Estimated reading time: 3 minutes
We normally dip during spring and summer to reduce tick quantities and prevent diseases such as redwater and gallsickness. However, ticks do not die during the winter months and cold does not affect the eggs laid by fully suckled females during late summer. The hatching of eggs is merely slowed down by colder weather.
It is important to understand that different types of ticks function differently and peak at different times.
This article is one in a series of informative articles on animal health. Follow the #VideoVet series.
Single-host ticks: There are two types of blue ticks that are the main carriers of
African redwater. They are Rhipicephalus decoloratus and Rhipicephalus microplus. Asian redwater is transmitted by the Asian blue tick, namely Rhipicephalus microplus. Rhipicephalus microplus and Rhipicephalus decoloratus are both single-host ticks.
Two-host ticks: Bont-legged ticks (Hyalomma spp.) are two-host ticks and their bites lead to tissue death (necrosis) at the bite site and sweating disease. Redlegged ticks (Rhipicephalus evertsi evertsi) are also two host ticks and are the carriers of African redwater and anaplasmosis, with peaks in autumn.
Three-host ticks: The bont tick (Amblyomma hebraeum) causes heartwater and abscesses, especially along the udder and sheath, in the summer. The brown ear tick (Rhipicephalus appendiculatus) is also a three-host tick. The adult tick causes damage in the form of ear abscesses, especially during January to March.
Hurdles to prevention
Preventing and controlling especially multi-host ticks can be difficult, as their life-cycle is long. Three-host ticks have a life-cycle of five months and, in the case of the bont tick, up to a year. Single-host blue ticks have a life-cycle of approximately 56 days.
Dip decisions are usually based on the presence of fully suckled adult females in summer, and do not consider the large numbers of immature ones found on cattle during the colder months.
When using a dip, only the ticks (almost invisible immatures and visible adults) on the cattle are affected. The stages not found on cattle during treatment come off unscathed and will climb on later, again necessitating dipping. Tick nymphs, for example, can survive two to three months away from the animal. If heartwater naïve cattle graze spare camps in late winter and/or spring, nymphs can be transmitted without the presence of adult ticks.
A dip strategy
Rotating cattle through most of the camps after a winter dip, especially for the period during which the dip is active, is one strategy to limit multi-host ticks in summer. This rotation process ensures that any stages of the ticks waiting on the pasture will climb on the cattle and be exposed to the active dip.
The active period of a dipping agent can vary, depending on the base of the agent (oil versus water), rainfall, hair length and grass length, etc. This will help reduce the tick burden and associated problems in summer.
Winter dipping is therefore never farfetched and should be used judiciously together with a well thought out grazing rotation strategy. The benefits of less udder damage, abscesses, losses due to heartwater and brown ear ticks, make it worthwhile.
For more information, contact your MSD Animal Health representative or phone 011 923 9300. ZA-DEL-210800001.