Urine collection: Why "pee into the cup" doesn't work for dogs and cats
Urinary tract infections are quite common in dogs. (They're uncommon in cats, but a lot of cats get treated with antibiotics for non-infectious urinary tract disease.) An important aspect of managing urinary tract infections (UTIs) is getting a proper diagnosis. Diagnosing a UTI involves a few different things:
- Clinical signs: Does the animal have signs that indicate something abnormal is going on in the bladder? This can include frequent urination, abnormal urination, straining to urinate or similar problems.
- Cytological: When a urine sample is examined under the microscope, are there changes consistent with an active infection, like the presence of large numbers of white blood cells and red blood cells?
- Culture: Can bacteria be grown from the urine sample?
Culture is very important to help determine if a UTI is really present. It's also very important for determining the best treatment, especially since antibiotic resistant bacteria are becoming more common. A baseline culture is also useful if the infection comes back, as it provides information about whether the first bug was not actually eliminated or whether re-infection other bacteria has occurred. Differentiating these two situations is important for determining subsequent treatment as well as the need for additional testing to see if there are any underlying reasons for recurrent infections.
Culture is also something that can be done improperly. If a person has or may have a UTI, that person will usually be asked to collect your own "mid-stream" urine sample by collecting urine into a sterile cup part-way through urination, so that any superficial bacterial contaminants get flush out before the sample is collected. That's not so easy to do in dogs and cats. Collecting midstream free-flow samples into a sterile container without the sample being contaminated by the pets hind end or haircoat, or by the person doing the collecting, is very difficult. A contaminated sample can result in misleading conclusions and potentially inappropriate treatment. Getting a proper sample is critical.
There are two main ways to deal with this problem:
1) Look at the kinds and number of bacteria grown from the urine culture. General guidelines (that are completely empirical) give cutoffs for the level of bacterial growth that should be considered clinically significant versus incidental contamination, with a grey-zone in between. This can be tough to interpret with confidence, so while looking at bacterial numbers can provide some information, it's not the preferred approach.
2) Collection of a sample by cystocentesis. This is a very quick, simple and low risk procedure that involves taking a sample directly out of the bladder using a needle and syringe. The animal is placed on it's back (no anesthesia required, and usually even sedation is unnecessary), the skin is cleaned, and a thin needle is passed through the lower part of the belly, where the bladder lies directly under the skin. Often, if an ultrasound machine is available, a quick check is performed to see the size and location of the bladder, but the procedure can be done without ultrasound assistance.
While cystocentesis may seem like a big deal for collection of a fluid that the pet passes freely on a regular basis, it provides much better information and is largely considered the standard for urine collection in dogs and cats. Unless there is a medical reason not to do it, cystocentesis should be used for collection of urine samples for culture.
Image from: http://www.e-barrett.com/page59t.htm
Easter chicks and Salmonella
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It's encouraging to see the number of press reports warning people not to bring home baby chicks or ducklings as Easter presents for kids. The warnings are because of the potential risk of salmonellosis associated with contact with poultry and fowl, particularly among children. Young kids (less than five years of age) are at high risk for this type of infection, and are at higher risk of developing more serious illness and complications. They also tend to be at higher risk for exposure because of the close nature of contact that they may have with pets, or in this case Easter chicks. Add close contact and increased susceptibility to the generally low level of hygiene associated with household animal contact, and you have a perfect recipe for sick kids.
Salmonella carriage is an ever-present concern with chicks and duckings. It doesn't matter how they were raised or from where they came - you can never know by looking it it whether a baby bird is shedding Salmonella, and you should assume that they all are to be on the safe side.
The CDC has some basic advice on the topic. The key points are:
- Never buy chicks or ducklings on a whim. If in doubt, buy a stuffed animal.
- Never buy chicks or ducklings for kids under five years of age or people with compromised immune systems. These individuals should not have any contact with chicks or ducklings.
- Don't let these animals roam freely around the house. They're not house trained and can contaminate the household environment.
- Always wash your hands thoroughly after contact with chicks or ducklings.
- Don't eat around chicks and ducklings, since it increases the chance of inadvertently ingesting Salmonella.
Baby chicks and ducklings don't make good pets because of the Salmonella risk. They also grow up, and become larger, messier, and noisier birds for which many people are not prepared to care. Don't buy a baby bird unless you have a low risk household, can properly implement measures to reduce the risk of exposure to Salmonella, and have a plan to properly take care of the bird when it gets older.
Raw diet "research"
PetProductNews.com reports that Nature's Variety, a raw pet food company, has unveiled results of a recent "research study" on their products. Whenever you see "research," especially on the web, you need to consider whether it's really valid scientific information or a marketing ploy. This particular case certainly doesn't seem like anything approaching real research.
Apparently the study, commissioned by Nature's Variety, involved the feeding of six adult dogs variations of different diets over a 4.5 month period. They looked at stool quality, volume and odor, blood chemistry, quality of their skin and coat and body weight.
- In research, we worry about sample size. You need to have enough animals to detect any real differences. With 6 dogs, 4.5 months of feeding and different diets, you don't have much of a chance to detect a problem (or a benefit, usually). You could have a diet that kills 10% of the dogs that eat it every year and not detect it in study of that size!
- The number of dogs and time don't even fulfill AAFCO feeding trial requirements, so this doesn't provide any information that would be accepted using standard requirements.
Nature's Variety director of research stated “It’s kind of a sigh of relief.”
- It's pretty concerning that the head of research would be relieved that there were no obvious health problems in such a small study. If they don't have real confidence in the quality of the food, why are they selling it? If you have confidence in your diet, you say "Of course, as expected, our diet was shown to be nutritious and safe..." not "Wow, we're really happy no dogs died!" Research to indicate safety and nutritional value should be done before you sell, not well after.
Duclos said she expects the study to be published in a peer-reviewed journal in about one year.
- Not likely. For one thing, from what they are releasing, it's very weak and not defensible scientifically. For another, they've already released the results. It's inappropriate for people to release results before they've undergone peer review, and releasing data in a press release will probably prevent any reasonable journal from even considering the study.
It's good that Nature's Variety is trying to do some research. It's also good that they're addressing Salmonella contamination following their recent recall. The fact that they are doing something progressive is an encouraging sign. However, they need to do proper research, and make sure it undergoes appropriate scrutiny, instead of using small and relatively useless studies to generate press releases.
Raw feeding has inherent risks of exposure for people and pets to potentially harmful bacteria like Salmonella. Raw feeding can probably be done safely for both the pet and people in some, but not all, situations. More information about raw meat feeding can be found on the Worms & Germs Resources page.
Tamiflu and parvovirus in dogs
A somewhat controversial study has just been published in the Journal of Veterinary Emergency and Critical Care (Savigny et al 2010). The study looked at the use of Tamiflu (oseltamivir) for the treatment of parvovirus infection in dogs. Tamiflu is best known as a potentially important influenza drug in humans. It's a neuraminidase inhibitor that can prevent replication of some viruses, such as influenza. It actually has no effect on parvovirus, but has been used by some veterinarians based on the hypothesis that it can have an effect on bacteria and perhaps prevent secondary bacterial infections, which contribute to the severity of parvoviral disease.
The study examined a relatively small number of dogs (35) with parvovirus infection. Some dogs received Tamiflu along with standard treatments, while the others received a placebo and standard treatments. There was no difference in major outcomes between the two groups, but control dogs lost more weight during treatment.
The study has some weaknesses and doesn't tell us too much, but it's the first objective investigation of this drug in dogs. There was no significant difference in relevant outcomes, but was that because the drug doesn't work, because the dose was too low (as has been suggested by some) or because the study was too small to detect a real difference? That's the big question.
Some veterinarians are completely convinced Tamiflu works for parvovirus infections and disregard any suggestion that it doesn't. Currently, there is no scientific evidence whatsoever supporting its use, and this study doesn't help much one way or the other. There are abundant anecdotes, and it's plausible that this drug could be useful for treating this disease, but there are a few concerns:
- We really don't know whether it works. Continuing to use a treatment in the absence of objective information is not necessarily a good idea.
- We don't know the appropriate dosage and duration of treatment for dogs. We also don't know which animals Tamiflu might or might not help. It is probably most effective (or perhaps only effective) early in disease.
- Tamiflu is an important human influenza drug, and resistance is emerging in influenza. Can we justify using a drug that is a part of pandemic influenza control for the treatment of canine parvovirus, without any evidence that it is effective or needed?
The article's abstract concludes by saying "Based on these results, the true role of oseltamivir in the treatment of parvoviral enteritis remains speculative, although it is believed that further investigation is warranted." Very true.
We need two things:
- Rational discussion about whether use of drugs like this is justifiable in animals.
- Better studies to tell us whether it works, and if so, how to best use it.
If we end up using it, we also need surveillance to make sure routine use of this drug in animals doesn't contribute to resistance in humans. Unfortunately, the Tamiflu debate is too often full of anecdotes and arguments as opposed to logical discussion and sound evidence. Hopefully that won't get in the way of someone doing a more definitive study.
My dog has MRSP... Should I be concerned?
This is a question I get a few times a week. Because methicillin-resistant Staphylococcus pseudintermedius (MRSP) infections are becoming so common and people are aware of potential concerns regarding transmission of methicillin-resistant Staphylococcus aureus (MRSA) from pets to people, it's a logical concern.
Here's my basic thought process when answering this common question:
- Staphylococcus pseudintermedius is very common on the skin and in the nose of healthy dogs. A large percentage of dogs are carrying this bacterium on any given day, and you can never tell who's a carrier by looking at them. Therefore, a large number of people are exposed to this bacterium on any given day.
- Staphylococcus pseudintermedius is a common cause of infection in dogs, particularly skin infections.
- Staphylococcus pseudintermedius can be found in the nasal passages of a small but appreciable percentage of healthy people, most likely acquired from their dogs.
- Despite the frequent exposure, S. pseudintermedius infections in people are extremely rare.
So, the risk of getting a S. pseudintermedius infection from a pet is quite low. What about the methicillin-resistant version of this bug?
- MRSP and the susceptible version differ by the presence of antibiotic resistance, and not necessarily anything else. Methicillin-resistance does not, to our knowledge, increase the virulence of this bacterium or make it more transmissible.
- If transmission of S. pseudintermedius from pets to humans is very rare, and methicillin-resistance doesn't increase the risk of transmission, there should be no greater likelihood of someone getting MRSP from a dog compared to susceptible S. pseudintermedius.
So in the end there's not too much to be concerned about. Yes, there is a reasonable chance that MRSP can be passed between people and pets, but that's different than getting sick. Transmission of MRSP from healthy and sick pets to owners probably occurs on a regular basis, but since MRSP is not a normal bacterial inhabitant of people and it is not well adapted to cause disease in humans, not much happens.
But the disclaimer I always put in is "rarely doesn't mean never." The risks are very low, but they are not zero. While the odds of me picking up MRSP from a dog are very low, I'd rather not have an infection with a highly drug-resistant bacterium. Accordingly, the use of proper hygiene and infection control measures, particularly around an animal with an active infection, is always important. These measures include:
- Frequent handwashing after contact with the pet.
- Avoiding contact with the infected site.
- Keeping the infected site covered with an impermeable dressing, whenever possible.
- Reducing contact with the nose of the infected animal, since it may also be carrying the bacterium there. In general, reducing close contact (e.g. snuggling, nuzzling, hugging, kissing) during the period of infection is a good idea.
- Regular washing (in hot water with hot air drying, whenever possible) of pet beds and other items that come into close and frequent contact with the pet.
Is all that overkill? Probably. But it's also an easy and practical plan, and a reasonable approach to reduce the already-low risks.
More information about MRSP is available on the Worms & Germs Resources page.
(Photo credit: John Haslam)
Drug discovery disparity
On the way home from an MRSA symposium in the US the other day, I was (perhaps fittingly) listening to a podcast about new antibiotic development. The podcast, by The Lancet Infectious Diseases, discussed the small number of new antibiotics that are in the pipeline (about 15), particularly in contrast to the number of new anti-cancer drugs (about 800). There are many reasons for this, and development of new anti-cancer drugs is certainly important. However, we have definitely not "won the war" against bacteria, and resistance continues to be a serious threat to human and animal health.
The small number of potential new drugs (since many drugs in development will not ever make it past drug trials) is a concern if resistance continues to increase. The disparity in development between antibiotics and anti-cancer drugs is also concerning when you consider that good antibiotics are very important for cancer therapy - people with cancer often get infections, and often their infections are caused by multidrug-resistant bugs. As we develop more and better anti-cancer drugs, there will be more people who are susceptible to these potentially severe infections, and ways to treat them are needed.
Why are there so few antibiotics in development compared to other drug types?
- $$$ - Money. The potential return on investment for pharmaceutical companies is much greater for many other drug types. Huge amounts of money must be invested to develop, test and license drugs. Logically, companies are going to focus on the higher yield drugs, leaving some important areas with less research and development than would be desired.
What do we do?
Well, unless you own a pharmaceutical company or have millions of dollars to spend, you're probably not going to have an impact on drug development. Since we can't control what will be available to us in the future, we need to make sure that we delay, as much as possible, the emergence and dissemination of highly resistant bacteria.
Common sense practices such as only using antibiotics when necessary, using them properly (e.g. proper dose and route, giving the entire treatment course), good preventive medicine to reduce the risk of bacterial infections and good infection control measures are critical and often underused. While not as fancy as high-tech drug develop, these are the ways that we can have a positive impact in both human and animal health, and reduce our need for new drugs.
Ascaris lumbricoides and dogs
Roundworms (ascarids) are common parasites of many animal species. In dogs and cats, Toxocara canis and Toxocara cati are the main problems. In people, it's Ascaris lumbricoides, which is often called the "human roundworm." It's a very common parasite that is thought to infect about 25% of the world's population. Rates are highest in tropical, developing areas with poor sanitation, poor hygiene, and (as one author stated) a tendency for "promiscuous defecation." Basically, the more human feces in the environment and the lower the degree of hygiene, the greater the risk of inadvertently ingesting parasite eggs.
Traditionally, it's be thought that this parasite is specific to people, but occasionally, A. lumbricoides eggs have been found in the feces of dogs. The general assumption in these cases has been that the dogs just ingested eggs from the environment, and the eggs simply passed through the dog's intestinal tract and out the other end. However, a recent paper has challenged that thought. The study (Shalaby et al. Parasitology Research, 2010) found adult A. lumbricoides worms in the small intestine of 8% of tested dogs in Egypt. The presence of adult worms means that the dogs ingested the eggs and that the eggs were able to develop to adults in the dog's intestinal tract. The adult worms were producing eggs, suggesting that dogs could be a reservoir for A. lumbricoides, beyond just spreading around eggs that they ingested from human feces.
Overall, dogs probably play a minimal role in human infection with this parasite, but it's an additional dynamic to consider. However, the best approach to reducing the risks associated with dogs and A. lumbricoides probably don't have anything to do with dogs - rather, the keys are reducing environmental contamination with human feces and improving general hygiene practices.
Image: Adult female A. lumbricoides. (source: CDC Division of Parasitic Diseases (DPDx))
Raw food recall expanded
Nature's Variety has expanded their recall based on more concerns about Salmonella contamination of their products. In a lot of ways, this makes no sense to me since you have to assume that raw meat is contaminated with Salmonella, E. coli, Campylobacter and various other pathogens. That's been clearly shown in studies of raw meat for humans and animals, and that's why we cook meat intended for human consumption and emphasize good food handling practices. It's also why there are concerns about feeding raw meat to pets, and the explanation for various studies showing pets fed raw meat have much higher rates of shedding potentially harmful bacteria like Salmonella. You have to assume that a reasonable percentage of Nature's Variety's food has been contaminated with Salmonella, not that this is an uncommon and preventable event.
Because of the problem or consumer concerns, Nature's Variety has announced that they will be treating all of their diets using high pressure pasteurization. Basically, this process uses very high pressures (with only a slight increase in temperature) to reduce bacterial levels. I can't find any scientific literature about the effectiveness of this method on Salmonella contamination of raw meat (it's mainly used with milk and cheese) but it should be able to greatly reduce bacterial levels in meat. That's a good thing, as long as it works. What's important to know, however, is whether it is really highly effective in this situation and whether all potentially harmful bacterial will be eliminated every time.
I'm concerned that if people think this food is "sterile" and it's not, they might not take the necessary food handling precautions. If this method usually, but not always, kills all of the bad bacteria, or if it reduces levels greatly but not completely, then there could still be the risk of infection of people and pets. This information is critical. In the absence of clear scientific data, I think we need to assume that some level of contamination could still be present (although probably much less often and at a much lower level), and make sure that proper food handling practices are used.
It's good to see this company taking measures to reduce the risks associated with raw meat feeding. Let's hope that some objective research is made available to indicate what risks might remain.
Image source: www.defendingfoodsafety.com
2009 feline H1N1 case published
When the novel H1N1 influenza pandemic infected large numbers of people, it was not particularly surprising that the occasional infection was noted in pets, considering over 50% of North American households have pets, and the close nature of contact that many people have with their pets. While the few cases that occurred were highly publicized, in the end pet infections were rarely diagnosed (although that doesn't mean they were truly rare), and limited information about these cases has been available. Details regarding one H1N1-infected cat from Iowa (Sponseller et al. 2010) were recently published in Emerging Infectious Diseases.
Here are some of the highlights:
- The 13-year-old cat was an indoor cat that was admitted to Iowa State University's veterinary hospital because of depression, decreased appetite and signs of respiratory disease.
- Two of 3 people in the house had undiagnosed influenza-like illness a few days before the cat got sick. The cat was an affectionate pet and interacted closely with household members.
- Influenza was diagnosed in the cat by detection of H1N1 influenza virus using molecular diagnostic methods (reverse transcriptase PCR) on a sample of fluid collected from the lungs.
- The cat improved with supportive care alone (mainly intravenous fluids to correct dehydration).
Considering the cat lived indoors and people in the house had signs consistent with influenza, it's almost certain that the cat was infected by its owners. This isn't surprising, but it's a good example of how infectious diseases can move between people and pets, in either direction. There's no evidence that pets were a source of human infection, but if something can move from people to pets, there's certainly good reason to think that it could go back from pets to other people. This should be another wake-up call for the need to consider and investigate the potential role of pets in any emerging infectious disease, and to consider emerging "human" diseases in sick animals that might have been exposed.
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 not yet, but it not an uncommon problem in most dogs 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 kind of diarrhea is to make sure dogs don't eat anything unusual, but that may be easier said than done. If a dog does get into something it shouldn't, odds are it's not going to be a major problem in terms of infectious diseases. Most of these become typical cases of "garbage gut," the results of which are the dog vomits and maybe has some diarrhea, but is otherwise fine and gets over it 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. During this period you should be aware that, while the cause is unlikely to be infectious, there's still 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 afterwards. Cleaning up diarrhea takes a little more care, as I've previously discussed.
Garbage gut is 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 (e.g. bones, indigestible garbage), 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 (e.g. 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 your dog has underlying health problems, has a history of pancreatitis or is very young (i.e. a puppy) 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 while performing a necropsy. Occupational exposure to infectious diseases is an inherent risk in veterinary medicine. Veterinarians 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. Sometimes infections occur because of bad practices. This report highlights the latter.
In this case, a 4-month-old pony began showing vague signs of illness, then developed neurological abnormalities and was euthanized. A necropsy (post-mortem exam) was then performed by a veterinary pathologist with the assistance of two veterinary 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 veterinary student developed a fever, malaise, sore muscles, stiff neck and severe headache. West Nile virus infection in the student was confirmed, and the viruses from the pony and person were the same type based on testing. Fortunately, the signs of infection in the student subsided after approximately ten days.
Horses are considered "dead-end" hosts for West Nile virus, meaning they cannot naturally transmit the virus. This is because horses (even severely affected ones) only have very low levels of virus in their blood, so a biting mosquito can't pick up the virus and transmit it to other individuals. However, the brain and spinal cord, particularly in a clinically affected horse, may contain very large amounts of the virus. It's astounding that a veterinary school would have a student removing the brain and spinal cord of an animal that died from a neurological condition, especially without proper protective gear, since the 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...
This Worms & Germs entry was originally posted on our sister site, equIDblog, on 11-Mar-10.
Deworming dogs... How often?
Deworming has become 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 pets and some can pose a risk to people. There's no argument that 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 consideration of a several different things, including:
- What parasites are in the area?
- Are the risks the same all year round or are they seasonal?
- What parasites pose a risk to an individual pet or what are the pet's chances of exposure? (e.g. Does the pet go outside? Is it 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? (e.g. young children, people with developmental disorders that might be more likely to be exposed to pet feces?)
Everyone agrees puppies and kittens need more aggressive deworming, but there are a few different approaches to managing deworming in adult animals.
The Companion Animal Parasite Council advocates monthly deworming for a few reasons. One is that, based on the duration of activity of the drugs used, monthly treatment prevents establishment of significant parasite populations in the animal (and therefore also in the animal's environment). It also keeps the treatment user-friendly - it makes it easier for people to remember to treat their pet. Some concerns with this approach include its "one plan fits all" mentality, despite the fact that there are great differences in the risks between different regions, and even between pets in the same area. There are also concerns about such heavy use contributing to the development of parasite drug resistance (which is a problem in some other species like horses and sheep), although this doesn't seem to be a major concern... at least not yet.
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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.
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Yet another approach was recommended by a Canadian Parasite Expert Panel. With their 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 (and people) in all regions. Tailoring the deworming strategy to your pet, based on your pet's and your family's risk, is the 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 targeted by routine deworming. 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 (where 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, including indoor composters that can be used by apartment or condo dwellers who want to satisfy their eco-friendly side.
They mentioned that one of the composters they highlighted (NatureMill) can apparently handle pet waste, but composting animal feces is not a good idea. Pet waste (feces +/- cat litter etc.) can contain a wide range of potentially harmful parasites and bacteria. The composting process can generate enough heat to kill these 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, and (maybe more importantly) compost usually ends up in gardens where the bad bugs can contaminate the soil, as well as anything grown in the garden.
One concerning microbe is the protozoal parasite Toxoplasma gondii. Cats are the natural reservoir of Toxoplasma and can pass it in their feces (usually only for a short period), but most people that become infected by Toxoplasma are likely exposed to the oocysts ("eggs") outside in gardens, or from contact with contaminated foods (e.g. unwashed vegetables). (Undercooked meat can also be a source of infection, but that's another story). Composting may not kill this parasite, so when pet-waste compost is put into flower gardens or vegetable gardens in which people work, the risk of exposure to Toxoplasma may be increased. The risk of transmission from an individual cat is admittedly low, since only a very small percentage of cats are shedding the parasite at any one time (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 afterward, of course).
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 a bit differently: pay careful attention to hand hygiene after handling the compost, and make sure the compost isn't used in gardens or other areas where people might have contact with the soil.
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.
