Table 1. Clinical aspects of disease in 22L or RML scrapie-infected C57BL/10 and tg44+/+ mice.

Clinical Manifestations	C57BL/10	Tg44+/+a
Incubation period (days)	150–160	300–480
Duration of clinical signs (days)	15–25	30–60
Progression of signs	steady	erraticb
Kyphosis	mostc	fewc
Narrow-based tip-toe gait	most	few
Splayed hind legs, wobbly gait	few	most
Low body posture	few	most
Weight loss	all	all
Ungroomed coat	all	all
Hypoactive (late)	all	all
Rear leg clasping response	most	most

^aClinical signs were similar in infected tg44+/+ and tg23+/+ mice infected by IC inoculation with either 22L or RML scrapie strains as described in the methods. End-stage neurological disease in these mice was characterized by profound weakness, hypoactivity and reduced ability to eat or drink, requiring euthanasia. In heterozygous tg44+/− and tg23+/− mice clinical signs were similar, but less severe and more erratic. However, most heterozygous mice developed dermatitis, bladder distention, infection and tumors requiring euthanasia prior to development of end-stage neurological disease.

^bClinical signs were present on an erratic basis initially, but became more consistent and severe over time.

^cMost = 85–100%; few = 0–15%.