Mosquitos and Dogs/Cats in Sonora

Mosquitoes can be a real problem for dogs, mainly because of disease transmission, not just itchy bites. In Sonora, mosquitoes are definitely something to take seriously for both dogs and cats, especially near the coast (Guaymas/San Carlos, rivers, irrigation, water leaks, etc.).

1. How big is the risk in Sonora?

• In Mexico, canine heartworm (Dirofilaria immitis) is well established; studies report infection rates from about 2–60% depending on climate and region, with higher prevalence in coastal areas where mosquitoes are active most of the year.
• Nationwide reviews say Mexico’s overall heartworm prevalence has been around 7–8% over many years.
• Recent work on mosquito species in Sonora confirms plenty of competent vectors (Aedes and Culex species) in coastal and irrigated areas, i.e., exactly the places dogs and cats live with people.

Bottom line: Sonora—especially the coastal belt—is heartworm country.

2. What this means for dogs

• Mosquitoes pick up baby heartworms from an infected animal and pass them on with the next bite. The worms then grow in the heart and lung arteries, causing coughing, exercise intolerance, weight loss, and eventually heart failure if untreated.
• Because the climate in much of Sonora allows mosquitoes for long stretches of the year, the safest approach is year-round prevention, not just “in summer.”

Standard vet recommendations (adapted to Sonora):

• Year-round heartworm prevention (monthly chewable/topical, or long-acting injection where available).
• Annual heartworm test for dogs, even if they’re on prevention, to catch any failures early.
• If a dog is over 6–7 months and hasn’t been consistently on prevention, most vets will test before starting.

3. What this means for cats

• Cats can get heartworm from mosquitoes, even indoor cats (mosquitoes easily get inside).
• Cats usually have fewer worms, but they can cause serious lung disease and sudden death, and there is no safe “kill the adult worms” treatment like there is for dogs—so prevention is the only good option.
• Many vets in heartworm areas recommend monthly heartworm prevention for cats, especially if they:
  • Go outside, or
  • Live in a house where mosquitoes are common (open windows, patios, near estuaries, etc.).

4. Practical protection plan for Sonora

For dogs

• Put every dog on a veterinarian-prescribed heartworm preventive:
  • Chewables (often combined with intestinal worm/flea control),
  • Topical products, or
  • Long-acting injection if your vet offers it.
• Test once a year.
• If you’ve skipped prevention for more than a month or two, ask your vet how and when to restart and whether to re-test.

For cats

• Ask your vet for a cat-specific monthly preventive that includes heartworm.
• Strongly consider this for all cats, not just outdoor ones, in your area.

5. Mosquito control & what NOT to use

Good ideas:

• Eliminate standing water (buckets, plant saucers, boats, construction materials, etc.).
• Use window/door screens and fix holes.
• On patios, fans help keep mosquitoes off people and pets (they’re weak fliers).
• Bring pets indoors during peak mosquito times (dusk, humid evenings).

Avoid:

• Human bug sprays (DEET, picaridin, etc.) on dogs or cats – can be toxic.
• Essential-oil DIY mixes, especially on cats (tea tree, clove, citronella, etc. can be harmful).
• Using dog-only topical products on cats (some pyrethroids are deadly to cats).

Part of the solution to keeping a healthy population of animals is to have an aggressive spay & neuter program to reduce the overpopulation of stray animals which suffer disproportionately from mosquito borne diseases. Help the SBPA to control the overpopulation of street animals by donating or volunteering with the SBPA.