Is your dog limping? Does that limp appear to shift from one leg to another? Is your dog under two years of age and a large or giant-sized breed? Then your dog may be suffering from canine panosteitis or eosinophilic panosteitis.

German shepherds, Labrador retrievers, and golden retrievers have a higher incidence of panosteitis. In fact, the German shepherd breed accounts for 75% of the reported cases of panosteitis. More than 2/3 of all cases of panosteitis involve male dogs under the age of two. Young dogs are the most severely affected, but older dogs will occasionally show clinical signs of lameness. The lameness may last from days to weeks and be so severe that the dog does not want to place any weight on the affected leg. The lameness is prone to have periods of remission and exacerbation, and different legs may become affected. The condition is often called a “shifting leg lameness.” Most cases of lameness with panosteitis will resolve by 2 years of age regardless of the treatment used.

In addition to lameness the dog may run an elevated temperature, be anorexic (decrease in appetite), have muscle atrophy, or be lethargic. Upon physical examination, when the long bones are palpated, there may be a pain response elicited. Pain is especially prevalent at the nutrient foramen (where the blood supply enters the bone) when palpated. The ulna and the radius are the most commonly affected bones, followed by the humerus, femur, and tibia, respectively.

A diagnosis of panosteitis is confirmed through radiographic imaging. The earliest bony changes seen on radiographs include an increase in the density of the medulla (bone marrow) in the region of the nutrient foramen. Later there will be accentuation of the trabecular pattern to the bone; this change is most commonly seen at the distal and proximal ends of the diaphysis (long part of the bone). As the condition progresses a mottled or patchy radiodense area will appear in affected areas of the long bones. Finally, the medullary canal will appear normal in opacity but the cortices may remain permanently thickened.

Clinical signs of lameness may precede radiographic signs of disease by up to 10 days; therefore, it is not unusual to have to require repeated radiographs for a diagnosis of panosteitis to be confirmed.

The cause of panosteitis has yet to be conclusively determined. Stress, genetic predisposition, and over-supplementation may all be contributing factors.

Treatment of panosteitis consists of supportive care and pain management. Non-steroidal anti-inflammatory drug (NSAID) therapy is useful to control pain. Activity may need to be restricted and the pet gradually returned to normal activity. It is also important to ensure that the pet is not receiving excessive supplementation with calcium or other minerals, or being fed a diet high in protein.

The prognosis with panosteitis is good to excellent. Most affected dogs will eventually become pain-free and have normal function of the limbs by two years of age. Radiographically there may be some thickening of the cortical bone, and the bones themselves may appear straighter than what is considered normal.

References:

Bahr, Anne. “Reasons for Lameness.” Veterinary Practice News. September 2008. P. 16.

Maxie, M. Grant, Ed. Pathology of Domestic Animals. Vol.1. Saunders 2007. Pp. 104-105.

Wehrenberg, Aaron, and A.D. Elkins. “Juvenile Orthopedics.” Veterinary Forum. September 2006. P. 22.