Q. You wrote that people should not give their dogs garlic to control fleas because it could cause anemia. I gave my dog fresh garlic for years. She had a horrible flea allergy and nothing else helped at all. Without the garlic she was miserable.
I kept telling my vet that the garlic was what was helping her, though he would never admit it. By the way, she lived to be 16 years old. You really shouldn’t knock the garlic.
A. Several other readers agree with you, including some veterinarians. One wrote: “I am a holistic veterinarian with 30 years experience. During that time none of my canine patients have had anemia from garlic. Onions, yes; garlic, no. I don’t want dog owners to worry unnecessarily.”
Onions can be toxic to dogs and cats because they contain n-propyl disulfide that can damage the membranes of red blood cells. Garlic also contains this compound, but it seems to pose less of a problem. Rely on your vet for advice.

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  1. CVT & Analytical Chemist

    Please skip the garlic-or at least not too much, please.
    It (along with onions) is/are not really good for them, and can be toxic/fatal in large amounts (esp. if cooked).
    Now- WHY?
    Onions and garlic (alliums) contain sulfur-containing compounds that successfully compete for the oxygen receptor on hemoglobin (the compound in blood that transports oxygen to the cells- VITAL for life).
    Hemoglobin takes oxygen from the deep alveoli of the lungs (across the capillary barriers there), and transports oxygen to the tissues, then cycles back to the lungs through the bloodstream to pick up more oxygen- again and again.
    Since sulfur competes MORE successfully than does oxygen (for that spot on the hemoglobin molecule)- hemoglobin is permanently converted to sulfo-hemoglobin, which CANNOT transport oxygen to the tissues. Worse- it’s not reversible (as is the oxygen-hemoglobin complex). Once the sulfur from the onions/garlic locks up the hemoglobin- it’s useless for future oxygen transport.
    So- your pet ingests a significant amount of onions/garlic (depends on size of the animal)- and looks just.fine….. for about 24-48 hours.
    That’s how long it takes for the conversion to take place.
    It’s even faster if onions/garlic are cooked, as more sulfur compounds are available due to the increased bioavailability of the sulfur compounds due to the degradation of the cell walls by heat/cooking. That’s why such a SMALL amount of cooked onions/garlic can be fatal!
    They then start to look lethargic, anemic, hypoxic (lack of oxygen)- because no oxygen is getting to the tissues (sulfur is tying up the hemoglobin!). An oxygen mask/hyperbaric environ will NOT help that much -since there’s no carriers in the bloodstream to get the oxygen to the cells!
    Bloodwork will show Heinz body anemia (little red ketchup-colored splotches on the blood cells!).
    They CANNOT make new hemoglobin fast enough to meet demand- and may not even make enough to recover (rest alone won’t cut it). This IS a medical emergency. They will not ‘rest up and get over it’.
    A transfusion + supportive care (~10 days worth, longer if older) is REQUIRED, and is about all you can do-though I defer to DVMs for the more technical aspects of the curative arc.
    You need to get functional hemoglobin into the animal (from the transfusion) ASAP so that the tissues aren’t starved whilst the animal is trying to recover and restart the hemoglobin-making machine (so to speak), which takes ~ 10 days of supportive care (REST, iron rich foods, warmth, hand feeding and watering as required- it’s NOT babying them to do so!).
    Even then- some don’t pull out of it (don’t start regenerating hemoglobin).
    Now- can you give tiny amounts of garlic and get away with it?
    Can you give tiny amounts of arsenic and get away with it?
    The answers are likely yes- but WHY?
    Personally- I steer clear!
    PS: NEVER EVER put additives in any animal’s water! (eg: vinegar mentioned above).
    If the animal is put off by the additive, they will stop drinking water- and dehydration sets up a cascade of issues that are likely worse than any problem you are trying to solve with the given additive!
    PURE, FRESH water (bowl rinsed & refilled with fresh clean water AT LEAST once daily) is the MOST cost-effective, EFFECTIVE way to stave off bad health.
    Do NOT put anything in an animal’s water that would cause them to drink less water!

  2. S.R.

    I’ve had many cats and dogs over the years and have found two things to be key in fighting off flea infestations: 1) the (careful!) use of diatomaceous earth in the living environment and 2) the use of a flea comb on the animals. The fleas will disappear over time and preventive applications of d.e. will keep them from returning. It’s that simple really – or at least it has been for me.

  3. Brian W.

    I adopted a fox terrier less then two weeks ago. He was starting to chew himself bloody because of fleas, so I took him to the vet. At first when I was told Garlic was toxic to dogs and damaging to the liver specifically-I didn’t buy it.
    After checking other professionals and reading the latest veterinary research there is no doubt, give your dog enough garlic to have any impact on your dogs flea situation, you are damaging their liver. In much smaller doses it is quite possible to boost your dogs immune response without doing significant liver damage-but you aren’t doing anything for flea and mosquito issues and your still taking a chance. IF you talk to vets who stay abreast of the latest studies and do a little of your own research you will find; the old school of thought may have been that Garlic was as good for dogs as people but it is not a matter of opinion.
    Enough garlic to get rid of fleas is probably enough to get rid of the dog within a few years. Don’t listen to anecdotal experts, check for yourself and in the meantime. Don’t feed your dog grapes.

  4. Mary H.

    As a Wellness Educator and pet owner for most of my adult life, I’ll ad my two cents worth.
    We who practice and preach a more holistic lifestyle believe that parasites will not be attracted to any animal with a strong immune system.
    There are products available to pet owners which can be taken orally or applied topically… however, an insecticide is an insecticide, i.e. poison.
    We never-ever gave our pets garlic, brewer’s yeast or any of the suggested remedies to prevent fleas. However, we did feed them a high quality (mostly organic) diet, gave them fruits & vegetables as treats, and supplements which included Digestive Enzymes, Probiotics, Sprouts and Super Blue Green Algae.
    We lived in a somewhat rural area on more than 5 acres which included woods. Our dogs and cats seldom ever had a parasite on them. If a tick hitched a ride, it seldom had bitten them. Our dogs & cats all lived to be a minimum of 15 years old, and two lived to be over 17 and simply died peacefully in their sleep.

  5. John C. Hill, DVM

    There have been no scientific studies showing the effectiveness of garlic in treating or preventing flea infestations of pets and their environment. Any such evidence is anecdotal. Treatment of flea-bite hypersensitivity is complete flea avoidance. This is usually impossible without a change in geographic location to areas that will not support flea reproduction. The next best things are rigorous environmental control and treatment of the pet with a long-acting topical or oral flea control medication such as dinotefuran or spinosad.

  6. Doug Ginno DVM

    As a veterinarian I’ve treated flea allergy dogs for thirty years and they can be quite a challenge. Garlic has been proven by numerous studies to have minimal effect on fleas. If a dog receives too much garlic it will cause gastrointestinal upset–diarrhea and flatulence. High doses of garlic were used historically as a purgative to remove intestinal worms. Get with the program.
    Today we have a number of safe insecticides both topical and oral that when given monthly achieve excellent flea control. I could write several paragraphs detailing the flea life cycle, the physiologic reaction that results in flea allergy and environmental as well as pet control measures but suffice to say that this person either didn’t take his or her veterinarian’s advice to heart or didn’t listen. Publishing an uninformative letter such as this discredits your organization. This makes me wonder whether or not the advice and information on human health is bogus or not. To be continued……or not.
    People’s Pharmacy response: Our original recommendation, not to rely on garlic to fight fleas, was contested by some veterinarians as well as some dog owners.

  7. Jim

    what about garlic for cats? What form do you give it in? Is there a garlic supplement of some sort that the animals will eat?
    People’s Pharmacy response: We understand that cats are much more susceptible than dogs to the toxic effects of onions and garlic. We recommend you not give your cats garlic!

  8. Katherine T. Brown

    Two other flea remedies my vet recommended for my Labrador retriever were brewer’s yeast in the dog’s food and vinegar in her water. Though we lived in the country at the time, I used both with success for a number of years.

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