Tick tock, it's time to raise your arachnid radar
Ticks! These obligate blood-sucking arthropods and the diseases they carry are on the rise, and if you aren’t already hitting tick prevention hard with your clients, there’s no time like, well, right now! Fetch dvm360 conference speaker Richard Gerhold, DVM, MS, PhD, is on deck with what’s new in tick-borne disease, full of advice to assist you in your battle with these super stealthy arachnid vampires.
Recommend year-round tick prevention.
In much of the United States, there isn’t a “break” from tick season. Ixodes species ticks are out in the fall and winter, says Dr. Gerhold. To protect your clients, strongly recommend year-round tick prevention.
Ticks live indoors (Ewww. Really?)
Rhipicephalus sanguineus, the brown dog tick, is a tropical tick that doesn’t survive the winter outdoors in temperate areas. So Dr. Gerhold warns that these spooky ticks can hide in warm indoor nooks and crannies for up to a year, waiting for the right host to come along. Don’t forget though that the brown dog tick can survive outdoors year round in Arizona and New Mexico and has been infecting dogs and people with Rocky Mountain spotted fever, causing human morbidity and mortality.
Pull, don’t twist.
When it comes to tick removal, keep “pull, don’t twist” in mind, which is contrary to popular belief. Dr. Gerhold says to tell clients that when they encounter an embedded tick, they should slowly pull the tick straight out to avoid breaking the hypostome. The hypostome (mouth part) may transmit pathogens, and if you twist you risk breaking it. Here’s a client handout on tick removal best practices.
Positive in-house test result? Don’t treat the result ...
It happens all the time—a clinically normal, happy, wagging dog comes up positive for Ehrlichia species. What to do? Treat the animal not the test, Dr. Gerhold says.
Tell the owner this: “The test indicates your dog has been exposed to ticks. Now we need to run additional tests to see if your dog actually has the disease, because the result could be from antibodies, or it could be a false positive.” Then recommend a complete blood count and serum chemistry profile. If you see a thrombocytopenia or an anemia, then the index of suspicion goes up, especially if the dog has joint pain or neurologic dysfunction.
If you have a positive result for Lyme disease, do all of the above and also add in a urinalysis to look for proteinuria. Serologic tests take a while (especially IgG), so polymerase chain reaction (PCR) testing is best for early infections, Dr. Gerhold says. The gold standard is to run both tests at the same time. Lyme disease moves into tissues very quickly and is difficult to diagnose via serology. With Lyme disease, Dr. Gerhold recommends performing a biopsy of the skin.
Test the tick.
While waiting on serology, if you have an animal with clinical signs and a tick that came off the animal, you can ship the tick off to a laboratory and have it DNA tested. If it is positive, then you have a diagnosis. If the tick comes back negative, however, it doesn’t rule out disease because disease may have come from another tick that has already fallen off, says Dr. Gerhold.
Cats deserve tick protection too.
Cytauxzoon felis is a rapidly fatal tick-borne disease mainly vectored by the lone star tick seen in domestic cats on the eastern side of the United States. The bobcat is the main reservoir host. If a cat recovers, which is uncommon, Dr. Gerhold says it may be an infected carrier for life. Merozoites penetrate macrophages and replicate rapidly, causing the macrophages to swell. This can cause ischemic necrosis that may resemble saddle thrombus. Other signs include anorexia, fever, and pale mucous membranes. The piroplasm stage occurs late, and cats may die even before it occurs, so Dr. Gerhold says a negative blood smear should not be considered diagnostic. Confirmatory testing is through PCR testing. Historically, imidocarb was used for treatment, but the success rate was poor. Dr. Gerhold says the current recommended treatment is atovaquone and azithromycin. In endemic regions, the most effective prevention is to apply products such as fipronyl and to keep cats indoors to minimize exposure.
The CAPC website is your friend.
Local disease prevalence should be used as a lens through which to interpret diagnostic test results. The Companion Animal Parasite Council has put together a great website that includes prevalence parasite maps to help you interpret your data.
Don’t be afraid of the great outdoors.
Many times, clients are so spooked by the idea of themselves or their dogs acquiring a tick that they stop going outside. Encourage your clients that with a few simple precautions, there is no need to forgo the health benefits of being in nature. Dr. Gerhold’s tips: Wear light-colored clothing, tuck shirts into pants and pants into socks, apply tick control to the pets, and do a thorough tick check on humans and dogs after enjoying Vitamin D time.