effect of this biting stress can cause loss of appetite and loss of blood. These two losses result in reduced feed intake and anemia; combined, they cause a lower rate of growth or of milk production compared to hosts without tick infestation. The feeding of soft ticks can cause severe biting stress because of the pain whilst they feed; Ornithodoros savignyi feeding on livestock that are herded in enclosures during nighttime is one notorious example. Physical damage At each feeding site of hard ticks, granuloma and wound healing produce a scar that remains for years after the tick has detached. When the skin of livestock animals is made into leather, these scars remain as blemishes that reduce the value of the leather. Larger ticks cause obstructive and painful damage, such as Amblyomma variegatum adults, which often feed on udders of cattle and reduce suckling by the calves. Hyalomma truncatum adults feed on the feet of sheep and goats, causing lameness. Wounds caused by dense clusters of adult ticks can make the host susceptible to infestation with larvae of flesh-eating myiasis flies, such as the screw-worm, Cochliomyia hominivorax. Poisoning When ticks feed, they secrete saliva containing powerful enzymes and substances with strong pharmacological properties to maintain flow of blood and reduce host immunity. Sometimes, this causes a poisoning of the host. This is not because of a functional toxin in the sense that snake poison is functional for the snake. However, the result can be various forms of toxaemia caused by a variety of ticks. A moist eczema, sometimes with hair loss (alopecia) known as sweating sickness in cattle is caused by Hyalomma truncatum. Tick paralysis can be life-threatening and is caused in sheep by feeding of Ixodes rubicundus of South Africa. In cattle, paralysis is caused by both Dermacentor andersoni in North America and the Australian paralysis tick, Ixodes holocyclus. I. holocyclus also causes paralysis in dogs and humans. Ticks as vectors of disease Because ticks feed repeatedly and only on blood, and have long lives, they are suitable hosts for many types of microbes, which exploit the ticks for transmission between one domestic animal and another. Ticks are thus known as vectors (transmitters) of microbes. Most of these parasitic relationships are highly developed with a strict biological relationship between the microbe and the tick's gut and salivary glands. However, some microbes, such as Anaplasma marginale and A. centrale, can