DISTEMPER (DAHPP) VACCINE

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8 Parvo Vaccination Options/Prevention

Distemper vaccine is often given in combination with other vaccines. Sometimes it is a five-way vaccine including adenovirus cough and hepatitis, parainfluenza and parvovirus. In areas where there is a high risk, a seven-way vaccine may include protection from leptospirosis and coronavirus.

Adenovirus Cough and Hepatitis
- Adenovirus Cough prevents hepatitis and respiratory disease and the vaccine is included with distemper.
Parainfluenza
- Parainfluenza vaccine is included in the five-way injection and is recommended for dogs who will stay in kennels, participate in shows or live in large colonies.
Parvovirus
- Parvovirus is very contagious, and the disease is often fatal even with treatment.
Leptospirosis
- Leptospirosis is a bacterial disease that is quite serious. Early treatment can prevent organ damage. This vaccine may be included in the seven-way vaccination.
Coronavirus
- Coronavirus is an infection of the upper respiratory and gastrointestinal systems. This is often included in the seven-way vaccination.
  
  Maternal Antibody: Our Biggest Obstacle

The biggest problem in protecting a puppy against this infection ironically stems from the natural mechanism of protection that has evolved. As mentioned previously, puppies obtain their immunity from their mother’s first milk, the colostrum, on the first day of life. This milk contains the mother’s antibodies against parvovirus and until these antibodies wane to ineffective levels, they will protect the puppy.

The problem is that they will also inactivate vaccine.

Vaccine is a solution of inactivated virus, either live and weakened (attenuated or modified) or killed. This virus is injected into the puppy. If the puppy still has adequate maternal antibodies, this vaccine virus will be destroyed just as if it were a real infection. There will be a period of about a week when there is not enough maternal antibody to protect the puppy but too much to allow a vaccine to work. (This period is called the window of vulnerability.) After that period, vaccine can be effective.

The next problem is that the age at which vaccine can be effective is different for each individual puppy.

To get around this, we vaccinate puppies in a series, giving a vaccine every 2 to 4 weeks until age 16 weeks. By age 16 weeks, we can be certain that maternal antibodies have waned and the vaccine should be able to take. It should be recognized that some individuals, especially those of well-vaccinated mothers, must be vaccinated out to 20 weeks (unless a high titer vaccine is used.)

After a puppy is born, maternal antibody levels drop by half approximately every 10 days. Puppies that were born first or were more aggressive at nursing on the first day will get more maternal antibody than their littermates.

Mother dogs vaccinated at approximately the time of breeding will have the highest antibody levels to pass on to their puppies.

Canine Parvovirus

Maternal A

A puppy with a bloody diarrhea could have a parasite problem, a virus other than parvovirus, a stress colitis, an intestinal foreign body, or may simply have eaten something that disagreed with him. It is important to confirm the diagnosis of parvovirus before embarking on what could be the wrong treatment.

The Fecal Parvo ELISA Test

The ELISA test has become the most common test for parvovirus in puppies. ELISA stands for Enzyme Linked ImmunoSorbant Assay. This sounds complicated and high tech but is actually the same type of technology that home pregnancy test kits use. The parvo ELISA test is also a kit and is performed in the vet’s office in about 15 minutes or less. There are many different brands and testing is sensitive in its ability to detect the actual presence of the virus in stool.

The test has some limitations that are important to realize. Recent vaccination with a live vaccine (the type of vaccine that is most effective) may interfere with the test results. This means that the test may detect the live virus from the vaccine and show a positive reading when, in fact, the puppy does not have a parvo infection. Classically, this interference occurs 5 to 12 days after vaccination so if a positive fecal ELISA test is obtained within this period after vaccination, additional tests may be recommended.
Further, the puppy could be infected but no longer shedding virus in its stool. Or the virus particles may be so thoroughly coated with antibodies that they cannot react with the chemicals of the test. In almost all cases, one can trust a negative ELISA reading but it is important to realize that no test is perfect.

The Drop in White Cell Count

Technologist prepares hematology slides for cell review

Recall that one of the first actions of the canine parvovirus is to inhibit white blood cell division in the bone marrow. The virus essentially turns the immune system off before making its deadly way to the GI tract. This is a feature of parvoviruses in all species, which means that a characteristic drop in white blood cell count is seen on a blood panel. This characteristic finding is especially helpful in the diagnosis of a recently vaccinated puppy as the ELISA test maybe positive from the vaccine but if the white count is normal, the puppy is probably not infected. The white blood cell count is commonly monitored in the treatment of a parvovirus case. If the puppy doesn’t go to the veterinarian until later in the disease course, it is possible to miss the white cell drop and not correctly make the diagnosis. Similarly, a puppy presented early in the course of infection may not yet have the white cell drop and sequential tests may be needed to confirm diagnosis.

Antibody Titers

There are two types of antibody titers that can be run: IgG and IgM. With the advent of ELISA testing, titers are not frequently used in making this diagnosis. The IgG titer is a more long-lasting antibody level. A high IgG titer would probably indicate active infection in a puppy that is old enough to generate antibodies and who has not yet received any vaccinations. Most of the time, the IgG titer simply reflects antibodies generated by vaccination. The IgM titer reflects recent antibody production so if a vaccinated puppy had not been vaccinated recently, a high IgM titer might indicate active infection.

Serum is prepared for lab testing

Because parvovirus infected puppies have frequently received vaccinations in their recent past and are frequently too young to generate their own antibodies (which is how vaccinated puppies get infected in the first place), these test results are difficult to interpret. It is easy to see why the ELISA test that directly detects the virus has become so popular.

Biopsy

Parvovirus lesions in the GI tract are of a classical appearance. There is no mistaking them under the microscope. Unfortunately, tissue samples of the GI tract are not readily available and most infected puppies are not good surgical candidates. Still, if a puppy has died and the cause is unclear, submitting samples of the GI tract can generally confirm or rule out a parvovirus diagnosis provided the tissue has not degenerated.

It is also important to realize that puppies with parvovirus infection may have concurrent intestinal parasites or may have swallowed foreign bodies.

There will be complicating conditions that must be monitored. This means that other tests will be required during the management of the parvo patient. The above tests are simply those that can be used to confirm the parvovirus diagnosis.

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