Is There Increased Interest In Using Medical Marijuana In Pets ?
Relaxation of the laws prohibiting cannabis use in humans is at the root of this increased interest. Pets have become family members. People have begun thinking: “If there are legitimate medical uses for marijuana for my human family members, why not for my furry family members too ?” Veterinarians are not immune from that line of reasoning either; they are being asked that question more and more by the owners of the pets they treat.
So about a year ago, a popular veterinary newsletter published this article. It was followed by an article on the subject in the AVMA Journal, which you can read here , a letter to their editor by a Florida vet (ref) and a note of very cautious optimism by a distinguished veterinary pain specialist. (ref) Many more articles in the popular press followed.
But building a knowledge base for the safe use of cannabis products in dogs and cats today presents many problems. The greatest are legal and political issues. No one wants to upset the Feds. No one wants to sully his or her reputation.
The second problem is animal experimentation. The kind of experiments that are required to determine safe and effective doses for pain control in dogs and cats are now quite difficult to perform in the United States because of our heightened sensitivity to humane issues. Besides, getting a government grant today to do that research would be quite a challenge.
At one time, gruesome techniques were commonly used to measure the effect of medications on pain sensation (such as timing how long it took a rat to get off a hotplate). Thankfully, experiments like that can no longer be performed in the civilized world. Today, we would be limited to things like activity monitors that might measure an old dog or cat ‘s inclination to move about after receiving one drug or another. Performed scientifically, those experiments are expensive.
Because of those issues, using cannabinoids (marijuana,Hashish, etc.) in pets today relies on word of mouth, subjective opinion and assuming that dogs and cats will react to these medications the same way that we do. None of that makes for good medicine.
Marijuana (cannabis) does what it does because it mimics (copies) natural messenger compounds in your body and in your pet’s body that have a similar function. It just delivers those messages louder, stronger and for a longer period.
Your pet’s natural messenger cannabinoids are anandamide
and (2-AG). They stimulate receptors present in your pet’s brain (CB1 receptors) and throughout its body (CB2 receptors). The cannabinoids in marihuana attach to those same receptors. However, they resist letting go of those receptors so their effect is more powerful and longer lasting. Drugs that hang on to receptors longer than the natural messengers are called an agonist. The chief agonist cannabinoids in marijuana are Δ9-tetrahydrocannabinol (aka THC or delta-9) and cannabidiol (aka CBD). Echinacea has a few similar compounds. When the effects of cannabinoids wear off, it is because they were processed (metabolized) by the pet’s liver into compounds that left through the bile and urine or were stored in the pet’s body fat.
We do not know much about its effects on pain in dogs and cats. It can be very hard to objectively evaluate pain in our pets. They are so attune to us – the stroke of your hand, a calm optimistic voice, your body language, all make your pet feel better and make it hard to decide what affect the medications you gave actually had.
When it comes to our pets, we have to rely on the feedback we get from humans that take cannabinoids to deal with chronic pain and other health issues. Most do feel some benefit. I have read many of the articles published on that subject. Most describe the benefit as “modest” (ref)- about the same as topical capsaicin liniments. (ref)
Other studies found more benefit. (ref) The pain-relieving benefits never approach that of the powerful opiate narcotics like fentanyl patches nor did they match the pills dentists commonly prescribe for a toothache (ref). (However, it is hard to separate pain from mood and cannabis certainly makes one leave their worries behind.)
Marijuana-based oral sprays seemed to help alleviate some of the pain of one form of arthritis, rheumatoid arthritis, in humans. (ref) That is an autoimmune disease, not the wear-and-tear osteoarthritis common in dogs and cats. But even osteoarthritis may generate neuropathic pain, a type of pain marijuana seemed to help. (ref) Studies in mice seemed to confirm that. (ref)
Pain studies are still allowed to be performed in rodents. Arthritic rats did seem to benefit from the (delta 9) THC that is present in marijuana. (ref)
Not all pain is the same and it may well be that cannabinoids/marijuana deal better with some forms than with others. Again, when we rely on human feedback, it can be hard to separate how much benefit is due to pain relief and how much is due to mood elevation (the high). Perhaps cannabis can elevate your pet’s mood – I do not know..
The optimistic studies I mentioned were small in size. But they were enough to get the NIAAA to fund human trials with standardized amounts of cannabinoids to see how they might affect osteoarthritis pain (knee joint arthritis). These trials were halted due to an unacceptable number of heart and circulatory problems as well as undesirable changes in liver function >in the patients that received the medications. (ref)
Other Chronic Inflammations
In humans, marijuana might have the potential to lessen inflammation occurring at various points in the body through its action on CB2 receptors. The cannabidiol portion of the plant, rather than the TCH portion is thought to be more potent in doing that. (ref) But I know of no studies that examined that effect in animals.
The same goes for appetite. We all know that marijuana stimulates appetite in people. We could assume it has a similar effect in pets or allows them to regain lost weight but no veterinary studies have ever been done. What we have for the moment is folks telling us that the appetite of their sick pets improved on edible cannabis butter or liquid marijuana extract. With time, it should become more apparent if that is really true.
Veterinarians know the signs of marijuana overdose in pets considerably better than they know the drug’s benefits to pets. When overdoses have occurred, 96% have been in dogs and only 3% in cats (perhaps because cats are less attracted to sweets).
It has been very rare for pets, consuming a single dose, to die.
What veterinarians see instead is often a staggering pet (ataxic) with a slow heart rate and low blood pressure. Drooling and salivation are common. Many have dilated pupils (mydriasis). A few develop eye twitches (nystagmus).
Some pets develop diarrhea and/or vomit – although it is common that they ate multiple things (including stem fiber) they found when their owners were not looking. Some loose bladder control, others show muscle twitching or tremors.
In more serious cases, the pets come in fearful, anxious, disoriented or in a state of collapse. Anxiety seems worse in dogs that had a prior tendency to fearfulness. You would expect that in a pet with an altered mental state that it did not understand. Those tense pets are more likely to react in an exaggerated way to sudden movement or noises.
Because chocolate often forms part of what the pet consumed, it is hard to tell which signs were due to the stimulants in the cocoa (Theobromine, caffeine) and which were due to the marijuana.
Most cases of marijuana intoxication in pets from a single ingestion incident resolve over a period of 3 – 12 hours with no lasting damage.
Test kits designed to detect marijuana in the urine of humans have been used to detect cannabis exposure in pets. But those tests may miss some cases. The test only measures an end product of cannabis (11-nor-9-Carboxy-THC, aka 11-nor-9-carboxy-delta-9-tetrahydrocannabinol, 11-COOH-THC, THC-COOH) that occurs in urine and it is known that dogs do not produce those same end products in the quantities that humans do. (ref)