Diseases Transmitted to Dogs by Mosquitoes

Beyond being annoying, some mosquitoes can transmit very dangerous, even potentially fatal diseases to our dog through their bite. These are known as vectors, and this category also includes other types of insects, such as ticks.

Vectors don't only transmit diseases to dogs — they can also infect humans, potentially causing diseases like malaria, and can even act as a bridge between infected animals and humans, as in the case of West Nile virus.

This is what's known as "neglected tropical diseases," which cause hundreds of thousands of illness and death cases, especially in developing countries, and represent one of the biggest public health problems worldwide.

That's why it's important to know the main diseases mosquitoes can transmit to dogs. That way you can take some precautions, especially if your dog spends a lot of time outdoors or near areas with standing water.

What diseases can mosquitoes transmit to dogs?

Among the diseases mosquitoes can transmit to dogs, two are especially common: leishmaniasis and heartworm disease (dirofilariasis). Both are diseases with a chronic systemic course, with a poor prognosis if not properly treated. To catch them early, it's important to stay informed and know the most common symptoms.

Canine leishmaniasis

Leishmaniasis is a parasitic disease caused by the protozoan Leishmania infantum, a microscopic parasite transmitted by the sandfly, also known as the "sand fly," which can affect dogs of any age or breed. Since it's a chronic disease, early diagnosis is essential to ensure our dog a good quality of life.

After infection, the disease's incubation period usually lasts between 3 and 18 months. The signs it causes vary, though they mainly show up on the skin. The most common include:

• Flaking skin (acral/exfoliative dermatitis).
• Alopecia, or hair loss, especially on the legs and head.
• Skin lesions, especially dermatitis localized around the eyes, ears, and limbs.
• Loss of appetite and weight, which in extreme cases can lead to malnutrition.

When the disease is very advanced, the dog can also develop kidney problems. You should know that there's currently no definitive cure for leishmaniasis — treatment is lifelong, involving daily medication such as allopurinol or miltefosine.

So, the best approach against this disease is prevention, through vaccination and, above all, through using insecticide collars and spot-on treatments to keep mosquitoes from biting our four-legged friends.

Canine heartworm disease

Canine heartworm disease, popularly known as "heartworm disease," is one of the most serious parasitic diseases a dog can develop. This parasite is transmitted by mosquitoes of the Culex, Aedes, and Anopheles genera. For its larvae to develop and turn into worms, it needs an intermediate host, such as a dog.

When a dog is bitten by an infected mosquito, the larvae, or immature worms, invade their body. Once inside, they reproduce very quickly and spread to other parts of the body through the blood. After a period of 80 to 120 days, the larvae reach maturity. At this stage, the worms mainly settle in the heart and lungs.

One of the difficulties with this disease is that its signs aren't always easy to spot. The most common symptoms in dogs infected with microfilariae are the following:

• Coughing or dyspnea (difficulty breathing).
• Exercise intolerance, weakness, or apathy.
• Weight loss and loss of appetite, which can lead to anorexia and malnutrition.
• Tachycardia, or an increased heart rate.
• Bleeding from the nose (epistaxis) or mouth.
• Fainting or loss of consciousness.

Many dogs show no symptoms until several days or even weeks after being infected. Because of this, the best way to catch these parasites is through regular vet check-ups.

How do I keep my dog from developing these diseases?

Besides vaccination, regular deworming/parasite treatment will help keep the dog from getting infected by these parasites. There's a wide range of spot-on treatments, collars, and other anti-parasite products on the market, useful for reducing the risk of mosquito bites that can transmit the parasites causing these diseases. It's also very useful to take certain control measures against these vector insects.

Either way, your trusted vet is the one who can help you find the best option for your dog.

Tips for repelling mosquitoes at home

Keeping mosquitoes away from our lives and our furry friends' lives isn't an easy task; however, keeping these tips in mind can help you avoid some trouble:

1. Install screens on the house's doors and windows.
2. Mosquitoes love dense vegetation, so don't let your garden plants grow too much.
3. Avoid keeping containers that could collect water, since these are breeding grounds for mosquito larvae.
4. Insect repellent is a classic that never hurts, but remember, the ones sold for human use aren't suitable for dogs.
5. With the arrival of warmer seasons, there will be a greater presence of mosquitoes, so you should take extra precautions and be much more careful when walking your dog.

We know it's impossible to completely eliminate the mosquitoes that carry diseases for dogs; however, we can take control measures to prevent bites and infection by these parasites, such as vaccination and/or deworming.

References consulted: Lima-Netto, C. (2002) "Todo sobre la Leishmaniasis Canina." Tikal – Susaeta. Javier Encinas Aragón, Francisco José Fernández Gómez, María Dolores Lasheras Carbajo, José Francisco Barbas del Buey (2006) "Leishmaniosis canina y humana: una visión de conjunto." Revista "Profesión veterinaria," Vol. 16, no. 63, pp. 28-33 (COLVEMA). http://www.colvema.org/pdf/leishmaniosis.pdf