Along with the Rabies outbreak Arizona has experienced this year, wild and domestic animals are also suffering from a Canine Distemper virus outbreak as well. I have seen several puppies with distemper this year, when I only saw three cases in the preceding decade.Canine distemper is very rare in domestic dogs because the vaccine is very effective. Several common types of wild animals-Canids (dogs, foxes, coyotes), Mustelids (skunks and weasels) and Procyonids (raccoons and coatis)-are susceptible to canine distemper and are capable of spreading it. This is a good reason for universal vaccination of dogs, as individual immunity is probably as important as herd immunity when a wild animal reservoir for disease exists. relying on other pet owners having their pets vaccinated ignores the potential of spread from wildlife. Distemper is an RNA virus related to measles, rinderpest, and of particular interest to this discussion, Newcastle virus. All of these viruses are Paramyxoviruses. In the process of treating one of these puppies with distemper, a client asked me about a treatment invented or discovered by a retired veterinarian named Dr. Alson Sears using Newcastle virus vaccine, and primarily promoted online (several websites and a facebook group) by someone named Ed Bond, who apparently has no medical or veterinary background, but who thinks his dog was cured by Dr. Sears' treatment. this treatment is not really "alternative", but it does illustrate how clients and veterinarians can be fooled into thinking something works without taking into account possible confounding factors. At least Dr. Sears and Mr. Bond seem to be sincere and do not seem to be making much if any money on this treatment.
Like many viral infections, many factors including varying strains of virus, and multiple host variables affect the severity and course of the disease. Young puppies 3-6 months old are the most susceptible-younger puppies have some protection from maternal antibodies acquired through the placenta, and older dogs are both less susceptible to the virus and more likely to be immune to vaccination or mild infection. Effective vaccinations have been available since the 1960's, and I cannot find any data with specific information about mortality rates. Canine distemper does have a high mortality rate in puppies, probably much greater than 50%, and dogs that survive are likely to have severe neurological complications months or years later. However, depending on factors such as age and immune status, some dog do have mild cases, and some dogs do recover completely. These cases have the potential to convince clients and veterinarians that a variety of ineffective treatments work. It is natural for owners to bond with puppies quickly, and providing supportive care to a very sick puppy is tedious and frustrating, which leads people to look for other potential treatments for the disease.
Saturday, January 2, 2010
Sunday, December 13, 2009
Known unknowns and unknown unknowns in herbal veterinary medicine.
I am afraid I can't resist stealing my title from Donald Rumsfeld, because I think it describes the problems of using herbal remedies in different species quite well. What are the risks of using herbal products in animals?
There are the known problems common to herbal treatments such as unknown and.or variable concentrations of active compounds in herbs from different sources and even from the same source but harvested at different times and under different conditions. Sometimes demand for herbs or other natural products can lead to damage or even extinction to rare species used in various healing traditions. There are many examples of contamination of herbal products, and some traditional remedies that may be represented as natural or herbal may be neither. When demand for a certain herbal product rises quickly (Such as the use of Chinese Astragalous for influenza viral infections) there may be a strong motivation to use different portions of the plant than usual or to substitute other related plants or to adulterate the product with something else to make up the volume.
These types of problems are common to many if not all herbal remedies sold and are what I consider known unknowns when dealing with these types of products in veterinary medicine.
When herbal products that may have been used traditionally for humans (it is fairly common for veterinarians to use Chinese herbal medicines on their patients) unknown unknowns come into play.
Often different species absorb and metabolize the same plant or drug very differently, and sometimes unexpected toxicities can arise in different species. Even in herbivores, different species can react differently to toxic plants, and one species may be able to consume a given plant safely, while another species may not.
Once you give a carnivorous animal (especially cats) herbs other problems arise. Cats have much lower levels of some liver enzymes such as glucuronosyltransferase(1) which converts toxic metabloites of drugs such as acetaminophen to less toxic compounds. One reason cats may have lower levels of such enzymes is that cats are obligate carnivores, and eat less plant material than other carnivores such as canines and bears, and probaly have less need to metabolize plant toxins.
Cat's red blood cells are also more sensitive than those of other species to oxidative damage, and small amounts of onion or garlic can cause Heinz body anemia in cats. when I was in veterinary school in the late 1980's, it was common to syringe or tube feed sick cats baby meats. Some baby meats have onion powder added for flavor, and there were cases of cats developing heinz body anemia after a few days of feeding baby meats containing onion powder. Now special diets are available for critically ill pets and this problem is not so common. Cats are also more sensitive than dogs to plant-based insecticides such as Pyrethrins and "natural" insecticides such as essential oils. Both dogs and cats have been poisoned by the use of pennyroyal oil, a popular substitute for flea and tick control products (2).
While some of these examples are well known and documented, I call this type of problem "unkown unkowns" because these issues are often unanticipated and are discovered when someone gives their pet a product and then discovers that the animal is not responding well. Other examples of this type of discovery include grape/raisin toxicity in dogs, and Lilly toxicosis in cats (3).
Because of the variable nature of herbal remedies and the potential for unknown and unforeseen toxicity, I think veterinarians and pet owners should be very cautious when using these types of products in animals. Unfortunately, the primary reference for veterinary herbal medicine, while giving lip service to these issues, also seems to put great value in untestable concepts such as Chinese and Ayurvedic forms of vitalism, and repeats standard CAM claims that natural products are always safer and less toxic than standardized pharmaceuticals. While they do state that essential oils should be avoided, they often state that many of these products "appear to be safe", without much consideration for the variables and unknowns I have discussed here. The book does not inspire confidence in me at least.
References;
There are the known problems common to herbal treatments such as unknown and.or variable concentrations of active compounds in herbs from different sources and even from the same source but harvested at different times and under different conditions. Sometimes demand for herbs or other natural products can lead to damage or even extinction to rare species used in various healing traditions. There are many examples of contamination of herbal products, and some traditional remedies that may be represented as natural or herbal may be neither. When demand for a certain herbal product rises quickly (Such as the use of Chinese Astragalous for influenza viral infections) there may be a strong motivation to use different portions of the plant than usual or to substitute other related plants or to adulterate the product with something else to make up the volume.
These types of problems are common to many if not all herbal remedies sold and are what I consider known unknowns when dealing with these types of products in veterinary medicine.
When herbal products that may have been used traditionally for humans (it is fairly common for veterinarians to use Chinese herbal medicines on their patients) unknown unknowns come into play.
Often different species absorb and metabolize the same plant or drug very differently, and sometimes unexpected toxicities can arise in different species. Even in herbivores, different species can react differently to toxic plants, and one species may be able to consume a given plant safely, while another species may not.
Once you give a carnivorous animal (especially cats) herbs other problems arise. Cats have much lower levels of some liver enzymes such as glucuronosyltransferase(1) which converts toxic metabloites of drugs such as acetaminophen to less toxic compounds. One reason cats may have lower levels of such enzymes is that cats are obligate carnivores, and eat less plant material than other carnivores such as canines and bears, and probaly have less need to metabolize plant toxins.
Cat's red blood cells are also more sensitive than those of other species to oxidative damage, and small amounts of onion or garlic can cause Heinz body anemia in cats. when I was in veterinary school in the late 1980's, it was common to syringe or tube feed sick cats baby meats. Some baby meats have onion powder added for flavor, and there were cases of cats developing heinz body anemia after a few days of feeding baby meats containing onion powder. Now special diets are available for critically ill pets and this problem is not so common. Cats are also more sensitive than dogs to plant-based insecticides such as Pyrethrins and "natural" insecticides such as essential oils. Both dogs and cats have been poisoned by the use of pennyroyal oil, a popular substitute for flea and tick control products (2).
While some of these examples are well known and documented, I call this type of problem "unkown unkowns" because these issues are often unanticipated and are discovered when someone gives their pet a product and then discovers that the animal is not responding well. Other examples of this type of discovery include grape/raisin toxicity in dogs, and Lilly toxicosis in cats (3).
Because of the variable nature of herbal remedies and the potential for unknown and unforeseen toxicity, I think veterinarians and pet owners should be very cautious when using these types of products in animals. Unfortunately, the primary reference for veterinary herbal medicine, while giving lip service to these issues, also seems to put great value in untestable concepts such as Chinese and Ayurvedic forms of vitalism, and repeats standard CAM claims that natural products are always safer and less toxic than standardized pharmaceuticals. While they do state that essential oils should be avoided, they often state that many of these products "appear to be safe", without much consideration for the variables and unknowns I have discussed here. The book does not inspire confidence in me at least.
References;
- Sellon, R.K. Acetaminophen, pp. 550-558 in Small Animal Toxicology, 2nd ed. 2006, Peterson and Talcott, eds, Elsevier/Saunders, St. Louis.
- Poppenga, R.H. Hazards Associated with the Use of Herbal and Other Natural Products, pp. 312-344 in Small Animal Toxicology, 2nd ed. 2006, Peterson and Talcott, eds, Elsevier/Saunders, St. Louis.
- Mason, J.A., Khan, S.A. and Gwaltney-Brant, S.M. Recently Recognized Animal Toxicants pp. 138-143 in Current Veterinary Therapy XIV, 2009, Bonagura and Twedt, eds.Elsevier/Saunders, St. Louis.
Wednesday, November 18, 2009
Ray Comfort edition of "Origin"
A local church group was handing out free copies of The Origin of Species with a special introduction by "banana man" Ray Comfort. This introduction contains many fallacious arguments that have been refuted many times, such as the idea that Darwin is directly responsible for Adolf Hitler and the holocaust, and ideas that there are no transitional forms or "missing links" in the fossil record.
It is interesting to note that the announced date of distribution was the 19th, but apparently fears of handouts of information countering the introduction from the NCSE led them to bear false witness yet again and change the date. Unfortunately typical behavior from the young earth creationist crowd.
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