Panosteitis In Dogs
Panosteitis is a condition that affects the bones of puppies and young adult dogs, causing intermittent lameness. In affected dogs, the fat within the bone marrow becomes inflamed before breaking down, and eventually being replaced by new bone. Although this does not cause long-term problems, the inflammation and subsequent remodelling is painful in the affected bone.
Panosteitis is seen in young, large-breed dogs, with males more commonly affected than females.
Any large breed can develop Panosteitis, however, German Shepherds are significantly over-represented. The cause is unknown; theories have included viral or bacterial infection and a genetic predisposition, but have not been proven.
The majority of dogs with Panosteitis develop symptoms between 6-18 months of age. Inflammation in the bone causes pain and lameness, which often comes on quickly and can be severe. Most bouts of lameness will resolve in 2-3 weeks, however, it is common for multiple bones to be affected. Typically, this is one after the other, so dogs recover from lameness in one limb but develop lameness in another limb shortly after. Less commonly, different bones in the same limb can be affected, causing a lameness of longer duration. Lameness due to Panosteitis will completely resolve in between episodes, and a continuous mild lameness should raise concern that another cause is present.
Rarely, dogs with Panosteitis can experience inflammation elsewhere. This most commonly presents as a fever and tonsillitis, and can be sufficient to make the dog systemically unwell.
On examination, dogs with Panosteitis will be painful when pressure is applied directly over the affected bone/s. Depending on the dog and the lesion, sometimes firm pressure is required to generate a response, while other times even light pressure can be very uncomfortable. Unlike many other causes of lameness, the joints are not affected so manipulation is usually well tolerated, and there is no visible swelling.
Definitive diagnosis of Panosteitis is achieved with x-rays, however, this can be challenging to achieve. When the bone is inflamed and sore, there are no visible radiographic changes. Instead, it is the subsequent remodelling that leaves a mark, often 2-3 weeks later. This means that taking x-rays of the leg the dog is currently limping on will often show no abnormalities. For animals who have had multiple bouts of lameness already, taking x-rays of legs that were previously lame may demonstrate a characteristic “thumb-print” lesion typical of resolved Panosteitis.
X-rays are, however, very useful to rule out other causes of lameness. The age range for Panosteitis is similar to when developmental conditions such as elbow dysplasia or hip dysplasia present, and it is possible for dogs to have more than one condition at the same time. It is often impossible to differentiate between conditions on examination alone.
