for the presence of antibodies against the Ehrlichia organism. During the
acute phase of infection, however, the test can be falsely negative because
the body will not have had time to make antibodies to the infection. Thus,
the test will need to be repeated if the first result is negative. In addition,
blood tests will show abnormalities in the numbers of red cells, white
cells, and platelets. Uncommonly, a diagnosis can be made by looking under
a microscope at a blood smear for the presence of the Ehrlichia organism,
which sometimes can be seen within a white blood cell.
Prognosis
The prognosis is good for dogs with acute ehrlichiosis. For dogs that
have reached the chronic stage of the disease, the prognosis is guarded.
When bone marrow suppression occurs and there are low levels of blood cells,
the animal may not respond to treatment.
Transmission or Cause
The Ehrlichia organism is passed to the dog through the saliva of a tick
called Rhipicephalus sanguineous. These ticks are prevalent throughout
most of the United States, but most cases of infection tend to occur in
the Southwest and Gulf Coast regions.
Treatment
Supportive care must be provided to animals that have clinical signs.
Subcutaneous or intravenous fluids are given to dehydrated animals, and severely
anemic dogs may require a blood transfusion. Treatment for ehrlichiosis involves
the use of antibiotics such as doxycycline for a period of at least six
to eight weeks; response to the drugs may take one month. In addition, steroids
may be indicated in severe cases in which the level of platelets is so low
that the condition is life threatening.
Prevention
Prevent tick infestation by avoiding tick-infested areas. In addition,
there are many methods for controlling fleas, including medicated shampoos,
dips, sprays, the Preventic® collar, or spot-on drugs such as Frontline®
or Advocate®. If tick control is not feasible, tetracycline at a lower
dose can be given daily for 200 days during the tick season in endemic
regions.
©Reproduced
with permission from Roger Ross DVM,
Foxnest Veterinary Hospital, Seneca, SC.
For further information go to www.foxnest.com
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Ehrlichiosis
— Not Just for German Shepherds
Ehrlichiosis Rickettsiaceae
Zoonoses severe haemorrhage cervical pain, bleeding gums,
lethargy, muscle atrophy, swollen popliteal lymph glands
By Fred Lanting
It’s been around a long time,
and it’s not going to go away. Once considered an exotic or tropical disease,
later associated specifically with German Shepherd Dogs but not your little
Fifi, Ehrlichiosis is a disease that can range from stubbornly persistent
to downright fatal. Actually, we might not be technically correct in calling
it a disease — some prefer to call it a syndrome, which means a collection
of symptoms, not all present at one time or in one individual.
In what we were taught in high school is the shady area between the
Animal Kingdom and the Plant Kingdom, lays a large and varied assortment
of organisms that have one figurative foot in each. Analogously, in the
grey area between bacteria (simple one-celled “plants”) and viruses there
are micro organisms that some would classify in one of those groups or the
other, or separately, but act like both in some ways. Whether you identify
bacteria as plants and one-celled flagellant microbes like Giardia as animals
because the latter are somewhat motile, doesn’t make much more than academic
difference, nor does it matter much whether you call Ehrlichia microbes
bacteria, rickettsia, or anything else. Rickettsia has been thought of as
a separate genus of evil little critters intermediate between bacteria and
viruses, but today, most medical references list it as “a bacterium in the
Rickettsiaceae family”. The name has nothing to do with the disease of
rickets; rather it is named after a pathologist named Ricketts. The bottom
line for the average person is that it seems the smaller the organism, the
nastier it is likely to be. More people are killed by virus particles than
by elephants. Some of the micro organisms are so small; they slip through
the most sophisticated filters and barriers.
There are a few rickettsial-like Ehrlichial species, sometimes hard
to tell apart, that affect dogs: Ehrlichia canis, E. phagocytophilia, E.
ewingii, and E. equi, for examples. Some cause milder symptoms than do others.
Each species results in a disease state that may have more than one name,
usually based on what it does to the body’s cells, especially blood cells,
or its history of discovery. Ehrlichia organisms are “gram-negative”, meaning
they can be made visible and identified under the microscope by the way
in which they are stained by certain dyes.
The E. canis designation is self identifying as the species perhaps
of greatest importance in dogs, canis or canidae referring to the canine.
E. equi, associated with the horse, and E. ewingii, named after its discoverer,
cause granulocytic Ehrlichiosis, which is not as severe a disease as that
as that produced by E. canis, especially in regard to neurological signs.
E. platys and others were later added to the list of Ehrlichia species.
Another canine affecting species that has not yet been fully characterized
is similar to E. risticii (which causes Potomac horse fever) in its DNA.
Other rickettsial diseases include Canine Infectious Cyclic Thrombocytopenia,
Rocky Mountain Spotted Fever, Elokomin Fluke Fever, and Salmon Poisoning
Disease.
Transmission
Although medication may appear to give a “cure”, there may be many
untreated (or even a few treated) dogs that serve as reservoirs for the
microbes, and can donate some to subsequently encountered ticks. The microscopic
invaders infect and kill white blood cells: monocytes, neutrophils, lymphocytes,
and leukocytes are attacked. The way this happens is that micro organism,
like any foreign substance that is recognized by the body’s defence mechanisms,
is consumed by the white blood cells in an attempt to isolate and destroy
them, but the little devils are too hardy and multiply inside those cells
faster than they can be “digested”. Breaking out of the ruptured white
cell, the aliens also attack other blood cells and damage their function,
frequently leading to anaemia and problems in bone marrow (where blood
cells are manufactured). It also disrupts the host’s autoimmune system
so that the animal starts phagocytizing (consuming) its own red blood cells;
with a weakened immune system, the host is then susceptible to many secondary
infections and illness symptoms. No vaccine is available.
In the early 1960s, military dogs were found to be contracting Ehrlichiosis
in Vietnam (or perhaps being stimulated into the chronic severe phase
by repeated exposure to the bacteria and under a great deal of physical
and psychological stress). Some returned to the States where the disease
was identified, others stayed and perhaps shared the infected ticks with
their handlers. The military K-9s were erroneously or unfairly blamed for
the appearance of the disease in America and its spread throughout Southeast
Asia. By the early 1980s, it had spread across nearly the whole U.S., and
soon thereafter was to be found wherever the brown dog tick existed, which
is almost universal.
At Texas clinics used by GSD breeders, vets such as Harold Krug and
Marc Rachovsky have seen so many cases as to become equivalent to Ehrlichiosis
specialists. While transmission is primarily via the bite of a tick as
intermediate host, it may be possible to spread Ehrlichiosis through blood
transfusions, although Dr. Edward Breitschwerdt and colleagues were unable
to induce the disease in “clean” or “naïve” dogs that way. According
to a few vets I conferred with in the greater Dallas area, where Ehrlichiosis
has been rampant for many years, and where probably 80% of imported GSD’s
had it, it can be transmitted also by saliva, fleas, and maybe mosquitoes
and seminal/prostatic fluid. Dr. Ibulaimu Kakoma intimates that Ehrlichiosis
may wisely be handled as if it were also a venereal disease, and recommended
that infected dogs be kept out of the breeding pool. Certainly, while
a couple types of ticks are the most common vectors, it can also be carried
by the same tick species that spreads Lyme Disease. If fact, a single
tick can infect a dog with two or three diseases at once, the third of
these most common diseases being Rocky Mountain Spotted Fever. Since Ehrlichia
is so widespread, there may be a chance your vet’s blood donor dogs could
be carriers. By the way, many dogs test positive for all three of these
tick-spread diseases, and some have also picked up Babesia and Bartonella
infections from ticks.
Since ticks are by far the most important means of transmission, you
can reduce the odds of contracting Ehrlichiosis by vigorous attempts to
control the ticks. Some Ehrlichia species, perhaps all, can affect any
number of animals: dogs, horses, cats, goats, rodents, deer, humans, and
more. It seems to take a day or two of attachment to the host before efficient
transmission of the micro organism is effected. Because cats tend to groom
themselves often and thoroughly, there is a decreased opportunity for the
disease to bother cats — perhaps we should learn from Kitty.
Zoonoses
A zoonosis is a disease that can be transmitted directly or indirectly
from one species to another and the context is usually one in which we
speak of humans getting it from their pets. Often, there is an intermediate
host or “carrier” that does not suffer from the disease but that transfers
it, sometimes after it undergoes a change in the body of that “middleman”.
You are already familiar with the spread of heartworm and tapeworm by mosquitoes
and rodents or fleas. Most diseases, such as “the common cold” are not
transferable, but there are enough out there to give us concern. One is
Ehrlichiosis.
You probably cannot get it directly from your dog, but if a tick feeds
on him and then you, you could. The first human case was in Japan in 1954,
and it wasn’t until 45 years later that it became serious enough in man
for the Centre for Disease Control (CDC) to list it as a “reportable disease”.
That year (1999) there was over 300 human cases, including several deaths.
Besides E. canis, E. chaffeensis and E. phagocytophilia are known to have
caused human Ehrlichiosis. In the U.S., the first reported case of E. canis
infection in a human was in Arkansas in 1986, where a man who was bitten
by ticks showed a dramatic rise in antibody titers. Prior to this, only
E. sennetsu was known to affect humans, and then only in Japan, in the case
mentioned above, and parts of Southeast Asia. Humans develop the acute
phase, but so far it appears Homo sapiens does not get the chronic form;
perhaps this is because people tend to aggressively seek remedies during
the acute phase, but I believe it is more likely due to a more efficient
immune system.
Earliest identified cases of Ehrlichiosis in dogs were mostly found
in Africa and Israel. Canine occurrence was first recognized in 1935 in
Algeria and later found in horses, cattle, man, and other species. It is
surmised that a “species jump” occurred as a result of minor evolution or
mutation in order for varieties of Ehrlichia to be able to infect humans.
Bacteria do not mutate nearly as fast as the smaller viruses do, but eventually
many diseases jump from the original host to humans; examples: AIDS, SARS,
Ehrlichiosis, and more. Cattle are subject to at least one variety of
Ehrlichia, and ranchers would love to use some of the more potent treatments,
but some leave a toxic residue in the meat.
Besides in Texas, where GSD’s imported from Germany have been plentiful,
the early heavy pockets of disease were in Northern Georgia, the Carolinas,
and other east coast areas.
Symptoms
Symptoms range from as mild as a little itching, to severe haemorrhage
from gums and other tissues. Some dogs appear to develop resistance to
it, but in actuality might merely be in the sub clinical phase, which can
last for years. Some show only occasional, mild signs after an apparent
recovery. Variability of symptoms from dog to dog and between species of
animals, are part of the reason this disease is so hard to diagnose. In
humans, signs can appear from as short as one day after a tick bite, but
usually it’s about 12 days when suddenly the person gets one or some of
these: muscle ache, chills, nausea, sweating, headache, overall discomfort,
abdominal pain, vomiting, and diarrhoea, problems with blood vessels, seizures,
blindness, or even coma. Rarely, there is a rash on the extremities or around
the trunk.
Similar symptoms are found in the canine. Cervical pain, bleeding gums,
lethargy, muscle atrophy, swollen popliteal lymph glands behind the knees
— the list is lengthy and symptoms confusing because so many point to other
diseases, too. Incubation in dogs apparently (and incredibly) is at least
3 weeks in dogs, according to most reports, and evidence of platelet destruction
might not be discovered until 2 or 3 months after infection. Prophylactic
shots may be the best idea, then; besides, the shots are cheaper than the
test. Some GSD breeders in northern Texas routinely give shots to pups at
12 days of age! Many buyers and importers treat dogs even before taking
them from the airport. A blood test on a newly imported or purchased dog
might not reveal the problems you might face a month later, as you can get
a “false negative” test result. Texas A&M’s vet school stopped doing
the blood tests years ago, while Auburn in Alabama was still offering a series
of 3 tests.
Typically, the disorder first goes through an acute severe stage, then
the dog seems to improve (often coincidental with an administration of
antibiotics or almost any or no treatment) as if to lull the owner into
a false sense of security. This second part of the progression of the syndrome
is called the sub clinical phase, although lab tests and titers will tell
you the danger is still there. Later, in most dogs, symptoms come back with
a vengeance in the third, chronic, phase. This severe period can happen
years after the first acute phase ends; even without another tick bite,
the dog’s immune system may be overwhelmed and it becomes very sick again.
Emaciation, lack of co-ordination, kidney failure, paresis, poor proprioception,
and other signs are common in the severe chronic cases.
Nosebleeds are common in the doliocephalic (long faced) breeds, and
even without that sign, the dog’s olfactory powers may suffer. This can
be a factor in some GSD’s having trouble passing their tracking title exams.
It also may play a very important part in lack of interest in breeding,
since scent of a bitch approaching ovulation is necessary to stimulate a
stud dog. Sterility and reproductive problems are also found in affected
dogs, in all three phases.
The immune system has reduced efficacy, which means that more of the
affected dog’s blood cells are overwhelmed, and the animal is more susceptible
to other diseases. In the autoimmune response, the dog’s body tries to
combat the micro organism inside its blood cells, but is tricked into developing
antibodies that attack its own platelets as well. Polymyositis, neuro-
or poly-myalgia, and other probably autoimmune responses can be as deadly
as the trigger disease itself. German Shepherd Dogs typically have more
immune system related disorders than many or most other breeds, and frequently
they respond poorly to challenges from organisms such as Ehrlichia. Thus,
they often have more severe symptoms than other dogs do, but all breeds
are at risk.
The Merck Veterinary Manual says, “Dogs with [Ehrlichiosis] often have
thrombocytopenia, anaemia, leukopenia, hyperglobulinemia, and mononuclear
pleocytosis and marked increase in protein on CSF analysis.”
Diagnosis
Diagnosis can be difficult, and often is a process of elimination.
Very helpful, though, is a test called IFA, for Indirect Fluorescent Antibody,
which can (sometimes) detect antibodies from one to 4 weeks after infection.
Antibodies are a class of reaction chemicals produced by the body when a
disease antigen or foreign organism or chemical is introduced. A positive
test is positive, all right, but a negative test is not always proof that
an animal is not infected. The IFA test is often quite variable between labs,
technicians, and other factors. We refer to this as a lack of sensitivity
and reliability. When it works, a single serum antibody titer is usually
sufficient for diagnosis of E. canis.
Treatment
When one drug does not work well, veterinarians have a choice of a
few others to try. The usual drug of choice for all forms of Ehrlichiosis
is tetracycline, given for a minimum of 2 weeks in acute cases, 1-2 months
in chronic cases. Puppies that are still teething are normally given something
else, because of the severe discoloration of tooth enamel produced by
tetracycline on developing teeth. Treatment of rickettsial myelitis (tissue
inflammation) may also be accomplished with doxycycline or chloramphenicol
for 2-3 weeks. Because of better intracellular penetration, doxycycline
seems to be effective in some cases in which tetracycline fails. Doxycycline
has some advantages in administration: dosing only two times a day, and
oral doses just about as good as injections, for example. Early treatment
is important to successful treatment and the prevention of lasting effects.
Treatment with either one might have to be continued for a couple of months
to kill the micro organisms; some claim that it takes up to 6 months to
kill them and get the lab tests back into normal range. Even then, a dog
may be left with permanent damage such as in co-ordination, muscle atrophy,
general poor resistance, inability to regain normal weight, and other neurologic
deficits despite treatment.
Two shots of imidocarb dipropionate 2 weeks apart, are variably effective
against both Ehrlichiosis and Babesiosis; however, the drug is not approved
for use in the USA. A series of 2 to 4 Diamperon shots in 2 or 3 weeks
usually (97-100%) seems to result in cure. (Rachovsky) Although Diamperon
has not yet been approved for use in dogs in the U.S. but has been used
for a long time in Israel, many American vets, beginning in the early 1990s,
bought it from there and used it “off-label”.
Some species of Ehrlichia, especially those that produce HGE, human
granulocytic Ehrlichia, seem susceptible to other antibiotics like ciprofloxacin,
trovafloxacin, and rifampin. Other species resist these drugs but are killed
by various drugs. Clients should understand that the vet might have to try
one after another until something works, because the identification of Ehrlichia
species is not always accurate or easy.
In acute cases, the temperature returns to normal within 24-48 hours
after successful treatment, and the dog becomes more active and begins
to eat. In chronic cases, the haematologicl abnormalities may persist for
3-6 months, although clinical response occurs much sooner. Supportive therapy
may help prevent or make wasting and specific organ dysfunction less severe;
platelet or whole blood transfusions may be required when haemorrhage
is considerable. The E. canis antibody titer should be measured again
within 6 months of illness to confirm a seronegative status, an indication
of successful therapy. If serum titers persist, even though at lower levels,
another test should be run in 6 months.
Prevention
It is probably impossible to absolutely prevent ticks from biting your
dog, but you certainly can reduce the incidence by diligently inspecting
your pet after every walk where there is any vegetation at all. Removing
ticks by feeling under the coat all over the dog’s body during daily combing,
and visually inspecting your own bodies when you bathe, is recommended during
at least the heaviest infestation period s of summer and fall. Several
years ago in Alabama we had two horrible tick years back-to-back, and beginning
treatment of our few dogs consisted of dipping them entirely up to their
eyes in a 50-gallon plastic garbage can nearly filled with a potent miticide
solution. Quite toxic to the ticks, and supposedly mildly so to us and the
dogs, but we had no practical choice. Rubber gloves helped, and we made
sure it was at least a week, usually two, between dippings.
Normally, it is sufficient and safer to remove them one at a time with
tweezers (fingernails will do in a pinch), depositing the ticks in a saucer
or bowl with concentrated dish wash detergent or soap water in it. That’s
because the ticks cannot breathe or crawl well through soap the way they
can through plain water, and they suffocate in a very short time. It’s
also a lot less messy than crushing them between rocks and risking the
spread of their eggs. Be sure you grasp them at the dog’s skin, to get
all or most of the mouth and head, even though you’ll probably pull off
a little piece of the dog’s epidermis with it.
Treating the premises may be of some value if you only have a small
back yard, but is not feasible if the dog has access to woods, tall grass,
and bushes off your own property. Wildlife may be hard to control, too,
although some limited success in preventing as much Lyme disease in New
England has been had by soaking cotton balls in tick killers, and leaving
this nice nesting material in tubes where mice can find it and carry it to
their boudoirs. The reason this works is that the tick goes through a few
different phases in its life cycle. After engorging on a dog’s blood, for
example, it will lay eggs which later hatch into larvae which feed on small
mammals and birds, Some varieties then drop off and molt into nymphs, and
lie dormant until the next spring when again they find the blood wagons in
the form of rodents, rabbits, birds, etc. In that fall, they molt again
into larger adults, and go after larger game such as deer, dogs, and you.
If control agencies can make mouse nests comfy for the mice but deadly for
the ticks, they can interrupt a year’s worth of tick development this way.
There are no Ehrlichiae in the eggs, but larva, nymph, and adult can all
carry the germ from stage to stage to host.
Copyright, 2003, by the author.
Permission to reprint can be obtained from him at: mailto:mrgsd@hiwaay.net or by mail.
Fred Lanting is a German Shepherd Dog breeder and judge and the author of
“The Total German Shepherd Dog”. Seminars available in conjunction with judging
dates or separately.
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The above information is simply informational. It's intent is not
to replace the advice of a veterinarian nor to assist you in making a diagnosis
of your pet. Please consult with your own veterinarian for confirmation of
any diagnosis. Your pets life may depend on it.