Ehrlichiosis in Dogs: From Symptoms to Prevention

With ticks becoming more prevalent, it is important to understand the risks and diseases they can transmit to our dogs. One such disease is ehrlichiosis, a tick-borne infection that can have serious consequences if left untreated. Ehrlichiosis in dogs is a tick-borne disease caused by the bacteria Ehrlichia canis, which is primarily transmitted through the brown dog tick. Early diagnosis and treatment are key to ensuring a healthy dog and preventing the disease from progressing to more severe stages. In this comprehensive guide, we'll cover everything you need to know about ehrlichiosis in dogs, from symptoms and diagnosis to treatment options and prevention strategies.

What is ehrlichiosis in dogs?

Ehrlichiosis is an infectious disease in dogs caused primarily by the bacteria Ehrlichia canis which is the result of a tick bite. This tick-borne illness is part of a group of diseases collectively known as vector-borne diseases in dogs. While there are multiple species of Ehrlichia responsible for ehrlichiosis in dogs, Ehrlichia canis is the most common culprit.

The disease manifests in different forms, often categorized into acute, subclinical, and chronic phases. Each phase presents its own set of clinical signs, making it important for dog owners to recognize the symptoms in dogs for early diagnosis and treatment.

How do dogs become infected with Ehrlichia?

Ehrlichiosis is primarily transmitted through the bite of an infected tick, specifically the brown dog tick (Rhipicephalus sanguineus). This makes Ehrlichiosis a tick-borne infectious disease that can affect many dogs, especially those who spend a lot of time outdoors.

The transmission of Ehrlichia canis, the bacteria most commonly responsible for Ehrlichiosis in dogs, usually requires several hours of tick attachment. This means that prompt and proper removal of ticks can significantly reduce the risk of infection in dogs.

Infections have been documented worldwide, with the highest prevalence observed in the Southwest and Southeast regions of the United States.

It's important to note that while dogs and people often come into contact with the same species of tick, direct transmission of the disease from dogs to humans is rare. Nonetheless, awareness of tick species and their habitats can help you keep your dog, and by extension, your family, safe from this disease.

Clinical signs and symptoms of ehrlichiosis

Ehrlichiosis in dogs can cause a wide range of clinical signs, which vary depending on the phase of the disease.

Acute phase

The acute phase of canine ehrlichiosis usually develops 1-3 weeks after a tick bite and lasts for 2-4 weeks. During this stage, your dog may exhibit symptoms such as fever, lethargy, swollen lymph nodes, and loss of appetite (anorexia). You may also notice enlarged lymph nodes and signs of thrombocytopenia, a condition characterized by a low platelet count, which can lead to bruising and bleeding tendencies.

Subclinical phase

During the subclinical phase, dogs may not show any obvious signs of illness. The bacteria may stay hidden in the spleen, avoiding the body's immune system. This phase can last for months or even years. Some dogs recover on their own, while others may develop into a chronic form of ehrlichiosis.

Chronic phase

The chronic phase of ehrlichiosis can range from mild to severe and can be life-threatening if not treated promptly. Symptoms in dogs during this phase include lethargy, weight loss, swollen limbs, uveitis and retinal hemorrhages, kidney disease, and a reduction in both red and white blood cell counts. German Shepherds are more susceptible to the severe, chronic form of ehrlichiosis.

How is ehrlichiosis diagnosed in dogs?

Diagnosing ehrlichiosis in dogs involves a multi-step approach that combines physical examination findings, history, and various diagnostic tests.

During the physical examination, your veterinarian will look for signs that may indicate ehrlichiosis. Dogs may have a history of tick bites and could show transient signs in the acute phase that may go unnoticed. In the subclinical phase, dogs typically appear clinically healthy. However, symptoms like inappetence, weight loss, and lethargy may be reported. Physical abnormalities such as swollen lymph nodes, enlarged spleen, and other symptoms like vomiting, diarrhea, and fever could also be present. Ocular and neurological abnormalities may also be present on the physical exam.

Next, your veterinarian will likely recommend blood testing to confirm the presence of Ehrlichia canis in your dog's system. A complete blood count (CBC) and serum biochemistry profile will be performed to assess your dog's overall health, look for signs of anemia or low platelet counts, and check organ function.

To check for Ehrlichia antibodies in your dog's blood, your veterinarian may recommend the 4Dx test, also known as the SNAP 4Dx test. This test is readily available with very quick results. Its downside is that it does not check for an active infection, only previous exposure.

When determining if there is an active infection, there are specific tests that can detect the presence of Ehrlichia in your dog's blood. These include a direct immunofluorescence assay (IFA) and a polymerase chain reaction (PCR) test.

Treatment options for ehrlichiosis

Effective treatment for Ehrlichiosis in dogs involves a multi-faceted approach that includes antibiotics, supportive care, and monitoring. Here are the key components:

Antibiotics

Doxycycline is the treatment of choice for ehrlichiosis, effective against Ehrlichia canis and other species responsible for the disease. The typical course involves several weeks to months of treatment, depending on the severity and phase of the disease.

Supportive care

In severe cases, especially those in the chronic phase, additional supportive treatments may be necessary. This can include blood transfusions for dogs with severe anemia or thrombocytopenia, and fluid therapy for dehydration.

Monitoring and follow-up

Regular follow-up visits to your veterinarian are important for monitoring the effectiveness of the treatment. Blood tests, including complete blood counts and biochemistry profiles, are often repeated to assess response to treatment.

What is the prognosis for dogs with ehrlichiosis?

The prognosis for dogs with ehrlichiosis varies depending on several factors, including the phase of the disease, the timeliness of diagnosis, and the effectiveness of treatment.

Dogs diagnosed in the acute phase generally have a good prognosis, especially when treatment with antibiotics like doxycycline is initiated promptly. Most dogs respond well to treatment and recover without long-term complications. Cure rates are as high as 95% in the acute phase.

During the chronic phase, dogs may encounter various difficulties that can affect their prognosis. One common complication is pancytopenia, which occurs when the bone marrow doesn't generate enough blood cells. In such cases, more aggressive treatments like blood transfusions may be necessary. It's important to note that the prognosis during this phase can range from guarded to poor, particularly in susceptible breeds such as German Shepherds.

Preventative strategies

When it comes to preventing ehrlichiosis in dogs, tick control and regular testing are your best lines of defense. Using a veterinarian-approved tick preventative can greatly reduce the chance of a tick spreading Ehrlichia bacteria to your dog. It's also essential to check your dog regularly for ticks, especially after being outdoors in wooded or grassy areas.

Secondly, we recommend performing an annual 4Dx test to test for Ehrlichia exposure. This can detect the infection in its early stages and allow for quick treatment.

In conclusion, ehrlichiosis is a serious and potentially life-threatening tick-borne disease that affects dogs. Key signs of the disease can range from mild to severe, including lethargy, weight loss, swollen limbs, and ocular and neurological abnormalities. Diagnosis requires a multi-step approach involving physical examination, history, and several diagnostic tests, including blood tests and the 4DX test. Treatment of ehrlichiosis involves a combination of antibiotics such as doxycycline, supportive care, and continuous monitoring. The prognosis of the disease varies based on its phase, with dogs diagnosed in the acute phase having a significantly better prognosis than those in the chronic phase. Prevention of ehrlichiosis heavily relies on tick control and regular testing, which proves to be the most effective strategy to keep your dog safe from this disease.

If you have any questions or concerns about ehrlichiosis affecting your dog, please contact your veterinarian for specialized and individualized advice.