Ehrlichiosis is a disease caused by the Ehrlichia bacteria, which is spread to your dog through a tick bite. The bacteria infects your dog's white blood cells.

Ehrlichiosis generally progresses through three stages: acute, sub-clinical and chronic.

The first stage, acute, generally occurs about three weeks after your dog has been infected. Your dog will have decreased energy, decreased hunger, a fever and swollen lymph nodes. During this period, the bacteria is multiplying and attaching itself to your dog's white blood cells. Many dogs will be able to rid themselves of the bacteria on their own during this stage. However, if your dog cannot clear the infection, it will then progress to the clinical stage.

The second stage is called the sub-clinical stage, because your dog will not show any symptoms during this period except, perhaps, a slight case of anemia. This is because the bacteria is hiding in your dog's spleen. However, during this time your dog's platelets, used for blood clotting, are being destroyed. Your dog's globulin levels will also be increasing. Globulins are proteins that are activated by the immune system. The sub-clinical stage will generally last for several months before your dog progresses to the chronic stage.

During the chronic stage you will likely notice that your dog has begun to lose weight, his eyes may be inflamed, he may have a fever, and a his legs may be swollen. Other signs can include more anemia, arthritis, joint pain, increased bleeding tendencies and even glomerluonephritis.

Ehrlichiosis is transmitted to your dog via a bite from a tick carrying the bacteria.

Your vet may suspect that your dog is suffering from ehrlichiosis based on your dog’s symptoms and if your dog has been exposed to ticks. Your vet will also take a blood sample to check for low platelet levels, elevated globulin levels and anemia. A blood-smear evaluation may allow your vet to identify the organism itself. However in some cases, the bacteria can be difficult to locate. Your vet can also test your dog to see whether ehrlichiosis antibodies are in your dog's system. Finally, there is a new test called the polymerase chain reaction (PCR) test that enables your vet to look for the ehrlichia organism itself.

Your vet will generally prescribe a tetracycline antibiotic and, perhaps, corticosterioids. If your dog is very sick or weak, your vet may recommend hospitalization.

Putting your dog on an appropriate tick-preventative is the best prevention.

You cannot directly contract ehrlichiosis from your dog.