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Know the
Signs
Protect Your Pet From Common Parasites
Courtesy of Pfizer
Heartworm
How
Heartworm is Transmitted to Dogs and Cats
Heartworm
(Dirofilaria immitis) is a parasite that can infect
both dogs and cats. Transmitted by mosquitoes, D. immitis
can be found in most areas of the country where mosquitoes
breed. Infected dogs can carry the parasite to areas where
it normally is uncommon.
Adult
heartworms reside in the heart's right ventricle and pulmonary
arteries, and can grow to a length of 5-to-12 inches in dogs
and 5-to-8 inches in cats. When adult heartworms living in
animals mate and produce offspring or microscopic heartworm
larvae (microfilariae), the offspring can live in an animal's
bloodstream for three years.
Heartworm
disease is caused by adult heartworms and fragments of dead
worms obstructing the normal blood flow through the heart
and can lead to congestive heart failure and obstruction of
the pulmonary blood vessels which carry blood to the lungs.
Mosquitoes
transmit heartworm. When a mosquito bites an infected animal,
the heartworm microfilariae are ingested along with the blood.
In the mosquito, these microscopic pests develop into infective
larvae, which are transmitted back to an animal through another
mosquito bite. During the microfilariae maturation process
in the animal (which lasts about six-to-seven months in dogs),
the heartworms travel to the lungs and the right side of the
heart, where they can grow and mate for several years.
Treating
all animals in a household is essential. Both dogs and cats
often show no signs in the early stages of heartworm disease.
Treating dogs for heartworm disease can be lengthy, expensive
and life threatening. Currently, there is no approved treatment
for heartworm disease in cats. For these reasons, prevention
is the key. While fewer cats than dogs contract heartworm
disease, those that do are prone to blockage of an artery
and subsequent death. Whereas normally 10 or more adult heartworms
need to be present before dogs exhibit severe heartworm disease,
just one adult heartworm can be fatal to cats.
Signs
in Dogs
Heartworm
signs can take years to appear in infected animals. Early
canine signs often are easily attributed to other conditions
or diseases. Those signs can include fatigue, non-productive
cough, difficulty breathing, exercise intolerance, coughing
up blood, weight loss and fluid accumulation in the abdominal
cavity. Untreated heartworm disease can result in death. Testing
for heartworm most often involves a blood test that indicates
whether microfilariae are present in blood. In recent years,
more veterinarians have begun to use antigen testing to detect
and confirm whether adult heartworms are present in the heart.
Signs
in Cats
In cats,
heartworm signs can include chronic vomiting, coughing, difficulty
breathing, collapse, weight loss, lethargy, rapid heart rate,
diarrhea, convulsions, asthma-like signs or sudden death.
Because heartworm blood tests in cats rarely uncover microfilariae,
veterinarians must rely on other methods such as testing for
certain antibodies in the cat's blood.
Treatment
and Treatment Outcomes
Treating
dogs for heartworm disease is a multi-step process that is
both costly and very risky for the animal. Successfully treating
heartworm disease involves a multi-step program to kill the
adult worms and microfilariae, followed by additional ongoing
treatment to prevent future infections. While heartworm disease
is less prevalent in cats than in dogs, there currently is
no approved treatment for heartworm disease in cats. Deadly
side effects to treatment in cats are common. Prevention should
be ongoing in areas where mosquitoes live and breed year-round
and seasonal in other areas depending on the length of the
mosquito season. Blood tests to check for existing heartworm
infection are recommended before administering prevention
therapy. Because heartworms are sometimes difficult to detect
in various stages of their life cycle, periodic blood tests
also are recommended in areas where animals receive heartworm
prevention medicine.
Human
Health Connections/Concerns
Incidents
of humans being affected by Dirofilaria immitis are
rare. In humans, the disease can cause small pulmonary lesions,
which may be confused with other serious diseases (Archives
of Internal Medicine; Sep. 22, 1997, James S. Tan, author)
Fleas
How
Fleas are Transmitted to Dogs and Cats
Ctenocephalides
felis, the fleas that affect most dogs and cats, can breed
year-round indoors. The flea life cycle varies according to
where they live. In the south, fleas may hatch year-round,
while their northern counterparts flourish in warm summer
months. Moving through the life cycle from egg to larvae to
pupae to adult can take a flea anywhere from 14 days to 140
days in certain conditions. Adult fleas mate shortly after
contact with animals. Once they produce eggs, the eggs often
drop off the animal to complete their larval and pupal stages.
The pupal stage can last from 3-to-4 weeks to several months
depending on the environment (warm, humid conditions with
temperatures above 80 percent humidity are optimal). Once
hatched, adult fleas search for a host, and if fleas are not
removed from the host they can live for more than two months,
depending on environmental conditions.
Signs
in Dogs and Cats
Pets that
exhibit signs of itching, scratching, and unusual amounts
of chewing and licking may have fleas. Although fleas are
sometimes difficult to spot, black specks (flea feces) on
pets' skin and coat are one sign - these specks turn reddish
brown when placed on dampened white paper. Flea-infested dogs
may scratch mainly on the lower part of their bodies while
cats may scratch more around their heads and necks. Fleas
also can cause an allergic reaction called flea allergy dermatitis,
a hypersensitivity to flea saliva, which can cause a rash
inflammation or hair loss in some pets. If ingested, fleas
also can transmit tapeworms to pets.
Treatment
and Treatment Outcomes
Effective
treatments for fleas require killing fleas and breaking the
flea life cycle. Because fleas multiply rapidly, treating
fleas involves removing them form the animal's environment
as well as its skin and hair.
Human
Health Connections/Concerns
When no
suitable animal hosts are found, fleas often look to humans
for the blood they need to survive. Although fleas are mostly
a nuisance to humans, some research indicates that fleas play
a role in transmitting cat-scratch disease and plague. If
ingested, fleas also can transmit tapeworms to humans.
Sarcoptic
Mange (Scabies)
How
Sarcoptic Mange (Scabies) is Transmitted to Dogs and Cats
Sarcoptic
mange (Sarcoptes Scabei var. canis) is caused by a
microscopic mite that burrows under a dog's skin. Sarcoptic
mange has a 17- to 21-day, four-stage life cycle that consists
of egg, larva, nymph and adult stage. Passed from dog to dog,
adult female sarcoptic mange mites tunnel under a dog's skin
to lay eggs. The eggs hatch and mature into adults that lay
eggs in a cycle that lasts two to three weeks.
Signs
in Dogs
Dogs that
exhibit signs of intense itching, scratching, and biting especially
around the face, chest, legs, elbows, ears or hocks may have
sarcoptic mange. Small red bumps, hair loss and crusty scabs
often appear. Secondary bacterial infections also may occur
as a result of scratching. Mites can be detected in skin scrapings
but are often difficult to find.
Treatment
and Treatment Outcomes
Treating
sarcoptic mange normally requires several treatments to kill
adult mites as well as all newly hatched mites. Because sarcoptic
mange is very contagious, all dogs in a home should be treated
if sarcoptic mange is suspected. Traditional treatment options
include insecticide dips and treatment with oral medications
or injections. Skin infections resulting from sarcoptic mange
mite infestations also should be treated.
Human
Health Connections/Concerns
Dogs can
pass the sarcoptic mange mites to humans (scabies). A red,
itchy rash may appear on arms, waist of other areas.
Ear
Mites
How
Ear Mites are Transmitted to Dogs and Cats
Ear mites
(otedectes cynotis) are small microscopic mites that
feed on the pet's ear lining. Ear mites are highly contagious
and easily passed from pet to pet. Ear mites have a four-stage
life cycle that includes an egg, larva, nymph and adult stage.
Signs
in Dogs and Cats
Signs
of ear mites can include infection in both ears, intense irritation,
scratching, head-shaking, rubbing black, red-brown, or waxy
ear discharge. Additional signs include itchy skin located
around ears, head and neck as well as thick crusts around
the outer ear and possible crusts and scales on the neck,
rump and tail.
Treatment
and Treatment Outcomes
Because
ear mites are very contagious, treatment should be administered
to all pets in a household.
American
Dog Tick (Dogs)
How
American Dog Ticks are Transmitted
The American
dog tick is probably the most widespread tick species in the
country and, therefore, the most commonly found on pets (Archives
of Internal Medicine; Sep. 22, 1997, James S. Tan, author).
This species of tick is commonly found in fields, woods and
grassy areas. The American dog tick is a blood-feeder and
is capable of transmitting a wide variety of diseases, including
tularemia and Rocky Mountain spotted fever, between animals
and from animals to humans. Adult tick activity begins in
mid-April, peaks in June and then declines in September. All
stages of the American dog tick, however, may be found year-round
in southern states.
Signs
in Dogs
A bite
from a disease-free tick normally doesn't cause clinical signs
other than a crusty lesion, although a heavy infestation of
ticks could cause anemia. In diagnosing a tick infestation,
the first sign is to find a tick on the pet. This could be
easy or challenging, depending on the severity of the infestation
and whether the thick had had a recent blood meal - that is,
whether the tick is engorged. The second means of diagnosing
a tick infestation is to look for evidence of a tick-born
disease - which may remain after the tick is gone.
Human
Health Connections/Concerns
The American
dog tick is the primary carrier of Rocky Mountain spotted
fever and is also a carrier of tularemia. These diseases can
be passed from infected ticks to humans. Rocky Mountain spotted
fever most often occurs in the eastern and southern U.S.,
typically from April to September. Signs and symptoms of Rocky
Mountain spotted fever in humans include fever, headache,
muscle aches and a red rash appearing between the second and
sixth day of the fever. In severe cases, the disease can be
fatal, especially in the elderly. Tularemia is usually acquired
through the bite of an infected tick. Patients will develop
an ulcer at the site of infection and experience a swelling
of the lymph nodes. Sever fever and flue-like symptoms may
accompany the ulcer or lesion. Symptoms may persist from 1-14
days, with 3-5 days being most common.
Intestinal
Hookworms (Cats)
How
Intestinal Hookworms are Transmitted to Cats
Hookworms
are small parasitic worms, with hook-like appendages on their
mouths, that feed off the wall of the small intestine and
can cause severe damage. They are blood feeding parasites
that enter a cat's system either through ingestion of larvae
or through the skin. Kittens can get the worms from ingesting
their mother's milk.
Signs
in Cats
Signs
may include poor appetite, dry cough, pale gums, dark stools
or constipation. Blood-loss anemia, weakness and bloody diarrhea
are also symptoms of hookworm infection.
Human
Health Connections/Concerns
Certain
species of hookworms can affect humans when the larvae burrow
under humans' skin and cause an itchy rash. Hookworms also
may affect humans if larvae from soil are ingested.
Intestinal
Roundworms (Cats)
How
Roundworms are Transmitted to Cats
Roundworms,
also know as ascarids, are transmitted from mothers to nursing
kittens or through the cat ingesting eggs or other hosts (such
as mice) that are infected with the eggs.
Signs
in Cats
Roundworms
interfere with digestion and absorption of nutrients. They
can cause malnourishment, low stamina, dull coat, abdominal
distention, abdominal pain, vomiting of adult worms, diarrhea,
loss of condition, loss of appetite and coughing.
Human
Health Connections/Concerns
Cat roundworms
are known to cause visceral larval migrans in children, although
less so than their canine counterpart. The disease results
from ingesting the eggs.
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