| Disorder |
Age of affected pigs |
Cause |
Lesion distribution |
Gross features |
Histopathology |
| Osteoporosis (Doige 1982, Craig et al. 2016) |
Growing and adult pigs |
Cu/Ca deficiency, starvation, vitamin A toxicity, increased stress |
Vertebrae, ribs, long bones, flat bones of the skull |
Reduced breaking strength of ribs. Marked depletion of cancellous bone in the metaphyses and epiphyses. Reduced cortex thickness |
Bone trabeculae decreased in thickness and number, disconnected, “free-floating trabeculae”, increased porosity of the cortical bone due to enlargement of Haversian canal, low level of osteoblastic activity |
| Fibrous osteodystrophy (Thompson & Robinson 1989) |
Growing and adult pigs |
Ca and vitamin D deficiency, excess P |
Skull bones, especially mandibles and maxilla. Also, scapula and vertebral column |
Bilateral enlargement of the bones of the skull, movable teeth, jaw swelling. Soft, pumice-like bones, and decrease in bone density. Ribs may bend or snap with little effort |
Increased osteoclastic bone resorption, marked fibroplasia, and increased osteoblastic activity with formation of immature woven bone, frequently poorly mineralized |
| Rickets (Pepper et al. 1978, Dittmer & Thompson 2011, Madson et al. 2012, Gris et al. 2020) |
Growing pigs |
Deficiency of Ca, P, vitamin D. Ca/P imbalance |
Sites of rapid growth, metaphyseal and epiphyseal regions of long bones, and costochondral junctions of the large middle ribs |
Weak bones that bend before breaking with a weak snap and have enlarged growth plates, giving a clinical appearance of swollen joints, increased volume of costochondral joints (rachitic rosary), kyphosis |
Decreased mineralization of the growing bone, evident persistence of hypertrophic chondrocytes at sites of endochondral ossification |
| Osteomalacia (Craig et al. 2016) |
Late finishing and adult pigs |
Deficiency of Ca, P, vitamin D. Ca/P imbalance |
Vertebrae, femur, pelvis, and ribs |
Bones with reduced resistance to pressure and tension. In severe cases the marrow cavity is expanded, the cortex is thin, spongy, and soft |
Decreased mineralization with the significant remodeling of the mature bone. Localized accumulation of osteoid at sites of mechanical stress |