Leptospirosis, a bacterial disease that can lead to kidney failure and even death, isn't new, nor is its effect on animals.
But one veterinarian in Los Angeles said they'd seen maybe a dozen cases over the span of 40 years of work. In the past three weeks, however, that same vet has seen triple that number of cases.
Allison Mellon, a Brentwood resident, is just one person whose dog has been affected.
"He was so sick it was frightening," Mellon said of her dog, Thor. "He was just laying down lethargic and wouldn’t move."
Get Southern California news, weather forecasts and entertainment stories to your inbox. Sign up for NBC LA newsletters.
Lenny, West LA resident Daniel Mastracco's dog, also got sick.
"He wouldn’t eat or drink anything," Mastracco recalled. "That’s when I got really concerned."
Veterinary surgeon Dr. Alan Schulman says, based on the other veterinarians he's spoken to on the Westside in recent weeks, 50 to 100 cases is a conservative estimate for how large the canine leptospirosis epidemic has become.
"It's truly an epidemic," Schulman said.
LA County Public Health has confirmed a large increase in cases in July, mostly from the west side of LA County or the San Fernando Valley.
"People [are] saying 'My dog is just not right,'" Schulman said. "'He’s sluggish, his eyes are red, he just don’t want to eat,'" all common symptoms of the bacterial infection.
Early detection of the disease is key to catching the cases and treating them. And they can be treated using antibiotics, or prevented with leptospirosis vaccines - though there are many different strains.
But how are dogs getting infected in the first place?
According to Schulman, leptospirosis can come from contaminated water or urine.
"It’s the rats," Schulman said. "They urinate places, they defecate places, dogs get it from them. The other way it does get transmitted is directly through human urine."
Dogs can also pass it on to each other. One outbreak came from a boarding facility in Santa Monica, according to LA County.
An increase in homeless encampments may be one possible reason the disease is spiking in West LA, he added.
"In those encampments we are seeing a phenomenal growth in the rodent population," Schulman said - rodents that are the source of the disease.
"This is not a bacterial epidemic that is coming in from someplace else. It is coming from here and dogs are at that much risk."
While humans can also contract leptospirosis, LA County Public Health has no reports of people becoming ill.
So far, Schulman has not heard any recent reports of dogs dying, but he cautions that people using doggy day care centers or who go to dog parks should get their dogs vaccinated against leptospirosis as soon as possible.
If you have questions about leptospirosis or wish to report a case, call 213-288-7060 or email firstname.lastname@example.org.