Bee Stings

Denali has always been a bug chaser. Unfortunately she doesn't know about bees. How could she? The first time she was ever stung was at the end of last summer. My husband and I had been at our new house painting all day. When it was time to go back to the apartment for the night my husband called Denali in from the backyard. Once back at the apartment we were shocked to see her face.

It's ok to laugh at the poor girl, I sure did!

My husband said he saw her tossing her head and pawing at her face when he had called her in, but he didn't think anything of it. She had obviously been stung on the lip. I got really close and to my surprise I could see the stinger! I grabbed the tweezers and pulled it out. The swelling never got worse than what is shown in the above image. As this was her first sting I kept a very close eye on her. I looked up allergic reactions and discovered that we would have definitely known by then if she was allergic. Allergic reactions happen fairly quickly. We watched her the rest of the night just to make sure she could still breathe, drink, and swallow normally. She was acting like nothing was wrong.


At the time I didn't look up other ways to help her. I knew that getting the stinger out was most important. I later discovered that dogs can be given Benadryl for bee stings. You should consult your vet about the appropriate dosage for your dog's size. You can also ice the area if possible.

About 2 weeks ago on June 9th she was stung again. Neither of us knew it. My husband suddenly called out to me "What's wrong with Nali's face?!?" We knew what was wrong. Unfortunately I couldn't find the stinger this time. The swelling was on both sides of her face making me think she was probably stung inside her mouth. I looked inside. Her tongue was fine and I couldn't see a stinger anywhere. She looked like she'd had a few good rounds of boxing.

I sent my husband out to get Benadryl since we didn't have any at home. I called the vet to verify the dosage (which is 50mg for a dog her size- 40 lbs- and we could give it twice a day). We gave her the Benadryl and again kept an eye on her to make sure it wasn't getting worse and that she could still breathe and swallow normally. We gave her more Benadryl before bed and by morning the swelling was almost gone. The entire time she behaved normally.

Today she got stung AGAIN. I would have thought she'd learn by now! I let all three dogs out to potty as I finished up with the dishes. I heard a soft yelp. I stepped outside and Denali yelped quietly again. I called her to me and she yelped yet again while coming over to me. I yelled to my husband, "Nali's yelping and I don't know why!" and he came to help. I habitually checked her front paws first. I then figured it had to be a bee. I opened her mouth and saw a little dark spot on her tongue. OUCH!!! Hubby ran to get me the tweezers as I held her mouth open. I didn't want to lose sight of it or have her swallow it. I pulled the stinger out and hub immediately got the Benadryl. The stinger was in her probably less than a minute. She didn't swell at all. If you get the stinger out IMMEDIATELY there is much less chance of swelling or any reaction at all, though some dogs are more sensitive to bee stings than others. We kept a *very* close eye as if her tongue was to swell she could end up not being able to breathe, or choking on her own spit if she couldn't swallow.

Click to enlarge

I don't know if she can really learn that bees hurt. It makes me nervous for the times I leave the dogs out in the kennel outside when we're gone for a few hours. What if she got stung while we were gone? Thankfully she's not allergic and even when we couldn't find the stinger her 2nd time she was still fine.

Switching Your Dog to Raw

I already shared some of this information in my post Raw Feeding but wanted to give a better guide as to how to start and why things are done a certain way. This guide is for dogs, not cats. Cats have special requirements which were mentioned in the Cats on Raw post.

Why feed raw? Feeding a prey model raw (PMR) diet is about feeding your pet as nature intended, as they've evolved to eat. Dogs thrive on raw. The external effects I see or that I've heard others experience after switching include: clean teeth and healthy gums, no bad breath, no "dog smell", no runny eyes, less/no ear infections, healthy skin and coat (no dry itchy skin, and fur is soft and shiny), allergies disappear, no more hot spots, smaller poo, dog poos less often, less smelly poo, more balanced energy opposed to the spikes and crashes caused by kibble, reduction or cessation of seizures, no more tumors, old dogs act young again with more energy and their joints aren't nearly as stiff.. on and on it goes.

Should raw be mixed with their current food? No. The best way to switch a dog is to do it cold turkey. Mixing kibble or canned food with raw is not recommended. Some dogs can handle both but many will have very bad tummy upsets. The switch is smoother without mixing. Giving the dog 24 hours of digestive rest by not feeding them also helps make a smooth transition but it is not required. I would not fast a puppy for an entire day, only an adult dog over a year old. With a puppy I would wait just 12 hours or even less if it's only a couple months old. It's important for puppies to eat often. With my own dogs I didn't fast them and they were fine.

What should the dog eat? The guideline for a PMR diet is to feed 80% meat, 10% edible bone, 5% liver, and 5% other organ. This is based on the makeup of a whole prey animal such as deer. Variety is the key to providing the nutrition the dog needs. As getting whole large animals like deer is not possible for most people the concept of "frankenprey" is used. Think of the head of a rabbit, the neck of a turkey, the shoulder of a pig, the heart of a goat, the liver of a cow, and the lung of a sheep. The idea is not to feed variety and a balanced diet every single day but to provide variety and balance over the course of a week or month. It is not important to feed exactly 80-10-5-5 every single day. A good way to do it is to figure out how much your dog needs for one week or one month, buy that amount, and when it's gone you know that balance and variety has been achieved. It's also not important to strictly adhere to the 80-10-5-5 guideline. It's just that- a guideline. The simple way to think about it is you're feeding mostly meat with a little bone and a little organ.

How much should the dog eat? The starting guideline is to feed 2-3% of the dog's ideal adult weight. For most dogs starting at the 2% mark is best. Small dogs and highly active dogs may need more than the guideline even up to 10%+, and giant breeds or inactive dogs may need less. I'll use my own dog as an example. Denali's ideal weight is 40 lbs. Multiply by 16 to get the dog's weight converted into ounces. [40] x 16oz = 640oz. Multiply that number by 2%. 640oz x .02 = 12.8oz. Denali's starting guideline is to feed 12.8oz per day. That 12.8oz includes the meat, bone, and organ. I buy a lot of meat and package it up into tupperware and ziplock baggies. At first I found it very helpful to weigh the meals so I knew exactly how much was in each container. I still sometimes do, but I've had enough practice now that I can eyeball it close enough. For example if a get a pork roast that weighs 4 lbs, I'll cut into 6 chunks that are about the same size, add a few ounces of organ to each, and call it good. Most of her meals are between 12 and 14oz. Not all include organ and not all include bone but they all have meat. Exactness is not important for a dog her size, though a tiny dog may require more precision to keep it at a healthy weight. If you notice the dog is getting too skinny or too heavy then adjust accordingly.

What about puppies? If you have a purebred puppy you should be able to guess the approximate adult weight and feed based on that guideline, adjusting as needed. For mixed breeds it can be impossible to know how much the dog will weigh as an adult. A general guideline is to feed 10% of the puppy's weight. It may take a lot of adjusting in the beginning. A puppy does not need to be fat or have a fat puppy belly to be healthy. And yes, most puppies will need to eat the same amount as an adult dog if not more. They have a lot of growing to do and are using a ton of energy! Puppies can begin raw feeding as young as a few weeks old. An 8 week old puppy is more than capable of eating raw. They do have to build up their jaw strength and may tire out quickly in the beginning. If the puppy is not eating enough and is stopping before they have eaten as much as they should have you may need to offer bite-sized pieces of meat some meals. The puppy might be getting too tired to wrestle with larger chunks. Puppies, and small breed adults for that matter, can absolutely handle larger pieces like chicken leg quarters or whole rabbit, and even handle very large pieces like deer spines, large roasts, an entire goat leg, you name it! It's not uncommon for the piece of meat to weigh more than the dog does. They do not need ground or minced meat and you should not assume they can only handle tiny pieces like chicken wings. Small dogs and puppies can typically eat exactly the same things that the big dogs do.

www.examiner.com/article/differing-opinions-on-a-natural-diet-for-dogs

How often should the dog be fed? Puppies from 2-3 months old should be fed at least 4x a day if not more. Figure out, to your best guess, how much the puppy needs each day and split it into 4x+ meals that are approximately the same size. From about 3-5 months old the puppy can be fed 3x per day. At 6 months it can be fed twice a day. At about a year old when the dog is close to being done growing you can feed once a day if you prefer, or continue with twice if that works better for you. Giant breeds may do better being fed twice a day until about 2 years old.

What should the first raw meal be? Chicken is usually the best protein source to start with. I prefer to give chicken leg quarters, for a few reasons. First, they have a decent though not ideal amount of meat on them. Second, they have enough bone to help keep the dog's poo firm while their digestive tract is adjusting. Third, they are very cheap. Fourth, they are big enough that the dog should not be able to swallow it whole (though you should ALWAYS supervise just in case your dog decides to try to gulp). Fifth, chicken bones are very soft. They are easy for the dog to chomp and easy for the dog to digest. Some people start with chicken backs but I find them to be much too boney and they are usually very small. If you are feeding a puppy or small dog, chicken leg quarters can be difficult to break up into small pieces. You can let the dog eat about as much as it needs to and then "trade up" by offering some really tasty treats as you remove the raw food. Put the raw back in the fridge until the next feeding time. If leg quarters aren't working, try getting split chicken breasts of half breasts as they include the ribs and breastbone. They are easier to cut up than the leg quarters. [Edited to add:] Cornish game hens, aka rock hens, are also great for smaller dogs and puppies. They are smaller and much easier to cut up. Downside is that they tend to be more expensive. Quail or pheasant might also be a good option, keeping in mind that any wild game should be frozen solid for at least a week before feeding.

What next? I feed leg quarters for about a week which allows the dog's system to adjust. Beginning the second week, add a new protein source. Pork is usually a good choice as it's red meat and also tends to be cheap. Look for roasts like picnic, arm, shoulderblade, and boston butt. If pork is not an option then try beef, goat, sheep, venison, llama, whatever is available to you. When introducing a new protein source it's important to take it slow. I like to keep chicken as the strong foundation. When first feeding raw, I feed twice a day. In the morning I feed chicken and in the evening I rotate through other sources. For example, the second week of raw I would feed chicken every morning but in the evening I would feed chicken one day, pork the next, chicken the next, and pork the next. The third week, add another source. Let's say it's goat. I'd continue feeding chicken in the morning and then in the evenings I'd rotate chicken, pork, goat, chicken, pork, goat. Continue adding new sources when you can and always introduce new sources gradually. After about a month or two I stopped feeding only chicken in the morning and would rotate different sources through in the morning too.

What about organs? I don't like to add organ until the dog is doing well on 3-4 different protein sources. Too much organ, or introducing it too soon or too quickly, will cause very loose poops. It's ok for the dog to go a month or two without any organ, but organs provide a lot of nutrition and are an essential part of the diet. When first introducing organ I offer tiny pieces about the size of the end of my thumb. I give a tiny piece almost every day for a week. I then start to increase the size of the piece every time I feed it, and I feed it 3 times a week. For my dogs, which are about 40 lbs, they get organ 2-3 times a week and the pieces are about the size of a deck of playing cards. You do not want to give an entire meal of organs as your dog will have "cannon butt," meaning very runny poo which is miserable for the dog. You should feed it with meat. Remember that liver should be about 5% of the dog's diet and other organ should also be about 5% of the diet. It can be difficult to find every single organ at the grocery store which is why I like to feed whole prey like rabbit or fish when I can that has NOT been gutted and is complete from nose to tail. It' important to note that heart is NOT organ, it is meat. Lung is also considered meat, NOT organ. The saying goes "if it doesn't secrete, feed it as meat." Secreting organs are liver, kidney, spleen, pancreas, testes, etc. Stomach, uterus, and penis are also fed as meat NOT organ. Both heart and lung should be introduced slowly as they are known to cause cannon butt. When introducing heart or lung I feed it as if it were organ- very small pieces a few times a week, then gradually increasing the size of the piece. Some dogs may never be able to handle an entire meal of heart of lung without getting cannon butt. It's fine to feed a meal of half heart or lung, and half something bonier like a chicken leg quarter to help balance the poo. Each dog is different. Mine can both handle entire meals of either one, and beef heart is one of the things I feed most.

Are eggs ok to feed? Eggs are completely fine! There is no reason to avoid them, but there is also no reason to go out of your way to feed them. They offer variety but should not frequently take the place of meat. Make sure to feed both the yolk and white. I leave the shell up to the dogs if they want to eat it or not. Sometimes they do, sometimes they don't. You can break the egg for your dog yourself or you can let them figure it out on their own. My dogs typically get one or 2 eggs per week. Some people give an egg every day. Others almost never give egg. See this article for more about feeding raw eggs.

What supplements should be given? The only supplement a healthy dog may need is fish oil. Unless you are lucky enough to be able to feed naturally raised animals that have been grass fed or fed naturally, the omega 3s are out of whack. The maintenance dose to get the omega 3s back where they should be is 100mg per 10 lb of dog per day. For example, my 40 lb dog would need 400mg per day. Make sure you get fish oil, and NOT cod liver oil. Check the ingredients and avoid oil that has added things, and avoid mixed tocopherols if you can as that is soy. Soft gels have the ingredients glycerin and gelatin as that is what forms the shell of the pill. You can also get fish oil in a liquid form you pump but I have no experience with those. The soft gels are typically 300mg of omega 3s each. Read the label on the back of the bottle, not what it says on the front. Most will give you the dose for 2 pills, which would be 600mg. Since my dogs need slightly more than one pill per day, I give them one every day plus once or twice a week will give them a second to make up the difference.


Where should the dog be fed? I like to feed on a tarp inside. I taught the dogs to stay on the tarp. Tarps are very cheap and easy to clean. Similarly, feeding on a large towel or a cheap shower curtain are good options. I also feed outside sometimes- it's fine if the meat gets dirt or grass on it. Crates are also a good option, either a wire crate or plastic airline crate. They are easy to clean and your dog is confined. Confining the dog can be especially helpful if you have multiple dogs who don't eat well together, or if you have children and need to keep them away from the raw meat. I do not like to feed on hard floors as they are slippery which makes it difficult for the dog to eat.

Kaytu eating a pork roast in the grass

The dog won't eat raw, what's wrong? Some dogs are picky eaters, and some don't seem to understand raw. After all, if the dog has eaten nothing but little pieces of hard crunchy kibble it's entire life and is suddenly given a large, cold, slimy chicken leg quarter, that's quite a change! There are a few things that can be tweaked to make raw more appealing and appetizing to the dog. The first thing I try is to cut the drumstick meat off the bone into small bite-sized pieces(or offer bite-sized pieces of chicken breast instead of the leg quarter). I also remove any skin- I swear neither of my dogs liked the slimy chicken skin at first! I leave the chicken out for 15 minutes, and if it has gone untouched then I put it back in the fridge until the next feeding time. Next feeding time I offer the chicken again. If the dog will still not eat it then try feeding it at a different temperature. If the meat was completely thawed then try offering it semi frozen. Put it in the freezer for an hour or two and try again. Mine both preferred semi frozen meat at first. If the dog still will not eat it after ~15 minutes of having it out, you can get a frying pan screaming hot then drop the meat it for a split second to sear the outside of it on all sides. This does the trick for many dogs as it helps bring out the smell. If this doesn't work, try cooking the meat or a chicken breast completely through (DO NOT cook bones). Again, leave it out for only 15 minutes before taking it away until the next feeding time. By this point your dog may have not eaten for a day or two and that's perfectly fine, assuming your dog is otherwise healthy. Dogs will not starve themselves to death. This game of "tough love" while figuring out a way to get the dog to eat it will eventually work. Do not be giving your dog any treats or table scraps or any food at all during this time. You can try other things like the "oops I dropped this on the floor" game where you drop a piece when your dog is watching. The dog will likely sneak in and eat what you dropped. You can also try offering pieces as treats. Tough love is an important part of feeding raw as it teaches your dog to eat what is available. If you cater to your dog it may encourage it to become picky. For a dog with health issues that requires regular meals you may be forced to cater to it in the beginning.

If all else fails, try a different protein source. You don't absolutely have to start with chicken, though you may be much more likely to have a round of tummy upset. Kaytu was not liking chicken at first. The first week I had her she ate half of what she should have and she was quite underweight when we got her. I randomly offered her a strip of raw fat from a steak we were cooking for ourselves and she loved it, so I offered her beef heart. She loved it. Beef heart is notorious for giving dogs very loose, tar-like poo. She had nothing but beef heart for 3 days, and I gradually increased the size of the pieces I gave her to teach her to how to eat it. Poo was dripping from her poor little butt the entire 3 days. The fourth day I offered her a chicken leg quarter and she ate it, and from there I went back to the beginning and fed her just chicken for a week to get her digestive tract adjusted more nicely than the beef heart had been doing.

What if the dog doesn't have many teeth, or has bad teeth? Dogs that are dentally challenged can still enjoy raw! Since dogs have no need to chew their food, cutting the food into bite-sized chunks is a good option. A good food processor can slice and chop meat well enough for the dog to be able to eat it, and it's faster than chopping by hand (be careful if you put organ in a food processor, it turns to goo very quickly). Bone can be fed to dogs that don't have even a single tooth. Stick to extremely soft, small bones from animals such as fish, chicks or Cornish game hens, or other small birds like quail or pheasant. Their gums will toughen up as they get more practice. Smashed or ground up egg shells can provide a lot of nutrition they may be missing from bone. Feeding ground meat is not ideal but for some dogs it may be the best option as it is possible to get whole ground animal including bone, and it can save you a lot of prep time. If feeding ground make sure it does not include added veggies, carbs, dairy, or supplements.

What's with this poo? There are a lot of changes you will notice with the dog's poo on a PMR diet. It's gross, yes, but it must be discussed. As mentioned, smaller poo, pooing less often, and less smelly poo are all normal. The dog is actually using the food you are giving it meaning there is less waste compared to kibble. Most raw fed dogs poo only about once a day and it will be a much smaller poo than you're used to. The color and pattern will be different too. Kibble poos are very uniform but it's common for rawfed poo to have a couple different colors in it. Chicken, turkey, and other poultry and white meat will usually produce poo that is yellow or light brown. Pork, beef, and other red and dark meat will produce poo that is darker or even black. Beef heart is known to cause extremely dark poo that has a tar-like consistency. If the dog has very runny or loose poo it could be caused by a number of different things. It could be the dog is not getting enough bone, was introduced too quickly to a new protein source, had too much organ, had too much fat or skin, or ate too much in one sitting. If the dog has a really bad case of cannon butt then giving 24 hours of digestive rest is recommended (no feeding), and giving slippery elm bark can also really help. Don't hesitate to go to the vet if you think your dog is actually sick. Cannon butt caused by diet is in itself not reason to go to the vet. If the dog gets too much bone they may have hard, white poo. This can be quite painful for the dog and can cause damage as well. Very firm poo is ok as it helps the dog express its anal glands naturally but rock hard poo should be prevented. It's a process of trial and error to figure out how much is too much, and each dog is different. Beyond the rock hard poo is powder poo. It literally looks like sand pouring from the dog's butt. It does seem funny but I can't imagine how uncomfortable it is for the dog. This is caused when waaaay too much bone is given.

Is there anything that should be avoided? Avoid feeding the large, weight-bearing bones of animals like cows. Bones like femurs and knuckle bones are very dense and hard and will damage the dog's teeth. Many dogs have cracked or broken a tooth on such bones. Even if there are no visible signs of damage these bones still cause microfractures and weaken the teeth as well as wear them down. They aren't worth the risk. The marrow is fatty and dogs love it, so it won't hurt to get a bone and scoop the marrow out for your dog. When I had llama legs I allowed Denali to strip the meat and tendons off and to eat the foot but then I threw away the bones before she gnawed on them. My general rule is that if the dog has to gnaw then the bone is too hard. Typically bones in goat, sheep, and pork are all fine. In my opinion there are no beef bones that are ok for dogs unless they are veal bones which are still soft. Very fresh bones from adult cows *might* be soft enough. I do give my dogs beef ribs but once the meat is stripped off I throw away the bones.


In the United States there is not much meat that needs to be avoided. Wild caught salmonids in the Pacific Northwest should be frozen for at least a week before feeding. See the post about Parasites and Bacteria for more information about that. Bears can carry trichinosis. Personally I would not feed any bear meat from Alaska or Canada. Bear from the lower states should be fine but personally I'm not sure I would risk it. It's very uncommon for raw feeders to give the meat of a carnivore to their pets such as big cats like cougars and members of the weasel family. Only herbivores and omnivores should be fed. I would also never feed opossum as they are known to be full of parasites like fleas that I don't want to bring into my home. A general rule I follow is to not feed things critters that have pointy teeth. Possum, skunk, and raccoon are a few examples of ones I would not feed. All wild-caught game should be frozen solid for at least a week or two in order to kill any parasites and then it is fine to feed.


It's also important to avoid feeding meals that are too small for your dog. If a great dane was offered a chicken neck it would most likely swallow it whole. This is an unnecessary choking hazard. Dogs do not have jaws that grind side to side as ours do making it impossible for them to really chew their food, and therefore they will often chomp meat and bone but end up swallowing pieces whole. This is ok and natural, and it will be digested. Again, always keep an eye on your dog when it's eating just in case it chokes. It's also common for a dog to be chomping and swallowing a large piece, then to force up the part that was already down its throat in order to chomp it further. If a dog completely swallows too large of a piece it may throw it up, again in order to chomp it better. If this happens it's fine to let the dog re-eat it. I know it's gross, but it's natural. If the dog refuses to eat what it threw up then throw it away and don't offer any food until the next scheduled feeding time to allow their digestive tract to rest.


On a final note, it's also normal for the dog to drink much less water. Raw meat has a ton of water in it, meaning your dog will be less thirsty throughout the day.

Heartworm

Disclaimer: Before I begin I must stress that I am not a veterinarian and I have had no formal medical training. Always discuss preventatives and treatments with your vet and have a clear understanding of how drugs work (all drugs, not just heartworm related) and all possible side effects before administering them. It's okay to say no to your vet if you don't know about a certain product they want to use on your pet. You can always come back after doing your own research, but you can't undo an injection or oral treatment. Don't let your vet pressure you.

This morning I read a blog post about a dog who died due to the effects of a heartworm vaccine called ProHeart 6. A full necropsy is underway to verify that it was the drug that caused the dog to die, but the dog experienced known side effects right down to the vomiting and dying in a pool of its own blood. ProHeart 6 was pulled off the market in 2004 due to the high rate of adverse side effects but was put back on the market in 2011. Veterinarians are supposed to explain the side effects and owners are supposed to sign a consent form. In the case of this dog the owners were not told what could happen, and never signed anything but the drug was given anyway.

An informed veterinarian stated that Proheart caused more deaths in one year than all of the oral heartworm preventives combined did in ten years. Monthly oral heartworm treatments are out of a dog's system within a few days, with the idea being for them to take care of any previous month's heartworm infection. With ProHeart 6, the idea is for the drug to be in the dog's body for 6 months. On drugs.com in large bold lettering it states "Because Of Its Potential For Serious Adverse Drug Reactions And The Absence Of Identifiable Risk Factors Associated With Those Reactions, Proheart 6 Is Only Indicated For Those Dogs In Which Alternative Preventatives Cannot Be Effectively Administered." It's not intended to be given as a routine vaccine. The site also states "The most frequently reported adverse events requiring clinical intervention have been allergic in nature. These reactions appear to be idiosyncratic, with no identifiable risk factors such as health status, age, sex, or breed. Anaphylaxis is the most clinically significant serious allergic event. The great majority of these adverse events have occurred at the labeled dose."

In light of this tragedy and with mosquito season upon us, I feel the need to share what I've learned about heartworm. As with all other issues of health I am always ready and willing to learn more. Please share with me if you have more or differing information!

Understanding of the heartworm life cycle is the first step in understanding treatment. In the case of heartworm, "preventative" means preventing the larva from reaching adult form, which is when infection would occur. Preventative is treatment in the case of microfilariae, though adult heartworms may need additional treatment. From the American Heartworm Society (AHS):

"The susceptible mosquito becomes infected when taking a blood meal from a microfilaremic host. The microfilariae develop to the third stage in the mosquito’s malpighian tubules and then migrate via the body cavity to the head and mouthparts of the mosquito where they become infective. The time required for the development of microfilariae to the infective stage in the mosquito is temperature dependent. At 27°C [80.6° F] and 80% relative humidity, development takes about 10 to 14 days.

Infective, third-stage larvae (L3) are deposited in a droplet of hemolymph (mosquito blood) on the host while the mosquito is taking a blood meal. Immediately after the blood meal, these sexually differentiated L3 enter the animal’s body via the puncture wound in the skin made by the mosquito’s mouthparts. Three days after experimental subcutaneous injection of the L3 in the inguinal region of the dog, most of the larvae are found in the subcutaneous tissues near their entry site. By day 21, most of the larvae have migrated to the abdominal tissues of the dog, and by day 41, they may be recovered from either the abdominal or thoracic tissues. Apparently L3 and L4 travel between muscle fibers during migration, whereas juveniles (immature adults) penetrate muscle and eventually veins, transporting them toward the heart and lungs. The molt from L3 to L4 begins as early as day 3 and ends as late as day 9 to 12. L4 molt to the final stage at day 50 to 70. Worms reach the pulmonary vasculature as early as day 70 and all have arrived by day 90 to 120. The first worms entering the pulmonary vasculature on day 70 to 85 are 1 to 1.5 inches in length. Thereafter the female worms will increase in length by almost tenfold. They become sexually mature about day 120 post infection. Dogs develop patent infections (i.e., have microfilariae circulating in their blood) as early as 6 months but usually by 7 to 9 months post infection."

It is the adult worms that cause infection and harm to your pet. The L3 and L4 larvae are killed by oral heartworm treatments. As explained by the AHS, the L4 molt to becoming an infectious adult worm doesn't begin until day 50 to 70. About 2 months. It takes 6 months for dogs to even test positive for heartworm infection- meaning if your puppy is 5 months old and your vet wants to do a heartworm test, say NO, because it will not turn up positive and is a waste of money.

In many areas of the US, heartworm is very rare. The importance of monthly oral treatments cannot be emphasized enough. This map (source) tells that heartworm is not common, which I believe is due in large part to routine use of oral heartworm preventatives.

Click to enlarge. "Reported positives from more than 10,000 veterinary clinics, telephone surveys, and IDEXX Reference Laboratories' results collected from the year 2000 to the present."
[Present being 2007]

In 7 years, from more than 10,000 clinics, many states had less than 500 cases of heartworm. If I counted correctly, 32 states had less than 500, with 18 having over 500. California is in the 500+ category, but out of the 4,350 dogs tested in 1996-98 in LA county, a total of 18 positive dogs were identified (source, a good read for those in Southern Cali). Heartworm is not an epidemic. Again I want to emphasize that low numbers are probably in large part due to monthly oral preventatives. They are very important!!

However, giving a monthly preventative every month is not necessary. As already shown it takes a couple months for the microfilariae to develop. If an oral preventative is given at any point it will kill them.

VeterinaryPartner.com says "the microfilariae, L3, and L4 larvae can all be killed by monthly ivermectin-based heartworm preventive products (i.e. Heartgard, Tri-Heart, etc.). The milbemycin-based products (Sentinel and Interceptor) will also do the same job but will kill the microfilariae much faster, which can create circulatory shock if there are large numbers of microfilariae dying all at one time." The site also explains that ivermectin, while it does not kill adult worms, will sterilize them and shorten their life span.

A single dose of ivermectin will kill the microfilariae up to 3 months after a dog has been infected. A single dose! You also don't need to get ivermectin from your vet. Former executives from the makers of Heartgard make a generic version called PetTrust which is much cheaper and you can get it at Walmart. You do need a prescription from your vet. Or you can order an ivermectin solution, without a prescription. Given that some microfilariae develop faster than others, I would treat every other month- when the weather calls for it.

The weather?? Yes, the weather. By keeping an eye on the weather I have only needed to give Denali one dose in her entire life. The AHS says "It has been shown under laboratory conditions in three mosquito species that maturation of larvae within mosquito ceases at temperatures below 57ºF (14ºC)." If the mosquitoes aren't infected then your dog can't get infected. It takes 14 days or longer for the microfilariae to reach their infective stage. So your dog is fine for at least 2 weeks- and if during that 2 weeks the temperature goes under 57º again, the timer resets for another 2 weeks. There is no reason to give any preventative or treatment when the temperature is going under 57º F at least once every 2 weeks. If the temperature does remain higher then you should give an oral preventative after 2-3 months to kill any microfilariae that may have been transmitted to your pet during that time. As previously mentioned the dose will kill any microfilariae up to 3 months.

When giving an oral treatment make sure to smoosh the chewable tablet and basically break it into crumbs. Dogs who have been taking a monthly preventative may still end up testing positive for heartworm because the tablets were not chewed, and therefore passed through without the drugs being able to be absorbed.
My way of handling it is to just watch the weather, and give a oral preventative when needed. Even here in San Diego in early June the temperature is dropping to the low-mid 50ºs most nights. Last year the temp stayed high enough in August that I gave Denali one tablet in October. I hadn't seen any mosquitoes at all but it's always better safe than sorry. If you go on vacation with your pets make sure to check the weather there too! Remember, heartworm is COMPLETELY preventable.

To learn more about heartworm and preventing it, see the Current Canine Guidelines and Current Feline Guidelines from the American Heartworm Society.