Arthritis and Skeletal Disease in Bears

• Inflammatory and degenerative joint disease in bears
• Spondyloarthrosis
• Vertebral column disease

• Lack of an appropriate level of activity in zoo bears may be associated with the development of skeletal diseases in captive bears. (N18.51.w1, P28.2000.w2)

• Accommodation construction
• Restriction of normal movement

Clinical signs

• Bears with erosion of the articular cartilage would have severe pain, and would have loss of movement, stiffness and difficulties in walking, sitting and rising. (N18.51.w1, P28.2000.w2)
• Severe lameness was noted in an adult female Ursus americanus - American black bear with osteoarthritis of the stifles, tarsi and lumbar spine. (J2.35.w1, P1.2002.w5)
• In one male Ursus maritimus - Polar bear with hip arthritis, it was noted that the bear had not mated the female for several years. (P1.1988.w3)
• Bears with spondyloarthrosis may suffer mild to severe pain. If exostoses result in compression of the spinal cord, locomotion may be impaired. (N18.51.w1, P28.2000.w2)
• In zoo-kept Tremarctos ornatus - Spectacled bears, degenerative changes in joints (coxofemoral, femorotibial and tarsal joints), and thoracolumbar vertebral spondylosis, have been detected radiograpically. (P77.1.w19)

Treatment

• Anti-inflammatory and analgesic drugs such as NSAIDs may be useful. (N18.51.w1, P28.2000.w2)
• Prednisolone, 80 mg on days 1,3,5,7,9 and 40 mg on days 2,4,6,8,10, then reducing to 60 mg on "odd" numbered days and 25 mg on even days, gave clinical improvement of hip arthritis in a male Ursus maritimus - Polar bear; the bear mated with the female for the first time in the nine years that they had been together.  (P1.1988.w3)
• Euthanasia should be considered for elderly bears with severe lesions and which are likely to be, or showing signs of being, in severe pain.
  • A 24-year-old wild born male Ursus maritimus - Polar bear was euthanized due to arthritis and muscular disease. (J54.11.w1)

Prevention

• Comparison with skeletons of wild bears (which generally lack such lesions) and limited data from other large carnivores in zoos, suggests that ensuring an appropriate level of activity in zoo bears may be important to minimise the development of skeletal diseases. (N18.51.w1, P28.2000.w2)

Gross pathology

• A survey of skeletons and postmortem examination data from bears found osteoarthroses of limb bone joints in more than 90% of bears examined. (N18.51.w1, P28.2000.w2)
• Osteophytes also were found on the sacral area of the pelvis or at the hip joint in 75% of bears. 
• In severe cases (more than 40% of bears), erosion of articular cartilage of the head of the femur was found; in some cases severe eburnation was present.N18.51.w1, P28.2000.w2)
• Subacute septic arthritis was found in the acetabulum of a black bear cub secondary to fracture of the ischium. (J1.35.w5)
• A study of captive bear skeletons from three museums in the USA noted a range of degenerative arthritis (osteoarthritis) changes. No arthritis was noted in two skeletons of Ursus americanus - American black bear and only mild changes were noted in the skeleton of a relatively young Ursus americanus - American black bear ,while other black bears showed arthritic changes to the vertebrae as well as the bones of the extremities. Minimal to marked changes were noted in skeletons of four Helarctos malayanus - Sun bear. One Melursus ursinus - Sloth bear showed fusion of a proximal tibio-fibular joint and possibly early arthritic changes of some other bones. Out of 37 skeletons from the American Museum of Natural History, severe changes were found on the skeleton of one Tremarctos ornatus - Spectacled bear, moderate changes on one Ursus dalli (Ursus arctos - Brown bear), one Ursus maritimus - Polar bear, one Euarctos americanus (Ursus americanus - American black bear) and one black bear [probably Ursus americanus], while mild arthritis was noted in one Ursus floridanus (Ursus americanus - American black bear), one Ursus maritimus - Polar bear and one Himalayan bear (Ursus thibetanus - Asiatic black bear). (J429.57.w1)
• A survey of skeletons and postmortem examination data from bears showed that spondyloarthrosis was the most common skeletal pathological change, present in 96% of bears examined. (N18.51.w1, P28.2000.w2)
  • Lesions commonly occurring initially in the lumbar region, then advancing along the vertebral column. 
  • Exostoses (syndesmophytes) extending from the vertebrae and bridging the spaces between vertebrae so that individual vertebrae are fused to one another (ankylosed); this was found in 56% of bears (mainly individuals over 25 years of age).
  • Bone in the centre of vertebrae may be absorbed: this was noted in more than 50% of bears, generally in those with well-developed exostoses. The articular facets of the zygapophyses of the vertebrae may show exostoses.

  (N18.51.w1, P28.2000.w2)

• Examinations of the skeletons of a 30-year old female Helarctos malayanus - Sun bear, another adult female sun bear adult and a (probably aged) female Ursus thibetanus - Asiatic black bear, revealed spondyloarthropathy in all three bears, with nonmarginal syndesmophytes in all three bears, sacroiliac fusion in all bears zygapophyseal joint involvement and in two bears, with fusion on one bear, and smoothly formed ankylosis in one bear. Lesions of osteoarthosis were found also on various long bones. (J423.69.w1)
• Examination of the skeletons of 280 bears from several museums detected erosive disease in 42 animals. No skeletal pathology was found in the 42 immature bears (peripheral epiphyses not closed). In adults, lesions were found in 17.3% of skeletons and in both Ursus arctos - Brown bear and Ursus americanus - American black bear with similar frequencies, and in Melursus ursinus - Sloth bear and Tremarctos ornatus - Spectacled bear. Wrists, stifles, ankles, metatarsal phalangeal, metacarpal phalangeal, elbow, proximal interphalangeal, shoulder and hip joints were affected. The elbow of one Ursus americanus - American black bear and the wrist of one Ursus arctos - Brown bear were fused. In 86 % there was calcification of the annulus fibrosus forming syndesmophytes, zygapophyseal joint fusion and sacroiliac joint fusion; most syndesmophytes were non-marginal and bulky, but marginal syndesmophytes were seen on three bears. (J430.9.w1)
• In zoo-kept Tremarctos ornatus - Spectacled bears, degenerative changes have been found in the coxofemoral, femorotibial and tarsal joints, and spondylosis has been confirmed in thoracolumbar vertebrae. (P77.1.w19)

• History & Documentation
• Physical Examination of Mammals
• Necropsy of Mammals
• Environmental Assessment
• Treatment and Care
• Environmental and Population Management
• Preventative Medicine for Mammals
• Chapter 2 - B36 Field Manual of Wildlife Diseases - Specimen Collection and Preservation
• Chapter 3 - B36 Field Manual of Wildlife Diseases - Specimen shipment
• Appendix A - B36 Field Manual of Wildlife Diseases - Sample specimen history form

• Bears (Ursidae - Bears (Family))
• Helarctos malayanus - Sun bear
• Melursus ursinus - Sloth bear
• Tremarctos ornatus - Spectacled bear
• Ursus americanus - American black bear
• Ursus arctos - Brown bear
• Ursus maritimus - Polar bear
• Ursus thibetanus - Asiatic black bear

List does not contain all other species groups affected by this disease. [N.B. Miscellaneous / Traumatic Diseases tend to be under-reported and the majority are likely to affect all bird and mammal species, given exposure to the related disease agents/factors.]