4-H Companion Animal Health
Common Dog Diseases and
Whether your dog is a working companion, cham-
blood transfusions and intensive care; often it is not
pion show animal, hunting partner, or just a best
friend, the kindest and most responsible thing you
Leptospirosis. Canine leptospirosis is caused by
can do for him is to provide proper health care.
bacteria spread through contact with nasal se-
Knowing about common dog diseases and being
cretions, urine, or saliva of infected animals. The
aware of appropriate prevention and treatment can
disease also can infect humans. Lepto infects the
better help you provide that care.
kidneys and causes fever, vomiting, diarrhea, and
Many Diseases Can Be
jaundice. Treatment requires antibiotics, intensive
care, and intravenous (IV) fluid therapy. Dogs that
recover may be left with permanent kidney damage.
Some of the most common and serious
Kennel Cough. Canine infectious tracheobronchitis
dog diseases have been made less
is caused by several viruses (including parain-
common through vaccines; however,
fluenza) and bacteria (including bordetella). This
these diseases continue to threaten a
highly contagious disease attacks the respi-
dog that lacks proper immunization.
ratory system, causing a chronic, dry, hack-
Puppies may be vaccinated as early
ing cough. It is generally a mild infection,
as 4-6 weeks, depending on each
but it may progress to severe pneumonia
situation and the veterinarian’s advice.
in young pups or old dogs.
Through mother’s milk, puppies receive
Treatment can be helpful.
disease-fighting antibodies, which last
Parvo. Canine parvovirus
6-16 weeks. Vaccinations then take
is a deadly contagious viral
over. Yearly boosters should be given
disease that is spread by con-
throughout your dog’s life, including old
tact with infected fecal material.
age when your dog may become more
The virus is difficult to kill and is
susceptible to some diseases. The following
easily spread. It attacks the gastroin-
diseases can be prevented through vaccinations.
testinal system, causing fever, lethargy, vomiting,
Distemper. Canine distemper is caused by a highly
bloody diarrhea, and rapid dehydration. Treatment
contagious, airborne virus. It affects the dog’s respi-
requires intensive IV fluid and supportive therapy
ratory, gastrointestinal, and nervous systems. Early
and has a variable rate of success.
symptoms are those of a “cold” — runny eyes and
Corona. Canine coronavirus is a highly contagious
nose, fever, cough, and often diarrhea. Later in the
viral infection attacking the gastrointestinal tract.
course of disease there may be nervous twitching,
Signs are similar to parvovirus infection, except it is
paralysis, and seizures (convulsions). There is no
generally milder and more effectively treated.
Rabies. Rabies is a viral infection of all mammals,
Hepatitis (Adenovirus). Canine infectious hepati-
including man. It is transmitted by the bite of an in-
tis is a viral disease transmitted by urine, feces, or
fected animal. The virus infects the central nervous
saliva of infected animals. It affects the liver, kidney,
system, causing a brain infection (encephalitis),
and blood vessels. The signs are fever, tissue
which is always fatal. There is no treatment for dog
swelling, and hemorrhage. Treatment may require
or man after symptoms appear. However, a vaccine
4-H Companion Animal Health
is effective in preventing the disease in people if it
mother’s milk to newborn pups. Consequently, pups
is administered soon after their possible exposure.
may have hookworms at a very early age. Signs of
Because of the serious public health threat, Indiana
infection include lethargy, stunted growth, anemia,
law requires a rabies vaccination for all dogs.
and dark, tarry feces. Hookworms are a life-threat-
ening parasite at any age. Blood transfusions may
be necessary in advanced cases.
The most common internal intestinal parasites are
Whipworms are tiny worms that inhabit and de-
tapeworms and roundworms.
velop in the lower bowel. They often cause chronic
Tapeworms. Tapeworms are long, segmented
watery diarrhea and weight loss. Their life cycle is
worms. They are transmitted when a dog ingests
longer than most intestinal parasites, and proper
a larval stage of the worm found in a
timing of repeated deworming is impor-
flea or the raw meat of small mam-
tant for their control.
mals. A dog that hunts on its own
Heartworms are devastating
or has had fleas will likely develop
internal parasites that live in a dog’s
tapeworms. Individual tapeworm
heart and in the big vessels near
segments are easily seen in freshly
the heart, where they cause severe
passed feces or around the anus of
damage to the circulatory system and
an infected dog. Special dewormers
lungs. They are transmitted by the
are required for treatment.
bite of a mosquito that has bitten an
Roundworms. The roundworm
infected dog. Treatment is difficult,
classification encompasses many
but preventive measures are avail-
worm types, including ascarids,
able. Dogs should have a blood test
hookworms, whipworms, and
for heartworms in early spring before
heartworms. The intestinal worms
mosquito season begins. If the test is
are transmitted by the ingestion of
positive, treatment may be attempt-
feces or feces-contaminated soil
ed. If the test is negative, preventive
that contains worm eggs. The transmission of the
medication can be given to your dog
heartworm, however, requires an intermediate host
daily or on a monthly basis throughout the mosquito
such as a mosquito for propagation. Your veterinar-
season. Consult with your veterinarian to determine
ian will perform a specialized microscopic exami-
the best heartworm prevention plan for your dog.
nation of feces (for intestinal worms) or blood (for
heartworms) to determine the presence of round-
worms. Treatment or prevention with medication is
External parasites are “bugs” (insects) that live on
effective, but it should be repeated regularly and
the outside of a dog’s body. They include fleas,
monitored to determine if reinfection has occurred.
ticks, lice, flies, mosquitoes, mites, and others.
Deworm a dog with a veterinarian’s supervision.
They not only cause irritation, but also may transmit
The following describes in more detail the four
diseases and cause disease in humans. Careful
types of roundworms mentioned above.
skin examination by a veterinarian can detect these
Ascarids are long, thin spaghetti-like worms that in-
habit the intestine. Some types of these worms can
Fleas are readily seen in a dog’s haircoat. They
be seen in an infected dog’s feces. These worms
are pencil-lead size, brown, compressed side to
commonly create a problem in pups, where they
side and seem to be in constant motion. They are
cause stunted growth, lethargy, diarrhea, vomiting,
seen most easily at the base of the tail, between
and a pot-bellied appearance. In severe cases,
the ears, or in the short hair on the abdomen. Even
ascarids can cause seizures (convulsions).
if the flea is not visible, black specks of excre-
ment may be seen. Many treatments are available;
Hookworms are tiny worms that attach them-
however, the dog’s environment must be treated
selves to the intestinal wall and suck blood from the
just as vigorously, since the flea actually spends
dog. They can be transmitted in utero and via the
more time off the dog than on. Flea control should
4-H Companion Animal Health
be implemented at the earliest sign of flea infes-
The tendency to develop demodectic mange is
tation because fleas multiply rapidly and a small
thought to be hereditary. It is seen most frequently
problem becomes a major one in just a few days.
in purebred dogs. Demodectic mange is not con-
While most dogs scratch with fleas, some dogs are
tagious. Diagnosis and treatment by a veterinarian
also allergic to flea saliva. For them, one flea bite
are necessary; treatment is difficult.
can set off an allergic reaction of severe skin inflam-
Ear mites tunnel in the skin of the outer ear ca-
mation. A flea-allergic dog will require medication
nal. They are easily transmitted from dog to dog
to relieve the skin inflammation in addition to flea
or cat to dog. They can be seen in the ear with
magnification. Ear mites are suspected when dark
Ticks are most prevalent in early spring and are
coffee-ground debris is present in the ears. Infesta-
most commonly found on outdoor dogs that get into
tion signs are head shaking and scratching at the
underbrush and wooded areas. Ticks can transmit
ears. Left untreated, ear mites predispose the ear
several diseases (including Rocky Mountain Spot-
to secondary bacterial infection. Treatment requires
ted Fever) and should be removed with care. Grasp
cleaning of the ear by a veterinarian and use of
the tick near its head with a pair of tweezers and
mite-killing insecticide. Be sure to treat any other
pull away from the skin with a firm tug. Do not try to
cats or dogs in the household.
kill the tick first with fire or chemicals. Disinfect the
area with alcohol to prevent infection. Ticks should
Other Common Problems
be controlled by daily inspection and removal or, in
Ear infections are a common problem in dogs,
heavy infestations, by the regular use of chemical
especially those breeds with a heavy earflap.
Infections are caused by bacteria or yeast that
Lice are small, light-colored parasites that are
grow in the ear when the ear’s normal environment
transmitted dog to dog. They can be seen at the
is changed for any reason. Ear mites, ticks, and
base of the hair. Signs of lice infestation (pedicu-
water or grass awns in the ear can be predisposing
losis) are a rough and dry haircoat, matted hair, and
factors. (Grass awns are slender, bristlelike ap-
scratching and biting of the skin. Lice are effectively
pendages on the tips of many grasses. Dogs can
treated with a variety of chemicals available from a
get them in their ears as they run
Mange mites cause two types
Signs of ear infections are
of mange in dogs. Sarcop-
head shaking, pawing or dig-
tic mange is caused by the
ging at the ear, pain, redness,
sarcoptic mite, a microscopic
and inflammation of the ear
parasite similar to a chigger.
canal, and a foul smell in the
These mites are transmitted from
ear. Any ear infection should be
dog to dog and can also infect
examined by a veterinarian for
human skin. They burrow into the
proper treatment. To prevent ear
skin and cause severe itching
and consequent skin irritation
• Examine your dogs ears at least once
and inflammation. Hair loss
can be severe and generalized
• Try to prevent water from getting in
over the body. Diagnosis by a
your dog’s ears when bathing the dog.
veterinarian is essential, and treatment is usu-
ally quite effective. All animals in contact with the
• Ask a veterinarian for advice on wax
infected dog should be treated at the same time.
control and routine ear cleaning.
Demodectic mange is caused by demodectic
Dental problems arise frequently and need at-
mites that destroy the hair follicle in which they
tention. Drooling and/or foul odors coming from the
reside. This causes small patches of hair loss that
mouth are signals. Regular veterinary advice and
can spread to the entire body. The initial skin le-
maintenance programs are necessary to prevent
sions may become infected and are difficult to treat.
4-H Companion Animal Health
Dog anal sac problems also occur, causing
considerable animal discomfort. Anal glands may
become infected, causing drainage and foul odors
at times. The dog may exhibit uneasy behavior
such as rear-end scooting or nipping at the tail
area. A simple procedure may relieve the animal;
in severe cases, antibiotic treatment or surgical
intervention is necessary.
Regular visits to the veterinarian are important
to prevent or correct serious health problems. To
provide proper care and comfort for your dog, be
aware of potentially serious situations and take
Written by Dr. Duane Rice, University of
Nebraska Extension veterinarian, and Dr. Diana
Longfellow, practitioner, Broken Bow, Neb.
Reprinted with the permission of the Nebraska
Cooperative Extension Service by Colleen Brady,
Ph.D., Extension specialist, Department of 4-H
Youth Development, Purdue University.
It is the policy of the Purdue University Cooperative Extension Service, David C. Petritz, Director, that al persons shal have equal opportunity and access to the programs
and facilities without regard to race, color, sex, religion, national origin, age, marital status, parental status, sexual orientation, or disability.
Purdue University is an Affirmative Action institution.
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