Ehrlichiosis

Ehrlichiosis is an infection caused by bacteria carried by ticks. These bacteria live inside certain white blood cells and can affect how the immune system functions, sometimes leading to problems with blood cells, clotting, or the body's ability to fight other infections. The condition is seen primarily in dogs that have travelled to or live in regions where specific tick species are found, particularly parts of continental Europe, Africa, Asia, and the Americas. Owners may notice signs that develop weeks to months after a tick bite, though the range is broad. These can include lethargy, reduced appetite, fever, unexplained bruising or nosebleeds, swollen lymph nodes, or joint discomfort. In some cases, signs are subtle or intermittent, and the infection may only be discovered during investigations for other concerns. Some dogs develop long-term effects if the infection persists. This page explores the signs that may prompt consideration of ehrlichiosis, what happens inside the body during infection, how the condition is investigated through blood tests and other means, and the approaches used to address it. The focus is on helping owners understand the shape of the condition and the thinking that guides decisions around it.