Local veterinarians are divided over how serious the situation is now, but most say that heartworms, an often-fatal canine disease, could become a problem in San Diego County.
Helen Green is a veterinarian at North Park Veterinary Hospital in Hillcrest. Her clinic has documented three cases within the year. Before, the disease was virtually non-existent in the county.
The difference, say Green and other experts, has more to do with sociology than veterinary medicine. As more and more people move into the area, bringing with them dogs from the Midwest and Southeast--where heartworms are at epidemic proportions--San Diego is an area of greater risk.
The threat of heartworms is serious enough, officials say, that the California Veterinary Medical Assn. recently launched an ad campaign with San Diego as one of two target cities. Sacramento, the other, has a much higher incidence of canine heartworm disease.
"As more and more Americans travel around the country with their dogs," the ad reads, "heartworm disease literally travels right along with them. Right into California."
Even so, some local vets scoff at reports that San Diego could become a heartworm hot spot. Gary Rose, immediate past president of the San Diego County Veterinary Medical Assn., said flatly that canine heartworm disease is not a problem here and probably won't become one.
Rose said the local association recently conducted a study of more than 200 dogs and none turned up positive. He added that, in studies dating back to 1982, no native dogs tested positive for heartworms.
The seriousness of the problem is, however, a bone of contention among veterinarians. Green said that her North Park clinic tested more than 500 dogs in the past year, out of which came the three positives.
Because of what she called the high transience in the county, more positives are likely. She said several cases had turned up recently at a clinic in Encinitas.
Carried By Mosquitoes
Heartworm disease is carried by mosquitoes and, logically, is worse in areas of the country where mosquitoes are most abundant. In infected dogs, worms invade the pulmonary arteries on the right side of the heart. Male and female adult worms produce offspring known as microfalaria, tiny parasites that float under the capillaries.
The transmission of the disease works this way: A mosquito bites an infected dog. The microfalaria produce a larvae that makes the mosquito an intermediate host. The mosquito bites an uninfected dog; the parasite enters its bloodstream and, ultimately, invades its heart. One dog biting another cannot produce heartworms--the mosquito must be intermediary.
Heartworm disease cannot be contracted by humans, scientists say, but is similar in nature to malaria, which is also spread by mosquitoes. Cats can also get heartworms.
One of the problems in treating infected dogs is that symptoms don't materialize until six months after the first bite. Janice Sick, a veterinary technician at North Park Veterinary Hospital, said the prognosis for heartworms is "always guarded."
Costly, Painful Treatment
The treatment, she said, is costly for the owner and grotesquely painful for the dog.
"It's very unfortunate. It involves hospitalization and intravenous injections of arsenic. We often see severe complications with adult worms dying and clogging the blood vessels. The animal can have difficulty breathing. If allowed to become too active in recovery, the animal can die.
"Usually, the dog stays in the hospital 72 hours, then goes home under house arrest or cage confinement. We recommend that the dog stay still. Finally, the adult worms dying inside are a sign that the worst is over."
The best treatment, experts say, is prevention--the focus of the effort in San Diego. Sick described prevention as "the oral administration of a tablet given either daily or once every 30 days. We recommend that all puppies start prevention at 4 months of age. Puppies over 6 months need to be tested prior to taking the (preventive) medication. I'd call prevention reasonably effective. But we do recommend annual testing in all dogs."
Preventive medication costs anywhere from $16 to $30 for a six-month supply, Sick said. If the animal contracts the disease, she said treatments can be exorbitant--anywhere from $600 to more than $1,000 from beginning to end.
Can Strike All Breeds
Canine heartworm disease is not selective, she said. It strikes Pekingese as easily as German shepherds. Short-haired, smooth-coated dogs are, however, more susceptible because mosquitoes have an easier time biting them.
Gary Rose, whose practice is at the Cabrillo Veterinary Hospital on Point Loma, said: "Our advice is that, if the animal doesn't leave the county (on a vacation with its owner), we suggest doing nothing." Rose recommends prevention only if an out-of-state trip is in the offing.