Canine panosteitis is a disease that affects only large or giant breeds, most often the German shepherd, although it has been reported in the bassett hound, Scottish terrier, Great Dane, St. Bernard, Doberman pinscher, German shorthaired pointer, Irish setter, Airedale, golden retriever, Labrador retriever, Samoyed, and miniature schnauzer.
(1,4,9,10,12,14,17) Males are affected more commonly than females
(1,5,10) (reported range 67%
(6) to 84%
(10)). The disease cycle in the long bones of males is more predictable and repeatable. The female usually has her first episode in association with her first estrus.
(20)
The average age at presentation is 5 to 12 months,
(4-6,10,22,24) although German shepherds have been documented to have the disease as young as 2 months of age and as old as 5 years.
(4) In one study, 20% of the animals were 18 months old at initial presentation.
(4) The initial presenting complaint is usually an acute onset of lameness persisting for 2 to 14 days
(1,4,20) with no current history of trauma. The disease begins in the bones of the forelegs, with the ulna being affected most often (42%), followed by the radius (25%), humerus (14%), femur (11%), and tibia (8%). The severity of these attacks becomes reduced and the interval between successive episodes increased with advancing age.
(22) The degree of lameness usually increases during the first few days of an attack, remaining unaffected by either rest or exercise.
(5) Periods of lameness are often accompanied by anorexia and lethargy. There may be a spontaneous regression of signs within 3 to 4 days with or without therapy,
(22,23) however, more commonly the lameness is noted to shift from one limb to another every 2 to 3 weeks,
(2,9,23) with occasional lapses of one month between episodes.4 In general, the pattern is from front limb to hind limb to recur again in the forelimb.
(20) Recurrence of the disease in a previously affected bone is seemingly rare;
(2,22) however, in chronic cases the repeated occurrence of lesions can be found in the radius, followed by the ulna, with fewer repeats in the humerus and femur. The length of the cycle of disease is 90 days, but in some cases it extends to 160 to 190 days.
(5,24) The interval between each skeletal cycle is 160 to 180 days. In one study, 53 of 100 dogs manifested multiple bone involvement, while 49 of 100 dogs showed multiple limb involvement on initial presentation.
(4) As many as seven bones in various stages of disease have been observed to be affected during an episode in one dog. Clinical signs persist on an average of 2 to 9 months,
(5,24) with the disease generally disappearing when the dog reaches 18 to 20 months of age.
...There is, however, pain upon firm palpation of the diaphyses of affected long bones; the pain is believed by some to be directly proportional to the amount of periosteal reaction present.
(10) The degree of pain manifested clinically may range from slight to exquisite, with lameness being minimal to nonweight-bearing in severity. Since the pathologic bone formation occurs haphazardly in both time and location, multiple bones of the same limb or multiple limbs may be affected simultaneously; also, different phases of the disease may be occurring concurrently in any given animal.
(4,11) Radiography is generally necessary to distinguish panosteitis from other disease conditions; however, the radiographic changes in early and late phases are subtle and far less distinct than those of mid-disease. It is generally rewarding to radiograph multiple long bones in an attempt to reveal more pronounced lesions.
(4) It is important to realize, however, that generally there is no distinct relationship between the severity of radiologic changes, the amount of pain elicited on palpation, and the degree of lameness the animal manifests clinically
(4,5,22)
