“Worthy” of Special Care
A case for yearly preventive screening
Potentially dangerous mosquito- and tick-borne infections appear to be on the rise in more regions of the country each year. Changing environmental conditions, the expanding geographic range of tick vectors, suburban development into previously forested areas, and increasing numbers of deer and other wildlife all contribute to this increase.
Because of the dynamic nature of these infectious diseases, it is more important than ever to perform comprehensive testing for vector-borne infections annually and pair this with the use of year-round heartworm prevention, as well as flea and tick control.
The story of Worthy, a 3-year-old female hound, illustrates what may happen when regular preventive care is neglected or, as in her case, is not available. Worthy’s story highlights how comprehensive patient-side testing, along with in-depth reference laboratory diagnostics, help to guide a patient’s medical care. And best of all, this is a true story with a happy ending.
A risky situation
Within a few days of wandering onto a Midwest farm, Worthy whelped a litter of five puppies. Unable to care for the dogs, the farmer surrendered them to a shelter. Thanks to a dedicated rescue group in the region, the hound and her puppies were saved from the high-kill shelter and transported to a veterinary hospital in Ohio.
Worthy was in poor health when the veterinarian initially examined her. She was emaciated, weak, anemic and dehydrated. She had ear mites, Sarcoptes, fleas and ticks. She had significant pruritis and a secondary superficial pyoderma. Examination of a fecal sample confirmed that she also had multiple intestinal parasites including whipworms, tapeworms and Coccidia. And as if this weren't enough, what they found next was completely unexpected.
Worthy was tested for heartworm infection and tick-transmitted infections using the SNAP 4Dx Plus Test. She was positive on all four spots, indicating the presence of Dirofilaria immitis antigen and antibodies to Borrelia burgdorferi (Lyme), Anaplasma and Ehrlichia. A blood smear revealed the presence of microfilaria. The veterinarian called IDEXX asking to have these surprising results investigated.
IDEXX customer support worked with Worthy’s veterinarian to have whole blood and serum sent to the IDEXX headquarters in Maine. Repeated testing on SNAP 4Dx Plus Test confirmed the positive results for all analytes. Additional confirmatory tests were performed demonstrating a positive Ehrlichia canis immunofluorescence assay (IFA) titer of 1:100, a positive Anaplasma phagocytophilum titer of >= 1:3200, a Lyme Quant C6 Test antibody level of 642 U/ml and a positive heartworm antigen result on the PetChek microtiter plate ELISA. The Tick/Vector Comprehensive RealPCR Panel also diagnosed a Mycoplasma haemocanis infection.
Worthy presents a unique example of coinfection with confirmed positive results for all four spots on the SNAP 4Dx Plus Test. Studies have demonstrated that dogs having antibodies to more than one tick-transmitted infection (coinfections) may be twice as likely to have clinical signs or be more likely to have severe hematologic abnormalities. Identifying dogs exposed to infected ticks is the first step in determining which dogs will need antibiotic treatment.
Back at the practice, all the dogs began treatment for intestinal parasites and sarcoptic mange while Worthy was also treated for ear mites and the skin infection. Within a few weeks, Worthy and her puppies were fortunate to be placed in a long-term foster home in Illinois.
Thanks to the wonderful care they received in their foster homes and from their veterinarians, all the dogs were thriving. Yet there was still a question as to whether or not the puppies might have a tick-borne infection. When the puppies were 12 weeks old, samples were tested at IDEXX with the SNAP 4Dx Plus Test, as well as the confirmatory tests, and all results were negative. To everyone's great relief, the puppies were placed into loving homes.
Worthy was treated for her tick-borne infections with doxycycline and for heartworm infection using three doses of melarsomine (Immiticide) approximately 4 weeks after the puppies were weaned. When she was retested on the SNAP 4Dx Plus Test 6 months later, she was still testing positive on all four spots. Her positive heartworm results were confirmed by the PetChek microtiter ELISA, indicating that not all of the heartworm parasites had been killed. However, her E. canis and A. phagocytophilum IFA titers and Lyme Quant C6 Test antibody levels had all decreased significantly over this time, suggesting a good response to doxycycline and validating the doctor’s strategy to prevent new infections.
Worthy’s happy ending
Worthy found her forever home thanks to the support of the rescue group. She underwent a second round of treatment for heartworm and was retested on the SNAP 4Dx Plus Test in February of this year. Eighteen months after her initial diagnosis with multiple vector-borne infections, she was negative for heartworm antigen and antibodies to Anaplasma and Lyme. Although her Ehrlichia antibody response remained detectable, her complete blood count was normal. Today, she is a happy, healthy dog, enjoying a good life in a loving home and with regular veterinary care.
Lack of a complete environmental and medical history challenges any veterinarian to make sensible decisions about diagnostic tests and empiric treatments for possible infections in sick or healthy patients. Choosing a diagnostic panel that combines comprehensive RealPCR testing with conventional serology offers a practical way to cast a wide net for vector-borne infections that may be present and contributing to illness. The Tick/Vector Comprehensive RealPCR panel complements the SNAP 4Dx Plus Test and was an ideal choice for this sick and neglected once-stray dog. For the healthy pet, regular yearly screening with the SNAP 4DxPlus Test and fecal testing for intestinal parasites will help to verify the success of your preventive program. Test and protect—it’s the best solution for keeping dogs free of infectious diseases.
Worthy and her family
Melissa Beall, DVM, PhD
A graduate of the Ohio State University College of Veterinary Medicine, Dr. Beall worked in small animal practice and in laboratory animal medicine before entering a graduate program in Comparative Medicine at Cornell University. Over the last 13 years at IDEXX she has contributed to the development and launch of infectious disease, pancreatic lipase and the cardiac proBNP diagnostic products. As a Medical Affairs veterinarian, she currently supports IDEXX SNAP products, as well as IDEXX Reference Laboratories specialty tests, like the Lyme Quant C6 Test and the Cardiopet proBNP Test.