July 11, 2019 – Borrelia, babesia and rickettsia are all pathogens with one important thing in common – all are transmitted by ticks. Being aware of tick-borne diseases is important for dog owners, not only to protect their pets, but also other family members who share the same environment.
Tick-borne diseases are a subset of vector-borne diseases, meaning that an intermediate host (often a bug) is involved in transmitting an organism to another host. Diseases are spread when a susceptible host (for example a dog) is exposed to the vector, usually through a bug bite. In most cases, the vector is essential for transmission. For example, many vector-borne diseases can’t be transmitted from dog to dog or dog to human or vice versa.
Ticks are a specific type of vector and they belong to the arachnid family of arthropods. They share a lot of similarities with another notable denizen of this family – spiders.
Ticks live everywhere in the United States and are capable of carrying a lot of different pathogenic bacteria. Some of the more notable diseases spread by ticks include Lyme disease, Rocky Mountain spotted fever, and babesiosis. While there are some exceptions, most tick-borne diseases that affect humans also make dogs sick. And, there are a few diseases that are specific to dogs.
There are a few exceptions to the rule that tick-borne diseases are transmitted by a tick bite. Canine hepatozoonosis, for example, occurs when your dog eats an infected tick. This disease can be very debilitating to dogs without prompt veterinary care. The causative agent is the protozoan Hepatozoon americanum, which causes fever, pain and lameness in dogs. The disease is most common in the southern United States and is considered an emerging disease.
Another important condition caused by ticks is tick paralysis. Tick paralysis is caused by a toxin present in tick saliva. When a dog gets bitten by enough ticks, the toxin in the saliva causes paralysis. Tick paralysis is a serious but treatable disease with an excellent long-term prognosis if identified and treated before paralysis of the respiratory muscles occurs.
What to Look For
Although there are a number of different pathogens ticks can give to our dogs, many tick-borne diseases have similar symptoms. These include:
- fever (sometimes intermittent)
- loss of appetite
- decreased activity
The severity and duration of symptoms can vary greatly. Some dogs recover from tick-borne illnesses with little or no signs of illness. Other dogs become chronically infected and experience serious losses in quality of life and longevity. The reasons why these diseases can have a wide range of symptoms is an important and active area of research. Most researchers believe an individual dog’s response is due to a complex interaction between the genetics and environment of the host, vector and pathogen.
The situation gets even more complicated when we consider establishing a diagnosis of tick-borne disease – a tricky problem. These conditions are notoriously difficult to definitively diagnose for a lot of reasons, including:
- Pathogens hide out in a dog’s cells, making them invisible to the immune system and many diagnostic tests
- Symptoms are similar to lots of other diseases
- Symptoms might not appear for months after exposure
Treatment for a tick-borne disease involves antibiotics (sometimes for many months or lifetime in some cases) and addressing the symptoms of infection with supportive care and anti-inflammatory medications.
What You Can Do
The good news is that there are many prevention strategies to keep ticks off your dog. For tick-borne diseases, an ounce of prevention is truly worth a pound of cure!
Ticks tend to live in tall grass and brushy areas so keeping your dog on the trail will help mitigate access to ticks. Keeping your grass cut and trimming and removing brush from your yard can take away important tick hiding places.
Another important source of tick exposure for dogs and humans is at the interface with wild animals, so limiting your dog’s access to wildlife can minimize tick exposure. In addition, daily tick checks are vital to preventing disease transmission because the tick must attach for 36 hours before it can introduce most diseases to a host. If you find a tick, carefully remove it and put it in rubbing alcohol. Remember that ticks can be very small so you may not find all of them – a fine-toothed comb can help uncover these tiny hitchhikers.
There also are many different preventives available, including a variety of medications as well as vaccines. It’s important to talk to your veterinarian to devise the best prevention strategy for your dog based your location, lifestyle and relative risk of infection.
An excellent source for more information about important tick species, where they live and the diseases they carry, is the Centers for Disease Control and Prevention. They have detailed maps that show the regions where certain diseases are most prevalent.