Can dogs get Listeria

Listeriosis in Animals

Listeria organisms that are ingested or inhaled tend to cause septicemia, abortion, and latent infection. Those that gain entry to tissues have a predilection to localize in the intestinal wall, medulla oblongata, and placenta or to cause encephalitis via minute wounds in buccal mucosa.

The various manifestations of listeriosis occur in all susceptible species and are associated with characteristic clinical syndromes: encephalitis or meningoencephalitis in adult ruminants, abortion and perinatal mortality in all species, septicemia in neonatal ruminants and monogastric animals, and septicemia with myocardial or hepatic necrosis (or both) in poultry.

Listeric encephalitis affects sheep, cattle, goats, and occasionally pigs. It is essentially a localized asymmetric infection of the brain stem that develops when L monocytogenes ascends the trigeminal nerve. Clinical signs vary according to the function of damaged neurons but often are unilateral and include depression (ascending reticular activating system), ipsilateral weakness (long tracts), trigeminal and facial nerve paralysis, and less commonly, circling (vestibulocochlear nucleus), excitement, and recumbency.

Septicemic or visceral listeriosis is most common in monogastric animals, including pigs, dogs, cats, domestic and wild rabbits, and many other small mammals. These animals may play a role in transmission of L monocytogenes. This form of disease is also found in young ruminants before the rumen is functional. Although rare, septicemia has been reported in older domestic ruminants and deer. The septicemic form affects organs other than the brain, the principal lesion being focal hepatic necrosis.

The uterus of all domestic animals, especially ruminants, is susceptible to infection with L monocytogenes at all stages of pregnancy, which can result in placentitis, fetal infection and death, abortion, stillbirths, neonatal deaths, metritis, and possibly viable carriers. The metritis has little or no effect on subsequent reproduction; however, Listeria may be shed for 1 month or longer via the vagina and milk.

Infections acquired via ingestion tend to localize in the intestinal wall and result in prolonged fecal excretion. It has been postulated that contaminated silage results in latent infections, often approaching 100% of the exposed herd or flock; however, clinical signs of listeriosis may be seen in only a few animals.

Listeria in Dogs

Listeria in Dogs

Overview of Listeria in Dogs

Listeria is a food borne bacterial illness caused by the bacterium Listeria monocytogenes which can infect humans as well as dogs and cats. Listeria is a bacteria found in soil, water, and in some animals, including poultry, cattle, sheep and goats. It can also be found in rabbits, guinea pigs, and other species.

Dogs can be infected with Listeria by the same sources as human exposure, including infected meats and dairy product as well as contaminated dog food. There have been various pet food recalls due to contamination with listeria including the Bravo Pet Food Recall in May 2014.

Dogs fed raw diets are at a higher risk for Listeria infection. The U.S. Food and Drug Administration (FDA) cites a two-year study from October 2010 through July 2012 by the FDA Center for Veterinary Medicine (CVM). In the study, over 1,000 samples of pet food were screened for bacteria that can cause foodborne illnesses. The FDA stated, The study showed that, compared to other types of pet food tested, raw pet food was more likely to be contaminated with disease-causing bacteria. The participating laboratories analyzed the raw pet food for harmful bacteria, including Salmonella and Listeria monocytogenes.

Infection with Listeria, commonly called Listeriosis, can cause severe infection in pregnant women, elderly people and humans with suppressed immune systems. Healthy people and dogs are rarely infected.

Many aspects of the disease spread, symptoms, diagnosis, treatment and prevention in humans are the same as those in dogs.

Sources of Listeria

Dogs can be exposed to Listeria from contaminated dog foods as well as eating contaminated garage.

Listeria can be present in raw milk and foods made from raw milk and contaminate a variety of processed meats and dairy products. Unlike many other bacteria, Listeria can grow in refrigerated temperatures and even spread to other foods in the refrigerator which makes it a challenging organism. However, Listeria is killed by pasteurization and cooking.

Common sources of Listeria in dogs include:

• Raw pet food diets
• Contaminated dog food
• Dogs fed table scraps that are contaminated. Sources of human foods associated with Listeria include:
  • Raw vegetables (that have been contaminated from the soil from contaminated manure used to fertilize the soil) or deli-prepared salads.
  • Infected animal meats such as from deli meats, hot dogs, meat spreads
  • Dairy products such as ice cream
  • Unpasteurized milk or foods made with unpasteurized milk
  • Soft cheeses e.g. Feta, Brie, Camembert, Panela, Queso fresco and other blue-veined cheeses.
  • Smoked refrigerated seafood

Can Dogs Spread Listeria to People?

According to the Ontario Veterinary Medical Association, It is highly unlikely that a dog that has eaten contaminated meat would pass the infection on to humans. A small percentage of healthy pets can shed Listeria in their stool at any time.

Our research suggests that dog to human contact is unlikely. Most human infections are directly from the list above including contaminated meat and dairy products.

Listeria can be spread by eating the bacteria, direct contact or by inhalation.

Diagnosis of Listeria in Dogs

Blood tests can confirm the diagnosis of Listeria. For dogs with neurologic symptoms, analysis of the cerebrospinal fluid can also be suggestive of infection.

Symptoms of Listeria in Dogs

Symptoms can vary with the individual dog, from no symptoms, very mild flu-like symptoms to severe neurologic symptoms. Not all dogs exposed to listeria will develop symptoms or become ill.

Symptoms may include: Diarrhea, nausea, vomiting, weakness, fever, muscle soreness, lethargy, lack of coordination, and/or a stiff neck. A severe consequence of Listeria is meningitis which is a disease of inflammation of the membranes covering the brain and spinal cord. In addition to the above, infection of pregnant women can cause miscarriage; stillbirth or the baby can be born with a life-threatening infection. The same things are believed to be true of dogs. Listeria has also been shown to cause skin infections in dogs.

How Long Does it Take to Show Symptoms of Listeria

Due to the infrequent diagnosis in dogs, the incubation period of Listeria is unknown. In humans, it can take as little as 2 to 3 days from the time you are exposed to Listeria to show to as long as 2 months (70 days). The same is believed to be true in dogs.

Whos At Risk For Listeria?

Those at highest risk for Listeria include newborns, pregnant women, elderly and those with underlying health problems or those that are immunosuppressed are at greatest risk. For example, older adults, people receiving medications to prevent organ transplant rejection, and those with weakened immune systems such as those with cancer, those under treatment with chemotherapy, HIV/AIDS, liver disease, kidney disease, diabetes, or alcoholism. Pregnant women can have flu-like signs but can affect the fetus leading to miscarriage, stillbirth or life-long health problems. If you have any symptoms please contact your physician.

It appears risks of infection in dogs are similar to those in humans. Dogs with underlying diseases, weakened immune systems and senior dogs are at increased risk.

Treatment of Listeria in Dogs

Treatment may vary depending on the severity of the symptoms. Mild symptoms may be treated symptomatically with pain relievers and gastrointestinal protectant medications.

Severe cases may require antibiotics and hospitalization. Common antibiotics used include: Ampicillin, penicillin, amoxicillin, Trimethoprim-sulfamethoxazole, and fluoroquinolones such as baytril or ciprofloxacin. Gentamicin may also be given to patients with impaired immune systems.

Prevention of Listeriosis in Dogs

The following tips help prevent you and your dog from exposure to Listeria infections.

• Wash you hands well in warm soapy water for at least 20 seconds before and after handling food as well as after handling dogs, litter boxes, fecal matter or gardening.
• Use bags or tools to pick up and/or dispose of feces.
• Monitor for pet food and treat recalls that may affect your dogs food.
• Dont feed your dog human foods, especially uncooked meats and unpasteurized dairy products.
• Keep your refrigerator at 40 degrees or lower and clean your refrigerator regularly.
• Clean all food preparation surfaces (knives, countertops, and cutting boards) with warm soapy water after handling and preparing uncooked foods. If possible, nonporous boards should be washed in the dishwasher.
• Sanitize your kitchen using teaspoon of unscented bleach to one 1 quart of water. Spray surfaces and allow solution to sit for 10 minutes then wipe down with clean paper towels.
• Regularly laundry dishcloths and dishtowels.
• Do not drink raw unpasteurized milk or eat foods that have unpasteurized milk in them. Do not feed these products to your dogs.
• Thoroughly rice all raw fruits and vegetables under running water. Soil contamination can spread the bacteria.
• Keep uncooked or undercooked meats, poultry, and seafood separate from your other foods including vegetables, fruits, and cooked foods.
• Thoroughly cook raw food from animal sources. This includes meat, poultry, and seafood.
• Consume perishable and ready-to-eat foods as soon as possible.
• In addition to the above, persons or dogs in higher risk groups such as with weakened immune systems should heat hot dogs, cold cuts, and deli meats before eating or feeding them.

U.S. Food and Drug Administration

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Youve probably heard of Salmonella and are familiar with the symptoms of salmonellosis.But you may not have heard much about the lesser known foodborne illness listeriosis caused by the bacteria Listeria monocytogenes.After going through several name changes since the bacteria were first described in 1911, the name was officially changed to Listeria monocytogenes in 1940 to honor Joseph Lister, the British surgeon who discovered that sterilizing surgical instruments before operations reduced the risk of infections.

In 1929, A. Nyfeldt reported the first confirmed cases of listeriosis in people. But L. monocytogenes werent identified as a major cause of foodborne illness in people until the 1980s when several large outbreaks occurred.

The Statistics at a Glance

Compared to other foodborne illnesses, listeriosis is rare but very serious. Evenwith adequate antibiotic treatment, the disease has a high mortality rate of 20 to 30 percent. Over 90 percent of people with listeriosis are hospitalized, often in intensive care units.In the U.S., the Centers for Disease Control and Prevention estimate that about 1,600 people get listeriosis each year, and about 260 die. The hospitalization rate is 94%, meaning that of the approximately 1,600 people who get the disease each year, about 1,500 will be hospitalized.

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Characteristics

L. monocytogenes is widespread in the environment, especially in soil and water. The bacteria can survive in soil for many months. Animals, particularly cattle, can carry L. monocytogenes without appearing sick and shed the bacteria in their feces.

The bacteria are able to live in a wide range of conditions and environmentsthey can tolerate both acidic and salty conditions, both high and low temperatures, and a fairly low moisture content. These characteristics allow L. monocytogenes to survive a long time in a variety of food products and food processing plants. Because the bacteria can multiply and persist in food processing plants for yearseven more than 10 years in one documented caseL. monocytogenes is especially hard to control and can result in intermittent contamination of food.

Unlike most bacteria, L. monocytogenes can grow and multiply at low temperatures, making the bacteria a potential problem even in properly refrigerated food. One study also found a relatively high percentage of frozen raw beef products contaminated with L. monocytogenes. This finding highlights the ability of the bacteria to thrive in cold environments (Pao & Ettinger).

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How People Become Infected

People become infected with L. monocytogenes by eating contaminated food. People can also become infected by handlingcontaminated food,such as contaminated pet food, or touching contaminated surfaces and utensilsand then accidentally transferring the bacteria from their hands to their mouths. Babies can become infected in utero or at birth if their mothers ate contaminated food during pregnancy.

The bacteria can contaminate a variety of food, such as:

• Raw meat;
• Ready-to-eat processed meat such as hot dogs and deli meat (both factory-sealed packages and products sold at deli counters);
• Raw vegetables;
• Refrigerated pates;
• Ready-to-eat smoked seafood and raw seafood;
• Prepared or stored salads, including coleslaw and fresh fruit salad;
• Melons;
• Soft cheeses made with unpasteurized milk; and
• Unpasteurized milk and milk products.

Pasteurization, cooking, and most disinfecting agentskill L. monocytogenes. However, in some ready-to-eat food, such as hot dogs and deli meats, contamination may occur after the food is cooked in the factory but before its packaged. These products can be safely eaten if reheated until steaming hot.

The U.S. Department of Agricultures Food Safety and Inspection Service (FSIS) maintains a zero-tolerance policy for L. monocytogenes in ready-to-eat meat and poultry products. FSIS continues to strengthen programs and recommendations to reduce or eliminate the bacteria from ready-to-eat products.

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Listeriosis in People

Listeriosis occurs almost exclusively in pregnant women, newborns, the elderly, and people with weakened immune systems (such as those with cancer or other diseases).After a person ingests L. monocytogenes, the bacteria grow quickly in the liver and then move into the bloodstream and can invade many places in the body, including the:

• Brain;
• Membranes surrounding the brain and spinal cord (called the meninges);
• Gastrointestinal, or digestive,tract (the stomach and intestines); and
• Bloodstream.

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Pregnant Women and Newborns

Pregnant women are 18 times more likely to get listeriosis than other healthy adults,and 16 to 27% of all L. monocytogenes infections are in pregnant women. Scientists dont know why pregnant women are so susceptible to the disease. It usually affects pregnant women who are healthy and dont have other risk factors.

Diagnosing listeriosis in pregnant women is difficult because they usually dont have the gastrointestinal symptomssuch as vomiting and diarrheathat are normally seen with a foodborne illness. The most common, and sometimes only, symptom of listeriosis in pregnant women is fever. They often have a flu-like illness with non-specific symptoms, such as fatigue and muscle aches, whichare often temporary and go away on their own. Some pregnant women show no symptoms. In a series of 191 cases of listeriosis in pregnancy, more than one-quarter (29%) of the women had no symptoms(Lamont et al).

Compared to listeriosis in non-pregnant people, the disease in pregnant women has a longer incubation periodthe length of time between when a person ingests the bacteria and first shows symptoms. In one study, the median incubation period in pregnant women was 27.5 days, with a range of 17 to 67 days(Goulet et al, 2013).This long incubation period adds to the difficulty in diagnosing listeriosis in pregnant women.

Listeria from Food Safety for Moms to Be(En espaol)Food Safety for Pregnant Women(En espaol)

While listeriosis in the mother is mild, infection in the fetus and newborn can be severe. Listeriosis can develop at any time during pregnancy, and the disease causes miscarriage, stillbirth, premature birth, and life-threatening infection of the newborn, such as a blood infection, respiratory distress or pneumonia, and meningitis (inflammation of the membranes surrounding the brain and spinal cord). Listeriosis is one of the most common causes of meningitis in newborns.

With a mortality rate of 20 to 30%, newborns suffer the most serious consequences of listeriosis. They have either early- or late-onset disease depending on when their symptoms first appear.

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Non-pregnant People

Healthy children and adults occasionally get listeriosis, but rarely become seriously ill. In healthy, non-pregnant people, listeriosis can cause gastroenteritismainly diarrheaaccompanied by a fever. Other symptoms may include vomiting, joint pain, headache, and body pain. This form of listeriosis has a much shorter incubation period, with symptoms typically occurring within 24 hours after a person ingests a high number of the bacteria. The illness is usually mild and goes away on its own. The diarrhea can last up to 5 days.

The elderly and people with weakened immune systems have a higher risk of getting a more severe form of listeriosis, including:

• Inflammation of the brain (encephalitis)
• Inflammation of the membranes surrounding the brain and spinal cord (meningitis); and
• Infection of the blood.

In a joint risk assessment report on L. monocytogenes in ready-to-eat food, the Food and Agriculture Organization of the United Nations/World Health Organization found that the elderly (people 60 years and older) were 2.6 times more likely to get listeriosis than the general healthy population. In the U.S. in 2011, the median age of non-pregnant people diagnosed with a severe form of listeriosis was 71 years.

Symptoms of listeriosis vary depending on the form and can come on suddenly. Symptoms may include fever, muscle aches, severe headache, nausea, vomiting, stiff neck, confusion, loss of balance, and convulsions.

In contrast to the incubation period for other, more common foodborne illnesses, like salmonellosis, the incubation period for listeriosis can be long and also varies depending on the form. Cases involving a blood infection have a fairly short incubation period, with a median of 2 days. For cases involving encephalitis or meningitis, the incubation period is longer, with a median of 9 days.

There is also a skin form of listeriosis that results from intact skin coming into direct contact with the bacteria. The skin form is rare and mostly seen in people with at-risk jobs, such as veterinarians or farmers, who are exposed to sick animals or diseased tissues, especially after an animal has a pregnancy loss caused by L. monocytogenes.

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Listeriosis in Animals

L. monocytogenes can infect many animal species.Signs of disease are mainly seen in ruminants, such as cattle, goats, and sheep. Sheep are particularly sensitive to the bacteria. Listeriosis is one of the most common causes of encephalitis (inflammation of the brain) in adult ruminants. Infected animals most commonly show severe neurologic signs, such as loss of balance, circling, and unusual body spasms. Fever, loss of appetite, and decreased activity level are also usually seen. Some ruminant herds have had large numbers of late-term pregnancy losses. Newborn ruminants typically develop a blood infection. Listeriosis in ruminants most often occurs in the winter and early spring and is likely caused by the animals eating spoiled silage.

Listeriosis is more common in rabbits and rodents than dogs and cats. Rabbits and chinchillas (South American rodents) are particularly sensitive to the bacteria. The disease usually causes a blood infection. Pregnancy loss and uterine inflammation are also common, especially in chinchillas. These reproductive problems are often associated with gastrointestinal signs, such as diarrhea or constipation. Large outbreaks of listeriosis have been seen in captive rabbits and rodents. The source of infection in these outbreaks was thought to be contaminated food.

L. monocytogenes rarely cause disease in dogs and cats and, even when infected, pets usually have only mild gastrointestinal signs, such as diarrhea and vomiting. However, more serious signs are possible, such as fever, muscle pain, breathing problems, pregnancy loss, and even death. After consuming contaminated pet food, dogs and cats often dont show any signs of listeriosis but can become carriers of the bacteria. This means that even if the pets appear healthy, they can still shed L. monocytogenes in their stool and then spread the bacteria to the home environment and to people and other pets in the household. For example, cats can spread L. monocytogenes through shared litter boxes or when roaming throughout the house, such as on kitchen countertops. One way dogs can spread the bacteria is when they have stool accidents inside the home. Pet waste from both sick and healthy pets can be a source of infection for people.

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Animal Feed and Pet Food Recalls due to Listeria Contamination

Animal feed and pet food are recalled for various reasons, including for the presence of Listeria. For a list of recalled animal feed and pet food products and the reason for the recall, please see FDAs Recalls & Withdrawals webpage.

Reference List

• Centers for Disease Control and Prevention website. Information for health professionals and laboratories. Available at: https://www.cdc.gov/listeria/technical.html. Accessed Jun 7, 2016.
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• Food and Agriculture Organization of the United Nations (FAO)/World Health Organization (WHO). Risk assessment of Listeria monocytogenes in ready-to-eat foods: technical report. Microbiological risk assessment series; no. 5. 2004. Available at: www.fao.org/3/a-y5394e.pdf. Accessed Jun 2, 2016.
• Food and Drug Administration website. Food safety for pregnant women. Available at: https://www.fda.gov/food/people-risk-foodborne-illness/food-safety-pregnant-women. Accessed Jun 7, 2016.
• Goulet V, King LA, Vaillant V, et al. What is the incubation period for listeriosis? BMC Infect Dis 2013;13:11-17.
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• Girard D, Leclercq A, Laurent E, et al. Pregnancy-related listeriosis in France, 1984 to 2011, with a focus on 606 cases from 1999 to 2011. Euro Surveill 2014;19:pii=20909.
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• Gray ML, Killinger AH. Listeria monocytogenes and listeric infections. Bacteriol Rev 1966;30:309-382
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Resources for You

• FDA
• Centers for Disease Control and Prevention
• U.S. Department of Agriculture
• Foodsafety.gov

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