Watch out for worms
Dogs are victims of several internal parasites frequently referred to as worms. The most common are the roundworms that infest
most puppies at some time in their young lives and tapeworms that can be a big problem when flea infestations are high.
Evidence of roundworms and tapeworms can be seen without the aid of a microscope, but other worms are not so easily diagnosed.
Occasionally adult whipworms can be seen in the stool when the infestation has already caused some debilitation or weight loss in
the dog.
Early diagnosis of the presence and species of intestinal parasite is important, for not all worms respond to the same treatment.
Therefore, stool samples should be taken to the veterinarian for microscopic examination if worms are suspected. Many veterinarians
include the stool check as part of the annual health examination.
Most worm infestations cause any or all of these symptoms: diarrhea, perhaps with blood in the stool; weight loss; dry hair; general
poor appearance; and vomiting, perhaps with worms in the vomitus. However, some infestations cause few or no symptoms; in fact
some worm eggs or larvae can be dormant in the dog's body and activated only in times of stress, or in the case of roundworms, until
the latter stages of pregnancy, when they activate and infest the soon-to-be-born puppies.
Roundworms
Roundworms are active in the intestines of puppies, often causing a pot-bellied appearance and poor growth. The worms may be seen
in vomit or stool; a severe infestation can cause death by intestinal blockage.
This worm can grow to seven inches in length. Females can produce 200 thousand eggs in a day, eggs that are protected by a
hard shell and can exist in the soil for years. Ingesting worm eggs from contaminated soil infects dogs. The eggs hatch in the
intestine and the resulting larvas are carried to the lungs by the bloodstream.
The larva then crawls up the windpipe and gets swallowed, often causing the pup to cough or gag. Once the larvae return to the
intestine, they grow into adults.
Roundworms do not typically infest adults. However, as mentioned above, the larvae can encyst in body tissue of adult bitches and
activate during the last stages of pregnancy to infest puppies. Worming the bitch has no effect on the encrusted larvae and cannot
prevent the worms from infecting the puppies.
Although roundworms can be treated with an over-the-counter wormier found in pet stores, a veterinarian is the best source of
information and medication to deal with intestinal parasites. Dewormers are poisonous to the worms and can make the dog sick,
especially if not used in proper dosage.
Hookworms
These are small, thin worms that fasten to the wall of the small intestine and suck blood. Dogs get hookworm if they come in contact
with the larvae in contaminated soil. As with roundworms, the hookworm larva becomes an adult in the intestine. The pups can
contract hookworms in the uterus and the dam can infest the pups through her milk.
A severe hookworm infestation can kill puppies, but chronic hookworm infection is usually not a problem in the older dog. When it
does occur, the signs include diarrhea, weight loss, anemia, and progressive weakness. Diagnosis is made by examining the feces for
eggs under a microscope.
Tapeworms
Another small intestine parasite, the tapeworm is transmitted to dogs who ingest fleas or who hunt and eat wildlife infested with
tapeworms or fleas. The dog sheds segments of the tapeworm containing the eggs in its feces. These segments are flat and move
about shortly after excretion. They look like grains of rice when dried and can be found either in the dog's stool or stuck to the hair
around his anus. Tapeworms cannot be killed by the typical over-the-counter wormier; see the veterinarian for appropriate treatment.
Whipworms
Adult whipworms look like pieces of thread with one end enlarged. They live in the cecum, the first section of the dog's large intestine.
Infestations are usually light, so an examination of feces may not reveal the presence of eggs. Several checks may be necessary
before a definitive diagnosis can be made.
Prevention
Several worms that infect and reinfect dogs can also infect humans, so treatment and eradication of the worms in the environment are
important. Remove dog feces from back yards at least weekly, use appropriate vermicides under veterinary supervision, and have the
dog's feces checked frequently in persistent cases. Do not mix worriers and do not use any wormier if your dog is currently taking any
other medication, including heartworm preventative, without consulting the veterinarian.
When walking the dog in a neighborhood or park, remove all feces so that the dog does not contribute to contamination of soil away
from home as well.
Dogs that are in generally good condition are not threatened by worm infestations and may not even show symptoms. However, it's
a good idea to keep the dog as worm-free as possible so that if disease or stress do take a toll, you're not fighting worms in a sick pet.
Heartworm Disease
Once considered confined to the southern US where winters are mild, heartworms now infest dogs in all parts of the country.
Many veterinary clinics display a preserved heart infected with heartworm in a jar. However, seeing is not necessarily believing;
although clients can view the infested heart loaded with long, spaghetti-like worms every time they visit, many gamble that their
dogs will never be bitten by an infected mosquito.
Heartworm prevention costs money and requires commitment: blood must be drawn to examine for signs of infestation before the
preventive drug can be given, and the drug must be administered regularly whether the daily dose or the once-a-month type is chosen.
But the effort and the money are well spent to keep a loved pet from the discomfort and debilitation of the infliction.
The parasite
Like most parasites, the heartworm goes through several life stages before emergence as an adult and needs at least two hosts to
complete the cycle. The mosquito serves as the host for the larval stage of the worm, called microfilariae. The mosquito ingests the
larva when it bites an infected dog and deposits its cargo in an uninfected dog when seeking another blood meal. The microfilariae
burrow into the dog, and for three or four months, undergoes several changes to reach adult form. They then travel to the right side
of the heart through a vein and await the opportunity to reproduce. Adult heartworms can reach 12 inches in length
and can remain in the dog's heart for several years.
Female heartworms bear live young -- thousands of them in a day. These young -- the microfilariae -- circulate in the bloodstream for
as long as three years, waiting to hitch a ride in a bloodsucking mosquito. They undergo changes in the mosquito that prepares them
to infect the dog, and they transfer back to the original host species the next time the mosquito bites. The process of change in the
mosquito takes about 10 days in warm climates, but can take six weeks in colder temperatures.
The worms grow and multiply, infesting the chambers on the right side of the heart and the arteries in the lungs. They can also lodge
in the veins of the liver and the veins entering the heart. The first sign of heartworm infestation may not manifest for a year after
infection, and even then the owner may dismiss the soft cough that increases with exercise as unimportant. But the cough worsens
and the dog may actually faint from exertion; he tires easily, is weak and listless, loses weight and condition, and may cough up blood.
Breathing becomes more difficult as the disease progresses. The progression is traumatic: the dog's quality of life diminishes drastically
and he can no longer retrieve a Frisbee or take a long walk in the park without respiratory distress. Congestive heart failure ensues, and
the once active, outgoing pet is in grave danger.
Treatment
If a blood test or the onset of symptoms alert owner and veterinarian to the presence of this devastating parasite, treatment is possible
and successful if the disease has not progressed too far. The first step is to evaluate the dog and treat any secondary problems of heart
failure or liver or kidney insufficiency so that he can withstand the treatment. The next step is to kill the adult worms -- with an arsenic
compound. The drug is administered in two doses each day for two days, followed by several weeks of inactivity to give the dog's
system a chance to absorb the dead worms. Exertion can cause the dead worms to dislodge, travel to the lungs, and cause death.
Six weeks after the administration of the drug to kill the adult worms, further treatment to kill the microfilariae is needed. The dog
is dosed daily for a week, then the blood test is repeated. If microfilariae are still present, the dose can be increased. Follow-up studies
should be done in a year.
Prevention
Even if the dog, the owner, and the owner's pocketbook survive the treatment, the dog can be reinfected the next time a mosquito bites.
So, before mosquito season opens again, owners should have their dogs tested for heartworm and placed on preventive. Most
veterinarians use two tests before declaring a dog free of heartworm; the first test checks for microfilariae in the blood and the second,
done with the same sample, checks for adult worms in the heart that can be present even without the larvae in the blood.
Preventive doses can be given daily or monthly and are only available from a veterinarian. Some of the drugs also rid the dog of other
parasitic worms. Many veterinarians recommend and many owners use a year-round heartworm prevention program to guard against
the occasional mosquito flying about in southern Ohio's relatively mild winters. If your dog has already had his yearly check-up, call
your veterinarian to schedule a heartworm check. If he's due for yearly vaccination, be sure to include a heartworm check in the visit.
