Education Center

Why Do Dogs Need Shots? protect your dog from canine diseases

Learn why tests and prevention are vital protections against:

• Distemper and Parvovirus

• Respiratory Disease and Kennel Cough

• Heartworm and Rabies

To help your dog stay healthy and happy, you should both visit your veterinarian at least once every year. This annual visit is an opportunity for your dog to have a thorough physical examination.

With a quick series of tests and vaccinations, your veterinarian protects your dog against serious, often fatal, diseases. As a concerned dog owner, you should know what these procedures provide for your dog. With regular health care and a safe lifestyle, your dog can be with you for many years!

How vaccinations protect your dog

Vaccinations are necessary, inexpensive insurance. Even dogs who spend most of their time indoors are exposed to infectious diseases and should be vaccinated regularly.

Vaccines for pets work like vaccines for humans:

  • A vaccination against a certain virus is actually a small, slightly altered dose of the virus itself. Your dog’s body reacts to the vaccination by building up antibodies.
  • These antibodies circulate in the bloodstream and protect your dog against a real infection. But these antibodies will eventually weaken and die. An annual revaccination, or “booster” shot, is necessary every year to continue the protection.
  • With these injections, your veterinarian can help you and your dog avoid the pain, anxiety, and cost of many serious canine infections. And for some of these diseases, there is no treatment – only the prevention offered by vaccinations.

The primary vaccination your dog receives every year is a booster of the “puppy series” given when your dog was about six weeks old. This injection, known as DHLP/P, is given to young puppies in a series of three or four visits, spaced at three-week intervals. An adult dog needs the single DHLP/P booster every year.

This combination vaccination protects your dog against canine distemper, hepatitis, leptospirosis, parvovirus, and parainfluenza.

Canine Distemper Virus

EFFECT: Highly contagious and very often fatal, distemper affects your dog’s respiratory, digestive, and nervous systems. The virus is most common in puppies up to six months old, but dogs of any age are in danger of infection if they are not vaccinated.The first stage of distemper is signaled by cold-like symptoms: coughing, sneezing, discharge from the nose and eyes, and a lack of energy. The dog will also be highly sensitive to light. There may be a high fever for two or three days.

The fever will return a few days later, along with vomiting and diarrhea. The discharge from the dog’s eyes and nose becomes yellow, and the dog loses appetite and weight. Finally, the virus attacks the nervous system, causing the dog to pace, shake, and possibly experience seizures.

The few dogs and puppies that recover are often left with severe nervous disorders (uncontrollable shaking, tilted head, awkward manner of walking).

CAUSE: Distemper is spread to other dogs and puppies through direct or indirect contact with infected urine, saliva, or other body fluids.

Viral Hepatitis

EFFECT: Hepatitis, which primarily affects the liver, has symptoms which vary from a slight fever and discharge from the eyes to severe depression and abdominal pain. A high fever can last up to six days and may cause convulsions. Complications may include severe bleeding which is usually fatal.

CAUSE: The hepatitis virus is shed in the body fluids and stools of an infected dog. The virus most often affects very young puppies and very old dogs.


EFFECT: Contagious to both animals and humans, a leptospirosis infection in dogs is often without early symptoms and can go unnoticed until the condition is serious. If left untreated, the virus usually leads to a severe kidney infection which is accompanied by weakness, vomiting, high fever, loss of appetite and extreme weight loss. The dog can be left with serious kidney and liver damage, and the virus can be fatal.

CAUSE: Even after recovery, an infected dog can still shed the virus in the urine. Since the virus is then spread to the many places the infected dog urinates, the chances are very high that your dog can come in contact with the virus.


EFFECT: Parvovirus is the most common fatal virus for dogs. The infected dog or puppy suffers from severe bloody diarrhea, vomiting, and dehydration. The dog can die within three days. In a very young puppy (four to eight weeks old), the virus attacks the heart and can kill the pup within twelve hours – with little or no warning.

CAUSE: Parvovirus is spread through the urine, stool, saliva, and other body fluids of the infected dog. The virus can live on a surface for weeks and is very difficult to destroy.


EFFECT: Parainfluenza is a dangerous, very contagious respiratory disease. Symptoms include a harsh dry cough, loss of appetite, runny nose and eyes, and depression. If neglected, the infection causes serious damage to a dog’s respiratory system and can be fatal.

CAUSEPuppies and young adult dogs, or any dogs in a weakened condition are most likely to be infected with parainfluenza. The virus is airborne, so normal cleaning and disinfection of surfaces doesn’t always eliminate the risk of contamination. Chances of infection are greatest when a dog is kenneled with many other dogs.

Bordetella (Kennel Cough)

The Bordetella bronchiseptica vaccine is highly recommended each year to protect your dog against the Bordetella bacterial infection known as “kennel cough.” Many veterinarians now use an intranasal bordatella vaccine (sprayed into the dog’s nose) instead of an injection.

EFFECT: If the Bordetella bacteria is not combined with any other infection, a dog with kennel cough shows few symptoms. The primary sign is a stubborn dry, hacking cough or deep, harsh coughing accompanied by gagging (which may produce some foamy mucus).

Like the common cold, kennel cough cannot be “cured,” but antibiotics may be prescribed to treat or prevent a secondary infection (parainfluenza is often contracted along with Bordetella, creating a more serious infection). Kennel cough does weaken a dog’s resistance to other disease.

CAUSE: Normal cleaning and disinfection of surfaces cannot always eliminate these stubborn bacteria. Kennel cough flourishes where dogs are kenneled with many other dogs. In fact, the vaccine will probably be required before your dog is exposed to the stressful conditions of surgery, boarding, or grooming services.

Why your dog needs a rabies vaccination

An annual rabies vaccination is required by law for every dog and puppy, beginning when the pup is four months old. Even if your dog lives primarily indoors, you and your dog both need protection against rabies.

EFFECT: Rabies is a painful, fatal infection of the nervous system which affects warm-blooded animals… including humans. An infected animal will be stiff or paralyzed and will not be able to swallow properly (causing the heavy drooling we associate with a “mad,” or rabid, dog).

The final stage of the disease causes intense sensitivity to noise and movement which causes the animal to behave abnormally out of pain. A sick animal, which would normally avoid pets and people, may approach and attack anything (or anyone) that moves.

CAUSE: The infection is spread through the saliva of an infected animal (usually a fox, skunk, raccoon, bat, cat, or dog), so your dog can be exposed to rabies by a bite or scratch. So can you!
There is no cure for an unvaccinated dog infected by rabies; a vaccination is the only protection for your dog and for you against this serious disease. And it’s the law!

Why is it important to test for heartworm disease?

Heartworm disease is a serious infection caused by a parasite that lives in your dog’s heart. Because the infection is spread by infected mosquitoes, there is no vaccination for heartworm disease. However, there are tests and medication to help protect your dog from this potentially fatal disease.

EFFECT: Serious damage has already been done to your dog’s heart and other vital organs before symptoms of heartworm disease appear: coughing, fatigue, labored breathing, and general weakness. Any additional infection will place even more stress on an infected dog’s weakened system, exaggerating the symptoms of usually simple illnesses. Left untreated, a dog infected with heartworms will die from the damage.

CAUSE: When an infected mosquito bites a dog, the eggs or larvae travel through the dog’s bloodstream and into the heart. After about three months, they mature into adult heartworms. The adult female worms can grow to ten inches long, clogging the heart’s chambers.

Within three more months, the adult heartworms will produce microscopic immature heartworms which circulate in your dog’s bloodstream. (Any mosquitoes which then bite your dog will carry those heartworm larvae to yet another dog…and the deadly cycle continues.)

TESTING: To test for heartworms, your veterinarian uses a microscope to search for immature heartworms in a small blood sample taken from your dog. (If the immature heartworms are not yet present, it may take further testing to diagnose the infection.)

Your dog MUST be tested before taking any preventative medication for heartworms. A dog who already has heartworms can die from the preventative medication.

If the tests are positive, treatment is necessary to save your dog’s life. Treatment can be lengthy, expensive, and possibly dangerous for your dog. Your veterinarian will choose the treatment method appropriate for your dog.

PREVENTION: If the tests are negative, then there are no heartworms present in your dog’s bloodstream. Your veterinarian can prescribe preventative medication which will prevent heartworms from ever reaching your dog’s heart.

Some of these medications are designed to be given monthly; others must be given every day. Whichever type is prescribed for your dog, you must give the medication ON SCHEDULE – if you don’t give it regularly, your dog is not protected from heartworms. Follow the doctor’s instructions for dosage of the tablet, liquid, or chewable treat prescribed for your dog.

Preventing heartworm disease is cheaper and safer than treating it.



This information is part of the Atlanta Humane Society’s SmartHeart Educational Series.

The AHS depends on friends to provide funding for our services and programs of animal aid, support for individuals with animal related problems, and community animal issues.

The Atlanta Humane Society and Society For Prevention Of Cruelty To Animals, Inc. is a private nonprofit organization for the purpose of preventing cruelty, relieving suffering, and providing humane treatment of animals. The Society’s mission is to eliminate causes of animal suffering with an emphasis on education and the human/animal bond.