Module 3: Healthcare practices for common medical conditions in shelters

Canine Heartworm Treatment in Shelters

Treatment protocols for heartworm infection in shelter dogs may differ from the AHS best practices based on the shelter operational model, organizational philosophy, annual intake, and resources. Limited funding, staffing, housing, and technical expertise often make following the AHS Guidelines impractical.

A 2010 survey of heartworm treatment protocols in southeastern shelters found the following variations:

    • For shelters that performed heartworm testing, 39% treated all infected dogs, 4% treated some dogs, and 12% did not treat any dogs
    • Municipal shelters were more likely to euthanize infected dogs or release them without treatment
    • Municipal shelters were less likely to follow the AHS best practice treatment protocol than private nonprofit shelters
  • 35% of shelters that treated heartworm-infected dogs used the 3-dose melarsomine protocol, 44% used the 2-dose melarsomine protocol, and 22% used the monthly heartworm preventive “slow-kill” protocol instead of melarosmine
  • <50% of the shelters used doxycycline prior to adulticide treatment

A similar survey of shelter heartworm treatment practices in 2019 reported the following findings:

  • 93% of the responding shelters treated at least some of their heartworm-infected dogs
  • Municipal shelters were less likely to have treatment SOPs than private nonprofit shelters
  • 43% of shelters that treated heartworm-infected dogs used the 3-dose melarsomine protocol, 38% used the 2-dose melarsomine protocol, and 17% used the monthly heartworm preventive “slow-kill” protocol instead of melarosmine
  • 59% of treating shelters started infected dogs on macrocyclic lactone preventives
  • 92% used doxycycline prior to melarsomine
  • 71% gave prednisone with melarsomine injections
  • 65% of the shelters housed dogs in foster homes during treatment or provided treatment for dogs after adoption
  • 32% housed dogs in the shelter for the duration of treatment

These surveys revealed that shelters utilize a variety of heartworm treatment strategies ranging from full compliance with AHS guidelines to a complete lack of attention to heartworm infection. Many shelters develop their own protocols based on available resources and without the supervision of a veterinarian or support by evidence.

For both surveys, shelters reported that the biggest challenges for heartworm treatment were cost of treatment, long duration of treatment, housing during treatment, and managing activity restriction for ≥5 months during and after treatment without compromising the dog’s behavioral health and welfare. How to deal with these challenges is frequently discussed on shelter medicine practice listservs and discussion board and at continuing education conferences. Solutions will vary based on how shelter managers and veterinarians allocate their finite financial and staff resources to best serve a variety of competing needs for shelter operations and healthcare.

Think about the shelters you have worked in – what were their approaches to treating heartworm-infected dogs?

  • Was the policy to transfer infected dogs to a rescue for treatment instead of being done by the shelter?
  • Were infected dogs adopted out with the understanding that the new owner would seek treatment by their veterinarian?
  • If the shelter provided treatment, did they treat all infected dogs or only those considered most adoptable?
  • Did dogs stay in the shelter for the duration of treatment or were they in foster homes or new adopter homes?
  • If the shelter provided treatment, who paid for this?

Let’s review the ASV position paper on heartworm management in shelters. This statement provides recommendations to guide shelters in making decisions on treatment protocols, including choosing protocols based on available resources and options for providing treatment outside of the shelter.

ASV Statement on Heartworm Management

The ASV supports the application of the American Heartworm Society guidelines for the prevention, diagnosis, and management of canine and feline heartworms. The ASV also acknowledges that every shelter may not always be able to meet these practices. Resource allocation, capacity for care, compromised welfare brought on by prolonged shelter stays, and risks to population health may warrant alternative approaches to heartworm management.

Key Takeaways from the ASV Heartworm Management Statement

  • All shelters should institute some program for treatment for infected dogs to reduce pathology in the heart and pulmonary arteries and stop infection of mosquitoes that spread infection to other dogs
  • Shelter resources diverted toward heartworm treatment should not compromise care of other shelter animals
  • Treatment strategies that differ from AHS recommendations should only be undertaken with a thorough understanding of the risks and benefits to both individual animals as well as the shelter and community animal population
  • Alternative treatment strategies should include evaluation of scientific evidence and consultation with a veterinarian
  • Treatment policies and protocols must provide an environment that protects the behavioral health and welfare of exercise-restricted dogs with long lengths of stay
  • Transfer dogs to other partnering agencies or informed adopters for treatment if shelter resources cannot provide for proper treatment or welfare is compromised by prolonged stays in the shelter for treatment

Watch This

In the Takin’ It to the Heart Part 1: Understanding Heartworm Disease in Shelter Animals webinar (excerpts total about 13 minutes), Dr. Brian DiGangi provides further insights on treatment options for shelters. Dr. DiGangi is board-certified in Shelter Medicine Practice and is a Senior Director of Shelter Medicine for the ASPCA. He is also an American Heartworm Society board member and provides evidence-based recommendations for heartworm management in shelters and transport of heartworm-infected dogs between shelters. Dr. DiGangi is a past president of the Association of Shelter Veterinarians.

Focus Guide for Watching the Takin’ It to the Heart Webinar

Watch these time frames in the webinar and then answer the questions below.

    • Introduction: 1:30 to 2:58
    • Heartworm Treatment: 34:00 to 44:46
  1. What % of adult heartworms is killed with one dose of melarsomine? Two doses? Three doses?
  2. What is the approximate cost for treatment with 3 doses of melarsomine? Two doses? Treatment with moxidectin + doxycycline only (slow-kill protocol)?
  3. Based on cost, duration of treatment and activity restriction, and killing efficacy, which treatment protocols are more acceptable for both the dog’s health and the shelter’s budget?

What are some of the canine heartworm treatment policies and protocols in Florida shelters?

Watch This

Dr. Barton has been the veterinarian at the Tallassee Animal Services municipal shelter for 15 years and serves as the Chief Veterinarian. She completed a Master’s degree in Shelter Medicine at UF and is a fellow in the Maddie’s Shelter Medicine Fellowship Program hosted by UC-Davis and the University of Wisconsin (7:17) Download transcript.

Watch This

Dr. Fitzpatrick was a veterinarian at the Humane Society of North Central Florida and is currently the veterinarian at Alachua County Animal Services in Gainesville FL (5:01). Download transcript

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