Zika, Mosquitoes, and Our Dogs
By Katherine Falk
With the growing prevalence of Zika virus, it is a valid concern as to what role our pets play in this mosquito-borne disease. Zika may be transmitted through blood transfusion, sexual intercourse, or during pregnancy. However, the most common mode of transmission is through the mosquito, Aedes aegypti. The viruses causes brain defects, including microcephaly in infected fetuses. While the Aedes aegypti mosquito transmits numerous diseases to canines, there is currently no evidence stating that Zika can infect dogs, nor that they are involved in the spread of the virus. Non-human primates are the only animal, other than humans, to exhibit evidence of Zika infection. Antibodies to the Zika virus have been found in primates, signifying only exposure to the virus. The most significant infections in non-human primates have only resulted in minor flu-like symptoms. Although Zika does not affect our beloved pets, it serves as an important reminder of the numerous other mosquito-borne infectious diseases that do infect our canine friends.
Canine infectious diseases that are spread by mosquitos include heartworm, malaria, wuchereria bancrofti (lymphatic filariosis), dirofilaria repens (subcutaneous dirofilariosis), dengue fever, west nile virus, yellow fever, chikungunya fever, Rift-Valley fever, and tularemia. While most of these diseases are not currently present in the U.S., globalization and a changing climate pose a potential threat of emergence in the future. The majority of these diseases are zoonotic, meaning they may be transferred from animals to people. Often times transmission does not occur directly, but rather involves a vector. For example, subcutaneous dirofilariosis is transferred from animals to people by the same mosquito, Aedes aegypti, that infects dogs with heartworm. Although not yet present in North America, subcutaneous dirofilariosis is common in Southern Europe, where dogs are the main reservoir. It is also found in Eastern Europe, Asia, and Africa. A large proportion of pet owners in Mississippi have their animals on heartworm preventative, but the majority of these products will not protect against other mosquito-borne diseases.
Canine heartworm preventatives have come a long way and, given they are used consistently, are a fantastic defense against the disease. However, common preventatives attack the nematode after it has already invaded the body, but do nothing to actually prevent the mosquito itself from biting the dog. Therefore, while your dog is protected now, there is a concern of what the future may bring with a current trend of emergent zoonotic infectious diseases on the rise. Luckily, certain compounds have already been discovered to effectively repel mosquitos from treated dogs.
In one study, a 65% permethrin spot-on formulation reduced mosquito landing rates by 96.3% in dogs after treatment. Permethrin is the main ingredient in both K9 Advantix and Vectra-3D, the only two monthly topical products currently proven to actually repel mosquitos on the canine. Vectra-3D consists of dinotefuran and pyriproxifen, in addition to permethrin, and is proven to cause an over 80% reduction in mosquito landings. K9 Advantix is made up of Permethrin, Pyriproxyfen, and Imidacloprid. Another study found that a 10% imidacloprid and 50% permethrin compound had 94.1% repellent efficacy. Studies such as these prove that we can be one step ahead of mosquitos and two steps ahead of the diseases they carry.
We can sleep well at night knowing our dogs are protected with the best drugs on the market, but should still remain mindful of how quickly Zika invaded our backyard and prepare for what might be next to come. Thankfully, we already have the technology to fight these mosquitos, we just might have to switch from our tried and true products, to something new.
- Zika Virus and Animals FAQ (AVMA):
- Zika and Animals (CDC):