| Ticks: Life Cycle, Anatomy, and Disease Transmission Race Foster, DVM Marty Smith, DVM Drs. Foster & Smith, Inc. |
Ticks are a common external (on the skin) parasite of many animals, including dogs.
What are ticks?
Ticks are not insects like fleas, flies, and lice, but are arachnids like mites and spiders. There are
approximately 850 species of ticks worldwide. Scientists have classified ticks into two families based upon
their structure: Ixodidae and Argasidae.
Ixodid ticks
The tick family Ixodidae consists of ticks that have a hard outer covering called a 'scutum,' and therefore, are
termed hard-shelled ticks. Examples include:
Amblyomma americanum is the Lone Star Tick and is found throughout the South, east of the Rocky Mountains.
Amblyomma maculatum is the Gulf Coast Tick, and that is where it resides.
Dermacentor albipictus is also called the 'Winter Tick,' 'Moose Tick,' or 'Elk Tick' and is found in the northern
and western United States as well as Canada.
Dermacentor andersoni is the Rocky Mountain Spotted Fever Tick and transmits the deadly disease for which
it is named.
Dermacentor variabilis is one of the most famous of all. Its name is also the American Dog Tick and lives in the
entire eastern 2/3 of the United States.
Rhipicephalus sanguineus is the king of ticks. It is called the Brown Dog Tick and is a serious threat to kennels
anywhere in the United States.
Ixodes scapularis is a tiny little tick with a huge threat. It is also known as the Deer or Black-legged Tick. It
has one claim to fame and that is it transmits Lyme disease.
Argasid ticks
The family Argasidae contains the argasid ticks, which are soft-shelled. Their body lacks a scutum. An argasid
has its head located ventrally (on the underside of its body) and when the tick is viewed from above, the head
cannot be seen.The soft-shelled ticks or Argasids are fewer in number. The one most known is Otobius megnini,
also known as the Spinose Ear Tick. It is most common in the Southwest and usually attaches to the ears of
animals.
What are the anatomical features of ticks?
All ticks have three pairs of legs during the immature stage and four pairs as an adult. They crawl but cannot
fly. Wings are absent. In addition, ticks possess a sensory apparatus called Haller’s organ. This structure
senses odor, heat, humidity, and you. This is how the ticks locate their food source. They climb upon tall grass
and when they sense an animal is close by, they crawl on.
What do ticks eat?
A tick's diet consists of blood and only blood. Your blood, dogs' blood, cats' blood, and most blood. The tick
imbeds its mouthparts into the animal's (or human's) skin and sucks the blood. Except for the eggs, ticks
require a blood meal to progress to each successive stage in their life cycle.
What is the life cycle of a tick?
Most ticks are what we call three host ticks, that is, during their
development which takes two years, they feed on three different hosts.
All ticks have four stages to their life cycle: egg, larvae (seed tick),
nymph, and adult. Let us look at the life cycle of the deer tick,
as an example.
Adult female deer ticks lay eggs on the ground in spring. Later in the
summer (depending on moisture and temperature), the eggs hatch into
larvae. The larvae, which are smaller than the period at the end of this
sentence, find an animal (the first host, which is usually a bird or rodent),
live off its blood for several days, then detach and fall back onto the ground. For deer ticks, this most
commonly occurs in the month of August. In the ground, the well-fed larvae now molt into the next stage and
are called nymphs.
The nymphs remain inactive during the winter months and in spring become active. The nymph now finds an
animal (the second host - a rodent, pet, or human) and feeds again. Once well fed, the nymph detaches and falls
back to the ground. Here it molts and changes into an adult. Throughout the fall, both adult male and female
ticks now find another animal (the third host - a rodent, deer, pet, or human) and feed on blood and mate. Once
well fed, both males and females fall back to the ground. The male now dies and the female lives through the
winter and lays eggs in the spring, completing the cycle. If the adults cannot find a host animal to feed on in the
fall, they will survive in the leaf litter until the next spring when they will feed, mate, and produce eggs.
Other species of ticks may be at peak activity for each life stage at different times of the year than the deer
tick we described. Your local university or health department may have information on peak tick activity in your
area.
What diseases do ticks transmit?
Ticks can transmit or cause:
Babesiosis (Piroplasmosis)
Cytauxzoonosis
Ehrlichiosis
Haemobartonellosis in Dogs and Cats
Hepatozoonosis
Lyme Disease
Rocky Mountain Spotted Fever
Tick Paralysis
Tularemia in Dogs and Cats
What are ticks?
Ticks are not insects like fleas, flies, and lice, but are arachnids like mites and spiders. There are
approximately 850 species of ticks worldwide. Scientists have classified ticks into two families based upon
their structure: Ixodidae and Argasidae.
Ixodid ticks
The tick family Ixodidae consists of ticks that have a hard outer covering called a 'scutum,' and therefore, are
termed hard-shelled ticks. Examples include:
Amblyomma americanum is the Lone Star Tick and is found throughout the South, east of the Rocky Mountains.
Amblyomma maculatum is the Gulf Coast Tick, and that is where it resides.
Dermacentor albipictus is also called the 'Winter Tick,' 'Moose Tick,' or 'Elk Tick' and is found in the northern
and western United States as well as Canada.
Dermacentor andersoni is the Rocky Mountain Spotted Fever Tick and transmits the deadly disease for which
it is named.
Dermacentor variabilis is one of the most famous of all. Its name is also the American Dog Tick and lives in the
entire eastern 2/3 of the United States.
Rhipicephalus sanguineus is the king of ticks. It is called the Brown Dog Tick and is a serious threat to kennels
anywhere in the United States.
Ixodes scapularis is a tiny little tick with a huge threat. It is also known as the Deer or Black-legged Tick. It
has one claim to fame and that is it transmits Lyme disease.
Argasid ticks
The family Argasidae contains the argasid ticks, which are soft-shelled. Their body lacks a scutum. An argasid
has its head located ventrally (on the underside of its body) and when the tick is viewed from above, the head
cannot be seen.The soft-shelled ticks or Argasids are fewer in number. The one most known is Otobius megnini,
also known as the Spinose Ear Tick. It is most common in the Southwest and usually attaches to the ears of
animals.
What are the anatomical features of ticks?
All ticks have three pairs of legs during the immature stage and four pairs as an adult. They crawl but cannot
fly. Wings are absent. In addition, ticks possess a sensory apparatus called Haller’s organ. This structure
senses odor, heat, humidity, and you. This is how the ticks locate their food source. They climb upon tall grass
and when they sense an animal is close by, they crawl on.
What do ticks eat?
A tick's diet consists of blood and only blood. Your blood, dogs' blood, cats' blood, and most blood. The tick
imbeds its mouthparts into the animal's (or human's) skin and sucks the blood. Except for the eggs, ticks
require a blood meal to progress to each successive stage in their life cycle.
What is the life cycle of a tick?
Most ticks are what we call three host ticks, that is, during their
development which takes two years, they feed on three different hosts.
All ticks have four stages to their life cycle: egg, larvae (seed tick),
nymph, and adult. Let us look at the life cycle of the deer tick,
as an example.
Adult female deer ticks lay eggs on the ground in spring. Later in the
summer (depending on moisture and temperature), the eggs hatch into
larvae. The larvae, which are smaller than the period at the end of this
sentence, find an animal (the first host, which is usually a bird or rodent),
live off its blood for several days, then detach and fall back onto the ground. For deer ticks, this most
commonly occurs in the month of August. In the ground, the well-fed larvae now molt into the next stage and
are called nymphs.
The nymphs remain inactive during the winter months and in spring become active. The nymph now finds an
animal (the second host - a rodent, pet, or human) and feeds again. Once well fed, the nymph detaches and falls
back to the ground. Here it molts and changes into an adult. Throughout the fall, both adult male and female
ticks now find another animal (the third host - a rodent, deer, pet, or human) and feed on blood and mate. Once
well fed, both males and females fall back to the ground. The male now dies and the female lives through the
winter and lays eggs in the spring, completing the cycle. If the adults cannot find a host animal to feed on in the
fall, they will survive in the leaf litter until the next spring when they will feed, mate, and produce eggs.
Other species of ticks may be at peak activity for each life stage at different times of the year than the deer
tick we described. Your local university or health department may have information on peak tick activity in your
area.
What diseases do ticks transmit?
Ticks can transmit or cause:
Babesiosis (Piroplasmosis)
Cytauxzoonosis
Ehrlichiosis
Haemobartonellosis in Dogs and Cats
Hepatozoonosis
Lyme Disease
Rocky Mountain Spotted Fever
Tick Paralysis
Tularemia in Dogs and Cats
| This site was created by and is maintained by Belinda Winters for BFH Bassets. If you have any questions or comments email belindawinters@bfhbassets.com |
