The common cold and influenza are part of winter. We may try to reduce their incidence with flu vaccines, hand sanitizers or other remedies, but they seem almost as inevitable as snowflakes in January.

What about our pets? What serious viruses are out there, not just during the winter, but all year? And what can we do to protect our pets?

Distemper, parvovirus and rabies are lurking in our backyards. Because we live in a semi-rural environment, it is important to remember that these diseases are carried by wildlife. Some of these viruses persist in the environment for months, impervious to seasonal temperature changes, sunlight or even household soaps.

Fortunately, vaccines are effective at preventing these diseases. Your furry family members rely on you to make sure their immunizations are up-to-date. Even pampered indoor pets are at risk because some of these viruses may be carried into your home on your shoes.

Contrary to popular belief, neither canine distemper nor feline distemper have anything to do with your pet's normal temperament. Canine distemper is caused by a paramyxovirus, which is related to the human measles virus. In fact, a canine version of the human measles vaccine was once used to temporarily protect young puppies against distemper. To add to the confusion, what is commonly known as "feline distemper" is actually not a distemper virus but a relative of the canine parvovirus, called panleukopenia.

Canine distemper may be carried by all members of the dog family, including coyotes and foxes. Other susceptible wildlife include skunks, raccoons and weasels. Since pet ferrets are related to weasels, they are at risk, too.

Animals infected with canine distemper have a plethora of possible clinical signs. These include fever, loss of appetite, behavior changes, circling, inability to walk or move the legs, vomiting and diarrhea, coughing and discharge from the nose and eyes. Canine distemper is sometimes called "hardpad disease" because dogs that recover may develop thickened foot pads.

Although distemper is fairly common in wildlife, it is a mistake to assume that an individual wild animal with neurological signs has this disease. Behavior changes and difficulty walking are also classic signs of rabies. If you witness this, stay away and call your animal control officer for help.

Panleukopenia, or "feline distemper," affects all cats, both domestic and wild. Raccoons, mink and pet ferrets can also become sick with this virus. Panleukopenia is highly contagious and deadly. Sick animals develop gastroenteritis and profound dehydration.

Canine parvovirus is a severe gastrointestinal virus of dogs, coyotes and raccoons. Symptoms include bloody diarrhea and vomiting. Dogs may deteriorate rapidly and die within two days.

Rabies is a serious virus that can affect all warm-blooded animals, including humans. Any abnormal neurological sign could indicate rabies. It is essentially always fatal. This disease is of such public health significance that the government has laws mandating rabies vaccines for all dogs and cats.

Many people do not realize there really is no cure, even for human cases of rabies. What is commonly considered to be rabies treatment for people is actually medical prophylaxis administered very shortly after suspected rabies exposure. Clinical signs might not appear for months. If a person waits for signs to occur, there is no cure, and death is inevitable. (There has been one exception. A few years ago, a girl in the U.S. was diagnosed with rabies and placed in a medical coma. She eventually recovered, but has permanent neurological deficits. This is the only case of rabies survival recorded in the world.)

All pets are susceptible, and their rabies vaccines should be kept up-to-date. Some owners of indoor cats erroneously believe their pet is not at risk because they do not go outside. Several years ago, I diagnosed rabies in a cat. The owners insisted it never went outside. When laboratory tests confirmed rabies, everyone who had been near the cat or visited the owners in the past few weeks had to immediately seek medical care.

We are fortunate to live in the world of modern vaccines. Canine distemper and parvovirus, "feline distemper" and rabies are all commonplace in our environment. This will not change because our local wildlife serves as a reservoir. Although these viruses are not curable, they are virtually 100 percent preventable with vaccines. Special blood tests called titers are sometimes an option for pet owners who wish to use vaccines as little as possible. Discuss this with your veterinarian if it interests you. Not every vaccine needs to be given every year. Your veterinarian can help you determine the schedule that is best for your pet.

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Dr. Heidi Bassler is medical director of the Veterinary Center of Greater Newburyport. Do you have questions for Dr. Bassler? Send them to ndn@newburyportnews.com.