These epidermal parasites are found in nearly every country in the world. Their importance as agents and vectors of disease has long been recognized. Pathogenesis appears in several ways including anemia, dermatosis, paralysis and infections. Ticks transmit viruses, bacteria, protozoa, filaria, richettsias and spirochettes.

After a blood meal that engorges the female tick, she drops to the ground and lays thousands of eggs in the soil. The eggs develop, hatch and the larva climb low vegetation to look for a host. Ticks do not jump or fly. They wait on vegetation for an animal to brush against them. Usually small mammals like mice are the host for these juvenile stages. The larvae feed and molt to become nymphs that will develop and molt to become an adults. The adults, once on the host (a larger mammal), climb upward looking for a place to attach. They will generally choose a high point on the host or choose a tight place, like between the skin and an elastic waist band or collar, to attach and begin feeding.

Most ticks are opportunists and will feed on any suitable host. Ixodes scapularis is the blacklegged tick and can be a major pest on dogs, particulary in the eastern and south-central US. It will bite humans and often produces pain at the site and a short-lived general malaise. Lyme disease is also transmitted by the blacklegged tick.

Ixodes pacifica is found along the west coast on deer and cattle but will bite humans. Dermacentor andersoni is the vector of several diseases of humans including tick paralysis, Colorado tick fever, tularemia and Rocky Mountain spotted fever. The American dog tick,, D. variabilis, is common throughout the US and is the chief vector of Rocky Mountain spotted fever in the central and eastern US. This tick also causes paralysis in dogs and humans when bites occur on the neck due to toxic substances secreted by the tick. Rhipicephalus sanguineus, the brown dog tick, is widely distributed in most all countires. It likes dogs but will bite humans as well.
 

Tick Removal & Control
There are numerous products for veterinary use that prevent infestations of pets. Insecticides can be used to treat yards and humans before going into the woods. Visually checking for ticks is a good preventative measure upon returning from wooded or tall grassy areas.

Remove any ticks you might find on your body as quickly as possible. Do not give them a chance to bury their mouthparts deeper into the skin. Use tweezers to grasp the head close to the skin and pull it out firmly. Do not use other folk methods that may traumatize the tick and cause it to spit up the contents of its gut. Disinfect the wound afterward.

Avoidance of tall grassy or shrubby areas will prevent you from coming in contact with most ticks but this is not always practical. Wearing light colored clothing will help in finding the ticks before they attach. Mowing weeds or grass will help to dry out the soil and therefore kill the ticks as they require humidity. Repellants made of permethrin (Permanone®) or DEET (Cutter®, Off®)can be applied to clothing and skin or yard insecticides (Sevin®, Dursban®, diazinon, etc) can be applied to suspect areas. Care must be taken as these are poisons. Read the directions and cautions on the label before the application of insecticides.

Dogs should be examined and deticked daily by an adult. There are several products for control of ticks and fleas on pets. Permethrin is the active ingredient in BioSpot® for dogs and cats which kills and repels ticks. Frontline® contains fipronyl which kills ticks. Collars for dogs containing amitraz will kill ticks as well. Selamectin (Revolution®) controls the American dog tick. All of these, except the collars which are replaced every 4 months and BioSpot® for cats which is applied every 3 months, are applied topically each month.

Major Diseases Carried by Ticks
Rocky Mountain spotted fever (Rickettsia rickettsii) is tranmitted by ticks and has a rapid onset of symptoms. Four to six hours of tick attachment are required to transmit the disease. Symptoms include fever, malaise, chills, headache and aching muscles. A rash may develop on the wrists and ankles about the 2^cnd or 3^rd day. The rash spreads to the entire body if untreated. The fatality rate is 15-20% without proper treatment. Antibiotics are very effective at treating this disease.

Lyme disease (Borrelia burgdorferi) is diagnosed about 10,000 annually in the US. The blacklegged tick is usually the transmitter of this disease of humans and dogs caused by a spirochete bacterium. Be on the lookout for a small ring-like lesion developing at the site of a tick bite within 2-32 days. Fever and headache may also be symptoms. Treatment with antibiotics reduces the risk of cardiologic, neurologic or arthritic complications developing over time.