Lynn Vogel, a homemaker in the Annapolis suburb of Arnold, won't soon forget the night a couple of weeks ago when she applied some Blockade, a pet flea-and-tick repellent made by Hartz Mountain Corp., to her three Maltese -- Sasha, Veronica and Archie.

"Around 2 in the morning, they woke me up crying and howling. I walked in to where we keep them. They had diarrhea, had thrown up everywhere, and were hyperactive -- they were like gnats," Vogel, 36, said yesterday. "They could not be calmed down. They were sick. I thought, 'What did I do that was different?' "

She decided it was the Blockade, a new, popular and aggressively promoted product that she had used for the first time. After calling two poison control centers, Vogel fed the dogs some grass to keep them regurgitating and then washed them down in the bathtub -- both to get as much of the spray out of their systems as possible. All the dogs fully recovered.

"Although I have not had, except for one cat, a specific case where I knew absolutely without doubt that the illness was Blockade-related, I don't recommend using it," Vogel's veterinarian, Linda de Chambeau, said yesterday.

De Chambeau, who practices in Crofton, Md., only talked to Vogel over the phone, so she can't say authoritatively that the poisoning was a result of Blockade. "But I've had suspicions in two other cases," she said, "and heard reports from other veterinarians that indicate it is not a safe product to recommend." Hartz did not return repeated calls for comment yesterday, but the company has denied any link between Blockade and animal deaths.

De Chambeau's clients haven't been the only ones having problems with Blockade. The Environmental Protection Agency says the spray -- which is available for both dogs and cats -- has been implicated in the poisoning of at least 201 dogs and cats, 26 of whom have died.

The majority of these cases involved kittens, which could indicate they are getting more pesticide per pound than full-grown cats. Blockade's label, which says that "Highly sensitive animals may occasionally experience some discomfort from any pesticide. If this occurs, discontinue use," doesn't make any reference to the size of the animal being sprayed. In Vogel's case, she only put a "spurt" of the repellent on, she said, and then combed it through. "It was not a drenching," she said.

EPA pesticide spokesman Al Heier said there would "probably" be an interim announcement today regarding Blockade. "We've got quite a few more reports on this than on any comparable products," he said. "Veterinarians are getting more and more concerned. Evidently it's quite a big issue and we are taking it seriously."

The minimum the agency is expected to do is at least temporarily require Hartz to change the label on the repellent, making clear that consumers should use the product very sparingly and infrequently, and be especially careful using it on animals less than a year old.

The agency also is expected to say it will continue to research the issue. (The EPA said yesterday Hartz has "done everything that we asked them to do," and added that mandated label changes for chemical products are a fairly routine matter.)

Recently, the number of complaints about Blockade has increased. The National Pesticide Telecommunications Network in Lubbock, Tex., said that in the past couple of months, 100 people have called complaining about Blockade.

The Illinois Animal Poison Information Center (which, despite its name, is a national toxicology hot line) says it has received 339 complaints about Blockade, many in the past month. These complaints will eventually become part of the EPA's total, which presently includes cases up to Aug. 31. About 70 percent of the center's complaints were at least somewhat consistent with the general pattern.

"Not all the cases {of trouble with Blockade} are being reported to us. Our phone number is not widely known," said resident toxicologist Anita Kore. "We're getting specific inquiries by trade name, with animals showing close association between the use of the Blockade and the consistency of clinical signs" of trouble, which can include vomiting, muscle tremors, increased salivation, incoordination, depression or hyperactivity, loss of appetite, trouble breathing, skin irritation, seizures and death.

Hartz, based in Harrison, N.J., told the EPA that the number of poisonings is understandable, given the tremendous amount of Blockade being sold -- about 5 1/2 million cans. EPA spokesman Heier disputed that reasoning, saying "there's no question we've had ... more complaints than normal," even taking the high volume of sales into account.

"We're not questioning {Blockade} is having adverse effects, but under what conditions? We don't have a whole lot of data on these reports," he said. "We're trying to determine whether or not ultimately this product is too toxic to be used on animals."

Two of the chemicals in Blockade -- Fenvalerate and DEET -- have never been used in combination on dogs and cats, he added. "Maybe there's something here that we just haven't seen. Animals are having adverse effects, and it's not happening from nothing."

Meanwhile, the Illinois Animal Poison Information Center makes this general recommendation with regard to all animal insecticides: If used for the first time, only a small portion of the animal should be sprayed to see how the animal reacts.

"They're meant to be poisons," said toxicologist Kore. "Animals are susceptible to problems, depending on their sensitivity and the amount they're exposed to."