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28-11-2007 - Zoonoses Overview Cats and Dogs

Zoonoses are diseases of animals that can be transmitted to people. Transmission occurs by a variety of routes.

Some of these routes are listed below:

- Accidental ingestion of parasite eggs or infectious microorganisms through infected stool, water, or soil

- Direct handling of infected animal tissues (such as blood or pus) with bare hands

- Crushing an infected tick between unprotected fingers while removing it from the pet

- Inhaling infected airborne droplets from certain infected animal tissues

- Getting scratched by a cat

- Bite wounds from a dog or cat

- Having direct contact with infected urine

- Walking barefoot in area where there is infected animal stool

- Having direct contact with infected skin lesions on animals

Clinical signs in people vary and depend on the type of disease transmitted. Any person who becomes ill and has been around animals, even briefly, needs to be evaluated by their physician. A thorough physical examination and complete history often lead to the proper diagnosis.

Learn more about zoonotic diseases:

-Ringworm (Dermatophystosis)

What is dermatophytosis?

Dermatophytosis is the medical term for a fungal infection of the superficial layer of the skin, nails, or hair. The infections are caused by specific fungal species known as Microsporum or Trichophyton. This disease commonly is referred to as "ringworm," although the disease itself is not caused by a worm. Dermatophytosis affects dogs, cats, and people.

What causes dermatophytosis?

Dermatophytosis is caused by specific types of fungus (Microsporum or Trichophyton) that grow in the surface of the skin, nails and hair. Dermatophytosis tends to occur in animals that are immunocompromised, where their immune system is unable to fight off the fungal infection. Conditions that impair the function of the immune system include poor nutrition and severe, generalized infections. The incubation period from the time of exposure to the fungus and signs of disease ranges from 1 to 4 weeks. Some animals may be carriers of the fungus; in other words, they have the fungus on their body but they do not exhibit the disease. These carriers may infect other animals that are exposed to them.

What are the signs of dermatophytosis?

The most common clinical sign associated with dermatophytosis is a circular area of hair loss (alopecia). Other clinical signs include scaling, redness (erythema), darkening of the skin (hyperpigmentation), and itchiness.

How is dermatophytosis diagnosed?

Dermatophytosis is diagnosed by a good medical history and an examination of the skin. Some strains of fungus will glow (fluoresce) under a special black light (Wood's ultraviolet lamp); however, the absence of fluorescence does not rule out "ringworm." A small number of hairs are plucked from the edge of a hairless area. Some of the hairs may be examined with a microscope for the presence of fungal structures, such as spores. Dermatophytosis is diagnosed definitively using a fungal culture. The remaining hairs will be placed into a container with special fungal growth media. The sample then is monitored daily for characteristic changes associated with growth of "ringworm" fungi. Although blood and urine tests will not diagnose "ringworm" infection, they may identify an underlying disease that has allowed "ringworm" to develop.

Diagnosing animals that are carrying the fungus without having signs of disease is more difficult. A technique, known as the "toothbrush" technique can be used in the diagnosis. The toothbrush technique involves taking a new, sterile toothbrush and gently brushing throughout the animal's hair coat. The toothbrush will pick up individual hairs as the brushing proceeds over the body. A fungal culture is done using these hairs. The culture is done in the same manner as a culture for an animal with evidence of "ringworm."

How is dermatophytosis treated?

The treatment of dermatophytosis involves the use of systemic or topical antifungal medications for several weeks. Many animals will improve visibly; however, they may still have fungus on their body and test positive on fungal culture. Treatment should be continued until at least one fungal culture yields no growth of "ringworm" fungus (that is, the result is negative). The affected animal should be quarantined in the household to prevent spread of infection. Other animals that have been exposed may be treated with antifungal medications as a precautionary measure. Some antifungal medications have toxic side effects so the animals will need periodic monitoring. Recheck physical examinations, blood work, and repeated fungal cultures may be required to assess the response to treatment.

Dermatophytosis is a zoonotic disease. Zoonotic diseases are diseases that can be spread from animals to humans. Immunocompromised individuals should avoid handling infected animals. People should discuss their treatment with a physician.

What is the prognosis for animals with dermatophytosis?

The prognosis (outcome) for animals with dermatophytosis generally is good, as most animals will clear the infection over a few months. Treatment helps to speed the resolution of the disease. Unfortunately, some infections may remain persistent, particularly in longhaired cats or multi-animal households.

Infectious diarrhea(Giardiasis)

What is Giardia?

Giardia is a protozoan parasite that causes an intestinal disease known as giardiasis in dogs, humans, and less often in cats. There is no definitive proof that Giardia is spread directly from pets to people. However, it can be passed from species to species through a common infected source, such as well water.

What causes giardiasis?

Giardiasis is caused by a small parasite known as Giardia canis. Giardia canis is classified as a protozoan, and spends most of its life in the intestinal tract of infected animals. It will form a cyst - a hard-shelled, reproductive form - that is passed in the stool from time to time, infecting the environment. Most cases of giardiasis are caused by drinking water that is fouled with these cysts.

What are the signs of giardiasis?

The major sign of giardiasis is diarrhea. It may be severe, but most often consists of high volumes of stools that are soft, contain mucus, or are sometimes frothy. The stools may have a rancid smell. In most cases, the diarrhea comes and goes over time and the animal feels generally well. However, long-term or severe diarrhea can cause weight loss and debilitation.

How is Giardia diagnosed?

Giardia is diagnosed most often by finding the organism or the cysts on examination of a fresh stool sample under a microscope. It may be necessary to examine several different stool samples, as the organism is not always present in every sample. A test to detect Giardia antigen in the stool is available, but it is not considered to be much more sensitive to picking up infection than proper microscopic examination using zinc sulfate solutions.

How is Giardia treated?

There are various drugs available for treating Giardia, such as fenbendazole or metronidazole. Therapy will last from two-to-five days, depending on the drug chosen. Treatment may need to be repeated for a permanent cure. The stool should be checked several times after treatment to make sure all of the organisms have been removed. For severely ill animals, fluid therapy will be needed to fight dehydration caused by diarrhea.

What is the prognosis for pets with giardiasis?

In general, the prognosis (outcome) is good to excellent. Most pets do not become seriously ill, and treatment followed by monitoring of the stool is usually effective at clearing the disease. In a few pets, especially those with underlying disease or poorly functioning immune systems, Giardia can pose a serious health risk. Most of these animals recover as well, but treatment may be more intensive.

Cat scratch fever (Bartonellosis)

What is cat scratch disease?

Cat scratch disease is an infectious syndrome in people. Generally the person has enlarged lymph nodes, following a cat scratch or bite. It occurs worldwide, with an estimated 24,000 cases a year in the United States. Over 2,000 of these cases require hospitalization but almost no deaths occur from this disease.

What causes cat scratch disease?

The infectious agent that causes cat scratch disease is Bartonella henselae. The person is infected by a scratch or bite from a domestic kitten or cat. Young cats with fleas are frequently the carriers of cat scratch disease.

What are the signs of cat scratch disease?

The signs of cat scratch disease progress following the scratch or bite. A red pimple or papule will appear at the site of the scratch or bite. Then the lymph nodes in the region of the scratch or bite will enlarge and become painful. The person may have mild fever, chills, lack of appetite, muscle aches, nausea, and a general feeling of ill being. Less often, the central nervous system can be infected; for example, meningitis (inflammation of the membranes that cover the brain and spinal cord) can occur. Other conditions also can occur, such as inflammation of the lining of the eyes (conjunctivitis), inflammation of the liver (hepatitis), or pneumonia.

Cats are carriers of the disease. They usually have no signs of illness.

How is cat scratch disease diagnosed?

Cat scratch disease is the most common cause of chronic, benign (not cancerous or malignant) disease of the lymph nodes in children and young adults. The diagnosis is based on several criteria-history of contact with a cat, formation of a pimple at the site of the scratch or bite, symptoms, and exclusion of other causes of lymph-node disease, such as infectious mononucleosis or tuberculosis. Blood tests (serology) to identify Bartonella henselae may be done.

How is cat scratch disease treated?

The person's physician should determine treatment for cat scratch disease. The treatment generally is supportive (bed rest and applying heat to swollen lymph nodes). The scratches and bites are cleansed thoroughly. Needle aspiration of pus from lymph nodes may be done. Antibiotics have not proven to be effective in most patients; however, antibiotic therapy may be tried in severely affected patients.

What is the prognosis for people with cat scratch disease?

The prognosis (outcome) for people with cat scratch disease generally is good. Most cases resolve on their own in a few weeks or months. Complications are uncommon and one episode appears to confer lifelong immunity. People with immune system disorders should avoid young cats.


What is leptospirosis?

Leptospirosis is a serious disease that usually affects the kidneys or liver. It also may cause abortion, stillbirths, and life-threatening whole body infections (septicemia). Leptospirosis is found in many species of animals, including dogs, cats (rarely), and people. It is considered a zoonotic disease (a disease that can be spread from animals to humans).

What causes leptospirosis?

Leptospirosis is caused by a spirochete (a spiral-shaped, infectious organism). Several types of Leptospira cause disease in animals. The most common vaccines for dogs protect against only two types. A dog can catch leptospirosis from direct contact with an infected animal's urine, abortion discharges, or through sexual contact. It also can be caught from a contaminated environment. The spirochetes enter the body through a wound or by penetrating intact skin then rapidly infect the bloodstream. They then spread to other parts of the body and multiply in the kidneys and liver.

What are the signs of leptospirosis?

The signs of leptospirosis are fever, sore muscles, stiffness, shivering, weakness, dehydration, lack of appetite, and depression. Animals may develop diarrhea, a yellowing of the gums or skin, increased thirst and urination, a bloody vaginal discharge, and pinpoint hemorrhages or bruising of the gums. Death may occur suddenly, without previous signs. Some animals develop no obvious signs initially, but may develop kidney or liver failure long after being infected. Dogs tend to become infected more commonly and have more severe disease than do cats.

How is leptospirosis diagnosed?

Leptospirosis is diagnosed by a good medical history and thorough physical examination. A complete blood count (CBC) will show an increase in white blood cells during the early phase of the disease. The blood chemistry panel will show changes dependent on the various organs affected. Blood urea nitrogen (BUN) and creatinine often rise due to kidney infection, and liver enzymes (known as ALT, AST, SAP and LDH) increase when the liver is infected. Examination of the urine may demonstrate increases in urinary protein and sugar.

Definitive diagnosis can be made by collecting two blood samples (one sample early in the disease and a second sample three weeks later) and observing for increased antibody titers for Leptospira over time. Fluorescent antibody tests are used to find and identify the organisms in urine samples or in body tissues, collected during biopsy or after death.

How is leptospirosis treated?

Leptospirosis is treated with antibiotics such as procaine penicillin by injection or doxycycline by mouth. The length of treatment may last for several weeks or more. Mildly affected animals can be treated as outpatients, but severely ill animals must be treated in the hospital. These will receive fluid therapy and other supportive care, which will vary depending on the organs affected.

Infected animals will spread disease by passing organisms in their urine. The premises should be cleaned with an iodine-based disinfectant or a stabilized bleach solution in order to kill the spirochetes. Check with the veterinarian for recommended products.

What is the prognosis for pets with leptospirosis?

For mildly infected animals, the prognosis (outcome) is generally good. Recovery is expected with treatment. However, animals that are severely ill have a guarded prognosis. These animals may die suddenly early in the disease course. Kidney and liver damage may be permanent, and cause a poor quality of life or may result in death long after the initial episode.


What is rabies?

Rabies is a severe, usually fatal, viral disease of the central nervous system. It affects warm-blooded animals, including people.

What causes rabies?

The rabies virus causes rabies. The rabies virus lives in the saliva of infected animals. The virus enters the body through a wound, usually from the bite of a rabid animal, or via the mucous membranes, such as the mouth. The virus multiplies (replicates) and travels throughout the nervous system.

Rabies is found worldwide with the exception of the British Isles, Australia, New Zealand, Hawaii, Japan, and parts of Scandinavia. In the United States, the virus is found in fox, raccoons, skunks, and bats. Animals that are exposed to wildlife and unvaccinated animals are at risk of contracting rabies. Dogs and cats should be vaccinated against rabies.

What are the signs of rabies?

The signs of rabies vary. Some animals may be vicious ("furious rabies") while others will be withdrawn ("dumb rabies"). The animal will have a change in attitude; it may become apprehensive, nervous, or anxious. It may exhibit unusual shyness and try to be alone, or it may become aggressive. The animal may bite, snap, and lick or chew at its wounds. The animal may wander and dogs may have a change in the tone of bark. Signs will worsen, the animal becoming excitable, irritable, and vicious. It may be disoriented, have difficulty walking, or have excessive salivation or frothing at the mouth. Seizures can occur. The jaw may become paralyzed, causing the jaw to drop and the animal to be unable to swallow.

How is rabies diagnosed?

Rabies should be suspected in any dog or cat showing unusual mood or behavior changes, or any unaccountable nervous system (neurological) signs. The veterinarian will want to differentiate rabies from other diseases having similar signs, such as brain tumor, inflammation of the brain, head wound, and choking. Routine laboratory tests are not helpful in diagnosing rabies. A spinal tap may be done to remove and analyze the spinal fluid. The spinal fluid may show increased protein and white blood cells. Skin biopsy (removal and examination of skin tissue) may be helpful. In animals that have died, nervous tissue from the brain or the entire animal is sent to a state-approved laboratory for rabies diagnosis.

How is rabies treated?

Rabies is a public health risk. Animals suspected of having rabies, of being exposed to a potentially rabid animal, or that have bitten a person are handled as "rabies suspects" according to local laws. All animals with suspected rabies are hospitalized or housed at an animal control facility. They are confined to a secure, quarantined area with clearly posted signs. The time required for quarantine varies, depending on the local laws and the specific situation of potential exposure. An apparently healthy dog or cat that bites or scratches a person should be quarantined and monitored for 10 days. If no signs of illness occur during this time, the animal will not have been exposed to rabies prior to the bite or scratch. An unvaccinated dog or cat that is bitten or exposed to a known rabid animal must be quarantined for up to six months. Those animals that do not have rabies will be released following completion of the quarantine period.

If the animal appears to have rabies, no treatment is available; once the diagnosis is certain, euthanasia is indicated. Following euthanasia, the brain will be submitted to a state-approved laboratory for confirmation of the diagnosis.

The "treatment" for rabies is to prevent it. All dogs and cats should be vaccinated against rabies. Local laws determine vaccination schedules. Generally, dogs and cats should be vaccinated after 12 weeks of age, given a second vaccine 12 months later, and then every 3 years. Dogs and cats entering a rabies-free country are quarantined for long periods, usually six months.

What is the prognosis for animals with rabies?

The prognosis (outcome) for animals with rabies is grave. Nearly 100% of affected dogs and cats will die within 7 to 10 days.


What is salmonellosis?

Salmonellosis is a bacterial disease caused by Salmonella. Many types of Salmonella exist. Salmonellosis can be characterized by intestinal disease (such as diarrhea), abortion, or generalized infection (septicemia). The disease varies widely in intensity; infected animals may be carriers with no signs of illness, or they may have mild, moderate, or severe illness and debilitation. Infection with no signs of disease is more common than actual illness.

What causes salmonellosis?

Any one of more than 2,000 types of Salmonella can cause salmonellosis. The bacteria are ingested and colonize in the small intestine. Salmonella may remain in the intestine or may spread throughout the body via the lymphatic and circulatory systems. The disease is more common in young cats, young or pregnant dogs, and adult animals subject to stress (such as overcrowding, hospitalization, dietary changes, or travel). In general, cats have a high natural resistance to salmonellosis; however, stressed cats are at higher risk. The sources of the bacteria include:

- Dry dog or cat food (pressed food, such as kibble or dog biscuits, not as risky)

- Grooming habits of dogs and cats can result in contamination of the hair, which contaminates cages, dishes, and other objects in the animal's environment

- Unsanitary conditions

- Animal shelters and animal-care facilities, especially with overcrowding

- Dead animals

- Bowel movement from infected animals

What are the signs of salmonellosis?

The signs of salmonellosis vary. Many infected animals have no sign of disease. Some animals may have vomiting, diarrhea, or dehydration if the bacteria remain in the intestines and does not spread. More serious disease occurs if the bacteria get into the blood stream, causing widespread blood infection. From the bloodstream, the bacteria can cause severe damage to body organs, abnormal blood clots or blood disorders, and death.

Other signs of salmonellosis include fever, lack of appetite, fatigue, and weakness. Vaginal discharge or abortion may be seen in dogs. Some animals may have diarrhea containing mucus or blood, abdominal pain, and pale gums and tongue. Weight loss may be apparent. Recovering animals may have intermittent diarrhea for 3 to 4 weeks and may shed Salmonella in the stool for 6 weeks or longer. Cats may exhibit a syndrome of long-term (chronic) illness with persistent fever and vague, nonspecific signs (and no vomiting or diarrhea).

How is salmonellosis diagnosed?

Salmonellosis is diagnosed by a good history, a thorough physical examination, blood tests, and bacterial cultures of bowel movement, blood, or joint fluid. Complete blood tests (CBCs) may show abnormalities such as anemia (low red blood cell count). Blood chemistries may reveal fluid and electrolyte imbalances or other abnormalities. Bacterial culture of bowel movement or rectum will be positive for Salmonella. Blood and joint fluid cultures may be positive for Salmonella.

How is salmonellosis treated?

The treatment for salmonellosis depends upon the severity of the clinical disease. Pets with advanced disease, or newborns and young animals with debilitating diarrhea are hospitalized. Animals should be isolated because they may be shedding large numbers of Salmonella in their bowel movements. Seriously ill animals should rest and be kept warm. Food is restricted for 24 to 48 hours, and then food is introduced gradually. A highly digestible, low-fat diet is recommended. Antibiotics are not given to animals that are carriers of the bacteria but have no signs of illness. Antibiotics are not indicated if the infection is confined to the intestines. Supportive care is given. Fluids are administered either by mouth (orally) or through a vein (intravenously) as needed for dehydration. Drugs may be given to protect the intestines. Severely ill animals may be treated with plasma transfusions and steroids. Antibiotics are based on culture and sensitivity test results.

After recovery, bacterial culture of the stool is repeated monthly for a few months to assess development of a carrier state. The pet's contacts with other animals and people should be limited to minimize spread of the bacteria. Salmonellosis can be prevented with proper nutrition (no raw meat), sanitary conditions, and proper storage of food. Overcrowding of animals in pounds, shelters, kennels, or research labs should be minimized. Good hand washing can minimize the risk of infection to people.

What is the prognosis for animals with salmonellosis?

If the infection remains in the intestines, the prognosis (outcome) for animals with salmonellosis is excellent. Animals frequently recover with good nursing care. Severely ill animals can die without treatment.

Hookworms (Cutaneous Larval Migrans)

What are hookworms?

Hookworms are parasites of the small intestines. Several species of hookworms are found in dogs and cats. Some hookworms suck significant amounts of blood from the host animal while others remove only small amounts of blood. Hookworms have large mouths with hook-like teeth to attach to the lining of the intestine and to allow them to suck blood. Hookworms may have a bend or curve in their bodies, giving them a "hook" appearance. Some people believe that the hook-like teeth led to the name "hookworm" while others think it was the appearance of the body.

Adult female hookworms lay eggs in the animal's small intestine. The eggs move through the digestive tract and are passed in the animal's bowel movement. The larvae develop within a week if conditions (such as temperature) are satisfactory. The larvae are able to survive in warm, moist environments for quite some time. The larvae enter the host through the skin or mouth. Once in the host animal, the larvae may migrate through the body or they may go to the intestines directly. The larvae mature into adults in the small intestines. The animal's environment becomes very difficult to decontaminate when hookworm eggs and larvae are present.

What causes hookworm infection?

Dogs and cats may be exposed to hookworms in a variety of ways. Hookworm exposure includes:

- Hookworms cross the placenta, infecting developing puppies or kittens
- Hookworm larvae contaminate mother's milk, infecting nursing animals
- Swallowing infective hookworm larvae from bowel movement of infected
- Hookworm larvae can penetrate through the animal's skin

What are signs of hookworms?

Hookworms bite into the lining of the intestines, suck a blood meal, and leave behind a bite mark that continues to ooze blood into the intestinal tract. Larvae also migrate through the lungs following skin penetration. The signs of hookworms vary, depending on the number and species of hookworms present, the amount of blood loss, and the age of the animal. Some animals may have hookworms without any signs while others may have life-threatening blood loss. Signs include pale gums and tongue (mucous membranes); dark, tarry bowel movements (melena); diarrhea or constipation; or sudden death from blood loss. Puppies and kittens are more likely to die from hookworm infection than are adult dogs and cats. Some animals may cough because the hookworm larvae migrate through the lungs. The animal may appear to be "unthrifty" with poor body condition and hair coat. Fleas and hookworms are a particularly deadly combination in newborn puppies or kittens as both parasites suck blood.

How are hookworms diagnosed?

Hookworms are diagnosed by medical history, physical examination, and fecal examination. Additional diagnostic tests may be performed. A complete blood count (CBC) may be characterized by a low red blood cell (RBC) count, indicating anemia. Another change that may be identified by the CBC is a high number of eosinophils. The eosinophil is a type of white blood cell that increases in number in response to the presence of parasites or allergic reactions. Fecal flotation is the laboratory analysis of bowel movement (feces or stool) that separates parasite eggs from feces for microscopic detection. If hookworm eggs are identified on fecal flotation, the diagnosis is obvious. Unfortunately, some animals may have severe hookworm disease but not be passing hookworm eggs. In these cases, the diagnosis is made by the clinical signs. Examination of the bodies (necropsy) of deceased puppies or kittens can provide identification of hookworms and allow a definitive diagnosis.

How is hookworm infection treated and prevented?

The treatment for hookworm infection varies, depending on the severity of the clinical signs. If the animal has hookworms without clinical signs, medications will be given to kill the adult hookworms. Various deworming medications are available. Some medications treat hookworms only while others treat both hookworms and roundworms. Puppies and kittens are dewormed periodically during the nursing stage. If the animal has signs of hookworm disease, medications will be given to kill the adult hookworms and additional treatment will be needed. Fluid therapy, blood transfusions, and nutritional support improve survival of infected animals.

Prevention of hookworm infection is important for animals and people. Medications are available to control or prevent hookworms and roundworms as well as prevent heartworms. Drying the animal's environment theoretically eliminates eggs and larvae but is not practical outdoors. Treatment of breeding females prior to and during pregnancy (gestation) as well as after delivery minimizes infection of puppies and kittens. Puppies and kittens should be dewormed periodically during nursing. Fecal flotations should be performed on a regular basis for puppies and kittens and should be performed at least annually for adult animals. Animals should be kept out of known, hookworm-contaminated areas.

We recommend strategic deworming of dogs and cats even when laboratory tests are negative. The deworming prevents infection in dogs and cats and minimizes the human health risk associated with environmental hookworm contamination. "Creeping eruption" or cutaneous larval migrans is the condition caused by hookworm larvae penetrating skin and burrowing through tissue in people.

What is the prognosis for animals with hookworms?

The prognosis (outcome) for mature, and otherwise healthy, animals infected with hookworms is excellent following proper deworming. Prognosis for the young animal is fair with early and aggressive therapy. Hookworm infection in puppies or kittens can be fatal, especially if fleas or other diseases affect them simultaneously.

Roundworms (Visceral Larval Migrans)

What are roundworms?

Roundworms or ascarids are intestinal parasites that can infect either dogs or cats. They are relatively large worms (up to 10 to 12 cm in length). Roundworms are especially dangerous to puppies and kittens. Roundworms have zoonotic potential (they can be spread from animals to humans) and may cause disease in humans.

What causes roundworms?

Roundworms infect dogs or cats when the animal ingests the roundworm eggs in food or other matter contaminated with feces or when the animal eats rodents carrying dormant larvae. Roundworms also can be transmitted to puppies or kittens before or during birth.

What are the signs of roundworms?

The signs of roundworms vary depending on the number of worms present and the animal's age and general health status. Some animals may have roundworms without having any outward signs. Other animals with roundworms may have a variety of outward signs. Roundworms can cause distension of the small intestine because of their large size. This distension often leads to colic, poor gut motility, abdominal pain, and inability to utilize food. The abdomen may appear bloated. The pet may refuse to eat, vomit, have scanty bowel movements, and become weak. Due to the parasitism, the pet may be thin and malnourished. The pet also could be coughing due to the body's response to the migration of the roundworms following infection. During the first month of life, infected newborn puppies and kittens may refuse to nurse and will deteriorate rapidly. Entire litters may be affected.

How are roundworms diagnosed?

On physical examination, the veterinarian may be able to palpate the bloated abdomen and distended intestines suggestive of roundworm parasitism. A definitive diagnosis can be done by stool examination, looking for eggs and distinguishing them from other parasitic infections, such as hookworms. Puppies or kittens may have roundworms and not be passing eggs in the stool. Roundworm eggs cannot be seen in the stool of puppies and kittens until they are over three weeks of age. If performed, blood tests may reveal an increase in a specific type of white blood cell, the eosinophils.

How are roundworms treated?

The animal will be treated for roundworms based on its condition. Some animals may need medications only as outpatients while others will need more aggressive treatment. Acutely ill animals need to be hospitalized for deworming and to be given intravenous (through a vein) fluids and special feeding. Specific medications to kill the adult roundworms are given once or twice a month until no eggs are seen in the feces. To try to decrease roundworm infections in puppies or kittens, the mother dog or cat should be treated.

What is the prognosis for animals infected with roundworms?

The prognosis (outcome) depends on the age of the animal and on the timely initiation of treatment. Sudden death can occur. If the pet survives, there can be a long recovery period while the pet remains weak and debilitated. However, with proper treatment and good nutritional support, the pet can recover fully.


What is toxoplasmosis?

Toxoplasmosis is an infection by Toxoplasma gondii (T. gondii), a protozoan parasite that infects nearly all mammals. The only known complete hosts are cats. Complete development of the parasite only occurs in the intestines of cats. The parasite can exist in the cells of many organs and tissues of dogs, birds, cats, and other mammals including man.

What causes toxoplasmosis?

Cats and dogs can be infected with T. gondii by eating raw meat, bones, organs, or unpasteurized milk (especially goat milk), or by eating insects such as flies and cockroaches that have been in contact with contaminated food (mechanical vectors). Free roaming cats can be infected when they catch and eat birds and rodents. A healthy cat with positive T. gondii titers poses little danger to its owner. However, a sick cat will shed the parasite cyst form (oocyst) in its feces for a short period of time, and during that time, there is risk to anyone coming in contact with the feces. An oocyst is an encapsulated form of the parasite. Pregnant women should avoid all contact with a cat excreting oocysts in its feces, because if the woman gets a new infection, birth defects often result.

The parasite can live in a healthy host in tissues (e.g., skeletal muscle) until it is reactivated. The parasite can reactivate if the animal becomes ill, especially with diseases that suppress the immune system. Diseases that suppress the immune system include feline leukemia virus (FeLV), feline immunodeficiency virus (FIV), and canine distemper.

What are the signs of toxoplasmosis?

Approximately 30% of cats, and 50% of people are positive for T. gondii; however, most animals with toxoplasmosis have no signs, and clinical disease is uncommon. Cats have signs more frequently than dogs. The severity of illness depends on the location and degree of tissue injury caused by the parasite. If oocysts are ingested, they spread to organs via the blood stream, resulting in damage to many organs (heart, eye, brain). This widespread infection is rarely fatal. In more chronic forms, the parasite remains in the body, and signs are not apparent until other illness or suppression of the immune system allows T. gondii to proliferate, and cause an acute inflammatory response. Nonspecific signs are lethargy, depression, lack of appetite, weight loss, and fever. In cats, disorders of the eye may occur; the cat may be sensitive to the light, and there may be discharge from the eye. Other signs include respiratory distress, unsteady gait, muscle tremors, muscle weakness, paralysis, seizures, vomiting, diarrhea, abdominal pain, and yellowing of the skin (jaundice). Infected mothers may have stillborn kittens.

How is toxoplasmosis diagnosed?

Your veterinarian will diagnose toxoplasmosis by performing a thorough history and physical examination, and laboratory analysis. Routine blood tests and urinalysis are done. Complete blood counts (CBCs) usually show mild anemia (low red blood cell count). Blood chemistries and urine analysis may have abnormalities that can pinpoint the affected organ (or organs). Antibodies that form in response to the parasite can also be analyzed in the blood serum. Radiographs (X-rays) of the abdomen and chest may visualize abnormalities in the organs. Other diagnostic procedures include analysis of the spinal fluid, and examination of the stool. Oocysts may be detected on routine fecal examination in healthy cats.

How is toxoplasmosis treated?

Most pets can be treated as outpatients. Animals need rest. Antimicrobial medications are given by mouth, or by injection for at least 2 weeks after signs clear. Eye infections may be treated at the same time. Signs should begin to resolve two days after initiation of medication.

What is the prognosis for animals with toxoplasmosis?

Because of the varied response to drug treatment, prognosis is guarded. In acute (sudden and severe) cases, prompt and aggressive drug therapy is often successful. There may be some permanent damage if the nervous system has been affected.

Scabies mites (Sarcoptes)

What is sarcoptic mange?

Sarcoptic mange is a highly contagious, parasitic skin disease of dogs. It is a nonseasonal disorder caused by infestation of sarcoptic mange mites. The mites burrow through the upper surface of the skin and cause intense itching and irritation. The mites secrete substances (allergens) that produce an allergic or hypersensitivity reaction in some dogs.

What causes sarcoptic mange?

Sarcoptic mange is caused by infestation of the mite, Sarcoptes scabiei. Sarcoptic mange is contagious. The infestation follows exposure to a dog with sarcoptic mange. Roaming dogs and dogs living outside are potential carriers of the disease. The dog can be exposed to sarcoptic mange mites at shelters or kennels and during visits to grooming facilities or veterinary offices.

The sarcoptic mange mite can cause skin problems in human family members that come into contact with a dog infested with Sarcoptes. People who come in close contact with an affected dog may develop an itchy rash with small raised bumps (papules) on their arms, chest, or abdomen. Rashes in people usually are temporary and should resolve after the affected dog has been treated. Any affected person should contact a physician regarding possible treatment.

What are the signs of sarcoptic mange?

Sarcoptic mange is a very itchy condition. The pet will have hair loss and a red rash. The signs generally are seen on the elbows, hocks, abdomen, and chest. Scaling and crusting may be present on the ears. Rubbing the ears will cause the dog to scratch with its hind leg. The dog will scratch, leading to sores (skin excoriations) on the skin. Pus-filled lesions may develop. Occasionally, the lymph nodes will enlarge.

How is sarcoptic mange diagnosed?

Sarcoptic mange is diagnosed primarily upon history of exposure to other dogs (generally two-to-six weeks before the skin problems) and physical examination. The veterinarian will want to differentiate sarcoptic mange from other conditions with similar signs, such as food or flea allergies. Examination of skin scrapings may be attempted to identify the mange mite, but false negative results are common. Examination of the stool may reveal mites or eggs. Since it frequently is difficult to find the mange mites on the dog, the pet will be treated for sarcoptic mange based on the veterinarian's suspicion. If the dog's signs resolve following treatment for sarcoptic mange, the diagnosis is made based on the dog's response to treatment.

How is sarcoptic mange treated?

Sarcoptic mange is treated by killing the mange mites on the dog. A topical product has been approved by the FDA to treat sarcoptic mange. Other treatments include medicated shampoo baths followed by body dips. The dips include lime sulfur or pesticides approved for use against the sarcoptic mange mite. Baths and dips usually are done once weekly and continued for two weeks beyond remission of signs. When dips are used, the entire dog must be dipped, including the dog's face and ears, and the dog cannot be allowed to get wet between treatments. The veterinarian will choose the appropriate treatment for each case and will explain the use of the selected products. Instructions for use of these products should be followed carefully. Other medications may be prescribed; some dogs benefit from steroids. Antibiotics may be needed if the skin lesions contain pus, indicating possible infection. In homes with several dogs, all dogs should be treated, even those with no signs because they may be carriers; and it can take one month for signs to develop.

What is the prognosis for dogs with sarcoptic mange?

With proper treatment, the prognosis (outcome) for dogs with sarcoptic mange is good. Response to treatment should be seen within two weeks, although treatment will need to be continued for two weeks beyond remission of signs.


What are ticks?

Ticks are arthropods, closely related to scorpions, spiders, and mites. They are skin parasites of dogs and cats, feeding only on the blood of their hosts. Ticks have a great potential to act as carriers of a number of diseases. Organisms that transmit agents of disease are known as "vectors." When the tick bites the host animal, it can transmit a variety of disease-causing organisms (pathogens) including protozoa, bacteria, viruses, rickettsiae, and other agents. The resulting diseases are known by the broad term of "tick-borne diseases."

How do pets get ticks?

Direct contact with ticks may result in tick parasitism. While ticks do not jump or fly, they are attracted to hosts by motion, variations in light patterns, warmth, and the presence of carbon dioxide. Disease-causing agents (pathogens) may be acquired when ticks feed on previously infected hosts (such as rodents) and then attach themselves to a dog or cat. Transmission of the disease-causing agent often requires that the tick be attached to the host for periods from hours to days. The essentially painless tick bite often allows feeding times of adequate duration to allow for transmission.

The expansion of the suburbs into forests, prairies, and coastal areas has placed domestic animals in close contact with ticks. Ticks are seen in cats, even with their grooming habits. Tick-borne diseases are diagnosed routinely in dogs and cats.

What are the signs of tick parasitism?

The signs of tick parasitism include the presence of the tick itself as well as the signs of tick-borne disease, if the animal has been infected. Some dogs may develop paralysis due to a toxin from the ticks. Ticks may be seen attached to the animal's skin or feeding cavities may be seen on the skin where the ticks have detached themselves. Tick bites generally are painless, but local irritation may occur. The local irritation may cause some dogs to bite and scratch at the area, resulting in skin inflammation or infection. Signs of tick-borne diseases vary with the organ system affected. Tick-borne pathogens may affect virtually any organ system.

For more information on tick-borne diseases, go to Ehrlichiosis, Lyme Disease.

How are ticks diagnosed?

Diagnosis of tick parasitism is made by examining the skin for the presence of attached ticks or for tick-feeding cavities left by detached ticks. Diagnosis of tick paralysis or tick-borne diseases is made by a history of tick parasitism, a thorough physical examination, and a complete evaluation of ill pets. Generally blood work will be performed, including complete blood counts (CBCs) and blood chemistries. Specific tests may be performed for individual tick-borne diseases.

How are animals infested with ticks treated?

Ticks should be removed as soon as possible to limit the time available for transmission of disease-causing agents. The most efficient removal is done with fine-pointed tweezers. Ticks are grasped close to the skin and gently pulled free. Some skin may adhere to the tick's mouth or a fragment of the tick may remain imbedded in the skin. In either case, the area should be washed with soap and water, which generally is sufficient to prevent local inflammation. The pet guardian should not handle the tick directly and should wash his or her hands after removing ticks. No one should apply hot matches, petroleum jelly (Vaselin), or other materials to ticks because these methods fail to remove ticks and allow for longer periods of attachment and feeding.

The best means of "treating ticks" is to prevent them from attaching to the pet. One way to keep ticks from attaching is to avoid environments that harbor ticks. Unfortunately, suburban living has brought pets into environments frequented by many tick hosts; therefore, avoidance is sometimes difficult for all but pets kept strictly indoors or for city dwellers. A variety of products are available for tick control on the pet. They include topical liquids and sprays, special tick prevention collars, and dips. The veterinarian can provide advice about the best method for preventing ticks and about the best product or products to be used for a particular pet.

If the pet has signs of a tick-borne disease, treatment will be directed at underlying disease. Preventing tick attachment is the best way to avoid potentially debilitating tick-borne diseases. Dogs also can be immunized against Lyme disease, a tick-borne disease.

What is the prognosis for animals with ticks?

The prognosis (outcome) for animals with ticks varies. If an animal only has a few ticks on it, they can be removed easily. The animal then can be started on a tick prevention program and the prognosis would be considered good. If the animal has tick paralysis, removal of the ticks leads to rapid improvement. The prognosis for tick-borne diseases depends on the length of time the animal has been sick and the particular disease. If diagnosed early, many pets will recover with appropriate treatment. However, some tick-borne diseases can be very difficult to treat.

Frequently asked questions

What about pets in homes with immunocompromised family members?

A. Cancer chemotherapy almost invariably results in some impairment of the body's immune system so your child is more at risk for infection. Your physician does not want your child exposed to zoonotic infection (infection that can be passed from animals to humans). However, there are well-documented psychological benefits for your child in having a pet, especially if she is isolated from other children. While the choice of an adult neutered indoor cat would be preferable to a kitten, other species of companion animals also pose zoonotic disease risks. The following general recommendations may offer a compromise; your physician may agree to a kitten if they can be followed. Have your physician discuss the risks with your veterinarian.

Selection: Avoid young (under 6 months) animals because of their increased susceptibility to infection. Also avoid stray, debilitated, or obviously ill animals, particularly those from unsanitary facilities. Veterinarians can assist with the selection of an appropriate pet, particularly one that is unlikely to bite or scratch.
Feeding: Feed the animal a commercial or otherwise well-cooked diet. Keep the animal indoors to eliminate hunting. Do not allow the animal to drink from the toilet.
Personal Hygiene: Instruct your daughter to wash her hands thoroughly after handling the animal and avoid contact with feces and urine. Do not let her change the litter box and keep the litter box well away from food preparation and eating areas. The cat's environment should be kept clean. The cat's claws should be trimmed frequently, or have the cat declawed, to reduce the risk of scratch injuries. The animal should be groomed frequently and flea and parasite control instituted.
Health care: Newly acquired cats should be examined by a veterinarian and given routine vaccinations. The cat's feces should be checked for parasites. Testing for feline leukemia virus and feline immunodeficiency virus infection should be performed, not because these viruses infect people, but because cats affected with these viruses are more likely to develop other infectious diseases. An adult cat is at low risk of being infected with toxoplasmosis (a parasite), but an animal with antibodies against toxoplasma may be a safer choice for your daughter. The cat can be tested for toxoplasma antibodies. If the cat develops diarrhea, it should be immediately withdrawn from the house and evaluated for intestinal bacteria and parasites. Regular dental cleaning, including scaling or brushing, is recommended for pets exposed to any immunocompromised person.

What if both family members and pets are showing gastrointestinal symptoms such as vomiting and diarrhea?

Yes, a connection is possible. Dogs can be infected with a number of bacteria that cause diarrhea and are zoonotic (transmissible to people). These infectious organisms include bacteria such as Salmonella, Campylobacter, and Yersinia enterocolitica, and several parasites including Giardia and Cryptosporidia. Puppies appear to be particularly susceptible to these agents. The puppy needs to be examined by a veterinarian, including a stool examination, to establish a diagnosis and appropriate therapy. Similarly, the children should be examined by their physician, and the cause of their diarrhea should be confirmed by a laboratory examination. In situations such as this, communication between the veterinarian and the physician is beneficial to determine if there is a direct link between the puppy's illness and the children's illness. Bacteria that cause diarrhea can be transmitted directly by the fecal-oral route (putting hands contaminated with infected feces into the mouth) or indirectly via food or water contaminated with the microorganism. The children and puppy may have been infected from the same source, such as contaminated meat or milk.

Does my cat need vaccination against rabies?

Historically, dogs have been considered to be the greatest threat in transmitting rabies to people in large urban areas, and state and local governments have mandated that dogs must be vaccinated against rabies. In recent years, however, an increasing number of rabid cats have been reported. In fact, more cat patients with rabies are now seen than dog patients with rabies. The majority of rabid cats comes from foxes. Rabies in cats is reported most often during the summer months.

Because vaccination of companion animals is critical in preventing rabies in people, the Veterinarians now recommends requiring vaccination of cats. A high percentage of cats exhibit an excitement phase for 2 to 4 days following infection with the rabies virus. During this phase, the cat is erratic and aggressive. As a result, rabid cats often expose more people to rabies than do other rabid animals. Vaccination of cats is most strongly recommended for cats that go outdoors or that travel with a family periodically to areas where rabies is common in wildlife. Depending on the vaccine used, it can be given as early as 8 weeks of age, and be repeated annually or every 3 years. Rabies vaccines are now available in combination with other recommended feline vaccines. The rabies vaccine is considered safe and efficacious when used according to the manufacturer's label directions.

Can I get rabies even if get bitten?

I do not get bitten? Yes. However, the risk is low. The great majority of rabies cases in people occur because of animal bites. The rabies virus lives in the saliva of animals that are either incubating the disease and are not yet showing signs of illness, or in the saliva of animals that are demonstrating signs of rabies. Rabies is transmitted when the virus in saliva is introduced into a bite wound, into open cuts in the skin, or onto intact mucous membranes. Thus, it is possible that the virus can be transmitted by a dog licking a scratch or skin cut, or onto the mucous membranes in the eyes or mouth. Simply handling a rabid animal or being in the same room, however, does not constitute rabies exposure. In addition, there are a few instances of rabies in people developing as a result of receiving a corneal transplant from a person who died from rabies that was not diagnosed at the time of death. The virus can also be spread through the air in caves where high populations of bats roost.

My dog bit my neighbor. Should she have rabies and tetanus shots?

The bite should be immediately cleaned and flushed with water and any bleeding controlled. All dog bites should be examined by a physician as soon as possible. The physician will generally institute the following treatment:

The wound will be thoroughly cleaned to minimize infection and assess the extent of injuries. Bite wounds are not usually sutured unless absolutely necessary for cosmetic purposes.

Rabies immune globulin and vaccine are administered as indicated. A healthy dog that bites a person should be confined and observed daily for 10 days. If the dog is currently rabies vaccinated, this observation period may be carried out at the pet guardian's home. If not, the local authority may require that the animal be confined at the local city pound, or equivalent, for the 10-day period. If the animal shows no clinical signs of rabies within the 10-day period, rabies treatments are not necessary. If, however, signs suggestive of rabies develop, the animal is euthanized and the brain submitted to a laboratory. If rabies is diagnosed, your neighbor will receive rabies treatments. If the animal is not available for quarantine, these treatments will be given as a precautionary measure.

Tetanus prevention (prophylaxis) and antibacterial treatments are administered. Tetanus is an uncommon result of a dog bite, but a number of other bacterial infections such as Pasteurella and Capnocytophaga canimorsus are relatively common. These bacteria are usually killed by penicillin. If your neighbor is elderly or has an impaired immune system, he or she has a higher risk of developing an infection other than rabies.

Dog bites in most communities are events that should be reported to the local authority. If your dog has a history of unprovoked biting, it can be declared a "potentially dangerous" or a "dangerous" dog. Under these circumstances, you are required to minimize the risk of repeat incidents. Remedial behavior therapy for the animal may be indicated.

What about ringworm?

Your cats can infect you with ringworm even if they live indoors. Ringworm is not a worm; it is a fungal infection caused by either Micropsorum canis, or Trichophyton mentagrophytes. The name ringworm is used because the disease appears as a flat, spreading, ring-shaped rash on the body, beard, or scalp. Ringworm is relatively common in cats, and asymptomatic (without signs) infection has been reported in 30% (or more) of animals. Infection is very common in free-ranging cats, show animals, catteries, and also in multi-cat households. Young cats and cats that have depressed immune systems, such as those with feline immunodeficiency virus (FIV) Infection, are more susceptible to ringworm. Signs in cats include patchy areas of hair loss, scaling, and a nodular skin inflammation (granulomatous dermatitis).

The majority of persons living in a household with an infected cat can become infected. Young children and those individuals with deficient immune systems are at increased risk. Typical circular lesions are often seen on skin that has been touched by the cat, such as the arms, body, and neck where the cat has been held. Specific treatment with griseofulvin, an anti-fungal antibiotic, clears up most cases in people within 4 weeks. Infected cats are treated with anti-fungal medication by mouth, and applied to the skin. In addition, the home can be disinfected by vacuuming to remove hairs, followed by a chlorine-based product. If you suspect that you or your cat has ringworm, you should contact your physician or veterinarian.

A ringworm vaccine against Microsporum canis is available in the USA for the treatment and prevention of the lesions, but not the prevention of the infection.

What about cat scratch fever?

Yes, it is possible that you may have acquired cat scratch fever from your cat. This bacterial disease results from a cat scratch, lick, or bite. As well as the fever, cat scratch fever causes a red papular (bumpy) lesion at the scratch site, malaise, and often enlargement of the local lymph nodes. The disease is usually not severe. In a few cases, however, it can cause more serious illness, especially in people who have a suppressed immune system (immunosuppressed). Diagnosis is established by blood tests to detect antibodies to the causative agent, Bartonella henselae. A physician will discuss antibiotic treatment if the diagnosis is confirmed.

Cats (and especially kittens) are clearly the source of this infection, and recent evidence suggests that the infection is more common in flea-infested animals. Thorough cleaning of any cat scratches or bites is indicated, as well as effective flea control. While declawing of cats has been proposed, there is no sound evidence that this actually reduces the risk of transmission. Behavior modification may also be useful to prevent scratches.

What about roundworms?

Yes, children can acquire roundworms indirectly from both dogs (Toxocara canis) and cats (Toxocara cati). Both types are common parasites. However, dogs are more likely sources of infection, especially for children. Infected dogs pass the worm larvae to their puppies both through the placenta and also in the mother dog's milk. Cats appear only to transmit infection in their milk. The worm larvae develop in the puppy within 3 weeks of birth, and the eggs are excreted in the feces in very high numbers. After an infected dog deposits its feces, the eggs can survive for long periods of time, especially in moist soil. Studies have shown that parks and children's sandboxes are often heavily contaminated with roundworm eggs. Children are at much higher risk of infection because they may ingest soil (geophagia, pica) containing roundworm eggs, or eat unwashed vegetables that have been exposed to the roundworm eggs. While the adult worms do not develop in people, the larvae can migrate through body tissues resulting in a range of signs including fever, abdominal pain, and generalized rash. The most serious effect occurs if the larvae enter the eye, damaging the retina and causing progressive loss of vision.

Dogs and cats can be readily tested for roundworms by examining a sample of feces under the microscope. However, these parasites are so widespread that it is advisable to treat animals routinely. A number of broad-spectrum medications (anthelmintics) that can be given monthly are now available. Most of these drugs have the added benefit of also controlling the common heartworm parasite of dogs.

Young children must be supervised so they do not eat soil. Children need to be taught good hygiene such as thorough hand washing, especially after playing outdoors. Dog and cat guardians must be educated to prevent their dogs from defecating in public places, especially where children play, and to remove their pet's feces promptly. Note: Humans can be infected with a specific roundworm (Ascaris lumbricoides), but this worm is not acquired from dogs and cats.

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