Are you tempted to skip your pets' heartworm and flea medicines during the winter? Dogs and cats actually need parasite prevention all year round. Year-round parasite control for pets helps keep the whole family safe from parasite-transmitted disease.
 
Warm spells during the winter are common in North Carolina, so we can’t count on cold temperatures to suppress insects that carry disease. Mosquitoes, fleas, and ticks can also live through the winter in areas that are protected from the cold.
 
Heartworms
Heartworms are transmitted by mosquitoes. Mosquitoes become active when the temperature rises above about 50°F (which happens routinely in North Carolina during the winter). But occasional warm winter days aren’t the only reason pets need year-round heartworm prevention.
 
Heartworm preventives work by killing tiny heartworm larvae that are already in an animal’s bloodstream. These larvae came from mosquitoes that bit the animal in the past month or more. Skipping a month of heartworm prevention could mean that your dog isn’t protected from heartworm larvae that he was exposed to when it was warmer. The American Heartworm Society recommends giving heartworm preventives all year round.
 
Intestinal parasites (worms)
Some heartworm preventives also control intestinal parasites like hookworms and roundworms. These parasites can infect humans too. Giving parasite prevention to your pets throughout the year is a sensible safety measure.
 
Fleas
Fleas don’t just causing itching. They also transmit diseases like cat scratch disease, tapeworms, and plague.
 
Fleas lay eggs that drop off the infested animal into the environment. This means that flea eggs are present everywhere the animal has been, including inside a home. After the eggs hatch, the larvae and pupae (intermediate stages) can stay dormant for weeks to months before becoming adult fleas.
 
Because fleas can go through their life cycle indoors, they don’t need to wait for warm weather to develop into adult fleas. Flea infestations are easier to prevent than to treat, so the best chance of avoiding a flea problem is to give your pets year-round flea prevention.
 
Ticks
Ticks carry many diseases that affect both pets and people. Some tick species, including the type that transmits Lyme disease, are active during the winter when the temperature is above freezing.
 
Ticks tend to live in leaf litter, crevices of buildings, and underbrush. When they’re ready to take a blood meal, they move to grassy areas or shrubbery near paths and latch onto a passing animal or person.
 
Ticks can be hard to see through fur, so you might not realize that your dog has picked up a tick. Because of the risk of serious disease, the safest approach is to limit tick exposure: control ticks around your home and give your pets tick preventives recommended by your veterinarian.
 
Photo by Justin Veenema

Zoonotic diseases, or zoonoses, are infections spread from animals to people (and vice versa). Many zoonotic diseases are transmitted by insects, wildlife, and livestock, and some are carried by pets.
 
Controlling zoonotic disease is a cornerstone of One Health, the concept that human health, animal health, and the environment are all linked. July 6 is World Zoonoses Day and is also the anniversary of the day Louis Pasteur administered the first successful rabies vaccination to a person (July 6, 1885).
 
How to reduce your risk
Preventive care for pets helps keep everyone in the family safe. The chance of contracting a zoonotic disease from a dog or cat is low if you take proper precautions. Zoonotic infections are also spread by contaminated food, insects, ticks, farm animals, birds, reptiles, and rodents. Young children, older adults, and people with compromised immune systems are at higher risk than others.
 
These measures can lower your risk:

• Wash your hands after being around animals or handling their food. Soap and water are best; use alcohol-based hand sanitizer if soap and water are not available.
• Keep your pets' vaccinations up to date.
  
• Give your pets parasite preventives all year round and have them tested regularly for parasites. (This is why your veterinarian’s office asks for your pet’s stool sample.)
• Do not feed pets raw eggs or raw meat diets.
• Handle food safely to prevent food poisoning.
• Protect yourself against insect and tick bites.

 
Find out more at the Centers for Disease Control and Prevention (CDC) website.
 
Zoonoses in companion animals
Many zoonotic diseases have been identified, and the CDC estimates that 75% of emerging infectious diseases originated in animals (often insects). Some of the most common zoonotic diseases in companion animals are listed below.
 
Bacteria

• Salmonellosis can be transmitted through contaminated food. Outbreaks have also been linked to reptiles, poultry, and pet food. Salmonellosis is the reason small turtles cannot be sold as pets in the United States.
• Listeria and Escherichia coli can also contaminate food. One study showed high levels of bacterial contamination in frozen raw diets for pets. Others have shown that dogs fed raw diets have increased risk of antibiotic-resistant bacteria and of shedding disease-causing bacteria into the environment.
• Bartonella species cause cat scratch disease and other (sometimes severe) diseases in humans. The type that causes cat scratch disease is transmitted to cats by fleas and is usually spread to people through cat bites or scratches, possibly when the wounds are contaminated with flea excrement.

 
Parasites

• Intestinal parasites like roundworms and hookworms are common in dogs and cats, especially puppies and kittens. They are spread to people by fecal-oral contact—that is, by ingestion of feces. Children are at risk if they eat contaminated dirt or put their hands in their mouths after handling infected animals. Hookworms can also be transmitted through contact of bare skin with contaminated soil. Puppies and kittens typically receive deworming medication during their first veterinary visits, and many heartworm preventives also control these intestinal parasites.
  
• Scabies, a type of mange, is caused by an external parasite that can also cause skin disease in humans.
• Toxoplasmosis is caused by a parasite transmitted by ingestion of undercooked meat or cat feces. It can also be transmitted to an unborn child if a woman becomes infected while pregnant. Pregnant women do not need to give up their cats, but it’s wise to take precautions during pregnancy to reduce the risk.

 
Other infectious agents

• Rabies is a viral disease that kills an estimated 59,000 people every year worldwide. It is transmitted through the bites of infected mammals. Nearly all of these human deaths are caused by dog bites. In the United States, where rabies vaccination for dogs and cats is mandated by law, rabies in humans is rare and is almost always caused by exposure to wild animals.
  
• Ringworm is a fungal skin infection that is spread by direct contact. People and animals can give ringworm to each other.

 
For more information:
Zoonotic diseases (CDC)
Zoonotic diseases and pets FAQ (American Veterinary Medical Association)
 
Photo by Lydia Torrey

April is Heartworm Awareness Month. How much do you know about this infection? Check out the questions, then scroll down for the answers.

1. How are heartworms transmitted?
   a. By mosquitoes
   b. By eating raw meat
   c. Through the feces of infected animals
   d. By vampires

2. About how many dogs tested positive for heartworm in North Carolina in 2017?
   a. 90
   b. 900
   c. 9000
   d. 90,000

3. Adult heartworms grow to what length in a dog’s heart?
   a. 3 inches
   b. 6 inches
   c. 9 inches
   d. 12 inches

4. In addition to dogs, which animals can get heartworms?
   a. Cats
   b. Ferrets
   c. Both
   d. Neither

5. True or false: Dogs should receive heartworm preventives through the winter.
   a. True
   b. False

6. You forgot your dog’s monthly heartworm pill and now it’s a month overdue. What should you do?
   a. Have your dog tested for heartworms before giving the pill.
   b. Give your dog the pill now.
   c. Give your dog a double dose.
   d. Panic.

7. True or false: Heartworm preventives sold over the counter at pet stores work just as well as the prescription versions.
   a. True
   b. False
   c. Unfair trick question

8. Which state is free of heartworms?
   a. Maine
   b. Alaska
   c. Wisconsin
   d. None of the above

Answers
1. a. By mosquitoes
Mosquitoes pick up tiny heartworm larvae, called microfilariae, when they take a blood meal from an animal infected with adult heartworms. When the mosquito bites another animal, it injects these larvae into the new host. The larvae mature into adult heartworms in the new host in about 6 months.

2. c. 9000
According to the Companion Animal Parasite Council, 9457 dogs tested positive for heartworms in 2017 in North Carolina. This number has been increasing each year. To see more parasite statistics, see the Parasite Prevalence Maps on the Pets & Parasites website.

3. d. 12 inches
Adult heartworms grow about 12 inches long in dogs. Infected dogs typically have 14 to 20 of these foot-long worms in their heart and lungs.

4. c. Both
Both cats and ferrets get heartworm disease. In cats, heartworms do not grow as large as they do in dogs and are usually fewer in number. However, heartworm infection can be devastating in cats, potentially causing severe respiratory disease or sudden death. In ferrets, even a single worm can cause serious illness because ferrets’ hearts are so small. Medical options for heartworm removal (like those used in dogs) cannot be used in cats and ferrets. Heartworm preventives are available for cats and ferrets.

5. a. True
For best protection, the American Heartworm Society recommends year-round heartworm prevention for all dogs, not just for dogs in southern states. Also, think of this: for several days this past February, the temperature in Charlotte was 75°F or higher. Do you want to risk your pet’s health by guessing what the mosquitoes here consider “winter”?

6. b. Give your dog the pill now.
But do not give a double dose! Have your dog tested 6 months after missing a pill. The test detects adult heartworms, not larvae, so the test result will not be positive until the larvae have had time to mature.

7. b or c. False; unfair trick question
All heartworm preventives approved by the Food and Drug Administration for use in dogs and cats are available only by prescription. Deworming medications that are available over the counter (without a prescription) either don’t prevent heartworms or are not approved by the Food and Drug Administration for use in dogs and cats.

8. d. None of the above
Heartworms have been diagnosed in all 50 states.
 
For more information, see the American Heartworm Society website.

Hookworms are common in dogs and cats, especially young animals in warm climates. These parasites are also zoonotic: hookworms that infect dogs and cats can also infect people.
 
What are hookworms?
Hookworms are small parasitic worms that live in the intestines of host animals. Different hookworm species have different preferred hosts. Hookworm larvae can also infect other animals—accidental hosts—that they happen to come in contact with. The symptoms of infection depend on whether the infected animal is a preferred host or an accidental host.
 
Adult hookworms in the intestines lay eggs that are passed out of the body through feces. Once in the environment, the eggs hatch into larvae. Larvae enter a new host’s body by penetrating the skin. Preferred hosts can also be infected by swallowing hookworm larvae, such as by eating contaminated dirt. Puppies can be infected through their mother’s milk.
 
In preferred hosts, hookworm larvae migrate to the intestines, where they grow into adult worms that reproduce and lay eggs. In accidental hosts, hookworm larvae cause a local reaction where they have penetrated the skin, but they do not mature and reproduce.
 
Hookworm infection in dogs and cats
The hookworm species that most often infect dogs and cats are Ancylostoma caninum, Uncinaria stenocephala, Ancylostoma tubaeforme, and Ancylostoma braziliense. These worms attach to the lining of the intestines and feed on blood. Infection can cause anemia from blood loss, which can be fatal in young puppies and kittens carrying large numbers of worms.
 
Symptoms of hookworm infection in dogs and cats depend on the number of worms and the age, size, and overall health of the infected animal.

• Animals with mild infections usually have no symptoms at all.
• Young animals with heavy worm burdens can have pale gums, weakness, failure to thrive, weight loss, diarrhea, black stool (from intestinal bleeding), or sudden death.

 
A number of effective, safe medications are available to treat hookworm infections in dogs and cats. Young animals with severe anemia may need blood transfusions.
 
Hookworm infection in people
Humans can be infected by dog and cat hookworms if they come in contact with larvae in the environment—for example, by walking barefoot on sand or soil contaminated with hookworm larvae. The larvae burrow into the skin, causing an itchy skin reaction called cutaneous larva migrans. The larvae live only a few weeks in humans, so the symptoms may resolve on their own (contact your health care provider if you have more questions).
 
Humans are the preferred hosts for 2 hookworm species: Ancylostoma duodenale and Necator americanus. These hookworms are a major source of human disease worldwide and were once common in the southeastern United States.
 
Preventing hookworms
Because dog and cat hookworms cause serious disease in animals and are also a health risk for people, preventing hookworm infections in our pets is important for both animal and human health.
 
The Companion Animal Parasite Council recommends the following for dogs and cats:

• Have fecal samples tested regularly at the veterinary clinic.
• Deworm puppies and kittens multiple times.
• Deworm pregnant and nursing dogs.
• Use monthly parasite preventives. (Many heartworm preventives also control hookworms; check the label or ask your veterinarian.)
• Keep the environment and litter boxes clean.

 
The CDC recommends these steps to prevent zoonotic hookworm infections in people:

• Wear shoes and protect skin from contact with sand or soil, especially when visiting beaches in tropical or subtropical areas.
• Deworm dogs and cats regularly to reduce environmental contamination.
• Remove animal feces from the environment.

 
For more information
Hookworms (PDF from Worms & Germs Blog)
Hookworms – Dog Owners and Cat Owners (Companion Animal Parasite Council)
Zoonotic hookworm FAQs (CDC)
 
Photo by Andrew Pons

You probably know that ticks carry Lyme disease. But did you know that ticks also transmit other diseases that can make your pet seriously ill?
 
People and pets get the same tick-transmitted diseases. These diseases are not directly contagious between humans and animals (you won't catch Lyme disease from an infected dog), but we are all exposed to the same ticks outdoors. And one recent study showed that people with pets were more likely than those without pets to find ticks on themselves.

Rocky Mountain spotted fever
According to the CDC, North Carolina has one of the highest rates of Rocky Mountain spotted fever (in humans) in the country. The disease is caused by a type of bacteria called rickettsia. It is usually transmitted from a tick to its host within a few hours of tick attachment.

Symptoms of Rocky Mountain spotted fever in dogs generally begin a few days to two weeks after transmission. Some of the signs in dogs are fever, loss of appetite, joint pain (lameness or stiff gait), vomiting, and bruising of the skin or gums. It is potentially fatal but can be treated with antibiotics.

Ehrlichiosis
Like Rocky Mountain spotted fever, ehrlichiosis is a rickettsial infection. The Companion Animal Parasite Council reports that in 2016, over 16,000 dogs in North Carolina had positive antibody tests for ehrlichiosis--that is, they had been exposed to the bacteria at some point in their lives.

The symptoms of ehrlichiosis in dogs and cats depend partly on the rickettsia species and are similar to those of Rocky Mountain spotted fever. Dogs can also be infected without showing any symptoms. This disease is also treated with antibiotics.

Lyme disease
Lyme disease, also called borreliosis, is caused by Borrelia burgdorferi bacteria. It is not as common in North Carolina as Rocky Mountain spotted fever and ehrlichiosis, although dogs do test positive here. (These tests do not show where the exposure occurred; some dogs may been exposed elsewhere and then traveled here.) The Companion Animal Parasite Council warns that the disease is spreading and that North Carolina and other states bordering typical Lyme disease areas may start to see more cases.

Borrelia are transferred from tick to host a day or more after tick attachment. Symptoms of Lyme disease vary, although fever and lameness that shifts from one leg to another are typical. The symptoms can be similar to those of other tick-borne diseases. Some dogs have no signs of infection. This disease can affect the kidneys, heart, and nervous system and may be fatal.

Like the other bacterial tick-borne diseases, Lyme disease is treated with antibiotics. A vaccine is also available.

Tick paralysis
Some ticks produce a toxin that causes paralysis. The symptoms range from weakness (usually beginning in the rear legs) to a complete inability to move. In severe cases the patient can die from paralysis of the muscles that control breathing. Removing all ticks may be enough to cure the disease. However, some dogs require intensive treatment in the hospital.

And others
Ticks carry many other known diseases, such as anaplasmosis, babesiosis, and tularemia, and probably some that have yet to be identified.

Because tick-borne diseases infect animals as well as people, dogs can act as sentinels for these types of diseases in humans. For instance, a CDC report published in 2011 showed that the incidence of Lyme disease in dogs could predict the risk of Lyme disease for humans in the same geographic area.

To learn more
Parasite prevalence maps (Pets & Parasites)
Tick removal (Centers for Disease Control and Prevention)
Ticks (Companion Animal Parasite Council) -- guidelines for controlling ticks on pets

August 3, 2017
Image credit: CDC/James Gathany