Signs and Symptoms of Parasites in Dogs
Parasites in dogs can be a simple nuisance or a serious health
threat. Fortunately, internal and external parasites are easily
controlled with over-the-counter and prescription products.
Signs and symptoms of parasites vary. Fleas are the most
common external parasite, causing skin irritation, hair loss and
itching. Internal parasites—usually in the form of
gastrointestinal worms—cause digestive upsets such as diarrhea
Several types of worms may infect your dog; the symptoms will
help you identify and treat them.
Types and Symptoms of Dog Parasites
Heartworm is transmitted by mosquitoes and this parasite can
be fatal. These worms attack and destroy heart muscle tissue,
causing heart failure. Your veterinarian can prescribe a monthly
heartworm preventative to combat his mosquito-borne illness.
Early stages heartworm disease has few symptoms. As the disease
progresses, your dog will show symptoms of heart failure such as
coughing, lethargy and loss of appetite.
Pinworms are small, white worms that spread through
contaminated water, food and bedding. Common and highly
contagious, pinworms cause intense anal itching. Dogs with
pinworms often “scooch,” dragging their rear end across the
floor in an effort to relieve the itch.
Hookworms mature in the intestines of your dog. They deplete
the body of nutrients. In puppies, hookworms are serious—they
can cause diarrhea and poor growth as well as fatal anemia and
pneumonia. All puppies should be treated for hookworms during
the first 3 months of life.
Roundworms, also known as ascarids, are common in dogs and
puppies. Dogs with roundworms will often develop a potbelly.
Because roundworms are often transmitted to puppies in utero,
the mother dog should be dewormed prior to giving birth. As with
hookworms, all puppies should be treated for roundworms during
the first 3 months of life.
Whipworms are long, thin worms that live in the large
intestine. Common in dog kennels, they are easily spread to
other dogs. Whipworms cause vomiting and diarrhea. Severe
infestations can cause weight loss and bloody diarrhea.
Tapeworms live in the intestines of infected dogs. Usually
acquired when a dog ingests fleas or contaminated prey,
tapeworms cause poor digestion and mild diarrhea.
Worms There are other, less common worms that can infect dogs
and puppies. Dogs who eat raw fish may acquire flukes, a
parasite that causes intestinal inflammation, bleeding in the
lungs and skin disorders. Threadworms result in diarrhea with
blood. Dogs in humid areas with high temperatures are more
susceptible to threadworms. If your dog likes to eat beetles,
cockroaches, crickets or frogs, he may be at risk for stomach
worms. These parasites can cause vomiting, loss of appetite, and
Digestive system parasites are more dangerous for puppies
than adult dogs, but worms can cause discomfort and illness in
any dog. A fecal test will identify intestinal parasites, and
treatment is usually quick and effective. Some worms can be
spread to humans, so regular deworming of dogs and puppies is a
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