Ehrlichiosis in Dogs: A Tick-Borne Disease and How to Prevent It

How it spreads

The main carrier is the brown dog tick. This tick feeds mostly on dogs and does well in warm weather. Unlike most ticks, it can complete its whole life cycle indoors, in homes and kennels. In warm climates it also lives outdoors.

A tick picks up the bacterium when it feeds on an infected dog. It can then pass it to the next dog it bites. In studies, transmission started within a few hours of the tick attaching, so fast tick control matters. The infection can also pass through a blood transfusion from an infected donor.

The disease is established in all the European countries around the Mediterranean. Surveys have found antibodies against Ehrlichia canis in dogs in Bulgaria, Serbia, North Macedonia, and Greece. Some surveys suggest it may be spreading to countries farther north. Cases are also found there in dogs that traveled to the south or were adopted from it.

The three stages

Signs usually appear one to three weeks after an infected tick bite. The disease then tends to move through three stages.

The acute stage lasts about two to four weeks. Dogs may have a fever, low energy, and a poor appetite. Lymph nodes can swell. Blood tests often show a low platelet count. Platelets help blood clot, so some dogs bleed more easily. Many dogs seem to get better after this stage, even without treatment.

In the subclinical stage the dog looks healthy. This stage can last months or years. The bacterium may still be in the body, and blood tests may show mildly low platelets. Some dogs clear the infection. Others stay infected without showing signs.

Some dogs then move to the chronic stage, which is the most serious form. The bone marrow may stop making enough blood cells. The immune reaction to the infection can also harm the eyes, kidneys, joints, and nerves. German Shepherds seem to develop the chronic form more often than other breeds. Vets cannot always tell which dogs will progress, so a positive test is worth following up.

Signs to watch for

Signs vary a lot from dog to dog, and many are vague at first. Owners may notice the following.

• Fever, tiredness, and less interest in food
• Swollen lymph nodes, which you may feel under the jaw or behind the knees
• Nosebleeds
• Small red dots or bruises on the gums, belly, or skin
• Blood in the urine, or black, tarry stool
• Pale gums and weakness
• Weight loss over weeks or months
• Stiffness, reluctance to walk, or lameness
• Eye changes such as redness, cloudiness, bleeding inside the eye, or poor vision
• Poor coordination or other signs involving the nerves
• Long or heavy bleeding during a heat cycle

These signs overlap with many other illnesses, including other tick-borne infections. Your vet can help find the cause.

When it is an emergency

Contact a vet right away, or go to an emergency clinic, if your dog has a nosebleed that will not stop, pale or white gums, black stool, blood in the urine, sudden weakness or collapse, trouble breathing, or sudden loss of vision. These can be signs of serious bleeding or very low blood counts. Dogs in this state may need hospital care.

How vets diagnose and treat it

Diagnosis usually starts with a complete blood count. A low platelet count is the most common finding and often makes a vet think of a tick-borne disease. Mild anemia and high protein levels in the blood are also common.

The next step is usually an antibody test. Some are quick tests done in the clinic, and others go to a lab. A PCR test looks for the genetic material of the bacterium and can show an active infection. The organism is rarely seen under the microscope, so a normal blood smear does not rule it out. Antibodies usually take about two weeks to appear after infection, so a very early test can be negative. In that case your vet may repeat the test two to four weeks later.

Dogs from the same regions may carry more than one infection spread by ticks or sand flies. Your vet may also test for Anaplasma, Babesia, Hepatozoon, or Leishmania.

Treatment is a course of an antibiotic from the tetracycline family, usually given for about four weeks. Shorter courses may leave some dogs still infected. In the acute stage, fever often improves within one to two days, and blood counts usually recover over the next two weeks or so. Dogs with severe bleeding or very low blood counts may need hospital care, fluids, or blood transfusions.

The outlook is good for dogs treated in the acute stage. In the chronic stage it is more serious, and it is poor when the bone marrow has stopped working well. In dogs that do respond, blood counts can take months to recover. Your vet may suggest follow-up tests after treatment, such as a repeat blood count or PCR test.

What a positive test means for an adopted dog

A positive antibody test means the dog was exposed to Ehrlichia at some point. It does not always mean the dog is sick now. Antibodies can stay in the blood for months or years, even after the infection has cleared or been treated.

For a healthy dog with a positive test, vets usually look at the full picture. This may include a blood count with platelet numbers, a urine test for protein, a PCR test, and checks for other infections. Vets do not all agree on treating healthy dogs that only have antibodies. Your vet will recommend whether to treat now or to monitor with repeat blood tests.

Recovery does not give lasting protection. A dog can be infected again, so tick control continues after treatment.

At Paw Squadron, the first stops after every rescue are the vet and a bath. Each animal gets a checkup, deworming, and treatment against fleas and other parasites. Before adoption, every animal also receives treatment, vaccinations, and a microchip. When your new dog arrives, bring its records to your own vet. Ask which tests for tick-borne diseases make sense for your dog and the region it came from.

Prevention

There is no vaccine against ehrlichiosis. Prevention depends on keeping ticks off your dog and removing them quickly. For step-by-step removal, see the guide to ticks on dogs and cats.

• Use a tick product your vet recommends, and ask how often to use it where you live. Products that repel ticks or kill them quickly give the best protection, though no product stops every tick.
• Check your dog every day after walks. Look around the ears, head, neck, armpits, and between the toes.
• Remove ticks promptly with fine-tipped tweezers or a tick removal tool. Grasp the tick close to the skin and pull it straight out with steady pressure.
• Keep every dog in the household on tick control, since ticks can pass from one dog to another.
• Check a newly arrived dog carefully. A dog coming from a warm region can bring brown dog ticks into the home.
• If brown dog ticks are living in your home or kennel, treat the dogs and the space. These ticks hide in cracks, behind furniture, and under rugs. A pest control service can help.
• Ask your vet about extra protection before you travel with your dog to Southern Europe.

Other pets and people

Ehrlichiosis spreads through ticks and, rarely, through blood transfusions. Normal contact between dogs, such as play or shared bowls, is not a known route. If one dog in your home tests positive, ask your vet whether your other dogs should be checked.

Ehrlichia canis is not considered a major risk to people. A few human infections have been reported, mainly in Venezuela. Petting or caring for an infected dog is not a known way to catch it. Ticks can bite people too, so check yourself for ticks after time outdoors in areas where they live.

To learn about other conditions that are common in rescued dogs, browse the PawPedia library. If you are thinking of adopting, the Adoptions page is the place to start.