What are ticks?
Ticks are small ectoparasites, meaning they live on the outside of their host, and are members of the arachnid family (spiders and mites are also members of this family). There are over 800 species of tick, and their distribution is worldwide. Australia has around 70 species of tick. There are several diseases cats can pick up from tick bites which we will cover below.
Ticks feed on the blood of mammals, birds, and some reptiles. It is during the process of feeding that the tick can spread disease. Most diseases cats acquire from ticks are bacterial infections, and the tick is the intermediate host.
Then the tick feeds from an infected animal, pathogens enter the tick (via the infected blood of the host) and take up habitat in the tick’s salivary glands. Specialised mouthparts inject into the skin along with saliva, which contains anesthetic like properties as well as anticoagulants so that the host (your cat) can’t feel the bite and the blood doesn’t clot during feeding. Some ticks also inject a cement-like substance, to firmly secure themselves. When saliva enters the new host, pathogens may also be transmitted.
Ticks thrive in warm, humid, wooded areas. They are more prevalent in the summer months, although in warmer climates (such as Australia) they occur year-round.
This is the most commonly known disease that can be passed on by ticks. Caused by the bacteria Borrelia burgdorferi which lives in the blood of mammals. When the tick feeds on an infected animal (commonly a deer, rodent or raccoon) often a deer or raccoon), the bacteria are transmitted to the tick, and then passed on to the next animal it feeds on. The tick must be on the cat for 24 hours for transmission to occur, that is how long it takes the bacteria to migrate from the gut to the salivary glands.
Lyme disease is most prevalent in the Northern Hemisphere, particularly the United States. Transmission is most often via the deer tick, Ixodes dammini. All vertebrates can become infected with Lyme disease; humans and dogs are much more likely to become infected than cats.
Some cats may remain asymptomatic. In others, it can take weeks or months for symptoms to appear, which may include:
- Joint swelling
- Anorexia (loss of appetite),
- Swollen lymph nodes
A four-week course of antibiotics (doxycycline, cefuroxime or amoxicillin. Sometimes a second course of antibiotics will be necessary.
Also known as bobcat fever, cytauxzoonosis is a rapidly fatal disease caused by Cytauxzoon felis, a single-celled protozoan that affects cats in the south-central and southeastern parts of the United States. Its natural host is the bobcat, who appear to have the infection without signs. The lone star tick is responsible for the transmission of this disease.
The parasite has two life stages once inside the cat: the leukocytic or tissue phase and the erythrocytic piroplasm phase. During the leukocytic phase, the parasite invades white blood cells (macrophages) throughout the body where it asexually reproduces forming schizonts. As this occurs, white blood cells dramatically increase in size, blockages occur within the small blood vessels of many vital organs resulting in tissue necrosis due to the inadequate blood supply. Schizonts develop into merozoites which break out of the white blood cells and infect the red blood cells; this stage of the disease isn’t as severe as the tissue phase.
Symptoms cytauxzoonosis appear between 5-15 days after the tick bite and can often be vague and nonspecific, but may include:
- Loss of appetite
- Difficulty breathing
- Enlarged spleen
- Pale mucous membranes
Antiprotozoal drugs to kill the parasite, and supportive care. Prognosis is guarded and many cats succumb to this disease.
Also known as rabbit fever, tularemia is an infection caused by the bacteria Francisella tularensis. This infection is of importance as it is zoonotic, which means it can be passed on from a cat (and other infected animals) to humans. Transmission can occur when the cat eats an infected animal, inhaling the bacteria from soil, drinking contaminated water and via tick bites. The four ticks involved are the wood tick, lone star tick, and the American dog tick. This disease is more prevalent in the summer months.
Symptoms appear between 1-10 days after exposure and may include
- Loss of appetite
- Enlarged lymph nodes
Antibiotic therapy must be initiated early or the prognosis is poor.
Also known as feline infectious anemia, hemobartonellosis is a disease caused by a type of bacteria known as Mycoplasma hemofelis. These unusual bacteria have no cell wall; they attach to the wall of red blood cells. The cat’s immune system recognises these foreign invaders and launches an attack, this results in the death of the red blood cell hosting the pathogen, resulting in anemia in the cat. Transmission can occur via ticks, fleas, cat bites, blood transfusions and from the mother to her kittens in utero.
Symptoms of feline infectious anemia are typically due to anemia that the cat develops and include:
- Pale mucous membranes
- Fast heart rate
- Enlarged spleen and lymph nodes
Antibiotics to kill the bacteria, corticosteroids to dampen the immune response and prevent further destruction of red blood cells.
Oxygen therapy for cats having difficulty breathing, and in severe cases, a blood transfusion may be necessary.
Babesiosis is caused by single-celled parasite protozoa of the genus Babesia. Infection can occur via a tick bite, blood transfusion, from the mother in utero, or via a cat bite. The incubation of babesiosis is around 10-14 days. Dogs are more commonly affected than cats; the protozoa can be found in Europe, South Africa, Asia and the United States. The highest incidence is during the warmer summer months.
The parasite enters the red blood cells where it divides. Eventually, the infected red blood cells rupture, releasing merozoites, which then invade more red blood cells. The pathogenesis is hemolytic anemia, which occurs in two ways.
- Merozoites rupture and destroy the red blood cells
- The cat’s immune system destroys infected red blood cells
Symptoms can range from mild to severe, cats with poor immune systems are more at risk of developing clinical signs which may include poor coat condition, lethargy, loss of appetite and occasionally jaundice.
Anti-malarial drugs to kill the parasite. Your cat may require a blood transfusion if the anemia is serious enough.
Some species produce a neurotoxin that can cause paralysis and death in cats. Most cases of tick paralysis occur in the United States and Australia. In Australia, Ixodes holocyclus (also known as Paralysis Tick) is the species capable of causing paralysis. The two main species in America are the American Dog Tick and the Rocky Mountain Wood Tick. When the tick attaches to the host (in this case your cat), it injects a neurotoxin produced by the salivary gland into the cat. Left untreated, this can be fatal in cats.
The Australian paralysis tick causes more severe and life-threatening symptoms than the American Dog Tick or Rocky Mountain Wood Tick.
It takes between 3-5 days after the tick has attached for symptoms to develop. These may include:
- Loss of appetite
- Excessive salivation
- Dilated pupils
- Loss of ability to meow
Later stages of poisoning are
- Wobbly gait
- Laboured breathing
Without immediate and aggressive treatment, the cat will die.
- Oxygen therapy
- Supportive care
Tick paralysis is widespread along the east coast of Australia. The veterinary practice I use for my cats (in a small town) sees around 30 cases every month. Diligent tick control should be maintained, particularly in high-risk areas.
Reducing the risk
Don’t allow your cat to roam outside; keep him confined to a cat enclosure.
If he does go outside, check him daily for ticks. Start from the head and slowly work your way all along his body to the tail. Make sure you check between the toes too.
Make sure the cat is on a regular tick preventative.