Canine Ehrlichiosis

Canine ehrlichiosis is an infectious contagious disease, also known by the following names: Canine Typhus, canine hemorrhagic fever, canine pancytopenia or tracker dog disease. The last name on this list is due to the propensity of dogs to become bitten while running outside, potentially tracking animals or people in spaces where these ticks reside. The so-called brown dog tick or kennel tick (Rhipicephalus sanguineus) is the culprit, although this tick can also infect other animals.

The tick is a carrier of a bacterium called Erlichia canis, formerly called Rickettsia canis. When they bite the dog, they pass the bacteria into the blood stream of the dog, affecting their immune system and depleting white blood cells.

Part of the problem is that these ticks are opportunistic. This means after they bite the dog, they can and will jump to nearby dogs and other animals. There have been some cases of Erlichia canis being zoonotic (able to be passed on to humans), but they are rare. However, this does not mean they cannot pass on other diseases such as babeosis which is indeed zoonotic.

Any dog regardless of age or sex can be infected with canine ehrliciosis. However, there are studies which indicate the German Shepherd breed is particularly susceptible to infection.

Canine ehrlichiosis symptoms depend on the form which the disease manifests itself. These forms are either acute, subclinical or chronic.

Acute phase

The acute phase occurs after the incubation period. The incubation period is the time between the pathogen entering the body and when the symptoms begin to appear. This usually lasts around 8 to 20 days, after which time the acute phase begins. During the acute phase, the bacteria thrive inside the cells mainly affecting the liver, spleen and lymph nodes. This phase commonly lasts between 2 and 4 weeks.

At this stage the dog with canine ehrlichiosis may exhibit the following symptoms:

• Fever
• Depression
• Lethargy
• Anorexia
• Bleeding
• Eye injury: uveitis, bleeding, etc.
• Respiratory problems

Sometimes there may be neurological symptoms of canine ehrlichiosis as a consequence of meningitis. This happens because the cells affected by bacteria are taken to various parts of the dog's body, including the meninges. The result may be intense tremors, ataxia and other neurological signs.

Subclinical phase

In this second phase, the symptoms are not evident and usually lasts between 6 and 9 weeks approximately. That is, at this stage, you will not be able to observe any kind of symptoms in the dog. However, there are changes the blood level and can be detected by your veterinarian: thrombocytopenia, leukopenia and anemia.

The chronic phase

If the dog's immune system works properly, they can become a chronic carrier without exhibiting symptoms. However, if the dog has symptoms of the disease, these will be similar to those of the acute phase but much more serious. You can see the dog with the following symptoms:

• Apathy
• Cachexia
• Secondary infections
• Weight loss
• Bleeding
• Pale mucous membranes

Only a veterinarian can make a correct diagnosis of canine ehrlichiosis. The diagnosis of this disease is not always straight forward as many symptoms are shared with other diseases. If your dog has been bitten by a tick and they begin to exhibit symptoms then you need to take them to your veterinarian. After doing a complete physical examination and investigating the dog's medical history (a process known as anamnesis), they will order blood tests to achieve an accurate diagnosis.

The main method of diagnosis is called a blood film or peripheral blood smear. With this method the veterinarian takes a drop of blood and examines it under the microscope. In doing so they can confirm the presence of Erlichia kennels. This method is the most economical and fast, but not always the most effective. This is because the bacteria circulate around the blood stream, but it progresses in different ways. It is possible to take a blood sample which is unaffected, but there is infection in other parts of the body. For this reason, a vet may choose other diagnostic tools if the bacterium is not detected in the blood stream. These may include polymerase chain reaction (PCR) or an indirect immunofluorescence (IFI).

Image: researchgate.net

For decades it was believed that canine ehrlichiosis was a ‘species specific’ disease, meaning it could only be transmitted to the same species. However, several strains of Ehrlichia (the genus of the bacteria) have been found in humans, but the research is relatively scant. What is known is that areas with high-prevalence of tick-borne diseases need to be more suspect in possible cases.

The zoonotic potential, i.e. the likelihood of being passed on to humans, depends on the country of occurrence. in Conneticut USA, canine ehrlichiosis had been reported on since 1963, but the first record potential of it being passed on to humans wasn't until 1988^[1]. However, the chances of getting this disease from a dog infected by a tick are sill very small. In South American countries such as Brazil and Venezuela^[2], the probability is unfortunately higher.

Canine ehrlichiosis treatment depends on the stage of the disease at which the dog is given the diagnosis. The main treatment, especially in the chronic phase, is supportive treatment. This is when the veterinarian uses fluid therapy and may even need to make blood transfusions to compensate for hemorrhaging of the dog.

Combined with other treatment, the vet may administer different drugs to fight ehrlichiosis. These mainly include antibiotics like doxycycline. Additionally, provision should be made for treatments associated symptoms presented.

While canine ehrlichiosis can indeed be treated, it can also be fatal after it enters the chronic stage. It is possible for dogs who become infected to fight the disease off during the subclinical phase. It is also possible for the dog to have the disease for the rest of their lives, yet remain asymptomatic. However, they will still be carriers and can pass it on to others.

The main way to combat this disease, as with almost any other, is prevention. There is no vaccine against ehrlichiosis and the only way to prevent it is to engage the correct protocol when your dog is at risk of exposure to ticks. This should include:

• Keeping your dog out of long grass or brush, especially in places where tick presence is likely.
• Check your dog for ticks after a walk.
• Remove a tick immediately if you find one.
• Remove features in your yard where ticks may be likely to stay.

If you adopt a new puppy, it is important to keep separate from other dogs until they are adequately dewormed and vaccinated. This is why quarantine in kennels is so important. Ticks spreading in kennels is one of the most common ways for this disease to spread.

This article is purely informative. AnimalWised does not have the authority to prescribe any veterinary treatment or create a diagnosis. We invite you to take your pet to the veterinarian if they are suffering from any condition or pain.

If you want to read similar articles to Canine Ehrlichiosis, we recommend you visit our Parasitic diseases category.