The things my dogs eats....
Yesterday morning, I found part of a goose carcass in the backyard.
Yesterday afternoon, I found more of it....in a pile of dog vomit on the dining room floor. (Yes, my dog's an idiot, but that's a separate story).
Between the vomiting and my dog's rather solid gut, there hasn't been any diarrhea, at least yet, but it not an uncommon problem after an episode like this.
Diarrhea after dietary indiscretion can be caused by a number of different factors, including ingestion of disease-causing bacteria such as Salmonella. It can also simply be from eating too much, overloading the gut with a new substance, effects of fermenting material on the intestinal tract, and other physiological causes.
The best way to prevent this is to make sure dogs don't eat anything unusual. That can be easier said than done. If a dog does get into something, odds are it's not going to be a major problem in terms of infectious diseases. Most of these cases are typical 'garbage gut'...the dog vomits and maybe has diarrhea but is otherwise fine and gets better quickly. Sometimes, they puke once and never look back. Other times, they need to be kept off feed or be fed a bland diet for a couple days to let their system get back to normal. While that's happening, you should be aware that, while it's unlikely to be infectious, there's certainly a possibility that the dog is shedding more harmful bacteria than normal. Vomit isn't that big of a risk, particularly compared to diarrhea, but you should clean it up promptly and wash your hands thoroughly. Cleaning up diarrhea takes a little more care, as I've previously discussed.
These are usually more of a nuisance than a major health problem. You don't necessarily need to go running to your vet every time your dog throws up after eating something, but you also need to make sure you don't miss a potentially serious problem such as ingestion of a foreign body (i.e. bones), severe intestinal infection or pancreatitis. You should go to your vet anytime you have concerns. It's particularly important to get your dog evaluated if it has persistent vomiting or diarrhea, signs of abdominal pain (hunched up stance, crying, moving around like it hurts...), doesn't want to eat or drink or is lethargic. It's also wise to get to a vet quicker if you dog has underlying health problems, has a history of pancreatitis or is very young or very old.
West Nile virus from pony to vet student
The latest edition of the journal Emerging Infectious Diseases contains an article about a South African vet student that acquired West Nile virus from a pony. Occupational exposure to infectious diseases is an inherent risk in veterinary medicine. Vets know that they are at higher risk of encountering various infectious diseases and take (or should take) precautions to reduce those risks. Sometimes infections occur despite the best precautions. Sometime infections occur because of bad practices. This report highlights the latter.
In this case, a 4-month-old pony started off with vague signs of illness, then developed neurological abnormalities and was euthanized. A necropsy (autopsy) was then performed by a veterinary pathologist with the assistance of two vet students. As part of the necropsy, the student removed the brain and spinal cord for testing, but gloves were the only protective gear that were used. No face or eye protection was used, which is quite astounding.
The pony was eventually diagnosed with West Nile virus. Six days after performing the necropsy, the vet student developed a fever, malaise, sore muscles, stiff neck and severe headache. West Nile virus was confirmed, and the viruses from the pony and person were compared and were the same type. Fortunately, signs of infection in the student subsided after approximately 10 days.
Horses are considered 'dead-end' hosts for West Nile virus, meaning they cannot naturally transmit the virus. This is because the levels of virus in circulation in the blood are very low, and a biting mosquito can't pick up the virus to infect other individuals. However, the brain and spinal cord are a different situation since very high virus levels can be present in those tissues. It's astounding that a vet school would have a student removing the brain and spinal cord, especially without proper protective gear, since that procedure carries a risk of splashing or aerosol exposure to the virus. Anyone performing necropsies needs to be aware of the potential risks and take appropriate precautions. The paper states that after the incident, biosafety practices were improved to include the wearing of masks and eye protection during necropsies. Well, I guess it's better late than never...
Deworming dogs...how often??
Deworming is a controversial subject. There are numerous opposing views, strong opinions and conflicts of interest that drive a lot of debate on the subject. There's no argument that parasites can be bad for the pet and some can pose a risk to people. There's no argument we want to reduce parasite burdens in pets to improve pet health and decrease human risks. It's the 'how' that causes all of the problems. Developing deworming strategies requires you to think of a few different things, such as:
- What parasites are in the area?
- Are the risks the same the year round or mainly seasonal?
- What parasites pose a risk to the individual pet or what are the pet's chances of exposure? (Does the pet go outside? Does it get exposed to many other animals? Are there multiple pets in the household?...)
- Are there any people in the household at particular risk for parasitic infections? (Young children, people with developmental disorders that might be more likely to get exposed to pet feces?...)
There are a few different approaches to managing this in adult animals (everyone agrees puppies and kittens need more aggressive deworming).
The Companion Animal Parasite Council advocates monthly deworming. There are a few reasons for this. One is the fact that the duration of activity of the drugs means that monthly treatment allows you to prevent establishment of significant parasite populations in the animal (and therefore also in the animal's environment). It also keeps the treatment user-friendly, in that it's easy for people to remember to treat their pet. Some concerns with this approach as the 'one plan fits all' mentality, despite the fact that there are great differences in the risks between different regions and between pets in the same area. There are also concerns about drug resistance (which is a problem in some other species like horses and sheep), although that doesn't seem to be a major concern...at least yet.
Recent European guidelines take a somewhat different approach and use a philosophy more geared towards individual risks for each animal. These guidelines recommend that if regular deworming is used, animals should be treated at least 4 times a year, with no more than 3 months between each treatment. This is based on some research indicating that dropping treatment to 3-4 times per year had no effect on parasite levels. This approach is therefore more conservative (in terms of the number of treatments) and probably has less of an impact on the development of resistance, but it requires more organization and thought. If used properly, it's probably a good approach.
Yet another approach was recommended by a Canadian Parasite Expert Panel. With that approach, in low-risk households (both pets at low risk for parasite exposure and people at low risk of infection), treatment is based on fecal examination results or, if fecal testing is not performed, once or twice yearly treatment is recommended. In high risk households, fecal testing is recommended 3-4 times per year, with treatment based on results, or administration of routine preventive treatment at least 2, and preferably 3-4 times per year. The main criticism of this approach is that it's more complicated and perhaps prone to errors or missed treatments.
There's no clear answer, nor should there be. There really can't be a 'one program fits all' approach that properly addresses the risks for all pets in all regions. Tailoring the deworming strategy to your pet, based on your pet's and your family's risk, is a logical approach. Regardless of the chosen approach, regular fecal testing is a good (and underused) way to assess what's going on with parasites in your pet and to identify treatment failure or the emergence of drug resistance.
Monthly heartworm prevention has an impact on what you do as well, since typical heartworm preventives are also effective against roundworms and hookworms, the main parasites that routine deworming is aimed against. If you are in a region where heartworm is present, monthly treatment during the heartworm season is indicated, and the main decision that needs to be made is what to do the rest of the year (when heartworm isn't a risk year-round).
Composting pet waste
An article in Saturday's Toronto Star discussed composting options for people without organic waste pickup or the ability to have a backyard composter. The article discussed indoor composters that can be used by apartment or condo dwellers who want to satisfy their eco-friendly side.
One of the composters they highlighted states that you an add pet waste, but that's not a good idea. Pet waste can contain a wide range of potentially harmful parasites and bacteria. The composting process can generate enough heat to kill relevant bugs, but it's not guaranteed to do so, and I'd be especially concerned about small indoor composters. Having a few nasty things in the composter itself isn't necessarily a big deal, but what happens down the line? People can be exposed to these microorganisms when removing compost. Also (and maybe more importantly) compost usually ends up in gardens and can contaminate the soil, as well as anything grown in the garden.
One of concerns is the protozoal parasite Toxoplasma gondii. Cats are the natural reservoir of the parasite and can transiently pass it in their feces, yet most people that become infected are likely exposed outside in gardens or from contact with contaminated foods. Composing may not kill toxo, and therefore lead to a risk of exposure, particularly when compost is put into flower gardens that people work in or in vegetable gardens. The risk from an individual animal is admittedly low, since cats are rarely shedding this parasite (even though most have at one point), but it's a preventable risk. There are also various other microorganisms that are potential concerns. While composting is a great way to dispose of most organic wastes, it's best to keep putting dog and cat feces in the garbage or down the toilet (and wash your hands).
If you really feel the need to compost pet waste, the safest alternative is probably to have a separate composter for pet waste that you handle differently....pay careful attention to hand hygiene after handling the compost and make sure the compost doesn't get deposited in gardens or other areas that people might frequent.
Heartworm in people
Heartworm is an important problem in dogs. It's a parasitic disease caused by Dirofilaria immitis and is spread by mosquitoes. It can cause serious, even fatal disease, and routine testing and preventive medication is an important thing for dogs in areas where D. immitis is present. Dogs (wild and domestic) are the natural host for this parasite, but other species can be accidentally infected, including people and cats. People become infected by being bitten by a mosquito that is carrying the parasite, having acquired it from an infected dog. Human infections seem to be quite uncommon and, interestingly, while this is a serious problem in dogs, it tends to be rather innocuous in people. In fact, the biggest problem with heartworm infection in people is the fact that it can be confused with other, more serious problems, leading to invasive testing.
After infecting someone, D. immitis works its way to the blood vessels in the lungs. This can result in a small area of inflamed tissue in the area. If a chest x-ray is taken, a "coin lesion" (a small, usually 1-3 cm spot) is often present. The parasite infection usually doesn't cause any problems in people, but lung cancer and tuberculosis can look the same on x-rays. Usually, open-chest surgery ends up being performed to get a biopsy of the area because of the concerns about cancer. In heartworm cases,the biopsy identifies the problem as D. immitis, which is much better than cancer, but the risks associated with having undergone such an invasive procedure are much greater than that of the parasitic infection itself.
Typically, treatment is not recommended in people because the infection rarely causes problems and people are "dead end" hosts, meaning they cannot pass on the infection. (Unlike in dogs, infected people don't have the parasite microfilaria in their blood, which is how the infection is passed on to mosquitoes and other animals).
Heartworm is a rare and rather innocuous problem in humans - it's nothing to lose sleep about.
Image: A diagram of a very severe case of heartworm in a dog, in which there are so many worms in the pulmonary arteries that there is "back-up" of the parasites into the right side of the heart, which is how the parasite got its common name.
Indian man's approach to rabies prevention not recommended
A man from Jharkhand, India, was bitten by a dog and realized that there was the potential for rabies transmission. That's good, particularly given the huge problem with rabies in India. However, he didn't take the recommended approach of proper wound care and getting post-exposure vaccination. Rather, he killed the dog (getting bitten a few more times in the process), cut out its heart with a pair of scissors and ate it raw, exclaiming that now there would be no problem with rabies.
Not a good idea.
Rabies is widespread in India. Every year, 25 000-30 000 people die of this disease. A person in India is bitten every 2 seconds and someone dies of rabies every 30 minutes.
Every dog bite needs to be considered a possible rabies exposure. If a dog that bites someone is not available for quarantine or testing to determine whether it has rabies, post-exposure treatment is necessary. That involves an injection of anti-rabies antibodies and a series of 4 or 5 vaccines, not ingestion of the animal's heart.
Hopefully, the dog didn't have rabies and this will go down as a somewhat curious little story. Unfortunately, if the dog had rabies, there is a good chance that this person has been infected, and if infected, he will almost certainly die.
Eating an animal's heart to prevent rabies transmission may just be a bizarre belief of an unusual individual. This is something that needs to be investigated, however, because if the same belief is held by many other people in the area, they will all put themselves at risk if they are bitten by not seeking appropriate and effective treatment. Not only does killing the dog and eating its heart have no chance of preventing infection, it probably increases the risk of rabies by leading to more bites. More rabies education is often needed in problem areas, and this may be the case here.
Image: Canine heart (source: www.historyforkids.org)
Risks of Raw - More evidence
A study by Erin Leonard of the University of Guelph and others, that has just been published in the journal Zoonoses and Public Health, once again points to the increased risk of Salmonella shedding associated with feeding raw diets to dogs. The study looked at 138 dogs from 84 households in Ontario. One-quarter of households (21/84, 25%) had at least one dog (32/138, 23.2%) that was shedding Salmonella at one time, which is considerably higher than the 1-4% of pet dogs that are typically expected to be shedding this zoonotic pathogen. Only 4 of the 32 positive dogs had any history of diarrhea in the last month, so the vast majority of these dogs had no signs that they were shedding Salmonella. Here were the study's main findings:
1. Consuming a commercial or homemade raw diet, a homemade cooked diet, or raw meat and eggs, increases a pet dog’s risk of carrying Salmonella.
Raw is raw, and by now we're hoping that people are getting the message that raw is contaminated, whether we're talking about a commercial or homemade raw diet, or feeding any raw animal products (e.g. meat, eggs). The fact that homemade cooked diets also made the list could be explained by the fact that in order to make such a diet, owners still need to start with the raw ingredients. Handling and cooking raw meat and animal products for your pet should be done with the same precautions as handling and cooking raw meat for yourself or your family. If these homemade diets were not cooked as thoroughly as they should have been, or if there was contamination of the dog's dishes with raw product, that could explain the association with Salmonella shedding. Although traditional commercial diets can also be contaminated with pathogens (usually after processing), the risk with these is much lower.
2. Testing multiple consecutive whole fecal samples greatly improves Salmonella recovery in dogs.
This is no great surprise either. Dogs (and many other species) shed Salmonella intermittently, so not every fecal sample from a Salmonella-positive dog is going to yield Salmonella on culture. The authors tested five daily fecal samples from each dog. Based on this study, the sensitivity of testing a single fecal sample in a dog (i.e. the likelihood that a Salmonella-positive dog will test positive on one fecal sample) was only 35.5%. That means almost two-thirds of positive dogs will be missed if they're only tested once. The take-home message on this point is that in order to find Salmonella in a healthy pet dog, multiple samples should be tested.
3. Having multiple dogs in a household, using probiotics and contact with livestock are important potential risk factors that need to be investigated further.
These were factors that were flagged by the authors for future investigation, because at first they seemed to be associated with Salmonella shedding in the dogs, but when the feeding of raw diets was taken into account the associations were no longer significant. A larger study, or one using a different design, will be needed to help tease apart the potential effects of these factors from feeding practices.
The bottom line: Feeding raw is risky business. Some people swear by the benefits of raw diets, but the objective evidence is lacking. There is clear evidence of the risks. In my mind, the potential up-side simply cannot outweigh the well-established down-side of feeding raw diets to pets.
Ear mites and the strange pursuit of knowledge
Ear mites are a common problem in dogs and cats, particularly in young animals, as well as in strays and animals in shelters. The species of mite typically involved is called Otodectes cynotis. It is transmitted between individuals by direct contact (basically hopping animal to animal, as it does not survive for long in the environment), and causes an extremely itchy ear infection (which can get even worse if there is secondary infection with bacteria or fungi).
There are a few reports of suspected infections with Otodectes in people. Considering how common ear mites are in cats and the small number of reported human infections, transmission between pets and people is probably rare, but it certainly can occur. Most of the reports are somewhat circumstantial, involving people with itchy skin lesions that developed after a pet was diagnosed with ear mites. However, one curious veterinarian took it a step further.
Dr. Robert Lopez, of Westport, New York, intentionally infested himself with ear mites from infected animals, and described the outcome in a 1993 edition of the Journal of the American Veterinary Medical Association. First, he took a sample from the ear of a cat with ear mites and placed it in his own ear. He described the scratching sounds and movement that he could feel as the mites explored his ear canal. Severe itching developed, to the point where "sleep was impossible." The intensity of the itching and mite movement decreased over time and the infection resolved by itself within a month.
Personally, I think I would have stopped there. (Actually, I wouldn't have made it to that point, but if I did, I certainly wouldn't have tried it again.) Yet, Dr. Lopez wanted to confirm his findings so, a few weeks later, he infected himself again with mites from another cat. The same type of disease developed, although it was less severe and only lasted two weeks.
Guess what he did next - he tried again, wanting to see if the reduction in severity might indicate development of immunity. So, he infected himself a third time, with the outcome being milder disease. This suggested to him (logically so) that immunity to the mites might develop, something that fits with the fact that ear mite infestations are more common in young animals.
Self-experimentation is generally frowned upon, but has been the source of remarkably scientific discoveries, even Nobel Prize winning discoveries (e.g. the role of Helicobacter pylori in gastric ulcers in people). I don't think Dr. Lopez is in line for any prizes, but it shows how a little academic curiosity along with minimal squeamishness can provide some interesting information.
What's the relevance of all this? If your pet has signs of ear mite infestation (e.g. scratching at the ears, dirty material inside the ears), get it examined and treated. If nothing else, this needs to be done because it's a very uncomfortable problem for the pet. There's also some risk of human infection, but it's probably minimal. The mites have to make it from the pet's ear to your body to cause problems. The quicker they are treated, the lower the likelihood of this occurring. Human ear mite infestations, be they in the ear or on the skin, seem to resolve by themselves, with treatment of the animal being the most important part of control. However, it can be a pretty uncomfortable condition and one most people (with the possible exception of Dr. Lopez) would certainly rather avoid.
Stray dog rabies vaccination debate
In response to an ongoing rabies outbreak, Thailand has launched a program to vaccinate stray dogs. A posting to ProMed questioned this approach.
"The authorities plan to catch stray dogs, to vaccinate them, and to release them. This is inadvisable, since rabies incubation in dogs may extend to a year, although it is mostly between 2-3 months. Catching an animal which might already be incubating an infection and then vaccinating it will not only not protect the animal but put at risk the lives of people led to believe that the animal is safe", wrote Maya Kimchi.
True, you could not guarantee that a dog that was caught was not incubating rabies, and in that case, vaccination of the dog would not be effective. However, the odds of this are very low, and it doesn't make sense to not vaccinate. The worst case scenario is you have a dog that develops rabies, that would have developed rabies anyway, but it is less likely to spread it to the other dogs you've vaccinated. There would be no risk to people vaccinating the dog since it wouldn't be infectious at that point.
"In an endemic country where there are many stray dogs and many cases of rabies in animals and humans, as in Thailand, the solution of [the problem] of stray dogs is to reduce their number and carry out mass vaccination to all owned dogs, cats, and ferrets."
The problem is the stray animals. Vaccination of pets is very much an important component, but vaccinating pets and ignoring the reservoir (stray dogs) doesn't help in the long run.
"If a country decides to avoid the elimination of stray dogs, it will be necessary to catch them, to vaccinate them, and to [quarantine] them for 6 months at a minimum, and only subsequently, together with birth control measures (castration/sterilization), release them for adoption, after registration in a database for further control."
Here's what the World Health Organization's Expert Consultation on Rabies says:
"Mass canine vaccination campaigns have been the most effective measure for controlling canine rabies."
"There is no evidence that removal of dogs alone has ever had a significant impact on dog population densities or the spread of rabies. The population turnover of dogs may be so high that even the highest recorded removal rates are easily compensated for by increased survival rates."
and
"Attempts to control dog populations through culling, without alteration o f habitat and resource availability, have generally been unsuccessful."
Culling is rarely the answer. Vaccination of stray and pet dogs, education of the public to avoid contact with stray dogs, controlling roaming of pet dogs to decrease control with strays, educating the public about the need for post-exposure prophylaxis if they have been bitten by a stray dog and ensuring that the healthcare system has the appropriate resources (e.g. available rabies antibody and vacccine) and knowledge to handle exposed individuals is the best approach.
Giardia outbreak closes shelter
A Fort McMurray (Alberta) SPCA shelter has been closed because of a Giardia outbreak. Giardia is an intestinal parasite that can cause diarrhea in dogs (and other species, including people) but can also be found in about 7% of healthy dogs. Giardia infection was confirmed in four dogs in the shelter, which led to the rather aggressive measure of closing the shelter. Shelter personnel suspect that the infection started with one dog, who spread the parasite to some other dogs that were in close contact with it. Giardia is passed in stool and animals get infected by ingesting Giardia oocysts from stool contamination in their environment or water sources.Giardia usually causes pretty mild disease that gets better on its own or with treatment. Shelter personnel stated "We are in desperate need for help from the public as far as raising funds for medical, because obviously it costs a lot of money to treat the dogs. It's a lot of money to treat an animal with giardia." It's actually pretty cheap to treat individual cases, but this makes me wonder whether they are treating all dogs in the shelter. That's not something I'd recommend because there's little evidence that treatment of non-diarrheic animals is needed or useful.
Presumably this outbreak (whether it was caused by Giardia or something else) will end soon, either because of or despite of what was done. You never know if you did something to control the outbreak or whether it just ran its natural course. If it truly was Giardia, I'd be surprised if there are more problems, but resolution of the outbreak won't change the fact that many dogs that they bring in will be shedding the organism.
Giardia is a cause of diarrhea in people, but we now know that dogs probably play only a minor role in human disease. The type of Giardia that is most often found in dogs is a dog-specific type (Assemblage D) that cannot infect people. Unless these dogs were infected with a strain that can infect people (uncommon but not impossible), there's no risk to people. Regardless, avoiding contact with stool, especially diarrhea, is still a good idea - for prevention of Giardia and other diseases.
