section content

  • An orphaned, free ranging, approximately 10- to 11-month-old female American black bear (Ursus americanus) cub from northwestern Washington was admitted to the Progressive Animal Welfare Society (PAWS) for rehabilitation.
  • Physical examination revealed: appropriate body condition, scabbing with alopecia over the muzzle, a healed wound over the left side of the muzzle, pronounced brachygnathism, a missing left mandibular canine, adult incisors present with otherwise deciduous dentition.
  • Other notable findings included: significant palpable and visible skeletal deformities including bilateral angular limb deformities of the carpi, shortened forelimbs, and bowed and shortened hindlimbs.
  • CBC and Chemistry panels revealed adequate to mildly increased platelets (considered possibly reactive) but no other significant abnormalities.
  • A thyroid panel was also performed with the following results: total T4 1.1 ug/dL, free T4 2.9 ng/dL, TSH <0.03 ng/mL.

 

Lateral skull

Ventrodorsal skull

Lateral thorax

Ventrodorsal thorax

Lateral pelvis

Ventrodorsal pelvis

  • Generalized mild decrease in bone density
  • Generalized long-bone shortening, widened physes (and suspected delayed closure), thickened metaphyses and shortened and flattened epiphyses
  • Smooth periosteal reaction on many of the long bones
  • Shortened vertebrae when compared to bears of similar age
  • Cranial bowing of the radii, ulnae and tibiae and developing angular limb deformities
  • Mediastinal shift to the right
  • Alveolar pattern right lung lobes

 

  • Some form or manifestation of osteochondral dysplasia or dwarfism affecting all four limbs similarly
  • Atelectasis of the right lung lobes with mediastinal shift likely secondary to anesthesia; bronchopneumonia cannot be ruled out but considered less likely given absence of clinical signs and correlated lab work

 

  • This bear was euthanized due to both welfare and population health concerns. Initially congenital hypothyroidism was considered one of the possibilities for this cub. Previously reported cases of congenital hypothyroidism have been reported in bears (Duncan et al., 2002).
  • Thyroid hormone concentrations in black bears may not be as well understood as in other species such as canines. Additionally, there have been studies looking at the effects of hibernation and pregnancy on thyroid hormone concentrations in black bears (Tomasi et al. 1998). The laboratory results we were able to obtain for this bear did not seem to support congenital hypothyroidism. Due to funding concerns and lack of saved samples, additional thyroid testing and testing for other causes of dwarfism such as secondary to lysosomal storage diseases were not performed. Nutritional secondary hyperparathyroidism was discussed as a possible cause for the abnormalities seen for this bear but was considered less likely.
  • We would welcome any feedback on this patient as this was an unusual case.

 

  • Duncan RB, Jones JC, Moll D, Moon MM, Blodgett DJ, Vaughan MR. Cretinism in a North American black bear (Ursus americanus). Vet Radiol Ultrasound 2002; 43:31-36. DOI:10.1111/j.1740-8261.2002.tb00439.x
  • Tomosi TE, Hellgren EC, Tucker TJ. Thyroid hormone concentrations in black bears (Ursus americanus): hibernation and pregnancy effects. Gen Comp Endocrinol 1998; Feb;109(2):192-9.