In the southern United States, I. scapularis larvae and nymphs feed primarily on lizards, which do not maintain infection with B. burgdoferi. Consequently, nymphal and adult infection rates are low, often less than one percent. In contrast to human cases of Lyme disease, where three different stages are well known, disease in dogs is primarily an acute or subacute arthritis. The acute form may be transient and may recur in some cases. The devastating chronic stage in humans with systemic disease has rarely been seen in dogs.
Dogs show sudden lameness and sometimes signs of severe pain.
One or more joints may be involved. Joints are often swollen, hot and painful on manipulation. Dogs may have fever and be off-feed and lethargic. Some become severely depressed and are reluctant to move. Lameness may recur after a period of recovery lasting several weeks.