Saturday, February 16, 2013

When Vaccines can be Dangerous to Rescue Puppies

If you have ever worked in an animal shelter, you are terrified of  Canine Parvo Virus (CPV) commonly called simply "parvo". It is enemy "number two" of the shelter world (behind too many pets and not enough homes).

Parvo was first recognized as a separate virus in 1978 and spread like wildfire. While proper vaccination is the first step toward eradicating it, the problem is, too many pets remain unvaccinated. The virus spreads through feces. The infected pet defecates on the ground, the feces decays into the ground where it can live for up to ten years. Another pet visits the same area or a person walks on that infected ground and often, takes the virus with them.

Parvo has two forms. The most common form is explosive, bloody diarrhea that causes extreme dehydration if not treated. There is no cure for parvo, only medical support. A puppy that has been diagnosed as positive by a parvo test must be hooked up to IV fluids, and all medication given through the IV port, in the fluids, or by injection. Giving medication by mouth to a parvo pup will usually result in vomiting. In my book, Secrets of a Vet Tech, I do show how I gave subcutaneous fluids (fluids given under the skin) to a pet, but it is rare that subcutaneous fluids will do enough to save one with parvo. Its not impossible, but it does not give the pet the best chance for survival. 

The second form I have only observed once in my career and that is when parvo attacks the heart muscle. The one incident I saw was in one of my foster pups. It was the quickest I have ever seen parvo cause death. It was just a matter of hours from lethargy to death.

Here's how a puppy's world is supposed to be like: In an ideal situation, a puppy is given his/her mother's immunity through breastfeeding. This immunity lasts up to about 8 weeks old. Vaccines are usually started at 6-8 weeks to keep the immunity up as mom's immunity dissipates. Vaccines are continued every 3 weeks until 4 months.

Its important to understand how vaccines work. Usually a tiny strain of the virus is introduced to the body. Sometimes the virus has been deactivated (often called "dead") which tends to be safer. The body recognizes an invasion, creates the weapons needed to fight it. Those weapons are antibodies. Each time the virus in introduced, the number and strength of the antibodies grow until they have formed a huge army that is capable of eradicating the virus. It takes time and repeated exposure to make the army strong.  

Taking a young (under 4 months old) well vaccinated puppy out to the park or public areas where other pets have been can still be dangerous. While the army is in training, it is not ready for the war.
 I always recommend waiting until at least 2 weeks after all vaccines are completed before venturing out to the doggie park.

Shelter puppies most often have not come from this ideal situation. Few have been vaccinated at all, and if so, it is often improperly. This doesn't mean however, that adopting a shelter puppy is going to guarantee that you will get a parvo puppy. Some will have a bit of acquired immunity from small amounts of environmental exposure or be young enough that mom's immunity is still working. 

Many years ago, when I was on the board of directors of a humane society that ran the local shelter, one of our big discussions and conundrums was what to do with the puppies? While proper sanitation with bleach or other anti-parvo cleaners can do wonders, you still will miss some place, some how. Ideally, the puppy would have been vaccinated 2 weeks before coming into the shelter, but we had no control over that. We couldn't afford to vaccinate them coming in only to put them to sleep when no one adopted them. And then there was the issue of did vaccinating drop their immunity just at the time they are exposed?

Just like with human children, vaccinating a puppy will not immediately give him/her immunity. Vaccinate a puppy walking into the shelter, the immunity drops temporarily as he/she develops the antibodies to fight the introduced virus. Expose that puppy to a strong strain of parvo from a sick animal, and that puppy isn't prepared.

Most shelters, it seems has found that fostering is the best option. Get those puppies out and away and into a more controlled environment. I believe this has made a world of difference in survival rates.

I do think one mistake is often made in this process. Once we take them out to foster them, we vaccinate too early. If they were surrendered today, not even taken into the general population, then yes, I can understand vaccinating them immediately. However, if they have had possible exposure or were found in a questionable environment, then I believe, vaccinating immediately is the worse thing you can do.

From the moment of exposure to parvo until you are "in the clear" is ten days to two weeks. Anything that reduces immunity during that time is dangerous. And what to vaccines do temporarily? Exactly.

When I started fostering for a local humane society a few years ago, the common practice was for the animals to be pulled from the shelter, taken to the vet, vaccinated, and then brought to my rescue, T.Paws. I lost a precious chihuahua, Zorro to parvo, but his sister lived. I lost Sophie to parvo (that attacked her heart), but her sister Maggie survived. I had a group of chihuahuas come in from a hoarding situation, and Pearl, who was over a year old, came down with parvo, but lived as did the other chihuahuas. The dogs had all been fine at the shelter. No symptoms of any problems. All the deaths and parvo cases came within days of the vaccine.

So I said enough. Any pet that was to come to my rescue from the shelter were not to be taken to the vet for vaccines. If they wanted to test for heartworm and deworm, fine, but no vaccines. When the pups/dogs arrived, they were only allowed to be within a certain area of my property. They could be with my permanent pets who were well vaccinated, but not in any area a stray could access. If they had not been dewormed at the vet, I dewormed, usually with Panacur. If no sighs of parvo were evident after 10 days, I vaccinated.

As of this post, I have not had any incidents of parvo. (Knock on wood).

Right now, I have a 4 week old lab puppy named Rocky. He was given to me by an older couple who found him in the street. He was a hungry boy when I brought him home. His digestive system is getting used to Puppy Chow and he is having some loose stool. He has been getting Panacur for two days now, and today he threw up round worms which is not unusual for any puppy. I've been giving him bits of yogurt which is a good way to give his tummy the proper bacteria to digest as it should. The loose stool is not surprising considering the diet change, but I still watch his every move looking for parvo signs. I am hoping, if I am correct about his age of 4 weeks, that mom's immunity is still working in him. My plan is to give him until two weeks before vaccinating and focus on getting his digestive system in good working order with regular meals and give his body time to adjust.

To keep updated on his progress, join me  at T.Paws Rescue on Facebook. If you are interesting in knowing more about vaccines, I covered it very thoroughly in "Secrets of a Vet Tech". I think you will be very surprised at what you will discover.

1 comment:

  1. Very informative! Most vets can't take the time to go into this level of detail on diseases and the complexity of the vaccination issue, and this kind of knowledge is SO important.