Overview
First, we have to deal with a matter of name changes. The causative agents of Canine erhlichiosis (E. canis), Canine granulocytic ehrlichiosis(E. ewingii), and Human monocytic ehrlichiosis (E. chaffeensis) remain what they were, but science has changed the names of the organisms we've known as E. risticii, E. equi and E. platys to better reflect their natural relationships.
Erhlichia risticii has become Neorickettsia risticii. Ehrlichia equi has become Anaplasma phagocytophilum. Ehrlichia platys has become Anaplasma platys.
You'll see each of these three referred to by both the old name and the new one as you read on. For convenience, however, I'll continue to use "ehrlichiosis" as a generic term for them all.
According to the Erhlichiae Research Laboratory at Ohio State College of Veterinary Medicine, "New genus Ehrlichia, except for E. ewingii ...infects monocytes and macrophages. E. ewingii infects granulocytes.... The genus Anaplasma group infect granulocytes, platelets, red blood cells. The Neorickettsia group infects monocytes and macrophages. N. risticii in addition infects intestinal epithelial cells and mast cells."
Note: "ehrlichiosis" is the disease; "Ehrlichia" is the organism.
The Stages of Ehrlichiosis
Ehrlichiosis has three stages. The acute stage is brief and the symptoms are easily missed; it may appear as if the dog has a mild and passing viral infection: snotty nose, diarrhea, fever, a general lack of his usual oomph. In a stoic dog especially, a change in behavior may be the only alert he gives you to get him to the vet.
It's in this stage that the outlook for a cure is best. Very early on, however, testing is probably useless; until ten days to two weeks after infection, the immune system will not have had time to make sufficient antibodies for the tests to detect.
The acute stage over, the disease passes into the subclinical stage. This simply means a stage in which no symptoms are present. Cure, or at the very least, containment of the disease so that it cannot progress, is still a good possibility in this stage, which may last for years.
If the disease progresses to chronic, the outlook is grave, particularly in E. risticii and E. canis. Symptoms show up with a vengeance at this point. You can find lengthy but still incomplete lists of symptoms and the diseases for which ehrlichiosis is often mistaken here and here.
Dr. Cynthia Holland, Ph.D. has written an excellent and brief article on the importance of titers in determining treatment for canine erlichiosis that addresses the various stages of the disease here. Dr. Holland is an expert on tick-borne disease and she states emphatically: "The magnitude of antibody titers resulting from infection with Ehrlichia canis is directly correlated with the chronicity of the disease (i.e., the length of time the dog has had it). This information is extremely important in determining the treatment protocol since dogs which have been chronically infected for some time will require a more rigorous and lengthy treatment with doxycycline and, possibly, imidocarb in order to successfully clear the infection. This is in contrast to treatment during the initial acute phase, which generally requires only 3 weeks of doxycycline therapy." (Emphasis mine.)
Something you might also be aware of, that Dr. Breitschwerdt notes in his discussion of Rocky Mountain Spotted Fever, is that distemper, and erhlichiosis can present very similar signs in a young dog.
Misdiagnosis which delays or prevents a correct diagnosis of TBD is unhappily common.
Dogs which have had ehrlichiosis should not be bred
There is strong reason to believe that erhlichiae may not be completely eradicated by treatment, that at least some may be able to hide, much like Lyme spyrochetes, waiting for conditions to become favorable to show up again. In one case I know of, E. canis was found in the ovaries of a dog spayed after treatment, though post-treatment blood tests showed a negative titer. A clinical test done on infected ponies confirmed that N. risticii causes fetal abortions and can infect foals before birth. Anecdotally, N. risticii has also been known to cause prenatal infection in dogs, and while transmission through sperm hasn't been proven as far as I know, it's something to think about before using a dog at stud.
Bringing pups into this world infected with ehrlichiosis, especially if they are German Shepherd Dogs or Doberman Pinschers, dooms them to suffering somewhere down the road and their people to real heartbreak. Our dogs and the people who love them deserve better of us.
Ehrlichiosis canis - Canine monocytic ehrlichiosis
Named after Dr. Paul Ehrlich, who discovered the causative organism of ehrlichiosis, E. canis, the most common form of this disease in dogs, cripples the immune system by making it impossible for the white blood cells known as monocytes to replicate correctly or, in the end, to reproduce themselves at all.
It has gotten more attention from researchers than any other canine tick-borne disease, probably because of the number of military dogs in Vietnam that fell victim to what was then called Idiopathic Hemorrhagic Syndrome or Tropical Canine Pancytopenia. In a two and a half year period, it was the direct cause of death for 220 dogs, primarily German Shepherd Dogs, and a "contributing reason for the euthanasia of many others".
Yet, despite that, getting a diagnosis can be difficult because E. canis can be frustratingly non-specific at first, nothing special, nothing to get alarmed about. If a dog is brought in to a clinic with a number of vague complaints, because he's droopy, not eating very well, vomiting bile or just "ain't doing right", those are complaints veterinarians hear all the time and they don't really raise a red flag for TBD. For that reason, I can't stress enough how important it is for veterinarians to read the webpage that first brought clear, comprehensive information about this disease to anyone who has access to the internet, Ehrlichiosis, a Silent and Deadly Killer, particularly the foreword by Dr. Ibulaimu Kakoma, DVM PhD and the section specifically addressed to them.
"Perhaps the most critical thing for the clinician to remember is to look at the big picture. Does a client's pet really have several ailments affecting different systems, or could it be suffering from ehrlichiosis which, in essence, affects all systems?"
Progression of the Disease
In the acute stage, fever (pyrexia), diarrhea caused by inflammation of the intestines (enteritis), swollen lymph nodes (lymphadenomegaly) and enlargement of the spleen (splenomegaly) are common symptoms. There may be an increase in white blood cells. If you suspect your dog may have erhlichiosis, have your vet check your dog's eyes. Ocular manifestations include uveitis, retinal disease and corneal opacities.
When the disease goes into the subclinical stage where no symptoms are present, E. canis burrows in and undermines any of a number of organs, but the bone marrow, where production of the red blood cells, white blood cells and platelets takes place, is its primary target. "The only hint that Ehrlichia are hiding is a somewhat reduced platelet count and/or elevated globulin level on a blood test." Laboratory findings during this stage may also include mild thrombocytopenia and a positive antibody titer; slightly decreased packed cell volume (fewer red blood cells) or leukocytes (white blood cells).
The disease may stay dormant for years and then abruptly become chronic. In the most extreme example I know of, Adam, an Australian Shepherd, became visibly sick for the first time at five o'clock one afternoon and was dead by two in the morning despite a veterinarian working over him for hours, trying to save him after being rousted out of bed by the dog's frantic owner. The vet said afterward that it was clear to him that Adam had been harboring infection for some time, possibly years.
Undiagnosed and untreated, the disease sooner or later moves on to the chronic stage, triggered, perhaps, by stress, trauma, an unrelated infection, or just a body caving in to exhaustion.
According to a Purdue University newsletter, how severe the disease becomes depends on the dog’s age as young dogs are more likely to be infected; what kind of ehrlichiosis it is; whether or not the dog is already sick and what kind of dog it is. It goes on to say that dogs with a normal, healthy immune system (immunocompetent) may be able to shake off ehrlichiosis but that the organism persists in the cells of most dogs and progresses to a chronic stage that might be mild or severe.
Mild chronic ehrlichiosis sounds to me like a contradiction in terms. It seems to hint that the dog can survive well enough without treatment even though he's infected. Don't even think it. Failure to treat is asking for the worst possible outcome, especially for German Shepherd Dogs.
Dogs generally seem to show a serious loss of condition when the disease reaches the chronic stage. I've seen dogs that died of it described as 'emaciated'. A dog may cough or have trouble breathing. Sooner or later, the dog may go blind. He may develop an excessive thirst and urinate more than he normally would, signaling kidney involvement. He may develop a disorder of the eye, brain or spinal cord. Nothing seems to be beyond this disease.
Changes in the blood may show up as nonregenerative anemia, thrombocytopenia (an abnormal decrease in platelets) or leukopenia (an abnormally low number of white blood cells). In the severe chronic stage, secondary immune-mediated hemolytic anemia (IMHA) may cause a dog to have a hemolytic crisis in which destruction of the red blood cells is so rapid that the body just can't make replacements fast enough. Or the dog may develop pancytopenia.
When the immune system turns on itself, as it does in an auto-immune disorder, sometimes the only recourse is to use a corticosteroid such as prednisone or prednisolone to suppress it. Since the immune system is already under attack by E. canis, the vet has a fine line to walk in determining how much prednisone will be enough and not too much. Prednisone, given to a dog that has undiagnosed ehrlichiosis, can be dangerous but in the right hands, if the disease has been recognized and is being treated, this drug can be life saving.
Cross infection with other tick-borne diseases is common.
Ehrlichia risticii - neorickettsia risticii the "tick disease" organism that is not carried by ticks
Ehrlichia risticii, now known as Neorickettsia risticii, is familiar to horse owners as the causative agent of Potomac Horse Fever in the East and Shasta River Crud on the West Coast. For a long time, the vector could not be identified but we now know that the organism causing this disease is incubated in the larvae of flukes that live on certain water snails, is transmitted to caddis flies and other insects that ingest them, then is passed by these insects to the dog, presumably when he unintentionally eats them or drinks them in with water from rivers that contain these snails.
E. risticii was renamed to reflect the disease organism's close kinship to the organism that causes Pacific Salmon Poisoning Disease (Neorickettsia helminthoeca).
I was tempted to place N. risticii first, to be honest, because it killed my dog but also because there is no protection against it. There is a vaccine for horses but there is no vaccine for dogs and no way to prevent a dog ingesting an insect carrying this disease.
If E. canis affects monocytes and macrophages, N. risticii adds intestinal epithelial cells and mast cells to that list and appears to be much more severe, more resistant to treatment, more difficult to contain or to overcome than other forms of TBD. Since German Shepherd Dogs appear to suffer more severely than most other breeds from both E. canis and N. risticii, a timely diagnosis is especially critical for them.
I believe that any dog that is already ill when this disease is contracted, or was infected in the womb as Anne McGuire's Jasper was, is in serious trouble. Anne recounts in detail the battle she waged and won against chronic N. risticii on Jasper's website and provides a lot of useful information that I would highly recommend you read. It's rumored that one other person has successfully conquered chronic N. risticii in her dog; I've never heard of anyone else doing it.
In 1994, Dr. Ibulaimu Kakoma and his colleagues "reported serologic evidence of over 100 cases of atypical canine ehrlichiosis with three fatalities." Atypical canine erhlichiosis It acted like E. canis yet tests said it wasn't. What they found instead was E. risticii (N. risticii), the agent of Potomac Horse Fever, not in horses but in dogs.
Clinical signs for six of these dogs were reported and ranged from lethargy and vague signs of abdominal discomfort to persistant bleeding, polyarthritis (inflammation of several joints) and hind end paralysis. Bloodwork also showed results that varied from dog to dog: the time it took for some dogs' blood to clot was prolonged, some became anemic, some developed thrombocytopenia (low platelets), some had abnormally high concentrations of calcium in the blood. Some dogs responded well to treatment with tetracycline, some dogs didn't respond at all. Dr. Kakoma proposed calling this organism isolated from the dogs' blood E. risticii subspecies atypicalis. Only 12 years ago.
Since then, the ehrlichiae have been regrouped, some renamed, but the "common natural host" of E. (N.) risticii was (and still is) listed as the horse. Evidently this is still not considered a serious concern in dogs. Well, maybe it isn't, except to those breeds hardest hit by N. risticii, the working and sporting dogs most likely to encounter it.
N. risticii is contracted close to rivers. Tracking is a dog sport I love, at which my dogs have excelled, and I've often tracked my dogs in wetlands adjacent to the Chattahoochee River and sometimes near the Oconee River, both in Georgia. I am personally convinced that snails hosting the larval flukes which carry N. risticii are present in one or both of these rivers and that Thunder was infected while we were near one or the other. My older dog, Traveler, escaped it but whether that was luck or simply that he was an adult while Thunder was very young and more vulnerable, I'll never know.
Cross infection with other tick-borne diseases is common.
Anaplasma phagocytophilum
Once known as Ehrlichiosis equi, A. phagocytophilum and Human Granulocytic Erhlichiosis (HGE)now share classification as A. phagocytophilum as they are so closely related.
A. phagocytophilum can cause painful arthritis in several joints, lethargy, high fever, loss of appetite, vomiting and diarrhea. Less commonly, a dog may have neck pain or seizures.
Lester, Breitschwerdt, et al. report in this abstract from the Canadian Veterinary Journal that: "Canine anaplasmosis caused by A. phagocytophilum varies from a subclinical infection to an acute febrile condition accompanied by anorexia and lethargy. Central nervous system dysfunction and lameness have also been recorded in dogs. Based on reports to date, anaplasmosis appears to cause a less severe disease in dogs than does infection with E. canis, E. chaffeensis, or E. ewingii. Lethargy, accompanied by fever, appears to be documented consistently, and the lethargy is often disproportionately severe in comparison with the general lack of abnormalities documented on physical examination. Although most dogs have a mild thrombocytopenia, anemia is uncommon and changes in the leukocyte numbers are variable. Elevated ALP activities have been reported in dogs with anaplasmosis. Recent serologic assessments in California indicate that many clinically normal dogs have titers to A. phagocytophilum; this suggests that cases may be subclinical or that the disease may be underdiagnosed."
A. phagocytophilum infects granulocytes, as does E. ewingii, so both may be referred to as canine granulocytic ehrlichiosis or CGE.
The pathogenesis (origin and development) of polyarthritis, observed more often with infection by granulocytic ehrlichiae, arises from hemarthrosis (hemorrhage of blood into a joint) and immune complex deposition into the joints. (Immune complexes are formed by bound-together disease antigens and antibodies produced by the dog.)
Recovering Dogs: Exercise
"When a dog is recovering from a TBD it needs to concentrate its vital forces into the healing/recovery processes and not have those forces diverted by other activities that are stressful. So, its exercise level should be moderated down so it does not exceed the dog's comfort level at that stage.
"Now *comfort level* is different from *tolerance level*. Working to the
tolerance level implies working till the dog begins to flag or to limp or to
the point that the dog feels *stove up* on the following day. Giving this
much exercise is counterproductive because the dog is (a) stressed and
(b) will want to lay about and do nothing for the next day or two...when what we want is regular, consistent, moderate exercise. Staying within the comfort level involves stopping at a point where the dog still has a bit of *go* left, and on the following day feels fit and eager to repeat the
exercise activity.
"Determining the comfort level at any given stage entails judgment and a
small element of trial and error. The basic idea is to start small, work
up gradually, and if you find you have exceeded the comfort level, cut back in subsequent sessions before again increasing by small increments.
"It is really not possible to generalize about how much exercise, how soon, because there is so much individual variation in severity of illness, age, exercise tolerance, etc.
"Perhaps a rule of thumb would be to figure that after a moderately severe episode the dog needs a couple months of serious healing time with only moderate exercise, and then a gradual conditioning program that works up by increments before anything approaching exhaustive exercise is permitted.
"Also be aware that a dog that experiences a really severe TBD episode may not ever be able to tolerate the extremes of exercise that it formerly handled okay.
"That is all pretty vague, but as I said, it depends.....on the illness and
on the dog."
Tom Beckett, DVM
Austin, Texas
This is Calvin.
Janry's Calvin Klein was one of the top 25 agility dogs in 2000. Now, he can no longer walk without a cart due to severe neurological damage from chronic E. equi (Anaplasma phagocytophilum). He has ongoing periods of anemia and thrombocytopenia and has come close to death several times but both Calvin and his owner, Diane, are fighters and neither of them is ready to give an inch in their fight against the disease that has cost him so much but still hasn't managed to take away his joy in life.
On the 20th of May, 2007, this valiant fighter lost his last battle. He went with great dignity, deeply loved.
For anyone who might need a dog cart, there are links to cart manufacturers on the General References page.
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