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Know The Signs: Protect Your Pet From Common Parasites

Courtesy of Pfizer

Heartworm

How Heartworm is Transmitted to Dogs and Cats

Heartworm (Dirofilaria immitis) is a parasite that can infect both dogs and cats. Transmitted by mosquitoes, D. immitis can be found in most areas of the country where mosquitoes breed. Infected dogs can carry the parasite to areas where it normally is uncommon.

Adult heartworms reside in the heart's right ventricle and pulmonary arteries, and can grow to a length of 5-to-12 inches in dogs and 5-to-8 inches in cats. When adult heartworms living in animals mate and produce offspring or microscopic heartworm larvae (microfilariae), the offspring can live in an animal's bloodstream for three years.

Heartworm disease is caused by adult heartworms and fragments of dead worms obstructing the normal blood flow through the heart and can lead to congestive heart failure and obstruction of the pulmonary blood vessels which carry blood to the lungs.

Mosquitoes transmit heartworm. When a mosquito bites an infected animal, the heartworm microfilariae are ingested along with the blood. In the mosquito, these microscopic pests develop into infective larvae, which are transmitted back to an animal through another mosquito bite. During the microfilariae maturation process in the animal (which lasts about six-to-seven months in dogs), the heartworms travel to the lungs and the right side of the heart, where they can grow and mate for several years.

Treating all animals in a household is essential. Both dogs and cats often show no signs in the early stages of heartworm disease. Treating dogs for heartworm disease can be lengthy, expensive and life threatening. Currently, there is no approved treatment for heartworm disease in cats. For these reasons, prevention is the key. While fewer cats than dogs contract heartworm disease, those that do are prone to blockage of an artery and subsequent death. Whereas normally 10 or more adult heartworms need to be present before dogs exhibit severe heartworm disease, just one adult heartworm can be fatal to cats.

Signs in Dogs

Heartworm signs can take years to appear in infected animals. Early canine signs often are easily attributed to other conditions or diseases. Those signs can include fatigue, non-productive cough, difficulty breathing, exercise intolerance, coughing up blood, weight loss and fluid accumulation in the abdominal cavity. Untreated heartworm disease can result in death. Testing for heartworm most often involves a blood test that indicates whether microfilariae are present in blood. In recent years, more veterinarians have begun to use antigen testing to detect and confirm whether adult heartworms are present in the heart.

Signs in Cats

In cats, heartworm signs can include chronic vomiting, coughing, difficulty breathing, collapse, weight loss, lethargy, rapid heart rate, diarrhea, convulsions, asthma-like signs or sudden death. Because heartworm blood tests in cats rarely uncover microfilariae, veterinarians must rely on other methods such as testing for certain antibodies in the cat's blood.

Treatment and Treatment Outcomes

Treating dogs for heartworm disease is a multi-step process that is both costly and very risky for the animal. Successfully treating heartworm disease involves a multi-step program to kill the adult worms and microfilariae, followed by additional ongoing treatment to prevent future infections. While heartworm disease is less prevalent in cats than in dogs, there currently is no approved treatment for heartworm disease in cats. Deadly side effects to treatment in cats are common. Prevention should be ongoing in areas where mosquitoes live and breed year-round and seasonal in other areas depending on the length of the mosquito season. Blood tests to check for existing heartworm infection are recommended before administering prevention therapy. Because heartworms are sometimes difficult to detect in various stages of their life cycle, periodic blood tests also are recommended in areas where animals receive heartworm prevention medicine.

Human Health Connections/Concerns

Incidents of humans being affected by Dirofilaria immitis are rare. In humans, the disease can cause small pulmonary lesions, which may be confused with other serious diseases (Archives of Internal Medicine; Sep. 22, 1997, James S. Tan, author)

Fleas

How Fleas are Transmitted to Dogs and Cats

Ctenocephalides felis, the fleas that affect most dogs and cats, can breed year-round indoors. The flea life cycle varies according to where they live. In the south, fleas may hatch year-round, while their northern counterparts flourish in warm summer months. Moving through the life cycle from egg to larvae to pupae to adult can take a flea anywhere from 14 days to 140 days in certain conditions. Adult fleas mate shortly after contact with animals. Once they produce eggs, the eggs often drop off the animal to complete their larval and pupal stages. The pupal stage can last from 3-to-4 weeks to several months depending on the environment (warm, humid conditions with temperatures above 80 percent humidity are optimal). Once hatched, adult fleas search for a host, and if fleas are not removed from the host they can live for more than two months, depending on environmental conditions.

Signs in Dogs and Cats

Pets that exhibit signs of itching, scratching, and unusual amounts of chewing and licking may have fleas. Although fleas are sometimes difficult to spot, black specks (flea feces) on pets' skin and coat are one sign - these specks turn reddish brown when placed on dampened white paper. Flea-infested dogs may scratch mainly on the lower part of their bodies while cats may scratch more around their heads and necks. Fleas also can cause an allergic reaction called flea allergy dermatitis, a hypersensitivity to flea saliva, which can cause a rash inflammation or hair loss in some pets. If ingested, fleas also can transmit tapeworms to pets.

Treatment and Treatment Outcomes

Effective treatments for fleas require killing fleas and breaking the flea life cycle. Because fleas multiply rapidly, treating fleas involves removing them form the animal's environment as well as its skin and hair.

Human Health Connections/Concerns

When no suitable animal hosts are found, fleas often look to humans for the blood they need to survive. Although fleas are mostly a nuisance to humans, some research indicates that fleas play a role in transmitting cat-scratch disease and plague. If ingested, fleas also can transmit tapeworms to humans.

Sarcoptic Mange (Scabies)

How Sarcoptic Mange (Scabies) is Transmitted to Dogs and Cats

Sarcoptic mange (Sarcoptes Scabei var. canis) is caused by a microscopic mite that burrows under a dog's skin. Sarcoptic mange has a 17- to 21-day, four-stage life cycle that consists of egg, larva, nymph and adult stage. Passed from dog to dog, adult female sarcoptic mange mites tunnel under a dog's skin to lay eggs. The eggs hatch and mature into adults that lay eggs in a cycle that lasts two to three weeks.

Signs in Dogs

Dogs that exhibit signs of intense itching, scratching, and biting especially around the face, chest, legs, elbows, ears or hocks may have sarcoptic mange. Small red bumps, hair loss and crusty scabs often appear. Secondary bacterial infections also may occur as a result of scratching. Mites can be detected in skin scrapings but are often difficult to find.

Treatment and Treatment Outcomes

Treating sarcoptic mange normally requires several treatments to kill adult mites as well as all newly hatched mites. Because sarcoptic mange is very contagious, all dogs in a home should be treated if sarcoptic mange is suspected. Traditional treatment options include insecticide dips and treatment with oral medications or injections. Skin infections resulting from sarcoptic mange mite infestations also should be treated.

Human Health Connections/Concerns

Dogs can pass the sarcoptic mange mites to humans (scabies). A red, itchy rash may appear on arms, waist of other areas.

Ear Mites

How Ear Mites are Transmitted to Dogs and Cats

Ear mites (otedectes cynotis) are small microscopic mites that feed on the pet's ear lining. Ear mites are highly contagious and easily passed from pet to pet. Ear mites have a four-stage life cycle that includes an egg, larva, nymph and adult stage.

Signs in Dogs and Cats

Signs of ear mites can include infection in both ears, intense irritation, scratching, head-shaking, rubbing black, red-brown, or waxy ear discharge. Additional signs include itchy skin located around ears, head and neck as well as thick crusts around the outer ear and possible crusts and scales on the neck, rump and tail.

Treatment and Treatment Outcomes

Because ear mites are very contagious, treatment should be administered to all pets in a household.

American Dog Tick (Dogs)

How American Dog Ticks are Transmitted

The American dog tick is probably the most widespread tick species in the country and, therefore, the most commonly found on pets (Archives of Internal Medicine; Sep. 22, 1997, James S. Tan, author). This species of tick is commonly found in fields, woods and grassy areas. The American dog tick is a blood-feeder and is capable of transmitting a wide variety of diseases, including tularemia and Rocky Mountain spotted fever, between animals and from animals to humans. Adult tick activity begins in mid-April, peaks in June and then declines in September. All stages of the American dog tick, however, may be found year-round in southern states.

Signs in Dogs

A bite from a disease-free tick normally doesn't cause clinical signs other than a crusty lesion, although a heavy infestation of ticks could cause anemia. In diagnosing a tick infestation, the first sign is to find a tick on the pet. This could be easy or challenging, depending on the severity of the infestation and whether the thick had had a recent blood meal - that is, whether the tick is engorged. The second means of diagnosing a tick infestation is to look for evidence of a tick-born disease - which may remain after the tick is gone.

Human Health Connections/Concerns

The American dog tick is the primary carrier of Rocky Mountain spotted fever and is also a carrier of tularemia. These diseases can be passed from infected ticks to humans. Rocky Mountain spotted fever most often occurs in the eastern and southern U.S., typically from April to September. Signs and symptoms of Rocky Mountain spotted fever in humans include fever, headache, muscle aches and a red rash appearing between the second and sixth day of the fever. In severe cases, the disease can be fatal, especially in the elderly. Tularemia is usually acquired through the bite of an infected tick. Patients will develop an ulcer at the site of infection and experience a swelling of the lymph nodes. Sever fever and flue-like symptoms may accompany the ulcer or lesion. Symptoms may persist from 1-14 days, with 3-5 days being most common.

Intestinal Hookworms (Cats)

How Intestinal Hookworms are Transmitted to Cats

Hookworms are small parasitic worms, with hook-like appendages on their mouths, that feed off the wall of the small intestine and can cause severe damage. They are blood feeding parasites that enter a cat's system either through ingestion of larvae or through the skin. Kittens can get the worms from ingesting their mother's milk.

Signs in Cats

Signs may include poor appetite, dry cough, pale gums, dark stools or constipation. Blood-loss anemia, weakness and bloody diarrhea are also symptoms of hookworm infection.

Human Health Connections/Concerns

Certain species of hookworms can affect humans when the larvae burrow under humans' skin and cause an itchy rash. Hookworms also may affect humans if larvae from soil are ingested.

Intestinal Roundworms (Cats)

How Roundworms are Transmitted to Cats

Roundworms, also know as ascarids, are transmitted from mothers to nursing kittens or through the cat ingesting eggs or other hosts (such as mice) that are infected with the eggs.

Signs in Cats

Roundworms interfere with digestion and absorption of nutrients. They can cause malnourishment, low stamina, dull coat, abdominal distention, abdominal pain, vomiting of adult worms, diarrhea, loss of condition, loss of appetite and coughing.

Human Health Connections/Concerns

Cat roundworms are known to cause visceral larval migrans in children, although less so than their canine counterpart. The disease results from ingesting the eggs.

Should you have a concern regarding the health of your Beagle(s), you should contact your veterinarian. All information on this site is presented solely for educational and informational purposes and should not, at any time, be considered a substitute for seeking or receiving veterinary care for your Beagle(s).