Pet ownership – risky business?
Sharing homes with pets is a way of life for many Americans-at least 60 percent by some estimates. And the companionship, affection and trust of pets can provide distinct health benefits for their owners. Studies described at a 1987 National Institutes of Health workshop linked life with a pet with:
* higher survival rates in patients with heart disease
* increased self-confidence and independence in psychiatric patients
* improved ability of children to interact with others. But if you’re a pet owner-or thinking about becoming one-you need to consider that these trusted companions can also present some very real health risks.
In addition to giving affection, the millions of household cats, dogs, birds, reptiles, and other small animals can impart diseases to their owners as well.
Zoonosis is a disease communicable between vertebrate animals and humans, and between different species of animals. Some of these diseases have been known for a long time. The ancient Greeks, for example, were aware that rabies could be transmitted through dog bites. And the bubonic plague that decimated the population of Europe in the 15th century bridged the gap from animals (mainly rodents) to people by way of fleas.
The list of known animal-transmitted diseases constantly changes, as improved diagnostic techniques identify zoonoses previously mistaken for more common exclusively human diseases. For example, in the 1960s, the role of felines in transmitting toxoplasmosis in their feces was discovered. In addition, travel to more remote parts of the world by people and the increased international commerce in exotic animals have added to the list of zoonoses.
Fortunately, most zoonoses are rare, and almost all can be treated once a diagnosis is made. Here’s a list pet owners should be familiar with:
* Toxicara canis, or roundworm, is a parasite that is carried most often by nursing dogs and their puppies, and less often by cats. Scientists estimate that virtually all puppies have roundworm.
Because children like to play in the dirt, they are most vulnerable to picking up roundworm; and the disease is transmitted through contact with the dog’s feces or soil contaminated with it. Symptoms of roundworm in humans are fever, headache, cough, and poor appetite.
So prevalent and well-established is the dog roundworm in our pet population that roundworm-free puppies can only be obtained by raising several generations in isolation or administering repeated high doses of anthelmintics (a type of drug that gets rid of intestinal worms) to the pregnant mother dog.
Diana Post, V.M.D., a veterinarian with the Food and Drug Administration, explains that much of the roundworm infection of the mother dog is non-egg-producing and does not contaminate the environment. However, it is more resistant to elimination with anthelmintic drug treatment than the egg-producing contagious type of infection found in the puppies. Egg-producing infections may be found in adult dogs, although less frequently than in puppies.
For this reason, many parasitologists recommend that veterinarians consider treating very young pups two to three weeks after birth (the time they would be expected to pass infected eggs in their stool). This can be risky, though, because immature animals, including dogs, are very sensitive to any drug therapy. Such treatment should only be undertaken if it is recommended by a veterinarian.
Both puppies and people can be treated with anthelmintics, a class of drugs used in both human and veterinary medicine.
* Toxoplasmosis is a disease produced by infection with the one-celled animal Toxoplasma gondii, a parasite capable of surviving in many different animal species. It is sometimes spread to humans through cat feces or dirt contaminated with cat feces. All breeds of felines, even wild jungle cats, can become infected with Toxoplasma gondii. The cat becomes infected by killing and eating small rodents. But most people contract toxoplasmosis not from cats but from eating raw or undercooked meat. Meat becomes infected because cows and sheep graze in pastures that have been contaminated by infected cats.
Toxoplasmosis infection is common and can infect almost all species of warm-blooded animals. But most infected people do not develop symptoms because, according to most estimates, about one-third of the world’s population has antibodies to the disease. (Infected persons with immune system defects or those receiving immunosuppressive therapy may develop a serious form of the disease.)
Symptoms in humans are fever, headache, swollen lymph glands, cough, sore throat, nasal congestion, loss of appetite, and skin rash. The disease can be treated with antibacterial drugs. Expectant mothers-especially those in the first three months of pregnancy-should be especially alert to the possibility of this disease because toxoplasmosis can cause miscarriage, premature births’ or blindness in unborn children. For this reason, pregnant women should not clean a cat’s litter box and should avoid eating raw or poorly cooked meat.
* Ringworm is a skin disease caused by a fungus, not by a worm as the name would imply. Dogs, horses, cows, and most commonly cats pass the disease on to humans. Only children pick up ringworm. “Long-haired kittens seem especially prone to ringworm,” says Post.
The fungus infects cat hair, and a youngster can contract the disease by petting the kitty. Ringworm can be diagnosed by exposing the animal to a Wood’s lamp, an ultraviolet light in which the infected hairs look green. Treatment for ringworm should be prescribed by the veterinarian caring for the pet.
In humans, infection usually occurs on exposed parts of the body, particularly the scalp, appearing as an inflamed, scaly lesion. Iodine-based soap or antifungal drugs cure the problem in humans.
* Psistacosis (parrot fever) is a bacterial disease that affects 130 species of domestic and wild birds, most commonly pigeons, ducks, turkeys, chickens, and parrots. Humans can get the disease from parrots or parakeets through contact with their feces and the dust from their feathers that accumulates in cages.
In humans, respiratory symptoms of cough and chest pain usually predominate, but other symptoms may include fever, chills, malaise, vomiting, and muscular pain.
Typical symptoms in an infected bird may include poor eating habits or droopy feathers. On the other hand, the bird may show no symptoms. Wearing a surgical or dust mask and rubber gloves while cleaning the bird’s cage will help protect against contracting psittacosis. A blood test can confirm the diagnosis of psittacosis, and antibiotics are an effective treatment for the disorder in both humans and birds.
* Lyme disease was first identified in the mid- 1970s in the town of Old Lyme, Conn. (See the July-August 1988 FDA Consumer, “Ticks Carry Lyme Disease Across U.S.”) According to the U.S. Centers for Disease Control in Atlanta, the disease has been reported in all but seven states, but is most prevalent on the East Coast.
Lyme disease is caused by a bacterium called Borrelia burgdorferi, which is transmitted to humans and other animals by tiny deer ticks. These ticks pounce on white-tailed deer, field mice, and other wild animals whose bodies are full of these bacteria. The tick sucks blood from these animals, becomes infected with the bacteria, and moves on to other animals or humans, biting and infecting them. You may also catch the disease from the family pooch, which can act as a tick trolley if an infected tick being transported by the dog latches on to you. However, keep in mind that only a small percentage of these pinhead-sized ticks are infected with the bacteria.
Because Lyme disease symptoms are vague and numerous and may mimic the symptoms of other diseases, doctors are increasingly relying on two blood tests to help with diagnosis-the ELISA and Western Blot test. The first sign of the disease is usually a bull’s-eye insignia-a small red pimple that later expands to form a ring-shaped rash. Other symptoms include flu-like aches in the joints, chronic fatigue, dizziness, shortness of breath, and a rash. Treatment with antibiotics in early stages is imperative to prevent the disease from progressing to more serious states linked to arthritic, cardiac and neurological disorders.
* Rocky Mountain Spotted Fever-now found in all parts of the country despite its name-is primarily transmitted by the American dog tick. You can pick up the disease if bitten by an infected tick-either from your dog or in the woods. Symptoms include headache, fever, and skin rash. As with Lyme disease, early diagnosis and treatment with antibiotics is crucial to prevent development of more serious consequences.
* Rabies currently is common in certain wild animals, including raccoons, skunks, foxes, bobcats, and bats. (See September 1983 FDA Consumer, Raccoon-Borne Rabies Spreads.”) Rabbits and rodents, including squirrels, are seldom infected with rabies. Worldwide, people most commonly are infected with rabies through bites from unvaccinated dogs. On the east coast of this country, where canine rabies has been controlled, the main source of infection is wildlife or cat bites.
Though rabies is most often transmitted by a bite from an infected animal it can also be spread through contact of an animal’s saliva with an open wound. Animals can harbor and transmit the rabies virus long before the animal itself shows signs of illness.
Rabies is almost always fatal. Vaccination of pet cats and dogs is imperative to keep the disease from spreading both to humans and to other animals.
If you are bitten by a cat or dog, check with the owner to make sure the animal’s rabies vaccine is current. Most states require that, regardless of their vaccination status, the dog or cat be quarantined for number of days to double-check for signs of rabies. In the case of a bite by a wild animal, a rabies vaccine should be administered as a precaution.
To try to prevent infection after a bite, clean the wound immediately with a strong jet of water, soap or detergent, and a solution of alcohol or iodine. In some cases, this cleansing will get rid of the virus, but it is always necessary to consult with a physician immediately to see if you need a series of rabies shots.
* Cat Scratch Fever. The cause of this disease has not been positively identified, but the source of infection is a cat scratch or bite. The resulting sore at the site of the scratch is slow to heal, and after one to three weeks, lymph nodes may swell and become tender and painful. Although uncomfortable, the disease is rarely serious. If it lingers, however, check with a physician, who may prescribe antibiotics.
More Familiar Infection
Animals also can be the source of some more familiar infections. Isadore Rosenfeld, M.D., clinical professor of medicine in the cardiology division of New York Hospital-Cornell Medical Center and author of Modern Prevention: The New Medicine, offers this example: Children in a particular family are plagued by sore throats, which, cultures show, are caused by streptococcal bacteria. Penicillin is administered and the infections are cured, only to reappear after a few weeks. There must be a carrier in the family, but who is it? Finally, someone thinks to look at the throat of the family dog, and the culprit is found.
Similarly, Salmonella bacteria may be transmitted to humans by animals. Salmonella infections cause mild to severe gastroenteritis, inflammation of the stomach and intestine that may cause diarrhea and vomiting. But such an infection can have much more serious consequences in very young children and the elderly, as well as in those whose immune systems are compromised, such as AIDS patients.
Salmonella can be carried by dogs and birds, but turtles present a special risk, so much so that in 1975 FDA banned the sale of “pet-sized” turtles with a shell length of less than 4 inches. (See December 1987-January 1988 FDA Consumer, “Risky Shell Game: Pet Turtles Can Infect Kids.”) A turtle from the wild is just as likely to have Salmonella as is a domestically bred one; thus, any turtle should be ruled out as a pet.
For that matter, any wild animal should be ruled out, says veterinarian Post. The fact that a wild animal would allow humans to approach it is reason enough to suspect impairment, perhaps due to disease. If for no other reason, the prevalence of rabies should discourage the notion of a pet skunk or raccoon.
Choosing a Pet
Despite these risks, the companionship of many kinds of pets can be safely enjoyed, with the exercise of common sense and some reasonable precautions. The first rule of thumb is to be certain that the pet you choose is healthy. A dull coat or drooping feathers and lethargic behavior are not good signs. You may want to check with a veterinarian or animal welfare organization for further tips on the physical appearance of the kind of pet you are considering.
In addition to looking over an animal with care, check out its surroundings. Are they clean? Are cages and pens kept free from animal feces? And, if you are dealing with a pet store, do the other animals appear clean and healthy? Once again, a veterinarian or local animal welfare organization can be a good source of information on reputable stores and breeders in your area.
Even if you don’t consult with a veterinarian before obtaining a pet, you will want to line one up to treat and care for your animal. This is an especially good idea if you have chosen a bird or more unusual animal. Some vets may specialize in the care of these animals; others may not include them in their practice.
An initial check-up is definitely recommended to be sure there are no problems that may have escaped the untrained eye. For dogs and cats, puppies and kittens, you will need to provide the vet all available information on inoculations and worming treatments.
Determine whether your vet has a procedure for reminding you when it is time for new inoculations. If not, set up a schedule and follow it carefully. You should also keep in mind that dogs and cats may be exposed to parasitic worms and need to be routinely checked and possibly dewormed regularly.
Here are some other tips for protecting your pet and your family:
* Keep cages or pens scrupulously clean and free from droppings.
* Remove solid waste from the cat litter box daily.
* Keep household pets clean and free of ticks and mites.
* Do not feed your pets raw meat.
* Discourage children from attempting to pet or handle unfamiliar animals because there is no way of knowing whether they are healthy. Moreover, some animals do not recognize such attempts as friendly and respond by biting.
* Never allow children to pet or handle a sick animal. And teach children to wash their hands routinely after handling any animal.
* Do not adopt wild animals as pets if they are injured. Call the local humane society or a wildlife rehabilitator who will take care of the injured animals.
* Avoid walking dogs in tick-infested areas during the summer months.
* Never use pet waste as fertilizer. This material actually has little fertilizer value, but can spread disease.
* Keep children’s sandboxes covered when not in use. Otherwise, they make tempting outdoor litter boxes for neighborhood cats.
* If your dog or cat has access to a wooded area, check the pet daily for ticks. If you find ticks, remove them carefully to avoid being bitten. Deer ticks, associated with the transmission of Lyme disease, are much smaller than dog ticks. Roller-type lint removers are effective in removing non-attached ticks. Writing in the Journal of Pediatric Infectious Disease, Philip Goscienski, M.D., notes that animal-transmitted diseases are all too often unsuspected and unrecognized. He adds that a physician treating a veterinarian or a zookeeper who is ill will be apt to suspect an animal-transmitted disease at once, but a pediatrician treating a child who recently received a puppy as a birthday present may not. When any family member is in, therefore, it is important to mention to the treating physician the number and kinds of pets in your home.
Being alert to the possibility of animal-transmitted disease and following some simple and sensible steps can do a good deal to remove the risks from pet ownership and permit you and your family to enjoy the pleasures.
Judy Folkenberg, staff writer for FDA Consumer, contributed to this article.
COPYRIGHT 1990 U.S. Government Printing Office
COPYRIGHT 2004 Gale Group