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Parasites, Diseases to Consider When Examining Imported Dogs

Terry Albert

Thousands of dogs are imported into the United States each year, and at some point you may encounter one in your practice or shelter. No matter the dog’s background or country of origin, it’s important to be aware of issues that potentially affect the individual’s health, the health of other dogs and wildlife, and public health. Dogs entering the U.S. can spread new strains of diseases to which resident dogs have no immunity. Many of these diseases and parasites may also spread to wildlife and are difficult or impossible to eradicate. Some, such as brucellosis, are zoonotic. Here’s what to know about examining and caring for imported dogs.

Linda D. Mittel, MSPH, DVM, a faculty veterinarian at Cornell University College of Veterinary Medicine in Ithaca, New York, has advised The Ark at JFK Airport, which examines all dogs passing through the airport from foreign countries. She says adult dogs seem to bring in more exotic diseases than puppies, adding that puppies who are sick on arrival often don’t survive because they lack protective antibodies. The stress of travel also depletes their immune systems.

Protect existing dogs in your practice or shelter with careful cleaning, disinfection, and quarantine measures. Ideally, owners should quarantine imported dogs at home for at least 14 days (except for the initial visit to your office) if the dog appears healthy, has a negative fecal test, and received all core vaccines prior to import.


Dr. Mittel recommends administering core vaccines immediately to adult animals who appear healthy and have an unknown vaccine history. Imported puppies and adult dogs who come in having received only a rabies vaccine shouldn’t go out in public until all vaccinations are complete, including boosters. This means no visits to dog parks or other public places and no dog daycare or boarding stays for at least three to four weeks.

A newly identified strain of canine distemper virus called Asia-1 has been identified in dogs imported to North America from Korea. Vaccinated dogs may have some protection but Asia-1 is especially contagious if transmitted to wildlife, spreading quickly to new areas.

Almost eradicated in the United States, canine brucellosis (Brucella canis) has made a comeback since 2004, when cases were identified in dogs imported from Mexico. It is incurable, contagious between animals, and can be transmitted to humans. Dogs can be treated with antibiotic therapy for several weeks, but treatment is not always successful. These dogs should not be taken to public areas, and their contact with humans and other dogs should be limited. Consider testing any dogs imported from Asia, Mexico, or eastern Europe.

Rabies Rules

The Centers for Disease Control requires imported dogs to be at least four months old, and they must have had a rabies vaccine. In countries considered “rabies-free” the vaccine is not required. Importation of dogs from Egypt has been halted as of May 2019, since some have been diagnosed with rabies. Because many import papers are falsified and titer results can be delayed, the CDC recommends that veterinarians advise clients to vaccinate dogs against rabies in the following instances:

  • the client is unable to provide the original certificate;
  • the certificate comes from an unknown source;
  • the reported age does not match the physical appearance of the puppy.


Many adult dogs entering the U. S. from Asia test positive for heartworms. For puppies younger than 7 months, test for the parasite and begin heartworm preventive immediately to prevent microfilariae from developing.

Perform a fecal exam and deworm all imported dogs. A fecal test may turn up several types of parasites, including tapeworms, Giardia, and coccidia.

Some rare parasites have been documented in imported dogs. Leishmaniasis has been reported in animals coming in from Mexico, South America, and the Middle East. In rare instances, cats can also carry this parasite.

Although uncommon, alveolar echinococcosis, a species of “fox tapeworm,” has been reported in some dogs coming from Canada. Many tapeworm treatments will kill this parasite, which can also be transmitted to humans.

Inspect for ticks and fleas.

Canine Influenza Viruses (H3N2 and H3N8)

Prevention of these viruses requires specific vaccines. If an imported dog has CIV, vaccination won’t help, but vaccinating other dogs in the household can help to protect them if they are exposed to the highly contagious virus, which can be shed for more than 20 days.

The H3N2 virus was first identified (coming in from Korea and China) in 2015 and has since been reported in almost every state. It has also been found in cats, although this is uncommon. Shelter cats are at greater risk than pet cats.

The H3N8 virus, first identified in the U.S. in 2005, originated in horses and is not as prevalent as H3N2. Use thorough disinfection procedures and isolate any dog who shows signs.

Dr. Mittel says: “The concern is that a virus from Asia [where many flu viruses originate] may recombine and make a ‘new virus,’ so to speak, that could affect humans or dogs. Also, antimicrobial resistance [AMR] is a concern internationally. Asia has historically been an epicenter of AMR in humans, and antibiotic use in small animals and livestock is a concern. If a resistance organism arrives in an animal, it could get into the human and animal population.  There is a history of very resistant organisms in China [and] Korea.”

This article was reviewed/edited by board-certified veterinary behaviorist Dr. Kenneth Martin and/or veterinary technician specialist in behavior Debbie Martin, LVT.

Happy Paws Magazine

Fall/Winter 2019 Issue Available Now!