'It's alarming that it's so close to home': Veterinarian urges screwworm prevention for ranchers, pet owners
As New World screwworm moves closer to Webb County, one local veterinarian is urging ranchers and pet owners alike to focus on prevention before the parasite has a chance to spread.
With portions of Webb County now under quarantine following a confirmed case in neighboring La Salle County, Dr. Chase Jarman of C&C Veterinary Services said his practice has already begun emphasizing preventive treatments for both livestock and household pets.
C&C Veterinary Services, located off Bob Bullock Loop, treats a mix of small domestic animals, including dogs and cats, as well as livestock such as pigs, sheep and cattle.
"It's alarming that it's so close to home," Jarman said.
Mexican authorities have confirmed a New World screwworm detection in Nuevo Laredo, directly across the Rio Grande from Laredo, in late June.
Jarman explained that any open wound can become a breeding ground for New World screwworm larvae, which feed on living flesh rather than decaying tissue.
"The fly is going to lay her eggs in like a wound or scratch, or abrasion or whatever the case might be," he said.
Warning signs can include wounds or abrasions with a foul smell, an animal separating from the herd, not coming to feed or carrying a heavy fly burden.
"Those are all red flags and a sign that there may be an issue," he said, emphasizing that ranchers and pet owners should contact a local veterinarian or proper authorities if they suspect a case.
Reported cases have included calves, including one case in La Salle County and two in Zavala County. Another case involved a goat in Gillespie County. A dog initially reported in Andrews County was later determined to reside in Lea County, New Mexico, and was reclassified as a New Mexico case.
For domestic animals such as dogs and cats, prevention can include once-a-month parasite medications such as Credelio, Credelio Quattro and NexGard.
For livestock, which make up about 40% of the clinic's patients depending on the season, screwworm has become a growing concern. C&C Veterinary Services' reach extends beyond Webb County into areas such as Cotulla, west of Mines Road, Hebbronville and Zapata. Jarman estimated that, based on Texas Animal Health Commission data, the practice helps care for about 30,000 beef animals across its service area.
"We're the caretakers for a huge territory," he said. "We have several clients with hundreds of animals."
For larger livestock populations, treatment options include Exzolt, an FDA-approved prescription pour-on medication. Jarman said he first used it Saturday on an FFA show animal that was set to be dehorned. The blue-colored application is poured from head to tail.
"It can't go directly on a wound," he said. "It's systemically absorbed."
Beyond medication, Jarman said livestock producers may eventually need to consider management changes, including adjusting breeding and calving seasons to cooler months when screwworm flies are less active.
"There are recommendations - and this is not anything that can be done overnight, but ... change your breeding season and calving season to have calves born in cooler months, because the fly isn't really as active in cool to cold weather," he said. "That kind of, you know, helps just decrease the overall incidence there. That's definitely gonna be a huge management practice to help with things. That's what producers can do, on their own."
Other preventive measures include fly control methods such as ear tags for cattle, sprays and over-the-counter medications including ivermectin and doramectin, or Dectomax, which are injectables.
Jarman said he expects to have similar conversations with clients during ranch calls north of Laredo.
"I have several ranch call appointments, like north of Laredo and we're gonna, I'm gonna have the same conversation with them," he said.
He also reminded residents that New World screwworms can affect humans and small animals, not just livestock.
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