Mosquitoes do more than buzz around your backyard barbecue. For dogs across West Texas, these pests can carry a dangerous parasite known as heartworm, one that quietly threatens the heart, lungs, and blood vessels of an unprotected pet. The team at Andrews Veterinary Clinic wants local pet owners to understand this disease, spot the warning signs, and know how straightforward prevention really is.
The encouraging part is that heartworm disease is almost entirely avoidable with the right care plan. Below, we'll walk through what heartworm actually is, how it progresses, what symptoms to watch for, and why our region's climate makes year-round protection especially important.
What Exactly Is Heartworm Disease?
Heartworm disease comes from a parasite called Dirofilaria immitis, which enters a dog's bloodstream through a mosquito bite. Once inside, these worms travel to the heart, lungs, and surrounding vessels, where they grow, multiply, and interfere with normal organ function. Left untreated, the damage can progress to heart failure, lung disease, and in severe cases, death.
Many pet owners assume this is only a concern in humid or tropical climates. In reality, heartworm has been documented in every state, including Texas. Our warm, extended mosquito season here in the Andrews area means dogs are at risk far longer than owners in cooler climates might expect, sometimes nearly year-round given our mild winters.
How Heartworm Disease Progresses
Dogs are stoic by nature, often masking discomfort until a condition has advanced. That's exactly why understanding the stages of heartworm disease matters so much for early detection.
Stage 1: Early Infection
At this point, symptoms are subtle or entirely absent. You might notice an occasional cough or a bit less pep during walks. Dogs living in areas with heavy mosquito activity, which includes much of rural and suburban Texas, should be monitored closely even when nothing seems obviously wrong.
Stage 2: Moderate Progression
As the infection advances, coughing becomes more frequent, energy levels drop noticeably, and your dog may start avoiding play or exercise they once enjoyed.
Stage 3: Advanced Disease
By this stage, the damage to the pulmonary arteries becomes harder to ignore. Expect visible weight loss, labored breathing, and sometimes a distended belly caused by fluid accumulating in the abdomen.
Stage 4: Caval Syndrome (True Emergency)
This is the most dangerous phase, occurring when worms migrate directly into the heart and obstruct blood flow. Dogs may collapse suddenly, show pale gums, or pass unusually dark, coffee-colored urine. This stage requires immediate emergency veterinary attention.
Watching for Early Warning Signs
Because symptoms often stay hidden in the early phases, it pays to stay observant. Signs worth tracking include:
A dry, lingering cough
Getting winded more easily than usual
Eating less than normal
Unexplained weight loss
Breathing that seems labored or strained
None of these symptoms guarantee heartworm disease, but they're worth a conversation with your veterinarian, especially if your dog hasn't had recent preventive care.
Symptoms That Mean You Should Call Right Away
Some signs point to a genuine emergency rather than a wait-and-see situation. Contact your vet immediately if you notice:
Sudden difficulty breathing
A swollen or bloated abdomen
Fainting or collapsing
Pale or grayish gums
Dark, coffee-colored urine
These symptoms indicate the disease has likely progressed significantly. Even so, don't panic. Dogs diagnosed early and treated promptly have far better outcomes than those diagnosed in later stages. A quick blood test during your dog's annual wellness visit is usually enough to catch heartworm before it becomes a crisis, and we recommend combining this with regular parasite screening, particularly given how active mosquitoes are throughout much of the year in our part of Texas.
One misconception we hear often at Andrews Veterinary Clinic is that a dog on monthly prevention doesn't need annual testing. That's not accurate. No preventive is 100% foolproof, and yearly screening remains the best way to catch a breakthrough infection before it causes lasting harm.
Why Prevention Beats Treatment Every Time
The American Heartworm Society recommends monthly protection in chewable, topical, or injectable form, and for good reason. These preventives are inexpensive, simple to administer, and remarkably effective when given consistently.
Compare that to actual heartworm treatment, which involves weeks of strict activity restriction, a series of injections, and real risk of complications including permanent damage to the heart and lungs. Prevention isn't just easier, it's dramatically safer for your dog and far less stressful for you as an owner.
Our climate here adds another layer to consider. Ranch dogs, hunting companions, and pets that spend time outdoors near stock tanks, creeks, or standing water after our seasonal rains face higher mosquito exposure. Even dogs that mostly stay in fenced yards or indoors aren't immune, since mosquitoes have no trouble slipping through open doors or screened porches during our long warm-weather stretch.
At Andrews Veterinary Clinic, we build a prevention plan around your dog's actual lifestyle, whether that's a working farm dog, a house pet, or something in between. Pairing monthly preventive medication with routine wellness exams gives your pet the strongest possible defense.
Protecting Your Dog Starts With a Plan
Heartworm disease is serious, but it doesn't have to be scary. With consistent prevention, routine testing, and a veterinary partner who knows your dog's history, this is a threat you can manage confidently. Texas's climate means our local pets face a longer exposure window than dogs in cooler regions, which makes year-round diligence especially worthwhile here.
If it's been a while since your dog's last heartworm test, or if you're not currently using a monthly preventive, now is a good time to change that.
Frequently Asked Questions
What are the earliest signs of heartworm disease in dogs?
Early on, dogs may show a mild cough or slightly reduced energy, though many show no symptoms at all in the beginning stages. This is why routine testing matters even when your dog seems perfectly healthy.
How long can heartworm disease go unnoticed?
Because the parasite develops slowly, dogs can carry an infection for months or even years before visible symptoms appear, making annual screening essential.
Does heartworm disease cause pain?
Yes, particularly in advanced stages, where dogs often experience breathing difficulty and significant physical discomfort as the parasites damage the heart and lungs.
Are indoor dogs safe from heartworm?
No. Mosquitoes easily find their way indoors, so even dogs that rarely go outside remain at risk without proper prevention.
How often should Texas dogs be tested for heartworm?
We recommend annual testing for all dogs, even those on monthly preventives, since our extended mosquito season increases exposure risk throughout much of the year.
If you'd like help building a heartworm prevention plan tailored to your dog's lifestyle, reach out to the Andrews Veterinary Clinic team. Alongside heartworm testing and prevention, we offer wellness exams and parasite screening designed to keep your companion healthy through every Texas season. Contact us today to schedule a visit.
Call us at (432) 523-4355 to book an appointment.