Canine monocytic ehrlichiosis, referred to as ehrlichiosis [pronounced ur·luh·kee·ow·suhs], can be caused when a dog is bitten by a tick carrying the Ehrlichia canis bacterium. This bacterium is generally carried by the brown-dog tick, a species of tick which can also spread a variation of the disease anaplasmosis.
In the U.S., canine ehrlichiosis cases have been reported in all 50 states. The Companion Animal Parasite Council has interactive maps showing how cases are distributed across the U.S. and Canada.
Signs and Symptoms of Ehrlichiosis in Dogs
Ehrlichiosis in dogs has three main stages, including the acute, sub-clinical, and clinical or chronic stages.
This stage can appear several weeks or months after being bitten by a tick. Dogs in the acute phase may have:
Discharge from eyes and nose
Bruising on the gums and belly
Or dogs in the acute stage may show no symptoms at all. This stage often lasts two to four weeks, after which your dog may eliminate the ehrlichiosis infection or may progress to the sub-clinical stage.
This is the stage in which the bacterium is present but not showing outside signs of the disease. Dogs can go through the acute stage without symptoms and then progress further into the sub-clinical stage still not showing symptoms. A dog may eliminate ehrlichiosis at this stage or progress to the clinical stage.
Clinical or Chronic Stage
This stage occurs when the dog does not eliminate the infection through the first two stages and can develop serious long-term problems such as anemia, bleeding, lameness, blindness, neurological problems, swollen limbs, or (rarely) even death due to complications from the condition. A dog may eliminate ehrlichiosis after being treated at this stage. If the disease isn't eliminated, dogs can continue to cycle through the three stages more than once.
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Testing and Diagnosing Ehrlichiosis in Dogs
You should test your dog for ehrlichiosis:
If she displays any of the symptoms above.
If you suspect she's been bitten by a tick. It can take weeks or months for ehrlichiosis to register on tests. If your dog has been bitten by a tick, check with your veterinarian to see when to get a test.
Annually, in consultation with your veterinarian, especially in areas where ticks are prevalent.
Most veterinary clinics have an in-house blood test that can quickly test your dog for ehrlichiosis. These blood tests may also test for heartworm and the tick diseases Lyme disease and anaplasmosis, so your veterinarian may refer to it as a "four-way test."
If your dog tests positive for ehrlichiosis, whether she is symptomatic or not, your veterinarian will generally want to do more thorough testing including a PCR (Polymerase Chain Reaction) test, a blood test, and urinalysis, according to Anya T., LVT and claims adjuster at Embrace Pet Insurance.
Ehrlichiosis Treatment for Dogs
Like any bacterial infection, ehrlichiosis is treated with antibiotics. Dogs with ehrlichiosis generally need treatment with the antibiotic doxycycline for at least four weeks, Anya says.
Dogs experiencing significant bleeding or anemia with ehrlichiosis may require a blood transfusion in addition to antibiotics. They may also require steroids or other medications depending on their symptoms.
Is Ehrlichiosis in Dogs Contagious?
Ehrlichiosis is not contagious. Your dog can't get ehrlichiosis from another infected animal and can't give it directly to you. The only way for people, dogs, or other animals to get ehrlichiosis is through a tick bite. However, if your dog does get ehrlichiosis, you may have also been exposed to ticks carrying the organism and should watch for ticks or signs of disease in you and your family.
While ehrlichiosis in dogs is caused by the Ehrlichia canis bacteria, human ehrlichiosis is caused by the bacteria Ehrlichia chaffeensis, E. ewingii, or E. muris eauclairensis in the United States according to the CDC.
Preventing Ehrlichiosis in Dogs
The American Veterinary Medicine Association recommends keeping your dog on a year-round flea and tick prevention medication. Ticks can be active in temperatures as low as 40 degrees Fahrenheit, so your dog isn't necessarily safe in winter. In fact, Embrace Pet Insurance receives the most ehrlichiosis claims in October, November, and December. You should continue flea- and tick-preventive efforts year-round.
There are a variety of flea tick preventive medications on the market, including topical medications, oral medications, and collars. Not all flea and tick preventive measures protect against all types of ticks, so discuss the best fit for your dog with your veterinarian.
Ticks can transmit ehrlichiosis within three to six hours of attaching to your dog. They most commonly hang out in the woods and tall grass, so if you take your dog on a walk in one of these areas, check for ticks as soon as you get home and remove the tick promptly if you find one. Keep your lawn mowed short to discourage these pesky parasites from coming into your yard.
"If you live in an area high in ticks, you should probably check your dog—and yourself—for ticks daily," Anya says. "My border collie Kit had ehrlichiosis a few years ago, even though he's on preventive medication and I check him regularly. I found a tick on him, then a few weeks later he became lethargic and had a fever, so I had my vet run tests. We treated him with doxycycline for four weeks. Now I have him tested every six months, and he continues to test negative after the treatment.
"Tick diseases are becoming more common, so I encourage everyone to be vigilant."