Heartworms



Heartworms in the microscopic stage
(seen here at 400x size); photo by Joel Mills

I’ll kick this entry off with some good news:  heartworms are rare in the Willamette Valley area, and in the Pacific Northwest in general.  More good news:  heartworms are most commonly transmitted in warmer months, March or April through September or October, so we’re not currently in “heartworm season.”

But that’s about as far as the good news goes.  Heartworms are nasty little things, and the fact that they’re rare in this area or rare during this time of year does not mean that they shouldn’t be taken very seriously.  Advanced heartworm infections in dogs can lead to severe weight loss, respiratory difficulties, hemoptysis (coughing up blood), and eventually congestive heart failure.

The reason heartworms are rare in cold months is because they live out part of their lives in the guts of mosquitoes, and can only survive above certain temperatures (about 57 °F).  The reason they’re rare in the Pacific Northwest is, generally, because there’s a much less dense mosquito population here than in, say, the swampy, hot, and humid deep south.  However, any Portlander who frequents hiking trails or camp sites can attest to the fact that mosquitoes are anything but absent from the region, and some mosquitoes do manage to find their ways indoors.  So, while rare given the area and time of year, the risks associated with heartworm are still worth taking preventative measures.

A heartworm begins its life as a microscopic, live-born worm, birthed by an adult worm in a host’s pulmonary artery.  It is circulated in the host’s bloodstream until a mosquito ingests it through the skin.  After hanging out in the mosquito’s digestive tract for a while, it then makes its way to the bug’s salivary glands, where it’s able to enter a new host’s bloodstream during the biting process.  There, it takes several months to grow in size and eventually find its way, via blood flow, to the new host’s pulmonary artery, where it settles and can grow to nearly 30 cm in size, affecting a dog’s circulation and breathing.

While not common in cats, heartworms will occasionally target a cat as a host.  Or, rather, a heartworm or two will:  because cats are not heartworms’ ideal hosts, very few tend to end up inside of them, and even fewer survive to adulthood.  Since the most commonly used heartworm blood test is only sensitive to antigens given off into a cat’s blood by adult female heartworms, a cat that only has a few worms (and therefore an increased chance of having all male worms) may test negative for infection even though he has an advanced case.

So, as with all parasites, the best way to treat either a cat or a dog is with preventative care.  Most companies that manufacture parasite preventatives have some sort of “all-in-one” product.  For dogs, Sentinel and Trifexis both work against fleas, heartworms, and several intestinal parasites.  For cats, Revolution deals with all of those issues as well as ear mites (see our previous entry for info on them).  It’s especially true that “prevention is the best medicine” in the case of heartworms, because it’s possible that killing the thousands of microscopic heartworms in a heartworm-positive dog’s bloodstream could cause the patient to go into shock, maybe even resulting in death.  Besides, adult heartworms can’t be killed or dislodged with these misleadingly-named “heartworm drugs,” which only function as preventatives against the newborn parasites.

Veterinarians test for heartworm by dropping a blood sample onto a reactive chemical test:  the whole process only takes ten or fifteen minutes.  For cats, heartworm tests are often included as part of the viral testing regimen used to check for FIV and Feline Leukemia (more on both of those in future entries), which is a test that Linwood strongly recommends for our clients’ new cats.  To schedule a heartworm test and to talk to one of our doctors about the risks of infection and benefits of prevention, please feel free to contact us via telephone or e-mail.

Ear Mites

Ear mites and their eggs hanging out around an air bubble.

In the veterinary field, we encounter a lot of things that someone not acclimated to the world of animal medicine might think were a bit gross. Vomit, flea infestation, and abscessed wounds: all of these things are commonplace in our typical workday, and we’ve steeled ourselves to the extent that none of them are particularly offensive to us. Still, though, no matter how many times I encounter them, I can’t help but get a little grossed out when I lay eyes on a microscope slide full of hungry, wriggling, industrious ear mites. (Even just typing out that sentence gave me a little chill.)

Apart from the undeniable fact that they are totally disgusting, there are a few things that a careful pet owner should know about ear mites. First: they’re not really all that disgusting; I was exaggerating. They’re just bugs like any other, trying to survive the best way evolution has taught them to…admittedly, in an ear mite’s case, that survival is ensured by the consumption of animals’ waxy ear secretions…but you can’t fault the little guys for the hand they were dealt. The average ear mite lives for about four weeks, but in that time it will likely mate with another mite to produce a large number of offspring. In other words, they’re very good at surviving.

An ear mite is not even half a millimeter in length, and is therefore nearly invisible to the naked eye. However, an ear mite infestation may be visible as a large amount of thick, dark ear debris that looks something like used coffee grounds. This substance, put quite simply, is ear mite poop, as well as a collection of other materials such as dried blood (from the mites who bit off more than they could chew, so to speak), earwax, and the mites themselves.

The presence of such a substance does not guarantee a diagnosis of ear mites, though: since other, more serious issues may cause ear buildup that is similar in appearance, it’s important to have any ear issues examined and diagnosed by a doctor. A quick examination of ear debris under a microscope will determine whether or not there’s an active mite infestation; if there is, treatment is usually successful after a single dose of medicine. Also, mite infestations in cats are much more common than in dogs, and feline cases of ear mites are readily prevented by the monthly application of the topical pest control drug Revolution (which also protects against fleas, heartworms, and some intestinal parasites).

A mite infestation can lead to external skin infections or internal ear infections, and more serious ear issues might cause equilibrium problems and other neurological symptoms. So, if your cat or dog is having ear issues of any kind, do not hesitate to call Linwood Animal Clinic to have him or her examined.

February is National Pet Dental Month!

Some of the most common but least treated diseases that cause discomfort and potentially serious health concerns in pets are periodontal diseases like gingivitis and periodontitis. Unlike many other diseases that animals are only prone to based on their genetics, environment, or other circumstances, periodontal diseases (AKA dental diseases) will, with total certainty, eventually affect any animal who is not treated preventatively. This is because such diseases are usually nothing more than the result of teeth that are not regularly cleaned.

When plaque is allowed to build up on an animal’s teeth, it eventually hardens and turns into tartar, which can’t be removed by a simple brushing of the teeth. The bacteria that live in this stubborn substance (and there are a lot of them…over 1 trillion bacteria in a single milligram of plaque!) release toxins that eat away at the surface of the tooth, eventually making their way into the pulp and root, and consequently causing infections and entering the bloodstream. Possible results of this bacterial free-for-all include abscessed teeth, from advanced bacterial infection of the tooth itself; tooth loss, from the bacteria compromising a tooth’s root; or even a fractured jaw, when the bacteria begin to eat away at the bone, thus weakening it. Plus, bacteria that make their way into the bloodstream can cause irreparable damage to an animal’s internal organs, leading to heart disease, lung damage, and decay to the tissue of the kidneys and liver.

Veterinary dental treatment, as with human dental treatment, tends to get more expensive as the issue is neglected for longer periods of time. Therefore, Linwood Animal Clinic encourages its clients to brush their pets’ teeth as often as possible. (It’s actually a lot easier than you’d think if you take your time getting your pet used to it…just ask us next time you’re here!) But, if you’ve never been told the dangers of dental disease and your nine-year-old pet has never had its teeth cleaned or examined, it’s possible that a dental procedure could be costly.

Luckily, February is National Pet Dental Health Month, and Linwood Animal Clinic is offering 10% off of all dental procedures for the whole month! As an added incentive to take charge of your pet’s dental health, if you schedule the procedure before the first of the month, dental X-rays (normally one of the heftier charges associated with tooth cleaning) will be free! If you’re not sure about the state of your pet’s teeth, you can schedule a dental exam, and the $32.95 cost of that visit will be subtracted from the cost of your (already-discounted) dental in February! Call us today at 503-774-3363!

Fecal Examinations

Linwood Animal Clinic encourages its patients to have a fecal examination performed on a yearly basis. While poop is unquestionably the one aspect of pet ownership that most people don’t want to delve into as a subject for in-depth discussion, it is an important issue where an animal’s health is concerned. Today’s blog entry is going to discuss intestinal parasites and the importance of fecal examination, and I promise I’ll try to keep the infantile poo-humor to a minimum. Educating and informing our client base, after all, is just one of my many duties. (Haha, many doodies.)

“Worms” is a general term often used to describe a variety of intestinal parasites, many of which may require different methods of treatment, and all of which may be present in your pet’s digestive tract without you knowing it. While animals do occasionally shed live worms in their excrement, the actual worms occupying an animal’s system are rarely evident in a stool sample without subjecting it to microscopic examination: some worms are only detectable by the presence of their extremely small eggs in the stool, and some fully-grown parasites are themselves so small that they’re not visible to the naked eye.

Intestinal parasites can be transferred in a variety of ways, making an unprotected pet especially vulnerable to them. The most common method of transferal by dogs and cats is accidental ingestion of parasite eggs. This can occur while animals sniff and bathe one another, or even while they’re just nosing around a yard where another animal has recently defecated. Worms can also be transferred via bites by insects (e.g. fleas, mosquitos) or by the consumption of rodents like rats and mice. In short, your pet is always at risk of contracting an intestinal parasite infestation unless you take measures to prevent or treat it.

Preventatives against a variety of worms are included in several flea treatments available via prescription at Linwood Animal Clinic. Two medications called Trifexis and Sentinel, in addition to protecting dogs against fleas and heartworms, both also prevent hookworms, roundworms, and whipworms. Revolution protects cats against fleas, ear mites, and heartworms, but also roundworms and hookworms.

As an extra protective measure, though, Linwood veterinarians encourage pet owners to have their animals’ fecal samples tested microscopically on a yearly basis. Since many pets aren’t treated preventatively, and since some parasites are not easily prevented by available meds, it’s important to know whether an animal has an infestation that needs to be treated. While the pet may seem outwardly healthy, parasites can cause gastric upset, anemia, and weight loss, so it’s important for an animal’s health and comfort that parasites not be allowed to overrun their system. A quick fecal test once a year is an easy way to protect against these issues.

Panleukopenia

Panleukopenia (also known as "feline distemper") is a viral infection in cats that is highly contagious and often fatal. Similar to canine distemper (both illnesses are caused by a particular kind of virus called a parvovirus), the virus causes a breakdown of the intestinal wall's lining in its host, resulting in diarrhea, dehydration, and severe malnutrition. The disease is named for its effect of lowering the number of white blood cells (leukocytes) present in a cat's bloodstream, which lowers its immune system and leaves it vulnerable to secondary infection.

Panleukopenia is transmittable primarily through infected animals' bodily fluids, but it is an extremely hardy virus and can therefore survive for long periods of time on hard surfaces or bedding that have come in contact with the sick animal, not to mention on the shoes, clothing, and skin of the sick animal's handlers. In addition to the highly contagious nature of the disease and the difficulty in preventing its spread to other animals, it is also extremely difficult to treat without constant attention from medical professionals. For these reasons, an animal stricken with panleukopenia is best handled through quarantined hospitalization, which can be extremely expensive.

But, while it's easily spread and difficult to treat, panleukopenia can be prevented with nearly total effectiveness through a simple series of safe, widely used vaccines. A kitten should be vaccinated every 3-4 weeks until it reaches 16 weeks of age, then a one-year booster at the age of one, followed by a booster every three years for the rest of its life. This protocol has been proven to protect a cat with almost 100% effectiveness, which should give a pet owner peace of mind and should be a key step toward helping a cat lead a long, healthy life.

If you have any questions about panleukopenia, vaccines, or other health issues, please call Linwood Animal Clinic at 503-774-3363.

Holidays and Pets

This holiday season, we’ll skip the usual weekly posting of morbid information regarding diseases and briefly discuss pets and the holidays…

Firstly, of course, it’s important to talk about health concerns for pets around this time of year: pets shouldn’t be fed table scraps, since some foods (e.g. onions, garlic) can be toxic, and others (e.g. poultry bones) can present choking hazards; dangling tree ornaments and other decorations shouldn’t double as toys (no matter how tempting for an animal), since they can cause bowel obstructions if eaten; cats and dogs should not be allowed to play with decorative lights, as they pose a risk for electric shock (we’ve all seen Christmas Vacation, right?); and, as always, animals should have regular attention and care…if you’re leaving town, be sure to board your pet or find a friend or neighbor who can care for it while you’re gone.

But that stuff is all a bit depressing, and it’s much nicer to focus on the positive around the Holidays. We see a lot of greeting cards with family portraits, and our favorites are always the ones that include their pets in the photo. It’s refreshing to be reminded that so many people consider their dogs and cats to be important parts of their families. As our clients, neighbors, and friends gather their loved ones for celebration, each family following its own customs and traditions, it’s nice to think about the dog sitting hopefully by the table as dinner is served, or about the cat who rolls around in used wrapping paper on Christmas morning.

We hope your pets are healthy and happy this season. Have a happy holiday.

Leptospirosis

Leptospirosis is an infection caused by the Leptospira bacteria (pictured to the right), a microbe found in livestock and wildlife. In a city setting, it is most commonly carried by rats and raccoons, but can also infect a wide range of mammals common to the Portland area. In a temperate climate like ours, it is most prevalent in late summer and early fall months, but can be found year-round. It is present in the urine of infected animals and thus also in any areas of stagnant water (such as ponds, puddles, or even moist soil) into which they have urinated. The bacteria can then infect a new host through contact with open wounds or mucous membranes (e.g. eyes, nose, and mouth). It can also be transmitted directly from one pet to another, especially in urban settings where dogs encounter one another often.

Leptospirosis was widely publicized in the Fall of 2008, when there was a sharp increase in the number of California sea lions found dead along the Oregon coast. Later analysis showed that they had died as the result of a widespread outbreak of leptospirosis among their species, and beach-goers were cautioned against allowing their dogs to go near the animals, or even to walk on damp oceanside sand, without first being vaccinated. Since then, Oregon veterinarians have begun encouraging lepto vaccines as part of all dogs' regular yearly vaccination regimens.

Since cats seem to be resistant to Leptospira infection, we usually talk about it as exclusively a canine disease. But it's worth noting that leptospirosis is a zoonotic disease--that is, it can infect humans as well. Though very rare as a human infection in America, the Center for Disease Control and Prevention recognizes leptospirosis as a serious and potentially life-threatening disease for people. For this reason, it's important to limit the risk of human exposure to the bacteria, and one of the best ways to do this is through diligent vaccination protocols for dogs.

Common symptoms of dogs infected with leptospirosis are very similar to flu-like symptoms (fever, vomiting, diarrhea, lethargy, and dehydration among them), and are thus difficult for veterinarians to diagnose. Sometimes, by the time a lepto diagnosis has been reached, it's only after extensive testing has ruled out other diseases, costing significant amounts of time for an ailing pet and money for its owner. For this reason, Linwood Animal Clinic recommends that all of its canine patients receive leptospirosis vaccines, so we can avoid the frustration and stress caused by a potentially arduous diagnosis and treatment process.

The vaccination is initially given in a two-shot series: the patient receives a thorough examination to make sure it's in good health and is injected with a vaccine containing several strains of leptospirosis bacteria. Then, three to five weeks later, another brief exam (to ensure continued health) is followed by a second injection, which solidifies the patient's resistance to the disease.

If you have any questions about lepto or are interested in getting your dog vaccinated, please call us at Linwood Animal Clinic at 503-774-3363.