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News about Toxins

Dogs Going to Pot? Marijuana Toxicosis and Medical Uses for Dogs

Legalization may increase accidental ingestion incidents in dogs, but may also lead to use of medical marijuana to relieve pain and suffering.

News item by Mary Straus, published in the Whole Dog Journal, April 2013

I was watching a television show about a veterinary clinic the evening after completing an early draft of this article. One of the clients was a young man with a very sick dog, who lay at his feet, moaning softly.

“He's not himself,” the man said, his voice choked with emotion. “He's hardly moving, and when he did move, it was like his joints weren’t working. He can't control his bladder, he's peeing all over.”

Oh my gosh, I thought to myself, I know what’s wrong with that dog!

Legalization of medical marijuana in 18 states and the District of Columbia has been a blessing for many people, but it is also a concern for veterinarians. Marijuana ingestion can cause toxicity in dogs, and it’s more important than ever for vets to be able to recognize the signs of marijuana toxicosis now that recreational use has also been approved in two states.

Reports of dogs being affected by marijuana (Cannabis sativa) have been rising for the last decade. The ASPCA’s Animal Poison Control Center received 309 calls about dogs consuming marijuana in 2011, compared to 96 cases in 2002, a more than threefold increase. A recent study found that the number of dogs treated for marijuana toxicosis at two Colorado veterinary clinics quadrupled between 2005 and 2010 (medical marijuana was approved there in 2000). The number of cases of marijuana toxicosis at the two facilities increased from 1.5 to 4.5 and from 0.16 to 0.81 per 1,000 emergency cases during that period, indicating that this was not just a matter of seeing more patients in general.

It’s possible that the increase could be at least partly due to greater awareness of the possibility of marijuana toxicity among veterinarians, or greater openness from owners about the probable cause of their dogs’ symptoms.

Dogs can get into trouble after they raid their owner’s stash, eat food infused with marijuana, or munch on the plants as they’re growing. Even if you don’t have the drug at home, your dog could be exposed by eating something found in a park or on a walk. Dogs are the most commonly affected pets, accounting for 96 percent of 250 cases studied in 2002, but cats and other animals can also be affected (3 percent of those cases were cats). Signs can start within minutes or hours and can last for hours or days, partly because THC, the active ingredient in marijuana, can be stored in fat in the body.

Signs of possible toxicity

The mildest signs of marijuana ingestion in dogs include lethargy (sleepiness), reddened eyes from blood-engorged conjuctiva, disorientation, and other behavior changes, such as overreaction to touch, sound, or visual stimuli. Dogs may become agitated and hyperactive, or sedated.

More severe signs include ataxia (loss of balance, staggering, incoordination, difficulty walking), drooling, dilated pupils, vomiting, diarrhea, loss of appetite, and sometimes vocalization. A vet may find hypothermia (low body temperature), hypotension (low blood pressure), and tachycardia or bradycardia (fast or slow heart rate). In the worst cases, coma, seizures, and death can occur.

In one study done in 2004, neurologic signs, such as lethargy (or depression alternating with excitement), ataxia, and dilated pupils, were seen in 99 percent of dogs after ingesting marijuana. Gastrointestinal signs, such as vomiting and drooling, were seen in 30 percent of those dogs.

One classic sign observed in most dogs after marijuana ingestion is dribbling urine. Since it’s unusual to see a combination of urine dribbling with neurological symptoms in dogs, this can help to differentiate marijuana toxicity from other possible causes.

Fortunately, dogs can sleep off the effects most of the time, but since these signs can indicate other types of poisoning and medical conditions, it’s important to have your dog checked by a vet unless you know for sure what happened and your dog’s symptoms are mild.


THC, the active ingredient in marijuana, can be easily detected in blood or urine, but most veterinarians do not have this test readily available to them. Other drugs and toxins can cause similar clinical signs, including stimulants, chocolate, opioids, anti-anxiety drugs, antidepressants, amitraz (found in the Preventic collar and some newer tick control medications), rat poison, antifreeze (see below), and alcohol poisoning (which can come from consuming rotting fruit or bread dough).

Eating marijuana-infused goodies that are high in fat or contain chocolate may also increase the risk of digestive upset and pancreatitis. Blood tests can help to rule out causes linked to metabolic changes, and x-rays may be done to look for gastrointestinal foreign bodies or other abnormalities that might cause similar signs.


If it has been less than two hours since the drug was ingested, your veterinarian may induce vomiting. Some veterinary resources recommend that vomiting should only be induced within 30 minutes of ingestion, as once clinical signs are seen, the anti-nausea effects of marijuana can make this difficult. Vomiting is also dangerous for dogs who are severely sedated, as it can lead to aspiration (inhalation of vomitus into the lungs).

Veterinarians can also give activated charcoal in liquid form to help reduce the amount of THC that is absorbed. After that, most dogs can just sleep off the effects, with full recovery within 24 hours. In rare cases, dogs may be unconscious for several hours to a few days. Supportive care given during this time may include a urinary catheter for cleanliness, fluids to prevent dehydration, and repositioning every few hours to avoid circulatory problems.

When signs are severe, such as an extremely slow heart rate, inability to swallow or stand, repeated vomiting, or hypothermia, your veterinarian may recommend hospitalization with intravenous fluids, anti-nausea medications, thermoregulation to control body temperature, and sedation, as needed. In the worst cases, a type of intravenous lipid therapy can be used to help remove the toxic substance from the blood.

Rarely, dogs can go into a coma and die due to heart failure or respiratory arrest. Aspiration of vomitus can also lead to serious breathing problems and even death. Two accounts of death due to marijuana ingestion occurred after the dogs ingested products made with marijuana-infused butter. One was a Schipperke who ate half a dozen chocolate chip cookies, and the other a Cocker Spaniel who ate half a pan of brownies, both made with butter that had been infused with THC. Both died despite receiving veterinary treatment, apparently due to choking on their own vomit.

Reports of amounts needed to cause toxicity vary. According to one study of 213 dogs who ingested marijuana, the lowest dose that caused clinical signs was 84.7 mg/kg (38.5 mg/pound, or 1 gram of marijuana per 26 pounds of body weight). This study further found that the onset of signs occurred in as little as 5 minutes and lasted anywhere from 30 minutes to 96 hours (4 days), with most signs occurring within 1 to 3 hours after ingestion.

Many sources state that the lethal dose is thought to be 1.5 grams of marijuana per pound of body weight, but the study above found that the highest reported dose was 26.8 grams/kg (12.2 grams, or almost half an ounce, of marijuana per pound of body weight), and all dogs made full recoveries with appropriate treatment.

Note that synthetic marijuana is more toxic and can lead to fatalities. There are more serious side effects and longer treatment times may be required.

Honesty is the best policy

For those who have marijuana in the home, it should be treated as any other medication or toxic substance and stored out of the reach of pets. If your dog shows clinical signs after possibly ingesting marijuana, be honest with your veterinarian about what may have happened. Even in states that have not yet legalized medical marijuana, veterinarians want to help your dog, not turn you in. It’s important for them to have all the information they need in order to properly diagnose and treat your dog.

The veterinarian was very worried about the dog on the television show, but after blood and urine tests came back normal, and a bottle of pills that the dog might possibly have ingested were identified as antibiotics, which would not cause the symptoms seen, she questioned the owner more carefully about what else the dog could have gotten into. He admitted finding a chewed-up cup that his roommate used as an ashtray after smoking marijuana, and the mystery was solved. Since the dog’s heart rate, respiration, and temperature were all normal, he was sent home to sleep it off, while his very relieved owner prepared to have a serious talk with his roommate.

Update: A study on Marijuana Poisoning published in February 2013 provides an overview but no new information.

Medical Marijuana for dogs?

Marijuana can be toxic to dogs, but advocates say that it also has medicinal effects in pets similar to those found in humans. Medical marijuana may help with pain control, nausea relief, and appetite stimulation, while causing few adverse side effects, when used in appropriate dosages.

Most veterinarians want nothing to do with medical marijuana for pets due to its illegality (marijuana remains the target of federal laws even in states that have approved its use for medical or recreational purposes) and the dearth of clinical trials. But a few vets believe that marijuana can provide palliative care to reduce pain and suffering for some animals, and are hoping that medical marijuana may soon be available as a treatment option for pets.

Dr. Douglas Kramer, a veterinarian who works in the Los Angeles area, believes that "the combination of modern medications and traditional therapeutics produces the best clinical results." He started Vet Guru, an online source of information and products relating to “fusion veterinary medicine,” integrating modern and traditional herbal therapies in a holistic approach towards companion animal care.  Dr. Kramer developed Rapid Dissolve Pet Strips, blends of herbal products with natural flavorings that dissolve in seconds in the mouth, where they are absorbed sublingually rather than through the stomach, making them more effective and quicker acting, as well as avoiding the potential for stomach upset. Vet Guru also offers other products via innovative delivery systems that make administration to pets more effective and convenient.

Dr. Kramer’s interest in medical marijuana for pets started when his own dog, a Siberian Husky named Nikita, was suffering from cancer. Despite the use of all conventional pain control medication and therapies available, Nikita had reached the point where she spent most of her time lying on the floor, moaning. As a last resort, Dr. Kramer tried giving her a medical marijuana tincture in the hopes that it would improve her quality of life. The results were nothing short of amazing. Within hours of the first treatment, Nikita’s appetite returned and she appeared to be much more comfortable overall, with the moaning ceasing entirely. Of course, cannabis did not cure the cancer, but it afforded Nikita and her family several more months of quality time together.

Following Nikita’s death, Dr. Kramer dedicated himself to researching and documenting the therapeutic benefits of medical marijuana for pets for the benefit of his other patients. He founded Enlightened Veterinary Therapeutics in order to provide the same high level of palliative and hospice care for pets as for humans. Its stated goal is “relieving pain and suffering while enhancing the quality of life for pets and their families.”

As enthusiastic as he may be about the potential benefits of medical marijuana for dogs, Dr. Kramer is concerned about safety and efficacy of products developed without veterinary involvement. He is also concerned that pet owners are experimenting with the effect of medical marijuana on their pets without veterinary guidance. Dr. Kramer feels that clinical trials are needed so that veterinarians will know more about the effects of marijuana on pets. So far, the only trials that have been done on pets were those used indirectly for human studies, in which dogs and many other animals were found to have the same cannabinoid receptors as humans.

Dr. Kramer wants to see clear data in order to understand how marijuana may help relieve pain and suffering in dogs. He has interviewed dozens of owners who have reported improvements such as reduced anxiety and increased appetite, primarily in pets suffering from cancer. He is currently conducting a survey of owners who have used medical marijuana on their pets.

Cannabis has the potential for benefits beyond pain relief and appetite enhancement. There is evidence that, in humans, cannabinoids may help to control nausea and vomiting, reduce inflammation with less risk of gastrointestinal upset compared to non-steroidal anti-inflammatory drugs (NSAIDs such as aspirin, ibuprofen for humans, and Rimadyl for dogs), and reduce anxiety.

There is also evidence that cannabinoids may act synergistically with opioids, such as morphine, enhancing the effect of the pain narcotics, allowing them to be used at lower doses, as well as possibly mitigating some of their adverse side effects. In addition, new studies show promise for using topical, unheated cannabis to treat skin cancer. When it comes to topical treatment for dogs, however, additional risk arises from the potential for ingestion of toxic amounts of the drug.

Unfortunately, because of the politics surrounding the use of medical marijuana, there is no reliable information about what dosage of marijuana is safe and effective for pets. This problem is further complicated by the wide variety of products, including flower buds, oils, tinctures, and other extracts, as well as the variation in strengths for each of these based on the strain of marijuana grown, the timing of the harvest, and the preparation of the medical product. Concentrated forms in particular can cause toxicity even in small amounts. These sites have some information on dosage of CBD and THC for dogs:

UPDATE: Dr. Kramer passed away in August 2013. His eBook, Sweet Serenity, is no longer available. A new book, Medical Marijuana for Pets: A practical guide to prepare Cannabis for animals, is now available for Kindle readers. If you cannot access the book and need help with how to make tinctures or how much to give, contact me and I may be able to help.

UPDATE 6/19/19: Results from a small clinical trial at Colorado State Veterinary School show that 89% of dogs that received cannabidiol (CBD) experienced a reduction in seizure frequency. The CBD group received CBD-infused oil (2.5 mg/kg [1.1 mg/lb]) orally twice daily for 12 weeks in addition to existing antiepileptic treatments, and the placebo group received noninfused oil under the same conditions. See CBD trial results ‘encouraging’ for dogs with epilepsy for more information. The original study can be found here: Randomized blinded controlled clinical trial to assess the effect of oral cannabidiol administration in addition to conventional antiepileptic treatment on seizure frequency in dogs with intractable idiopathic epilepsy. Note these studies are ongoing and are recruiting additional dogs, if you live in that area.

UPDATE: It's difficult to know which CBD products are reliable and which are not. Two products for pets that were developed by veterinarians were introduced in 2014. These use cannabis made from hemp with little THC (the ingredient that makes you high). See \Canna Companion and Canna-Pet for more information.
Another company that is developing and testing products with veterinary support is HempMyPet. This company grows and processes their own organic hemp. These products contain trace amounts of THC, which may enhance the effects of CBD without causing side effects because the amount is so low. It is likely that full-spectrum products may work better than hemp products that contain only CBD, though not enough testing has been done to know for sure.

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Antifreeze Becomes Safer (Finally!)

Manufacturers agree to add bittering agent to deter pets from ingesting antifreeze.

News item by Mary Straus, published in the Whole Dog Journal, March 2013

On December 13, 2012, the Consumer Specialty Products Association (CSPA) and the Humane Society Legislative Fund jointly announced that all major marketers have agreed to voluntarily add a bitter flavoring agent to all antifreeze and engine coolant products manufactured for sale in the United States to deter animals and children from ingesting them. This is great news about a change that will save many lives.

Each year, up to 90,000 pets are poisoned by ingesting antifreeze that drips onto our garage floors and driveways, or is left in open containers. Antifreeze has a sweet taste that makes it attractive to pets, livestock, wildlife, and small children. As little as one teaspoon of antifreeze can kill the average cat. The minimum lethal dose in dogs is about 2 ml (less than half a teaspoon) per pound of body weight.

Most antifreeze products are 95 percent ethylene glycol, a potent alcohol that is readily absorbed once it is ingested. Its effects start with alcohol toxicity to the central nervous system, beginning as soon as 30 minutes after ingestion and lasting up to 12 hours. Signs may include ataxia (loss of balance), disorientation, and appearing “drunk.” You may also notice increased drinking and urination. The pet may seem to recover within a few hours, only to get worse again with possible coma or seizures. If the pet survives, the next stage involves cardiopulmonary effects due to severe acidosis and electrolyte disturbances. These generally occur 12 to 24 hours after ingestion and may include rapid breathing and heart rate, depression, seizures, and/or pulmonary edema. Within 24 to 72 hours, the pet goes into kidney failure due to damage caused by calcium oxalate crystals from the breakdown of ethylene glycol in the body. Early veterinary care is essential to survival; failure to properly treat within the first several hours may lead to irreversible damage or death.

Some newer antifreeze products use 50 percent or more propylene glycol in place of ethylene glycol, making them safer than older products, but propylene glycol can still cause alcohol poisoning. Doses over 10 ml/kg (about 1 teaspoon per pound of body weight) are considered potentially toxic to dogs.

Seventeen states have passed legislation requiring antifreeze manufacturers to add a bittering agent to their products that makes them unpalatable to animals and children. Federal legislation had been introduced but did not progress. Denatonium benzoate, the bittering agent used, is a common ingredient in many household products and has been used in formulas to stop people from nail-biting and pets from licking and chewing for decades.

Although the change takes place immediately, older products already on shelves and in cars will still be around for awhile, so continue to exercise caution regarding the products you use in your own vehicles, and to minimize exposure your pets may have to these substances. Also, remember that the bittering agent makes antifreeze less attractive to pets, but does not make it any safer. A few pets are willing to try anything, bitter or not, and may still ingest antifreeze. Antifreeze made from propylene glycol is still a safer choice.

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Your Estrogen Can Hurt Your DogPhoto of dog licking person

Topical hormone replacement products for women can cause health problems in dogs.

News Item by Mary Straus, published in the Whole Dog Journal, September 2010

Many women use topical estrogen creams, lotions, gels, or sprays to help relieve symptoms associated with menopause, such as hot flashes, mood swings, and bone loss. These preparations contain progesterone, estradiol, or similar hormones and are available both over-the-counter and by prescription.

According to the Veterinary Information Network (VIN) News Service, veterinarians have recently become aware that symptoms of hyperestrogenism in dogs can be linked to their owners’ use of topical hormone preparations. These products are often applied to the inner arms, and the hormones are then transferred from the hands or arms when the owner pets or holds the dog. Hormones can also be ingested if the dog licks the ointment from the skin or swallows a transdermal patch.

Signs of hyperestrogenism

Exogenous estrogen can cause swollen vulvas in spayed female dogs or young female puppies, often with even more swelling than if they were in heat. Females may be attractive to males and even allow mating.

Affected male dogs can develop enlarged mammary glands, and male pups may have an underdeveloped penis and testes. Prostate infection, particularly in young dogs, may also be linked to exposure to hormones.

These excess hormones can also cause hair loss in both sexes. Often referred to as endocrine alopecia, Alopecia X, or Adrenal Hyperplasia-Like Syndrome, the hair loss (alopecia) is described as bilaterally symmetric, meaning it affects both sides of the body similarly.

Veterinarians are often at a loss to explain such signs, and may try treatment with antibiotics or corticosteroids such as prednisone. Ovarian remnant syndrome, where part of the ovary is accidentally left behind during a spay, is often suspected, particularly if the dog was spayed during the prior year, and some dogs have been subjected to a second surgery to search for the ovarian tissue thought to be causing the symptoms.

Special endocrinology tests may reveal elevated levels of estradiol, called hyperestrogenism or hyperestrinism, but will not indicate the cause of the excess hormones. Adrenal disorders such as atypical Cushing’s disease (Canine Atypical Hyperadrenocorticism, or CAH) may be suspected, with treatments ranging from melatonin and high-lignan flaxseed oil to Lysodren or other drugs used to treat Cushing’s disease. None will have any effect on symptoms caused by exogenous hormones.

Cats may also be affected, often behaving as though continually in heat.

Treatment and prevention

If you use topical hormone preparations, apply them to areas that are covered by clothing, such as your inner thighs (this may not work if the dog sleeps under the covers with you and you sleep bare legged). It’s best to use gloves to apply the ointments, or at least wash your hands thoroughly afterwards. Do not allow pets to lick or touch areas where hormones have been applied.

Signs in affected dogs often resolve within a couple of months once exposure ceases, though it may take longer, particularly if exposure has been prolonged. In some cases, it may be necessary for the dog owner to switch to a transdermal patch rather than using topical ointments before signs in the affected dog improve.


Veterinarians need to be aware of the possibility of secondary estrogen exposure when confronted with patients exhibiting signs of hormone imbalance, and should ask their clients whether anyone in the household is using topical hormone preparations. Even young women may be using these products in certain cases, such as following a hysterectomy.

Comparable problems have also been seen in children exposed to hormones in a similar way. The FDA issued a warning in 2009 regarding the adverse effects that testosterone gel, used by both men and women, can have on young children who are inadvertently exposed through secondary contact.

According to VIN, the FDA said it “has received reports of inadvertent exposure to topical estrogen products in children and pets through contact with another person being treated with the products (secondary exposure). The Center for Drug Evaluation and Research and the Center for Veterinary Medicine are evaluating these reports.”

While problems relating to topical estrogen preparations appear to be on the rise, particularly as baby boomers reach the age of menopause, they don’t account for all cases of elevated hormones. One internal medicine specialist who is well versed in this issue estimates that ovarian remnant syndrome still outnumbers secondary hormone exposure by a ratio of ten to one.


The Veterinary Information Network is considering conducting a survey to determine the prevalence of secondary exposure to pets of topical hormone products. If your dog or cat (or, if you are a veterinarian, your client’s pet) has exhibited signs associated with such exposure and you would like to participate in the survey, please send your name and contact information to

To report a suspected case to the FDA, call (888) FDA-VETS and request form 1932a; fill it out and return. Go to the FDA's Veterinary Adverse Event Voluntary Reporting site for more information.

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Warning: Paintballs are Toxic to Dogs

Ingesting paintballs can lead to seizures and even death.

News item written by Mary Straus, published in the Whole Dog Journal, December 2009

My dog Ella and I spent an anxious night at the emergency clinic recently, after she found and ate paintballs while on our walk. She was off-lead at the time, so when I realized what she was doing, I had no way of knowing how many she had eaten. In fact, I did not immediately recognize the colorful, marble-sized gelatinous balls, and thought they were some kind of candy. It was only a few hours later, when she threw up bright turquoise, that I became concerned and investigated further.

Paintball ingredients can include polyethylene glycol, dipropylene glycol, glycerol, and sorbitol, all osmotic laxatives, which can lead to hypernatremia (“salt poisoning”) when ingested in sufficient quantity. These ingredients also taste sweet, which is why dogs find paintballs so attractive.

Signs of paintball toxicity are usually neurological, a result of the movement of water out of the brain, leading to hemorrhage. The most common signs include vomiting, ataxia (loss of coordination), and diarrhea. These can occur as early as 30 minutes after ingestion, but more commonly show up within two to four hours. Other signs may include tremors, rapid heart rate, weakness, hyperactivity, fever, blindness, and seizures. Blood tests may show elevated sodium and chloride, low potassium, and metabolic acidosis.

The number of paintballs needed to cause clinical signs is unknown. In one case, a 90-pound Labrador Retriever showed signs after ingesting 15 paintballs. As few as 5 to 10 paintballs may cause signs in dogs weighing around 65 pounds.

Vomiting should be induced if it has been less than an hour since the paintballs were ingested (activated charcoal is not recommended). If the number of paintballs the dog ate is either unknown or relatively high for the dog’s size, or if any clinical signs are seen, it’s best to get the dog to a vet right away for testing and treatment. There, IV fluids are given to help dilute and flush out the toxins, and electrolytes and acid-base balance are monitored every two to four hours. Additional treatment may include drugs to control seizures and vomiting; warm-water enemas to help move the paintballs through the digestive tract more quickly (especially for dogs with elevated sodium levels); and therapy as needed for low potassium, high fever, or acidosis. While the ingestion of paintballs can be fatal, most dogs recover within 24 hours with proper care.

Because I was unsure how many paintballs Ella had ingested, and because of her small size (11 pounds), both my own vet and the Pet Poison Helpline I called recommended taking her to the emergency clinic right away and keeping her on fluids for 24 hours. Luckily, her electrolytes were never more than mildly out of range, and she had no further symptoms. Her bright green stool the next day showed evidence of only one paintball, but I don’t regret the precautions I took, which I’m sure helped her recovery and gave me peace of mind.

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I regret that I no longer have much time to respond to questions. See my Contact page for more information. My name is Mary Straus and you can email me at either or


Rocky is a Yorkie-Poodle mix who had suffered from digestive problems his whole life. Click on his image to read about the diet his owner finally found to help him.
Pashoshe Fisher, a Chihuahua, was a wonderful, joyful companion to his owner for 19 & a half years. He was on a high quality raw diet for over half his life.
This is Ella, my Norwich Terrier.