My oldest son and I took our family dog to a veterinarian on a Saturday morning for a rabies booster shot after discovering a recently deceased opossum the night before outside the rear porch. There was no apparent contact between our dog Sammy and the opossum, and although any mammal can be infected with rabies, opossums are not considered a high risk for transmitting the virus.

Nevertheless, it seemed that being safe rather than sorry was far and away the best course of action.

That conviction has been formed after nearly three years of service to Orange County that includes the responsibility for investigating rabies exposures and controlling the spread of this fatal disease. Since I became the director of Orange County Animal Services, more than 60 cases of rabies have been confirmed in Orange County: 19 in 2007, 27 in 2006 and 23 in 2005. Those figures mirror trends throughout the state and region related to what is sometimes simply called "raccoon rabies."

So far this year we have had nine confirmed rabies cases -- and six of these occurred in the month of May.

There is much public awareness of rabies itself as a result of concerted efforts to prevent virus exposure to the public and its animal companions. But far too often we find that awareness of many of the most important and time-sensitive legal requirements concerning rabies is not as widespread. And we know from our experience that this can have dire and heart-wrenching consequences for pets and their owners.

It is too often assumed that a vaccinated dog or cat is safe and protected against rabies regardless of exposure to rabies carriers or rabid animals. What many pet owners do not understand is that staying up-to-date on regular vaccinations is not enough if exposure or suspected exposure occurs.

Even a dog or cat that is vaccinated must receive a booster rabies vaccination within 72 hours of an exposure, according to North Carolina law. North Carolina general statutes require animal control and public health authorities to enforce this three-day time requirement in their effort to control rabies.

Under the law, if a "booster dose of rabies [is not given] within three days of exposure," a vaccinated dog or cat must be treated in the same way as an unvaccinated animal to ensure human health. That means, according to the same statute, that the animal must be either immediately "destroyed" or quarantined for six months (which usually is done at a veterinary clinic at the owner's expense).

There is also too little awareness that each of those undesirable outcomes requires that a dog or cat must have received its initial rabies vaccination "more than three weeks prior to being exposed." Otherwise, under the statute, the animal is not recognized as vaccinated. Again, such an animal must be quarantined for six months or destroyed. The basis of this requirement is that the vaccine does not provide protection from the rabies virus until 21 days after it is given (since it takes that long for the animal to develop effective immunity in response to the vaccine that it received).

The good news, in this regard, is that this is only true if it is the very first (or initial) rabies vaccination an animal receives from either a veterinarian (who can offer one-year or three-year vaccinations) or a certified rabies vaccinator (who can only offer a one-year vaccination). If a cat or dog has an expired rabies vaccination, the animal is considered vaccinated immediately after a booster vaccination because a rapid anamnestic (or immunity) response is expected.

All of the aforementioned requirements are part of North Carolina's rabies laws. As such they are no different than the most basic requirement of these laws -- namely, that "[t]he owner of every dog and cat over four months of age shall have the animal vaccinated against rabies" (N.C. General Statute 130A-185). These laws are all imperative in the sense that they must be followed by any and all agencies responsible for these laws.

Of the many ounces of prevention we consider as responsible pet owners, none has more weight in public health than vaccinating our dogs and cats against rabies. But we must be no less sure that our animals always receive a rabies booster shot within 72 hours of a possible rabies exposure, whether it involves a raccoon in the yard with a family dog or a bat in the house with a cat that is kept indoors. And each of us would do well to be sure our dogs and cats have no opportunity to have a rabies exposure for 21 days after their initial rabies vaccination, and indeed, that their vaccinations are uninterrupted throughout their lives.

By way of conclusion, I should make a final observation about opossums. In North Carolina, they are not considered a high-risk concern in regard to rabies and its transmission. High-risk species for rabies transmission include skunks, bobcats, coyotes, foxes, bats and certain large rodent species. Testing opossums for rabies is only done in certain circumstances, in consultation with the N.C. Division of Public Health's Veterinary Public Health Program.

For information and resources about rabies, including a schedule of low-cost rabies vaccination clinics, see www.co.orange.nc.us/animalservices/rabies.asp. Information about the clinics is available by calling (919) 245-2075.