Do Ticks Make You Squeamish?

2017-06-21

Do ticks make you squeamish? Go ahead and put that ick-factor on hold for just a moment. Understanding how ticks live and function can be eye-opening (and, motivating for you to find a way to prevent them on your pets!)…

The two well-known tick families include the hard ticks (Ixodidae) and the soft ticks (Argasidae). There are some interesting differences between the two families that are highlighted in this table (4):

Hard Ticks

Soft Ticks

Life Stages

Egg, larva, nymph, adult

Egg, larva, multiple nymphal stages, adult

Blood Meals

After egg emergence, each stage acquires 1 blood meal

Feeding occurs several times during each life stage

Eggs

The adult female will lay one batch of thousands of eggs after her meal and then die

The adult female will lay multiple small egg batches between the blood meals

Life cycle

<1 to > 3 years depending on environment

Several years

Length of Time They Can Survive Without a Meal

Several months if not environmentally stressed

Several years!

Host Seeking Behavior

Questing (more below)

Some questing, many reside in nests with the hosts

Length of Feedings

Days to weeks

Rapid feeding when host returns to nest

How Large Will the Tick Grow While Feeding?

100 to 200 times the unfed body weight

5 to 12 times the unfed body weight

So what is questing?

A questing tick will crawl up a blade of grass or find a leaf on the ground and perch on the leaf edges. The tick will assume a posture where it extends the front legs in the air as certain cues (e.g., carbon dioxide, heat, movement) trigger the questing behavior. Then, as a host brushes against the tick, the tick climbs on the fur.

Interested in seeing a video of the questing behavior? Check out Dr. Michael Dryden’s website link with a variety of different questing tick videos.

What Makes Tick Saliva So “Special”?

The tick salivary gland can produce numerous substances that will aid in successful feeding. Here is a very broad overview:

  • Cement: Have you ever noticed it can be difficult to remove a tick? The cement-like substance helps anchor the tick’s mouthparts in the host tissue while the tick is feeding.
  • Anti-coagulant: The tick will produce a substance that helps prevent the host’s blood from clotting while the tick is taking a blood meal.
  • Anti-angiogenic: Angiogenesis is the formation of new blood vessels. The tick saliva can work to temporarily inhibit this process to some extent.
  • Anti-inflammatory: This keeps the host’s body from inciting an inflammatory response while the tick is feeding.
  • Anti-immunological: The tick can secrete substances in the saliva that will work to prevent the host’s immune system from attacking the tick while feeding.

Tick-Borne Illnesses:

While the tick salivary components may sound “fascinating”, let’s not forget about all the tick-borne diseases that can be transmitted while the tick is feeding. Various factors can contribute to the likelihood of a feeding tick transmitting a pathogen. Examples include the amount of pathogen the tick is carrying (as well as how much of that pathogen is present in the tick salivary and gut contents), and the length of tick attachment. Additionally, some pathogens may need to replicate after the blood meal begins before the tick can transmit the infectious agent (3). Unfortunately, we don’t always know exactly how long a tick needs to be attached to a host to transmit a particular pathogen. A recent publication by Richards et.al. reviewed what is known about estimated duration of tick attachment for pathogen transmission. The data was based mainly on rodent or human data. Depending on the tick and pathogen, times ranged from seconds or minutes, all the way to many days. For example, the tick Ixodes scapularis (blacklegged tick) could need 4 to 72 hours to transmit Borrelia burgdorferi, the pathogen that causes Lyme disease; or 24 to 50 hours to transmit Anaplasma phagocytophilum, a pathogen that causes Anaplasmosis. The pathogen that causes Rocky Mountain spotted fever (Rickettsia ricketsii) could take 2 to 96 hours to be transmitted by Dermacentor variabilis (American dog tick) or Rhipicephalus sanguineus (brown dog tick). In general, the longer the tick is attached, the greater the chance the disease(s) will be transmitted.

Tick Prevention:

After reading all this information about ticks, perhaps you have visions of questing ticks just waiting for your dog to pass by…. Or, you may be wondering about the best strategies to combat ticks. Here are some pointers:

  • It’s always a good idea to perform tick checks. But keep in mind that ticks are easier to find once they are engorged, which means they have already been feeding for a while.
  • Keep the yard mowed and keep weeds and underbrush pushed back to where your pet cannot roam through the tall plants.
  • A very effective tick prevention strategy is to keep your pet on year-round tick prevention. With a variety of topical products and collars available, and even oral products for dogs, there is no shortage of options for pet owners.

Questions or Concerns About Your Pet?

If you have questions about the best tick protection for your individual pet, contact us today. Our staff is ready to help. If your pet ever displays signs consistent with tick-borne disease (e.g. lethargy, fever, lameness, limping, anorexia, to name a few), especially if you have found a tick on your pet, then schedule an appointment right away. Finally, be sure to keep your dog up-to-date on the annual 4DX test. This test not only tests for heartworm, it also checks for exposure to 5 different tick-borne diseases.

References:

  1. CAPCvet.org Tick Information
  2. Francischetti, I.M.B., Sa-Nunes, A., Mans, B.J., Santos, I.M., and J.M.C. Ribeiro. 2009. The role of saliva in tick feeding. Front. Biosci. 14:2051-2088.
  3. Richards, S.L., Langley, R., Apperson, C.S. and E. Watson. 2017. Do tick attachment times vary between different tick-pathogen systems? Environments. 4(37):1-14.
  4. Vredevoe, L. Tick Biology. University of California Davis Department of Entomology and Nematology website. Accessed 19 Jun 2017.

Author: Dr. C. Noureddine, DVM, MS

Photo Credits: (1) Tick on grass (123rf.com/profile_t3rmiit'>t3rmiit / 123RF Stock Photo); (2) Engorged tick: (pixabay.com)

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