Clinical Suite: Heartworm Disease
Sheldon Rubin, DVM, American Heartworm Society
Jessica Goodman Lee, CVPM, Veterinary Credit Plans, Irvine, California
Overview
Sheldon Rubin, DVM, Past President, American Heartworm Society
First Steps
The statistics are in. Over a million dogs are infected with heartworm disease in the United States, and more than half of clients leave the practice without heartworm preventive.1 Pet owners need to hear the message about the seriousness of heartworm infection, guiding them away from the “it won’t happen to me” syndrome.
Challenges
Compliance is low and owners who do comply may run out of preventive and forget to refill the prescription in a timely fashion
Patients may spit out or vomit the monthly product
Travel and urban heat islands (ie, regions with increased temperature for prolonged periods) allow for mosquitoes to continue to exist in all seasons
Most heartworm preventives also control intestinal parasites. Patients infected with these parasites (eg, roundworms, hookworms) can pass eggs in feces, infecting the surrounding environment and putting humans at risk
Benefits of Prevention
Products come in oral, topical, or injectable forms
Preventives are safe and almost entirely effective when given continuously in a timely fashion
Most heartworm preventives help control intestinal parasites
Many topical products also prevent fleas and ticks
Monthly administration (year-round) can minimize risk for zoonoses and environmental threats from intestinal parasites
Team Approach
Successful heartworm prevention lies in the team effort
Year-round protection is strongly recommended
Practice communication requires delivering a unified message to the client, including recommendation of year-round prevention
At every step, heartworm prevention should be mentioned
Provide tools to help educate the client, such as a container of preserved heartworms
A comprehensive parasite control program is as important as a discussion about behavior, diet, and wellness
Every team member needs to be on the same page to give a consistent message to every client, every time
Primer
Sheldon Rubin, DVM, Past President, American Heartworm Society
Heartworm (Dirofilaria immitis) infection is spread by the bite of an infected mosquito. When a host is bitten, larvae are deposited on the skin next to the bite. The larvae migrate through the wound to enter the blood stream and reach the heart and pulmonary blood vessels. The microscopic larvae mature over 6–7 months to an adult size of 10–12 inches. Adult females begin producing microfilariae that circulate in the blood stream and are available to other mosquitoes that bite the host. The microfilariae incubate in the mosquito for 10–14 days and become infective 3rd-stage larvae (L3), which are then passed on to the next host the mosquito bites. Because heartworms can live 5–7 years in a dog and 2–3 years in a cat, each mosquito season can lead to an ever-increasing number of worms in unprotected hosts.
Signs
Dogs
As infection progresses and causes damage to the pulmonary arteries and lungs, signs include:
Mild cough
Reluctance to exercise
Fatigue after activity
Decreased appetite
Weight loss
Be aware that early-stage infection may not produce signs
Cats
If present, chronic signs include:
Cough and dyspnea (difficult to differentiate from feline asthma)
Acute signs of respiratory distress (heartworm-associated respiratory disease [HARD])
Clinical signs may not be present
Can lead to sudden death
Diagnostics
Dogs
Current heartworm antigen tests screen and detect protein secreted mainly by adult female Dirofilaria immitis
The American Heartworm Society recommends the antigen test and a modified Knott test for microfilariae
Puppies should not be tested until ≥7 months of age (the adult female worm takes that long to mature and secrete enough antigen to show a positive test)
If a test is positive, perform a second test to confirm.
Additional imaging may help diagnosis
Cats
Diagnosis is challenging
Cats are rarely microfilaremic; negative antigen tests do not rule out infection
Antigen tests are sensitive to adult female worm infections; male-only or symptomatic immature worm infections, however, are more common in cats2
A combination of antigen and antibody testing with imaging can increase likelihood of correct diagnosis
Prevention
Indoor-only patients are not immune from heartworm (mosquitoes have no barriers)
Heartworm preventives are very effective when used properly and on a timely schedule
Heartworm preventives are eliminated quickly from a dog’s body and do not protect from future infection
Heartworm preventives can be highly effective, safe, easy to use, relatively inexpensive, and protective against other parasites
As there is no heartworm infection treatment for cats, prevention is crucial
Communication
Jessica Goodman Lee, CVPM Brakke Consulting Dallas, Texas
Sometimes it seems easier not to “push” clients, but it is important to discuss parasitic infection risks with every pet owner, regardless of whether the owner has declined testing/medication in the past.
Always begin each new conversation as if it is the first time the topic is being discussed.
Always begin each new conversation as if it is the first time the topic is being discussed and do not judge the owner for his or her previous decisions. You are the expert and education is your responsibility.
One of the best ways to begin what may be an uncomfortable or frustrating discussion is to recognize something positive that the owner has done for the patient. This can be as simple as offering praise for bringing the patient in every year. Acknowledge what makes the client stand out as a responsible pet owner!
Dog Owners
When greeting the client and patient, review the reason for the scheduled appointment.
Receptionist: Hi, Mrs. Smith. Fred, you look so handsome today—did you just come from the groomer? And I love the scarf—very sharp!
By the way, Mrs. Smith, I know your appointment today is to recheck Fred’s ears, but I noticed that he is also due for both his heartworm and fecal screens. Would you like to do those today? We can have the results of his heartworm test before you leave today so you will be able to start him on his monthly preventive.
Client: I never bother with that—Fred doesn’t go anywhere except in the backyard and for several walks a day, but we never leave our neighborhood.
Receptionist: Wow, he’s pretty lucky—my dogs are ecstatic if I walk them more than once a day! But I do want to make sure that you realize that Fred’s lifestyle does not lower his risk for parasitic infections. Would you like me to give you some information to look over while you and Fred are waiting? That way you can talk to the technician or veterinarian about any questions or concerns you may have.
Cat Owners
The conversation with cat owners is somewhat different, especially when it comes to heartworm disease.
Receptionist: Wow, Mrs. Smith, Kitty looks great—you’ve obviously been working hard at weight loss! Do you have any tips I can pass on to our other cat clients? [Let the client bask in the praise and share his or her tips.]
As I was updating Kitty’s record for her appointment, I noticed that she is not currently on monthly heartworm preventive. I want to make sure you have all of the information on feline heartworm disease, especially since there is currently no treatment available once a cat gets heartworms.
Client: Yes, the veterinarian told me about it last year, but Kitty never goes outside so I really don’t think it’s necessary. Plus, I tried to give it to her once and she refused to eat it—even in tuna!
Receptionist: I hear your concerns, but it’s important to recognize that it would only take one mosquito to infect Kitty. In fact,a recent study reports that 28% of cats with heartworm disease never went outdoors!3 You know, I had the same problem with my cat—she’s very finicky and wouldn’t take the medication either. But the good news is I was able to use a different preventive that I apply topically every month.
Would you like me to give you some information to look over while you and Kitty are waiting?
Compliance Connection
Regardless of the pet owner’s response, document the conversation, and any information provided, in the medical record
An initial not interested response gives the technician and veterinarian the perfect starting point to reintroduce the subject
If talking with the client over the phone, offer to mail or email additional information
Email the client a link to the parasite prevention page on your practice’s website
True Story Communication
When it comes to heartworm disease, one of the best ways to communicate the importance of testing and prevention is to provide the relevant facts and information, such as data on the prevalence of heartworm disease in your state. Another way is to bring it even closer to home—inform clients the number of recent heartworm-positive tests in your practice’s canine patients.
When a dog is undergoing heartworm treatment, ask the owner if she or he would be willing to teach other clients about the importance of prevention by allowing the patient to be the practice’s Heartworm Prevention Poster Dog (consider a treatment discount as an incentive). Use newsletters, social media, and in-hospital displays to tell the patient’s story and chronicle heartworm treatment.
Nothing speaks as loudly as a real-life, close-to-home story to educate owners that their pets are equally at risk for this preventable disease.
Workflow
Jessica Goodman Lee, CVPM Brakke Consulting Dallas, Texas
Workflow
Technician/assistant
Escort client & patient to examination room
Review testing & preventive protocols, making sure to first note receptionist documentation
Provide education on heartworm disease
Obtain testing samples (blood, feces)
Review importance of monthly compliance
Document all conversations in medical record
Technician/assistant
Confirm that client has received preventives and they have been added to the invoice
Review importance of monthly dosing
Offer to text/call/email client monthly reminders
If client chooses to purchase <12 months of supply, put a reminder in record to contact client to refill prescription
Roles
Jessica Goodman Lee, CVPM Brakke Consulting Dallas, Texas
Technician
Role: Client educator
Responsibilities:
Educate on all parasitic infections and the importance of testing
Emphasize the importance of year-round heartworm prevention for cats and dogs
Use tools (eg, models of infected hearts, jars of preserved heartworms, videos, handouts) to educate client
Obtain test samples (eg, blood, feces) and process/prepare laboratory tests
Communicate heartworm-negative test results to clients
Practice Manager
Role: Supervisor of team education/practice policies & compliance analysis
Responsibilities:
Maintain up-to-date training for all new team members with details on parasites:- Medical standards, protocols, and policies- Medical information on canine/feline heartworm disease and zoonotic risk- Data on disease prevalence- Detailed information on all parasite protection medications sold in the practice
Consider requiring a written test on parasites—it’s that important!
Organize at least one team meeting annually to review parasite infections, treatment, prevention, and practice policies
Track testing and prescription compliance to share with team, celebrating and offering praise as numbers improve!
Training
Jessica Goodman Lee, CVPM Brakke Consulting Dallas, Texas
When it comes to parasitology there are several topics (eg, heartworms, zoonoses, ticks/fleas), so multiple team meetings are recommended to prevent information from becoming overwhelming. Also, take advantage of the educational opportunities offered by vendors, who can conduct lunch-and-learns for the team and can bring in a veterinarian to lead the discussion.
Agenda
Hand out and discuss the practice’s standards of care with regard to parasite treatment and prevention; if they are not in writing, ask the veterinarians to draft them ahead of time
Come to the meeting prepared to share the practice’s current client compliance data and discuss the biggest compliance challenges, as well as welcome suggestions for improvement
Utilize your practice management software to see if any one veterinarian stands out as obtaining greater client compliance; if so, invite him or her to offer tips and share his or her approach
Review client education materials and assign someone to keep these stocked and replenished as needed; familiarize the team with the dedicated page and links on your website role play!
Role Play
Role play different client communication scenarios regarding all parasitic diseases. Ensure each team member shares how he/she would educate the average client about the need to prevent, and remind the team of the practice’s expectations with medical record documentation (this is important, especially for legal reasons)
Focus on role playing the following conversations:
Resistant pet owners
Heartworm disease specifically (both canine and feline)
Zoonotic disease specifically
Fleas/tick-borne infections specifically
The importance of laboratory testing (blood, feces)
Preventive medications and cross-protection against several diseases
Tip: Similar role playing should be done by each team member, based on his or her role and interaction with the client.
Know the Sources!
A wealth of educational materials is available for both veterinary teams and pet owners—these sites can also offer free client education brochures:
Handout
Sheldon Rubin, DVM, Past President, American Heartworm Society
You asked… the expert answers!
What is heartworm disease?
Heartworm disease, prevalent in all 50 states, is serious and potentially fatal, primarily affecting dogs, cats, and ferrets. Adult heartworms live in the heart and pulmonary (lung) arteries and can cause heart failure and severe lung disease.
How are heartworms transmitted?
Heartworm is transmitted by an infected mosquito, whose one bite can infect a dog or cat. It cannot be transmitted from animal to animal. When a mosquito bites an infected animal, it receives young heartworms (microfilariae) with the blood meal. After a short incubation period in the mosquito (10–14 days), heartworms can then be passed on to the next animal the mosquito bites. Larvae migrate through the tissues and enter the blood stream to the heart and pulmonary blood vessels where they can grow up to 12 inches and produce new microfilariae, beginning the cycle again.
My pet never goes outside—does she need heartworm prevention?
Mosquitoes enter homes all the time. All pets are recommended to be on preventives, regardless of where they reside.
Can cats get heartworm disease?
Yes. Heartworm disease in cats is difficult to diagnose and a single worm can prove deadly.
How can I tell if my dog or cat has heartworm disease?
In later stages, as the heartworms develop, the dog may cough, become lethargic, have difficulty breathing, and lose stamina. Cats may develop coughing and breathing difficulties, resembling signs of feline asthma.
Can infected pets be treated?
If detected early, heartworm disease in dogs can be treated. While the process is prolonged and can be expensive, the success rate can be high. Currently, there is no treatment for cats.
How is heartworm disease detected in dogs?
Your veterinarian must perform an annual blood test, even if the dog is on year-round prevention.
How is heartworm disease prevented?
Many safe, relatively inexpensive preventives are available by prescription from your veterinarian. With their proper and timely use, heartworm disease is extremely preventable. Reduced exposure to mosquitoes is also necessary, but do not use human mosquito repellants on pets.
Can heartworms infect humans?
This is very rare. Heartworms have been reported in the lungs of humans as nodules that are not easily distinguishable from lung cancer.
Download the "You Asked...The Expert Answers" handout
Healthy Pets = Healthy Families
At our animal hospital, we recognize that your pets are a part of your family. As with any family member, you want to keep your pet healthy and happy. One of the most important things you can do to ensure your pets’ health, as well as the health of your 2-legged family members, is to keep them free of parasites with year-round preventive care. Several heartworm preventives also protect against other parasites.
What is zoonotic disease?
Zoonoses, or zoonotic diseases, are contagious diseases that can be transmitted between animals and humans. These diseases are caused by bacteria, viruses, parasites, and fungi.4 One example includes roundworms: humans can accidentally ingest infective worm eggs passed through the pets’ feces and left in the environment. The eggs can then hatch in the human intestinal tract, and the immature worms can travel to various tissues in the body (eg, eyes, lungs), potentially causing serious infections.
What is a vector-borne disease?
Vector-borne diseases are transmitted by fleas or ticks, as well as other ectoparasites that infest dogs and cats. Ehrlichiosis, Lyme disease, and Rocky Mountain spotted fever are serious tick-borne diseases that affect both pets and people. Protecting your pet from fleas and ticks can significantly reduce the risk for human exposure to these parasites.
What can I do to protect both pets and people?
Keeping your pets on preventive medication year-around is not only the best way to protect them from parasite infections—it also is the best way to protect people. All of the staff at your animal hospital are highly educated on parasitic infections and prevention and are ready to answer your questions and prescribe the most effective year-round preventive medication available.
Also, always remember to clean up pet feces immediately and practice good personal hygiene!