Beware the Chinese Chicken

True story.

No, a drumstick will not make your brain stop tickin'. However, over the last year the FDA has reported a rather dramatic increase in reports of pet illness that may be related to chicken jerky treats made in China. Concerns are now extending to duck and sweet potato products. Problems have ranged from vomiting and diarrhea to kidney failure and death; however, I should emphasize that no direct link or cause has been identified yet, and nothing has been recalled as of yet. In other words - don't panic.

On the other hand, there have been more than enough reports to warrant avoiding Chinese-made jerky treats and tossing any you may have bought, just to be on the safe side. Frankly, China has jack for safety regulations, a fact underscored by several recalls of very dangerous products produced there in recent years.  I try to avoid anything with "Made in China" on the back, period. Sorry, Beijing.

This is also a good opportunity to point out two great resources for information about pet food and product recalls. The American Veterinary Medical Association maintains two recall lists, one for foods and another for pet products:

• Pet Food Safety Recalls and Alerts (AVMA) 
• Pet Product Safety Recalls and Alerts (AVMA)

Of note, several brands of thyroid medication were also recently recalled. Manufacturing issues may have led to non-uniform pills (that is, varying drug strengths); this probably won't cause serious side effects, but if your dog is on thyroid meds you should ring your vet's office to see if you've received any of the problem lots. Also, some Petco food bowls were recalled due to radioactivity. I couldn't make this stuff up.

Out Of The Kitchen And Into The ER: Four Dangerous Foods For Pets

Folks often ask me if this-or-that food is okay for pets. I like to tell them all people foods are "toxic" to animals, since even moderate quantities can lead to a chronic condition proven to shorten lifespans and known colloquially as FAT, or Food-Amplified Tissue syndrome. You can read more about that in this article. Furthermore, anyone whose Lab has ever raided the trash can can tell you that enough of anything a pet isn't used to eating can result in a few days of sickness (and maybe a visit from the carpet cleaners). Of course, some things in the kitchen can harm your pet much more quickly and severely, and today's article covers the four biggest culprits.

Lets start with a few general notes. First off, if you are concerned about something Muffy indiscriminately scarfed down the first thing to do is call your vet. If they aren't open, try the nearest pet emergency hospital or Animal Poison Control. They can tell you if you should freak out, how much you should freak out, and what you should do next (after they get you to stop freaking out). The risk is usually going to depend on how much toxin went into how much dog; that is, a nibble of onion or milk chocolate probably won't faze a Great Dane, but it could be enough to kill your 2-pound chihuahua. Cats also tend to be more sensitive to most toxins, food or otherwise.

Anyone else suddenly craving Italian?

Onions and Garlic
Plants in these families contain sulfur compounds that can damage red blood cells, causing them to rupture. Since red blood cells are responsible for carrying oxygen to the body's cells, and those cells need oxygen, this is kind of bad. Common signs logically include weakness and pale gums; however, these problems occur hours to days after exposure. Note that garlic and onion powders are just as dangerous, and may be used in processed human foods in significant portions - just one more reason to keep pets out of the people food!

Grapes and Raisins
These can trash your pet's kidneys. Kidneys are rather important. Raisins are more potent in this regard, which shouldn't be surprising since they are basically grapes minus the water - and water, at least, is good for kidneys.

Before anyone asks -yes, some dogs and cats seem to tolerate grapes and raisins just fine, and we aren't sure exactly what the mechanism for the toxicity is in the first place. On the other hand, some pets die from eating these. Just keep them out of them, okay?


Chocolate

Fortunately, there is nothing wrong with
eating chocolate in front of your pet.
Which I think I shall now do.

Cocoa contains stimulants that are very dangerous for pets. Early signs include vomiting and diarrhea, leading to extreme excitement and agitation (imagine your chihuahua on three cups of espresso), and even death.

But wait - a culinary lesson! Chocolate is a blend of sugar, fats, and cocoa; the amount of these determines the type, flavor, and quality of the chocolate. Milk chocolate has little actual cocoa, dark has a good bit, and semi-sweet or baker's chocolate is mostly cocoa. This is important because the more cocoa, the more danger for your pet. White chocolate is made with cocoa butter rather than actual cocoa powder, and so is fairly harmless unless they try to eat their weight. How much is too much? Check out this excellent interactive chart from National Geographic. But remember, each dog is different - contact your vet if you are worried!


Xylitol (that's a sweetener, not a Russian side dish)
This is present in many sugar-free gums, mints, vitamins and even toothpaste. Within 30 minutes of ingestion it may cause a dog's blood sugar to drop to dangerous levels, resulting in seizures, coma, or death. Worse yet, even if they don't show these signs some dogs may develop liver failure hours to days later. Because of this overnight hospitalization and monitoring is advisable in most cases.

Lastly, this list is not exhaustive. These are the most common and dangerous food items; other things like macadamia nuts, avocados, and fruit seeds may be harmful as well. APC has a nice question-and-answer list covering the good, bad, and mostly-harmless foods folks often ask about. But definately keep Muffy out of  your stash of sugar-free, chocolate covered raisins dusted in onion powder! You can send me some, though. That sounds tasty.

Anesthesia - Keeping The Big Sleep Safe

Few things make owners as nervous as anesthesia. Heck, when I was first unleashed upon the world as "Dr. Rowland" anesthesia wracked my nerves way more than surgery. I distinctly remember the first time I knocked a patient out - I calculated the dose, double-checked it, then looked it up and checked it again, then read the drug monogram for the Nth time and checked the dose several more times. I've gotten over that, of course. Wouldn't see many patients at that rate!

Here's the thing - with the right drugs, good monitoring, and a relatively healthy patient anesthesia is quite safe. But anesthesia is never without risk, and should never be taken lightly. Today's article is geared toward relieving the anxiety most of us feel when our pets need to be anesthetized - by giving you knowledge about what the risks really are, and what we (vets and owners) can do to minimize them.

Monitoring
Guess what the best way to miss a problem is? Not looking for it.

A fully-functional veterinary monitor.

Anesthetic drugs don't just cause loss of consciousness - they may affect heart rate, blood pressure, respiration and more. In case you don't know, these things are kind of important. The body has needs - nutrients, oxygen, and removal of waste products produced by using those things. Respiration and circulation are how the body gets it done. So it only makes sense to closely monitor how all that's working, right? And since a living body is a pretty complicated bugger, there are many things that can go wrong and many things we can watch to recognize problems and address them before they get out of hand. Here's what I consider minimum monitoring for most procedures:

• Heart rate and blood pressure - These are the main determinants of blood flow, but they can also clue us in on "depth" of anesthesia and even other problems like blood loss.
• Electrocardiogram (ECG) - That's the green wave with the reassuring beep on the TV hospital shows. The heart is a complicated pump running on electricity; an ECG looks at that electricity to identify problems with rate, rhythm, or coordination of the heart.
• Respiratory rate and blood oxygenation - Blood flow to your pet's tissues does little good if it doesn't have oxygen. And, even if you are breathing, lung or circulation problems can keep the body from getting the oxygen it needs.

Except for pulse and respiration, all those require special equipment to monitor. But this belies an important question - who monitors the monitors? Indeed, the most important monitor of all is the human being keeping track of, interpreting, and responding to all this information. Since the veterinarian is usually kind of busy -cutting this, stitching up that, and keeping sterile all the while - the best monitor is a living, breathing, highly-trained veterinary technician. They keep an eye on all that data for problems, address the minor stuff, and let me know when I need to stop playing with this or that organ and focus on what the rest of the patient is doing. Plus they monitor important stuff no machine can, like reflexes and gum color, and administer whatever treatment the vet deems necessary if problems do arise. 

How Do I Know You're Healthy?

A 2008 British study showed that anesthetic risk increased almost 7 times for patients with significant systemic disease. That's not exactly surprising, but I'd go farther and say the most common reason for anesthetic problems in patients we think are healthy is that they aren't healthy. Pets with early or mild disease often compensate well and show no outward problems - until we knock them out with a bunch of drugs that reduce their ability to compensate. Here's what I recommend before any anesthetic procedure, to feel reasonably comfortable your pet is healthy:

Occasionally, bloodwork is really surprising.
This pet appears to be possessed by demons.
(okay, not really...)

• A Good History & Physical Exam - The importance of these can't be overstated. Changes in appetite, activity level, urination or other behaviors are major clues to systemic problems. Likewise, many problems with the heart and lungs can be heard with a stethoscope. Some diseases leave early signs that can be seen with a good look at the eyes, skin, or mouth. And more than once I've felt something that shouldn't be there in the abdomen of an outwardly normal patient.
• Basic Bloodwork - Simple blood tests can identify problems with the liver or kidneys that may not cause clinical problems in your pet - until we challenge them with a bunch of anesthetic drugs. A blood count can also catch problems like anemia or inflammation, which in turn may be clues to undiagnosed infections or immune diseases.

Realistically, even if we ran thousands of dollars worth of MRI's and fancy bloodwork we couldn't be 100% sure your pet didn't have some strange, subtle disease. But those simple things will rule out the majority of problems without breaking the bank - a simple blood panel runs about $40-$60 most places. 

Anesthetic Drugs

The drugs used for anesthesia are really your vet's prerogative, and far beyond the scope of this article. However, it's worth briefly mentioning two things about drug choices. First off, when we do find a health issue with a pet that requires anesthesia we use that knowledge to select the safest anesthetic drugs for the condition. Each drug has it's own profile of side-effects that may impact the heart, liver, kidneys, etc; none are without side effects, but we can choose those least likely to aggravate the patient's individual problems.

Secondly, pain and stress also impact many of the things we worry about during anesthesia - heart rate, blood pressure, and even the heart's electrical rhythm. While I haven't came across any studies establishing that good pain control leads to safer anesthesia, it stands to reason that a less stressed, pain-free patient should handle anesthesia better. Most of us nowadays provide sedation prior to inducing anesthesia and various kinds of pain relief (analgesia) during procedures for just this reason.

What Should You Do With This Knowledge?

Here's the point - understanding all this means you can make informed choices when your pet needs anesthesia. Here are some questions you should now be able to ask when choosing a vet for a procedure:

• What kind of things do you monitor when Muffy's asleep?
• Is there a person watching Muffy while he's out? What kind of training do they have?
• What kind of bloodwork do you recommend? 
• Based on your exam, do you think Muffy's okay for anesthesia? Is there anything else we should check?
• If the procedure may be painful, what kind of pain control do you provide?
• Do you have any other questions about Muffy, Doc? (That is a smart owner question.)

So, why tell you all this? Thing is, many great, smart veterinarians don't do all the things they'd like to or feel they should because of financial reasons - that is, you won't pay for it. Not every clinic provides all these services, and many clinics that do offer everything mentioned above make them "optional" for an additional fee. Those monitors I talked about run $3,000-$10,000, with a life expectancy of a few years. The technician monitoring the monitors is $13-25 per hour. If you won't pay for it, we can't pay for it - or we have to cut costs somewhere else, which isn't good for your pet either. Honestly, I don't put the blame for that on pet owners, but squarely on we vets - we can't expect you to pay more if you don't understand why the extra money is worthwhile. Hopefully now you do, and can make informed decisions about who treats your pet and how. The most expensive place in town may not necessarily be the best, but I can pretty much guarantee if you price-shop around for the cheapest place your pet is missing out on some or all of these safety measures. 

Likewise, some vets make good arguments that some of the things discussed here aren't necessary. And maybe they aren't strictly necessary - the vast majority of outwardly health animals are indeed healthy, and would probably be fine if knocked out with a 20-year old drug protocol and ignored. Bear that in mind if you truly can't afford the extra money for all the "best" care. But most of us can handle an extra $100-150 for good monitoring, pain control, and some basic bloodwork; the peace of mind it buys is worth a lot more, if you ask me. 

Dope on a Rope? Quick Tips for Leash Training

It's almost comical how often I see dogs dragging their owners in and out of my door. I have this theory that twenty-something men concocted a formula where "manliness" is computed via a dog-to-wife weight ratio. Best of all, the macho husband is usually worse at controlling that monster Great Dane than his tiny, exasperated wife. The humor dies out, though, when you can't keep the dog from darting into traffic, attacking another animal, or you wind up at your own doc getting rotator cuff surgery. Today's article will provide tips on keeping Fido under control so everyone stays out of trouble.

Properly fitted Gentle Leader.

The Right Tools for the Job

Controlling your dog on a leash really boils down to training, but the right equipment can make the difference between success and giving up in frustration. Any pet can be trained to behave on any leash or collar. But you can also train to run a 5k on stilts - it's just a heck of a lot harder. Here are my suggestions for what equipment works, and what you should shy away from.

Gentle Leader (TM) head harness: These are awesome. One loop goes behind the head, one over the nose, and the leash attaches under the chin. This takes the dog's mechanical advantage away - it's no longer using the full force of it's legs to push that leash snapped on it's back forward, but instead it's trying to awkwardly push it's own head around. Unlike choke/pinch collars, this doesn't rely on making the dog uncomfortable, though some do think the slight pressure applied across the bridge of the nose may stimulate pressure points that help them focus, much like mom nipping their nose to get their attention. 

Note that the biggest problem folks have with these is not fitting them properly. Most leave them too loose, which is actually more uncomfortable than a tight fit because it allows the loops to slide and rub across the nose, while also reducing your control over the dog. Make sure and buy the one that includes the DVD - watch it, fit it right, and you can literally train your dog to heel in an afternoon.

Second handle = manual retraction = control

Retractable Leashes: Throw these away. There is no firm, certain boundary with a retractable leash - meaning they train dogs to constantly test their boundaries. Likewise, they train owners not to control their dogs. Buy a short, fixed-length leash. I particularly like the ones with a second handle near the collar to give you firm control when needed - like when passing a pack of yippy, tasty Corgi's on the sidewalk.

Choke/Pinch Collars: Many obedience schools will base their programs around them - my advice is find another school. It's an old method that can work, and does if you learn it thoroughly (like many folks who run those schools, to be fair). But hardly anyone becomes expert enough after a few classes, and used improperly they have the ability to do harm - unlike a standard collar or harness. Too often I hear dogs gagging in the lobby as they stubbornly forego oxygen to continue dragging their owner around. 

If you use these, ONLY leave them on the dog when you are attached to the other end and paying attention! They CAN catch them on things and asphyxiate themselves.

Harnesses: These don't really provide any advantages or disadvantages for controlling you pet, but they do have the benefit of not encouraging the dog to tug on his own windpipe. They're a good option for small dogs, where physical control isn't so much an issue. 

Ok. Sometimes
Scott Baio is in charge.

Training

Who's in charge? I'm in charge. 

The key to training your dog (or child, or spouse) to do anything is rewarding the behavior you want while not rewarding behavior you don't. In this case we don't need treats - the reward is being able to keep going forward toward that next wonderfully disgusting odor Rover just has to sniff. At the first tug on the leash, we stop. I'm in charge. No reprimand, no attention, just no movement until they relax, stop pulling, and focus on me. Then we go forward again until they start tugging - and repeat. It's simple, but it takes a lot of patience and a bit of time. It should also be clear why retractable leashes are so counter-productive; how do you learn what they boundaries are when they keep changing?

Just like your kids (or your husband), as soon as you start thinking you've almost got them trained and let your guard down a bit they'll be testing those boundaries hard-core. You must be vigilant. Tugging shall not result in moving forward! Keep at it. You're in charge. It's also worth emphasizing the importance of getting them to focus on you before they get rewarded- you are the one providing guidance, instructions, and rewards. Focus doesn't have to be visual, though - many dogs benefit from staying right up against your leg, quickly learning to read subtle signals in your movements. 

As with all training, the right equipment makes things easier - but at the end of the day it boils down to patience, consistency, and work. But you can do it - and for any dog over thirty or forty pounds, you really need to do it for everyone's sake. 

Heartworm 103 - Those Pesky Cats

Cats are not just small dogs, and feline heartworm disease is a prime example. The first two articles of this series dealt with how heartworms cause disease and preventative/diagnostic strategies primarily in relation to dogs. Today's article will outline specifically how heartworms effect cats; in many ways they are a more frustrating and elusive problem in cats, made all the more dangerous because many owners don't realize feline heartworm is a serious concern.

Accidental Guests: Heartworm Disease in Cats

Cats are not the natural host for heartworms. Unfortunately, no one seems to have explained this to the mosquitoes that spread infection or the heartworm larvae that cause it. Consequently, these uninvited and unadapted parasites really, really tick off the cats immune system. The first consequence of this is positive - cats seem much better than dogs at killing off larvae before they develop into adults. Studies suggest only about one-third to one-half of naturally infected cats develop adult worms, though it's tough to nail down accurate percentages due to the difficulties in testing that we'll go into later. 

Hey, human. Indoor cats get
heartworms too.

The second consequence of cats' super-miffed immune system is a negative one, however. Killing off the larvae within the lungs results in significant inflammation. Vessels and lung tissue gets thickened, making blood flow and air exchange less efficient and resulting in the classic signs of respiratory disease - coughing, rapid or labored breathing, and general malaise. This is now referred to as heartworm-associated respiratory disease (HARD), and it is a major reason why I've started recommending all cats receive monthly preventatives. Depending on the studies you look at, perhaps as many as 15% of cats in some areas are exposed to heartworms and thus at risk for HARD - even if they never develop adult worms. And if you think your kitty is free and clear because it's indoor only, think again - in one published series of cases, 27% were indoor-only cats.

What about the ones who do develop adult worms, though? Whereas dogs may have dozens of adults, cats rarely have more than two or three - again, their immune system is pretty good at whacking those larvae. This means many cats with adults have such a low burden they may show none of the cardiovascular problems typical in dogs. The caveat to this is that when those adults die off after a year or three, the dead worms are big enough to block off major lung vessels - and between that and the cat's once-again huge inflammatory response it can be enough to quickly kill them. Indeed, most veterinary texts list "sudden death" as a major "sign" of feline heartworm infection. That's not the way I like to diagnose things.

Diagnosing Heartworms in Cats...

...is really, really frustrating.

In the second article we talked about how the main test used to diagnose heartworm in dogs looks for a protein produced by adult female worms. This test works equally well in cats, if there is an adult female worm. In one study on naturally infected shelter cats over 50% had only a single worm, and none had more than four. This means cats are fairly likely to have male-only infections, and thus come up negative on this test - even though a single male could potentially kill them. 

Cats aren't good at tests.

Even more importantly, a lot more cats will develop the serious respiratory disease discussed above (HARD) without ever developing adult worms. On the bright side, there are antibody tests available that check for exposure to heartworm larvae. These would be great for diagnosing HARD or even male-only adult infections...except studies suggest they aren't that sensitive and miss many exposed cats, maybe more than 50% of them. 

Not surprisingly, I don't spend much time screening outwardly-healthy cats for heartworm. I'll run both tests when I suspect a cat has HARD or adult worms...but if they're negative, I don't cross heartworm off the list. Chest x-rays or ultrasound of the heart can be useful, but diagnosing feline heartworm can be elusive even when you're sure that's the problem.

Treating Feline Heartworm

Here's a quick topic. Remember how one dead adult may be enough to gunk up the lungs and cause sudden death? We can kill the worms easily enough, but we're just as likely to kill the cat. Yeah...we don't treat feline heartworm. "Treatment" is pretty much relegated to using anti-inflammatory drugs to control the signs and hoping for the best when the worms do die off. It's pretty frustrating when you find yourself crossing your fingers and wishing a freeloading parasite a long, healthy life.

Heartworm Preventatives for Cats

Most veterinarians used to be wishy-washy at best about recommending monthly preventatives for cats because adult infections were relatively uncommon, and serious complications (like death) even moreso. But the respiratory complications - which can potentially be life-threatening themselves - are looking more and more common. Complicate this by the fact we don't have a great diagnostic method  (meaning we likely are underestimating prevalence) and hopefully you're starting to understand why I've started recommending all cats stay on a monthly preventative. 

As of this writing, there are two topical products and two oral products on the market, and all are effective for heartworm prevention. Both topicals are great products, covering fleas and some common intestinal parasites while sparing you the adventure of trying to get a pill into a cat. Neither oral product covers fleas, but Interceptor covers several of the more common intestinal parasites. It's a good alternative in areas where fleas aren't a concern as it's a fair bit cheaper than the topicals.

I've covered a lot of ground in these three articles, and in a good bit of depth. If you're not 100% convinced that heartworm is a serious risk that warrants monthly preventatives, I'm happy to address any lingering questions or concerns in the comments section below!

Quick Tip - Dealing with Firework Fears

It's so pretty! I think I'll go hide behind the toilet! 

Independence Day is here, when we celebrate our freedom to blow stuff up in the backyard, and consequently send half the dogs in the neighborhood cowering underneath the bed. With that in mind, I thought I'd share a few suggestions for easing everyone's stress this holiday. Some are short-term help that might be useful today; others are long-term projects geared towards a more well-adjusted canine companion. All are also equally applicable to similar fears, such as thunderstorms.

Safety First

• All dogs should be kept inside today, and leashes should be used for potty breaks/walks. This is one of the biggest days of the year for lost pets and hit-by-car accidents. Some firecrackers go off in the distance, and suddenly Muffy is over the fence and five blocks away.
• Likewise, make sure your pets have identification and your phone number on their collar. Microchips are good as well.
• We generally see a few firework-ingestion toxicities this time of year, too - keep that stuff put away!

Feeling Safe

• If you have a basement that's relatively sound-proof, it may be the perfect place for Fido to hang out today. What you don't know can't scare the living daylights out of you.
• Ever notice that your pet seems calmer when you hold them close, or that they tend to hide in tight spaces? Tight-fitting wraps may dramatically improve your pet's feeling of security and lessen anxiety. One good product is the Thundershirt; you can try improvising to help Spot out today by dressing him up in an appropriately-sized human tee-shirt and knotting the bottom to make it fit tighter.
• Many dogs that struggle with noise fears have already figured out a "safe place," usually a tight spot in a closet, under the bed, in their crate, or in my dog's case....behind the toilet. Often we're tempted to drag them out and console them, but it's generally best to leave them be - even to encourage them to seek these spots out.

Long-Term Improvement

• Try to desensitize fearful pets by exposing them to the problem at low levels in a controlled environment, gradually working up to full stimulus. For example, get a thunderstorm video and play it on low to start (guys - this a good wife-centered excuse to upgrade the home theater). Here's a good article that goes into more depth on desensitizing.

Better Living Through Chemistry

• Working through a desensitization process to overcome fears is always the best option. That's not always possible, though, and your veterinarian can prescribe medications to ease anxiety and lessen destructive or dangerous behaviors if necessary.
• There are a variety of nutritional supplements and pheromone-based products marketed over-the-counter that claim to calm pets. Always talk with your vet before putting anything in your dog - there's very little regulation of this stuff and lots of money to be made. One product that's safe and sometimes helpful is dog appeasing pheromone (DAP) - it's rarely enough for severe fears, but it can help some dogs. Tryptophan-based products may provide some helpful sedation, too (it's the stuff in turkey that leaves everyone passed out in front of the TV on Thanksgiving).
• A word about acepromazine, a drug sometimes prescribed for these problems. It is only a tranquilizer - it removes the ability/will to act out, but it does not reduce fear. That means Fido may sit there calmly, but inside he's likely still terrified - he just can't do anything about it. For dogs who become so panicked they are a danger to themselves and others it can be a valid option to keep them safe - but usually there are better choices.

Have any suggestions or questions of your own about dealing with noise phobias? I'd love to hear them; just click on the "comment" link below.

Heartworm 102 - Prevention & Testing

Click here for Part I.

In the last article, we talked about what heartworms are and how they affect pets. You might check that one out first if you missed it, as a basic understanding of the life cycle is helpful in understanding today's topics - prevention and testing.

Prevention Strategies

Yeah, Joe was skeptical too.

I'm forever the skeptic, so I'll admit if someone told me I needed to buy pills for my pets every month for life I'd be the first to scan their eyes for dollar signs - veterinarian or otherwise. I certainly understand when the occasional client looks at me incredulously, or asks about just giving during the summer. But we aren't making this stuff up - with a little understanding of preventatives and the biology of disease, you should agree.

First off, it's worth noting that we're generally talking about preventing disease, not infection. The major problem with heartworms are adults (cats are a bit different, but we'll address that in the last article), and it takes about six months for them to mature after infection. The microscopic larvae that cause initial infection are susceptible to low doses of certain anti-parasite drugs, so the idea is that by giving pets a dose at regular intervals we can stop the disease (adult worms) from developing, even if we haven't stopped infection per say. That's good, because as anyone who's been to Louisiana in July will tell you, it's bloody near impossible to keep from getting a bitten by mosquitoes no matter what you do. And it only takes one.

So, why monthly instead of every six months? That's how long it takes to get adults, right? Well, the trouble is that as they age, larvae develop resistance to those relatively safe anti-parasite drugs. Effectiveness gets unpredictable 4-5 weeks after infection, and eventually they become pretty impervious to those drugs. We have to resort to drastic measures to kill adults - in fact, the standard treatment for adult infection is in the arsenic family. So monthly dosing is the safest bet (and a lot easier to remember). On the flip side, it's worth noting that if you miss a dose by a week or two you'll probably be okay. No guarantees, but it makes for easier sleeping when life (or memory) inevitably mucks with your schedule.

And why every month? Mosquitoes don't wear snowshoes, right? I could tell you that "heat islands," warm areas near houses and the like, may create microenvironments where mosquitoes can hatch even in the winter. I could tell you it only takes one infected mosquito to threaten the life of your pet. I could tell you many preventatives have important benefits other than just heartworm protection, and I'll discuss those below. All are true, but I'll level with you. Even if I could guarantee your pet wouldn't see a mosquito until April 1st or after October 31st (I can't), I know most of us - myself included - would forget to start until sometime in May or miss that last dose in the fall. And say you snowbird it somewhere warm for Christmas - what then? It's just easier to be consistent if you're on a consistent schedule. And where heartworm is concerned, consistency can save pets' lives.


Types of Preventatives
The currently available preventatives fall into three broad categories - monthly oral or topical products, and one injectable product that's given every six months. All of these are valid, effective choices for heartworm prevention; the main difference between products is what they cover in addition to heartworm.

Most oral and topical products have additional anti-parasite drugs that worm your pets monthly for GI parasites they're likely to get into, such as roundworms and hookworms. This is actually another big argument for monthly preventatives, as those are parasites people can get - specifically, those small people who rarely wash their hands and like to suck on their fingers after playing with the dog. Roundworms would likely survive a nuclear fallout, so they can certainly infect your pet in the middle of winter, and that monthly "heartworm pill" is a good way to keep them from infecting your three-year-old in turn.

Certain products will cover additional parasites such as tapeworms, whipworms, and even fleas. To my knowledge no single product currently covers everything, so it's worth talking to your veterinarian about what product or combination of products best covers the risks specific to your area and your pets lifestyle. I should also point out that's the big drawback to the "heartworm shot" - it doesn't provide monthly protection against all that other disgusting stuff pets tend to get into, just heartworm. It will kill off hookworms, but only every six months at the time the shot is given. For most dogs I recommend an oral heartworm product in addition to a topical flea-and-tick; for cats I usually recommend a topical product since getting an oral product in them can be a feat in itself.

Heartworm Testing
Yes, your dog should be tested for heartworm yearly even if you give monthly preventatives. Nothing is 100% effective, and disease caught early and treated early does far less harm. There are many scenarios that might lead to treatment failure, such as:

• You miss a dose for whatever reason. This is by far the most common situation - heck, I've  missed doses.
• Your pet has some indigestion and throws up the pill, unbeknownst to you.
• Your pet goes swimming shortly after a dose, or another pet grooms it off them.
• The medication has been mishandled and has lost its effectiveness. Heat can destroy most drugs - say, you forgot and left it in the car for a few summer days, or you bought it from somewhere other than your veterinarian and it was inappropriately handled (that's a whole other can of worms, and the subject of a future article). 

There has also been some concern over possible resistance developing to the drugs we use; at this point reports of "treatment failures" are few, and I'm fairly sure most could really be traced back to one of the above reasons. However, realistically we have to expect that some degree of resistance will develop eventually. 

It's worth noting the standard heartworm test looks for the presence of adult female worms. Think back to the first article where we discussed the parasite's life cycle and you will realize this means the test won't be positive until at least six months post infection. Likewise, if there are only a few worms and all are male, the test would be negative as well - I don't generally recommend regular testing for cats partially due to this, but we'll come back to that in the last article. It's complicated.

So, to summarize - all pets should get monthly preventatives (or the six-month shot for dogs), and dogs should be tested annually. Hopefully it's clear now why that's in their best interest. Please comment with any lingering questions and I'll gladly address them. In the final article, we'll talk specifically about heartworms and cats. They have some unique concerns and complications - as a professor liked to remind us back in school, "they aren't just small dogs."