Are you poisoning your pet?

by Catherine Woulfe / 07 February, 2013
Photo/Louis Trerise

Adverse reactions to flea treatments have been soaring, prompting concerns about just how safe they are for our animals.

Pet owners in the hot and humid parts of New Zealand are midway through another summertime war on fleas – desperately bombing and spraying, shampooing and powdering, and squeezing tiny “spot-on” tubes between furry shoulder blades. But concerns are growing, here and overseas, about just how safe our anti-flea arsenal really is.

A file of adverse reactions – obtained under the Official Information Act – shows hundreds of cats and dogs are becoming sick after being dosed with popular flea treatments, and the number of reported problems has risen dramatically.

In the United States, authorities became alarmed five years ago when reported side effects to spot-on flea and tick treatments spiked from 28,000 in 2007 to 44,000 in 2008, including 600 deaths. Class actions have been launched in the US against many of the major spot-on manufacturers, alleging that the products are not as safe as marketing and labelling would have owners believe.

New Jersey lawyer Michael Green, who is leading some of that litigation, says the lawsuits cover “pretty much the entire industry”. He says he has received dozens of late-night phone calls from distraught owners.

“Their dog’s just died and they’re on the phone with me and they’re saying, ‘I didn’t know this, my vet never told me this, I can’t believe this has just happened, I basically just killed my dog.’ It’s tragic.”

He says it should be made clear that the active ingredients in most of the modern treatments are neurotoxins and that “adverse events include paralysis and death”. He believes it is “absolutely mind-blowing” that there have not been more independently funded studies on the products. “It’s such a huge, huge moneymaker for these pharmaceutical companies and the vets. It’s over an $8 billion a year industry worldwide.”

However, companies approached by the Listener said each product goes through a stringent research phase, conducted by university scientists, which is then audited by independent reviewers before the product can be put on the market. Companies often continue to research their products’ safety and efficacy after release.

The adverse-reactions file

In New Zealand, the Ministry for Primary Industries’ Agricultural Compounds and Veterinary Medicines Group (ACVM) maintains the adverse-reactions file, which covers all flea treatments, including spot-ons, pills, shampoos and powders, and treatments that also kill ticks and worms.

Since January 2004, reports on more than 800 cats and dogs have been lodged, mostly about side effects. Until 2008, fewer than 20 reports a year were received. But in 2009 that doubled to 40 and in 2010 it tripled to about 120. For the past two years the numbers have held steady at around 130.

Vets suspect the true number of incidents is higher and many don’t make it onto this official list. “It’s really, really difficult to know what’s going on out there,” says Lyn Thomson, vet and founder of the Raw Essentials clinic in Grey Lynn, Auckland.

If a product produces an adverse reaction, vets or owners can report this to the company, which is then obliged to tell the ACVM. But vets say there are all sorts of reasons reports are not made. “I suspect it’s under-reported,” says Invercargill vet Catherine Watson, who heads the Companion Animals Society, “because there’s always going to be a bunch of people out there that will just shrug it off.”

Owners might not link symptoms with the flea treatment, especially as more serious side effects are often not listed on labels. Even if they do suspect a link, many owners don’t know they can make a report or how to go about it.

Kathy Parton, a senior lecturer in small animal medicine at Massey University, says our data is poor. She would like to see a national veterinary poisons centre set up for reporting adverse events and accessing information. She floated this idea two years ago but says funding is the sticking point.

In the US, the Environmental Protection Agency (EPA) is taking tentative steps towards a centralised system that will make it easier for vets to report problems. This follows a year-long safety review by the EPA and Health Canada that found that small dogs – such as chihuahua, bichon frisé and dachshunds – were the most vulnerable to side effects, and that many owners were not following the instructions. In particular, they were using dog products on cats, which are much more sensitive to the treatments.

The EPA has since told companies to include clearer warnings on labels and to add more information about possible adverse events.

The New Zealand file

Nineteen of the cases on the New Zealand file involved pet deaths. Most of the rest were relatively minor – such as temporary hair loss and skin irritation at the application site, or vomiting and salivating. And some were the result of owners not following instructions.

But some pets became seriously ill, developing rashes or diarrhoea, becoming lethargic or going off their food. Others had neurological symptoms such as wobbly legs, convulsions, seizures or disorientation. Some animals were temporarily paralysed, or started “stargazing” – tipping their head a long way back and holding it there.

The flea-treatment companies concede many of the minor problems were “probably” caused by their products. But they generally distance themselves from the more extreme cases, saying not enough information was provided, or suggesting other possible causes.

Only three deaths were “probably” linked to flea products: a dog that was given two doses of the old-fashioned insecticide permethrin, a cat given something containing pyriproxyfen and permethrin, and a cat poisoned by a few drops of treatment meant for extra-large dogs.

The ACVM says the recent increase in numbers of adverse reports “may not reflect a significant trend and could be due to a number of different reasons”, including more products on the market, more people buying and using the products, more awareness of how to report adverse events and more vets reporting incidents. However, the officials do not track sales data, so they have no way of knowing whether rates of side effects are increasing or whether certain products are causing a disproportionate number of reactions.

The companies all insist their products are thoroughly tested and safe and effective when used as directed, and that only a tiny proportion of animals will experience side effects. Many vets back them up, saying that they have more complaints about efficacy than side effects, and that as with any drug, animal or human, both sorts of complaints are to be expected.

Perks of the job

The New Zealand flea and tick treatment market is worth $13-14 million a year, according to a 2010 AgResearch report. Vets say they usually sell products at the recommended retail price, a markup of roughly 80%. They all insist this does not get in the way of their top priority: making sure animals have the safest and most effective treatment and that owners have the right advice.

But at some clinics, staff who sell flea treatments at reception have taken part in incentive schemes run by the companies. One vet nurse, who did not want to be named for fear of compromising her career, says this used to happen “absolutely all the time”. Two years ago this nurse started work at a clinic that doesn’t let sales reps through the door. But she says freebies, vouchers and competitions were commonplace at her previous workplace.

She remembers two specific Advantage promotions linked to how much product the vet nurses ordered. One rewarded the seven or eight staff with petrol vouchers of $20 or $30 each. The second scheme saw the six vet nurses get about $100 each in Bendon vouchers.

“It was a great perk,” she says, and there was never any discussion about ethics. Bayer, which makes Advantage, said in a statement that it voluntarily brought in rules in early 2009 that stopped this sort of promotion.

Companies also organise “best stand” competitions, where clinics decorate product displays with balloons and banners, and the top clinic wins hampers or bottles of wine. Roger McKinley, a senior vet at Vet Services in Hastings, says that sort of promotion is fine. But “getting a personal kickback is not the right way to go for a vet clinic, that’s for sure”.

Resistance is inevitable

Vets say eventual resistance to flea treatments is part and parcel of this particular arms race. “That’s why they keep bringing out new products,” says Thomson. I can hear [owners] throughout the clinic saying, ‘I’ve used X, that’s not working; I’ve used Y, that’s not working.’ The next thing is ‘well, here, try Z’. It might work for a year but it doesn’t seem to work the next. It’s just chaos.”

The companies, and most vets, say it’s crucial to keep up flea treatments year-round. But Thomson advises clients to minimise their use of chemical flea treatments, maybe dosing their pets for three months over summer, rather than year-round. Her focus is on keeping animals healthy – particularly their skin and coat – as this makes them less attractive hosts.

Watson tells her clients to alternate products each year, so if one generation of fleas becomes resistant to a certain product, it will be knocked out by the next one.

McKinley says most vets are happy with the current options. “The old drugs that we used – the organophosphates and pyrethroids – became ineffective.” Organophosphates are “nasty things”, McKinley says – poisonous to humans and pets. “I don’t think you’ll find any vet that sells an organophosphate or a pyrethroid.”

Cheap and nasty

But you’ll find both these chemicals cheaply available in the supermarket – in collars, shampoos and powders. Vets say they realise some owners can’t afford the pricier options, but warn against resorting to organophosphates or permethrins.

Cheap collars often contain diazinon, an organophosphate banned by French authorities in 2010 over concerns it was causing neurological problems in humans. When that news broke, some manufacturers voluntarily pulled diazinon collars from sale in England.

Another cheap option, Spotton, contains the organophosphate fenthion. Bayer, which makes Spotton, says the product is being phased out.

Permethrin is still in many shampoos, powders, sprays and spot-on treatments. Megan Alderson, of The Strand Veterinarian in Auckland’s Parnell, says, “In the 90s we saw lots of seizuring animals with permethrin products, so we would class them as unsafe in all forms, and there are heaps of safer products now – just not in the supermarket.” Alison Harland, a practising vet who teaches at Massey University, wants permethrin to be made a prescription-only product.

Five years ago, Australian vets concerned about the numbers of cats poisoned by permethrin products meant for dogs negotiated label changes. Labels there must now carry pictures of a cat with a red cross through it and the words “toxic to cats”. They must also warn owners to keep cats away from dogs that have recently been treated, and advise that “there are reports of toxic effects in cats which groom or contact dogs treated 48 hours earlier. Toxic effects include behaviour changes, drooling, tremors and death.”

Here we have no such warnings, although Butler says there has always been concern in New Zealand over the use of organophosphates and permethrins.

“I wonder sometimes if the debates are only really sparked when the adverse event is severe enough to cause a response, such as when pets die, and perhaps that level of momentum has not been reached in New Zealand yet?”

Pry before you buy

In the meantime, Thomson advises that with any flea treatment, owners should pry before they buy. She urges owners to run any concerns past a vet they trust rather than relying on staff whose job it is to sell products. And do your own research.

“The biggest point would be don’t be taken in by the marketing of products. Identify the active ingredient and do an online search to see what you can find out about it.

“At the end of the day, it’s a very personal choice as to what you’ll put on your animal. You know how much you hate fleas, how much you love your animal and how much you believe the information online.”

Scratch that

Until contacted by the Listener, pet-care company MasterPet featured on its website a blistering attack on chemicals found in some of its own flea treatment products. Sold in supermarkets under the VitaPet brand, many of these products rely on old-fashioned organophosphate or permethrin insecticides.

The MasterPet website warned owners to avoid these “harmful chemicals”. It says organophosphates “are still available to the public, without supervision or education, in many forms including sprays, powders, shampoos, flea collars and as topical applications on the back of the neck.

“The products will often have fine print warnings against using them on young, old or unwell animals. However, they are not safe to use in any situation, especially as other pets or people in the household may also come in close contact with high levels of the substances. Organophosphates can be readily absorbed through the skin and children are particularly susceptible to poisoning because of their small size and close proximity to pets.

“And also of importance – these chemicals are not very effective in killing fleas! Organophosphate collars in particular are ineffective and dangerous, and it astounds many animal health workers that these products are still available.”

VitaPet collars contain the organophosphate diazinon.

The MasterPet website also warned against using permethrins on cats. Yet its VitaPet range includes a permethrin powder and shampoo labelled for use on cats and dogs.

Asked to comment, VitaPet general manager Peter Garwood says the article does appear to be at odds with the company’s products. He understands why consumers might be concerned, but the article was written by a vet contracted to MasterPet and is “her opinion … not necessarily the opinion of the company”. (There was no disclaimer or author noted on the article.)

He says, “Let’s be fair, [vets] have an axe to grind”, regarding VitaPet products, as they compete with products sold in clinics.

All VitaPet products comply with regulations and are tested for safety and efficacy, he says, but “there are better products available these days”, including the company’s new Evance range, which uses the same active ingredient as Advantage.

VitaPet constantly reviews its products and labels, Garwood says, and after concerns were raised last month, it will change the label of its permethrin powder to say “for dogs” only. It will also review the labelling of its permethrin shampoo. “We have a genuine desire to act in the best interest of pets.”

Keeping the fleas at bay

    • Keep your animal healthy, especially its skin and coat.
    • Groom pets and vacuum often; don’t assume that because you’re not seeing fleas, they’re not there.
    • Discuss flea treatment options with your vet. Read the instructions on any treatment first and follow them.
    • Never use dog products on cats, or split single doses meant for large animals between smaller ones. Check the active ingredients and never use permethrin products on cats. After treating dogs with permethrin, keep cats away from them for at least two days.
    • Make sure you’re around for 12 hours after using any flea treatment on your pet.
    • Watch for any behaviour changes – if in doubt, call your vet.
    • Garlic, pyrethrum, pine oil and tea tree oil are all toxic to cats. Consult a vet before using any natural remedy.
    • To make an adverse event report, talk to your vet, call the 0800 number on the packaging or go to


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