Bugs, Bugs, and More Bugs!

by Bruce W. Little, DVM

Bugs, Bugs, and More Bugs!


“Everybody talks about the weather; but, nobody does anything about it!” is a quote attributed to Mark Twain, noted author, newspaper man, and philosopher. Although there is some controversy as to whether Mark Twain was the first to use that phrase, I continue to hold fast to the belief that it was Mr. Twain who made the statement. Having grown up some forty miles from Hannibal, Missouri the boyhood home of Mark Twain, I have heard that quote since I was a child and hold it in my memories to be his.

During the months of late 2016 and into the winter and spring months of 2017, the Earth felt the effects of the strongest El Niño since 1999. It had been eighteen years since the last major El Niño influenced the weather patterns of the United States and Canada as they did during the past nine months. California and the Southwest had record rainfall while the Sierra Nevada, Grand Tetons, and Rocky Mountains had record snowfall during this weather phenomenon. Parts of California had 180% of its normal annual rainfall, and the mountains saw areas of more than four feet of snowpack. Tornados with devastating winds and heavy rain cropped up throughout Texas, Oklahoma, Kansas, and the Gulf Coast States bringing flooding and pools of water to in many cases dry, parched land. The Northeast had an unusual late winter snow storm that brought cities from Washington, D.C. to Boston, Massachusetts to a standstill. And, just three weeks ago, the Mississippi River brought havoc to the St. Louis and other Midwest areas with severe flooding leaving standing water in lakes, ponds and anyplace that would harbor the excess water in a rain-soaked terrain. I flew into St. Louis last week and while observing the land from my vantage point in an airplane preparing to land, saw flooded fields and water standing in the ditches and any other place that water could collect. In my humble opinion, a greater power controls the weather patterns in the United States than we the people.

One might ask, “what does this have to do with a blog aimed at household pets and their families?” The answer comes from the fact that bugs of most types seem to relish the moist, damp environment that excess moisture, whether in the form of rain or melting snow, brings for the number of parasites to increase greatly. These parasites will eventually be looking for a dog or cat or other animal from whom it can extract a meal for survival. The Companion Animal Parasite Council (CAPC) with its extraordinary capability of forecasting the populations of ticks, fleas, mosquitos, and other insect carriers of disease predicts a banner year for the proliferation of these parasites, especially ticks and their capability to carry many diseases including Lyme disease, and mosquitos that carry heartworm disease to pets because of the weather as El Niño influenced it. Much of the United States experienced above average precipitation during this time, and coupled with the moderate winter temperatures across most of the country, leading to perfect conditions for a bumper crop of both ticks and mosquitos this year. CAPC is forecasting an active year for heartworm disease and Lyme disease based on analysis of multiple environmental drivers of these diseases. CAPC is predicting heartworm disease and Lyme disease will increase well beyond their established endemic areas, leading to increases of exposure and incidence of both heartworm disease and Lyme disease. Above average precipitation and a warmer weather that allows many of these parasites to survive the winter months will lead to increased numbers of parasites; and therefore, increased diagnosis of these vector carried diseases. When climatic conditions are ideal these parasites literally explode in population creating a need for pet owners to pay closer attention to their pets and seek out veterinary advice for controlling the numbers of parasites that take up residency on their pets and in their households. As is usually the case, preventive care can make a world of difference in the health and well-being of our pets.

There are many external parasites that can do harm to pets. Ticks, fleas, mosquitos, mange mites, ear mites, lice and the common housefly can all be detrimental to the health and well-being of our pets. While controlling all external parasites in pets is important, it is critical that we direct our attention now to the increasingly obtrusive tick-borne Lyme disease, and the control of the mosquito that carries the larvae that causes heartworm disease in dogs and cats during these environmental conditions that set up a perfect opportunity for the parasites to flourish. Drain puddles of water, pour the collected rain water out of cans, bottles, old tires, or any container that may serve as a breeding ground for the proliferation of mosquitos and ticks. Reducing the numbers of insects that transmit these diseases is the first line of defense against infestation and infection of insect vector diseases.

Historical accountings of Lyme disease can be found in reports going all the way back to the 17th Century. The current accountings of the disease refer to the findings of the Borrelia burgdorferi bacterium found in wooded areas around the town of Old Lyme, Connecticut in 1975 for which the current understanding of Lyme disease was named. In 2013, a new, unknown strain of bacteria was discovered by scientists at the Mayo Clinic in Minnesota. That strain of bacteria was named Borrelia mayonii after the Mayo Clinic, and can be transmitted to people by ticks. Borrelia mayonii infections appear to have slightly different clinical signs than Lyme disease caused by Borellia burgdorferi. There have been no cases of Borrelia mayonii diagnosed in dogs and cats. Symptoms of Lyme disease in dogs vary greatly from symptoms in people. In people, symptoms include a telling “bulls-eye” rash at the site of the bite, fever, chills, headache, fatigue, joint and muscle aches, and sometimes more complicated signs that spread to the heart and nervous system. The signs of Lyme disease in dogs and cats are much more discreet. The characteristic rash does not develop in dogs or cats. Because the other symptoms of the disease may be delayed or go unrecognized and because the symptoms are like those of many other diseases, Lyme disease in animals is often not considered until other diseases have been eliminated. “Affected dogs have been described as if they were ‘walking on eggshells”, states Dr. Ernie Ward, a noted veterinarian and speaker at veterinary continuing education seminars. Many dogs affected with Lyme disease are taken to a veterinarian because they seem to be experiencing generalized pain and have stopped eating. Often these pets have high fevers and may limp. Frequently, the painful lameness may appear suddenly and may shift from one leg to another. If untreated, it may eventually disappear, only to recur weeks or months later. Some pets are infected with the Lyme disease organism for over a year before they show clinical symptoms. By this time, the disease can be widespread throughout the body. If your pet is showing these signs do not wait for things to get worse. Contact your veterinarian for a diagnosis, and if necessary proper treatment.

Dogs with lameness, swollen joints, and fever are suspected of having Lyme disease. Other diseases may also cause these symptoms, so it is imperative that you seek out the services of a veterinarian to determine the cause of your dog’s condition. There are two blood tests that confirm Lyme disease. The first is an antibody test and the second is the polymerase chain reaction (PCR) test. Your veterinarian will advise you on the need for these tests. Many times, veterinarians can determine the diagnosis of Lyme disease simply by collecting a history of the pet’s activities and the symptoms shown upon presentation. The key to prevention of Lyme disease is keeping your pet and yourself from being exposed to ticks. The causative agent of Lyme disease is not transmitted from pet to pet or people to pets. It can only be transmitted through the bite of the tick. Keeping animals from thick underbrush reduces their exposure to ticks. Use tick repellents that contain 30% DEET before going into areas that may harbor ticks. Check yourself, your children, and your pets for ticks after going into these areas. Remove ticks from all persons and pets as quickly as possible after leaving tick-infested areas. Wash the area of the tick bite thoroughly with soap and water. If you encounter ticks, call your veterinarian, and get her advice on next steps. A prompt call may save lots of time and money for both the pets and the humans in the family.

Heartworm disease is a serious and potentially fatal disease in pets in the United States and many other parts of the world. It is caused by foot-long worms that live in the heart, lungs, and associated blood vessels of affected dogs, causing severe lung disease, heart failure and damage to other organs in the body. Heartworm disease affects dogs, cats, and ferrets, but heartworms also live in other mammal species, including wolves, coyotes, foxes, sea lions and humans. Because wild species such as foxes and coyotes live in proximity to many urban areas, they are considered important carriers of the disease. The dog is a natural host for heartworms, which means that heartworms that live inside the dog mature into adults, mate and produce offspring. If untreated, their numbers can increase, and dogs have been known to harbor several hundred worms in their bodies. Heartworm disease causes lasting damage to the heart, lungs, and arteries, and can affect the dog’s health and quality of life long after the parasites are gone. For this reason, prevention is by far the best option, and treatment should be administered as early during the disease as possible.

The mosquito plays an essential role in the heartworm life cycle. Adult female heartworms living in an infected dog, fox, coyote, or wolf produce microfilaria that circulate in the bloodstream. When a mosquito bites and takes a blood meal from an infected animal, it picks up these microscopic “worms” which develop and mature into infective larvae over a period of 10 to 14 days. When the infected mosquito then bites another dog, cat, or susceptible wild animal, the infective larvae are deposited onto the surface of the animal's skin and enter the new host through the mosquito’s bite wound. Once inside a new host, it takes approximately 6 months for the larvae to mature into adult heartworms. Once mature, heartworms can live for 5 to 7 years in dogs and up to 2 or 3 years in cats. Because of the longevity of these worms, each mosquito season can lead to an increasing number of worms in an infected pet.

In the early stages of the disease, many dogs show few symptoms or no symptoms at all. The longer the infection persists, the more likely symptoms will develop. Dogs heavily infected with heartworms, or those with other health problems often show pronounced clinical signs. Signs of heartworm disease may include a mild persistent cough, reluctance to exercise, fatigue after moderate activity, decreased appetite, and weight loss. As heartworm disease progresses, pets may develop heart failure and the appearance of a swollen belly due to excess fluid in the abdomen. Dogs with large numbers of heartworms can develop a sudden blockages of blood flow within the heart leading to a life-threatening form of cardiovascular collapse. Without prompt, surgical removal of the heartworm blockage, few dogs survive. Heartworm disease in cats is very different from heartworm disease in dogs. The cat is an atypical host for heartworms, and most worms in cats do not survive to the adult stage. Cats with adult heartworms typically have just one to three worms, and many cats affected by heartworms have no adult worms. While this means heartworm disease often goes undiagnosed in cats, it’s important to understand that even immature worms cause real damage in the form of a condition known as heartworm associated respiratory disease (HARD). Moreover, the medication used to treat heartworm infections in dogs cannot be used in cats, so prevention is the only means of protecting cats from the effects of heartworm disease.

Even if heartworms do not seem to be a problem in your local area, there may be a greater incidence of heartworm disease than you realize. It is frequent that pet owners unknowingly travel with their pets to an area where heartworms are more common. Heartworm disease is also spreading to new regions of the country each year. Stray and neglected dogs, feral cats, and wildlife such as coyotes, wolves, and foxes can be carriers of heartworms. Heartworm disease has been diagnosed in all 50 states, and risk factors are impossible to predict. Multiple variables, from climate variations to the presence of wildlife carriers, cause rates of infections to vary dramatically from year to year, even within local communities. And because infected mosquitoes can come inside, both outdoor and indoor pets are at risk. It is important to schedule an appointment with your veterinarian each year to have a heartworm blood test performed. Upon that professional recommendation, most dogs and cats are prescribed to stay on heartworm preventative throughout the entire year, regardless of the incidence of heartworm presence in your geographic area.



For more information go to:
Companion Animal Parasite Council at: www.capcvet.org
American Heartworm Society at: www.heartwormsociety.org

Bruce W. Little, DVM