American dog tick

Dermacentor variabilis

Identification

Both males and females have eight legs and are typically brown to reddish-brown silver-gray markings on their scutum (back plate).

Nymph

Male

Female

Engorged Female

Approximate Distribution

The American dog tick is widely distributed in the United States, from Montana to south Texas and eastward to the Atlantic coast. It’s also been reported along the Pacific coast, in the eastern United States, and in central states including Iowa and Minnesota.^{13, 14}

Hosts

As the name suggests, this is most commonly found on dogs in its adult stage. Adults will also readily attach to larger mammals like cattle, horses, and humans. At the larvae and nymph stage, it targets smaller mammals.¹³

Habitat

This tick is commonly found along forest edges and in areas with little or no tree cover, like grassy fields and scrubland. It can also be found along walkways, sidewalks, and trails.¹⁵

Diseases associated with Dermacentor variabilis^{20, 21}

Cytauxzoonosis

Cytauxzoonosis is a severe and life-threatening disease in cats caused by the parasite Cytauxzoon felis. The disease is dangerous and requires prompt action for chances of recovery. Signs of infection usually begin about 10 days after a tick bite and peak about six days later.

Clinical Signs

In cats:^{31, 32}

● Depression
● Decreased energy
● Loss of appetite
● Fever
● Dehydration
● Jaundice
Cytauxzoonosis does not affect dogs.

Diagnosis and testing

Veterinary professionals diagnose cytauxzoonosis in cats using blood tests and/or fine-needle aspiration of lymph nodes, spleen, or liver to help identify the presence of the parasite.^{31, 32}

Treatment

The recommended treatment for cytauxzoonosis typically involves the drugs atovaquone and azithromycin. It may also include supportive care such as nutritional support and IV fluids.³²

References:

31. Blood Parasites of Cats. Merck Vet Manual. https://www.merckvetmanual.com/cat-owners/blood-disorders-of-cats/blood-parasites-of-cats
32. Cytauxzoonosis in Cats. Merck Vet Manual. https://www.merckvetmanual.com/circulatory-system/blood-parasites/cytauxzoonosis-in-cats

Ehrlichiosis

Ehrlichiosis is a serious disease caused by the Ehrlichia bacteria. It affects both dogs and cats.^{33, 34}

Clinical Signs

In dogs and cats: ^{33, 34}
● Fever
● Swollen lymph nodes
● Loss of appetite
● Depression
● Muscle stiffness
● Coughing
If the disease progresses, long-term signs include bleeding and bruising caused by low levels of platelets in the blood.

Diagnosis and testing

Diagnosing ehrlichiosis involves a combination of observing clinical signs and conducting blood and laboratory tests, which help confirm the presence of the Ehrlichia organism and assess the severity of the infection.^{33, 34}

Treatment

The primary treatment for ehrlichiosis in both dogs and cats typically involves the use of doxycycline, an antibiotic. It can also include supportive care to address symptoms and keep your pet more comfortable.³⁵

References:

33. Ehrlichiosis and Related Infections in Dogs. Merck Vet Manual. https://www.merckvetmanual.com/dog-owners/disorders-affecting-multiple-body-systems-of-dogs/ehrlichiosis-and-related-infections-in-dogs
34. Ehrlichiosis and Related Infections in Cats. Merck Vet Manual. https://www.merckvetmanual.com/cat-owners/disorders-affecting-multiple-body-systems-of-cats/ehrlichiosis-and-related-infections-in-cats
35. Ehrlichiosis, Anaplasmosis, and Related Infections in Animals. Merck Vet Manual. https://www.merckvetmanual.com/generalized-conditions/rickettsial-diseases/ehrlichiosis,-anaplasmosis,-and-related-infections-in-animals

Rickettsiosis (spotted fever group)

Spotted fever group Rickettsiosisis a group of diseases caused by various species of the Rickettsia bacteria. They can affect both cats and dogs, though cats generally show no symptoms and may have been infected by contact with fleas, not ticks.^{38, 39}

Clinical Signs

In dogs:³⁸

● Fever
● Loss of appetite
● Swollen lymph nodes
● Painful joints
● Coughing
● Vomiting
● Diarrhea
● Swelling of face or extremities

Diagnosis and testing

To diagnose a dog, your veterinarian will likely use a combination of observing the signs and conducting blood and laboratory testing.³⁸

Treatment

Treatment typically involves the use of the antibiotic doxycycline. In addition to medication, your pet may receive supportive care and careful monitoring to help manage symptoms and ensure well-being.³⁸

References:

38. Rocky Mountain Spotted Fever in Dogs. Merck Vet Manual. https://www.merckvetmanual.com/generalized-conditions/rickettsial-diseases/rocky-mountain-spotted-fever-in-dogs
39. Flea-borne Rickettsiosis. Companion Animal Parasite Council. https://capcvet.org/guidelines/flea-borne-rickettsiosis/

Tick paralysis

Tick paralysis is caused by the exposure to neurotoxin released by a tick’s salivary glands when it bites. It’s a severe and potentially fatal condition that requires immediate veterinary attention. Both dogs and cats can be affected. Signs typically appear between three and nine days after the tick attaches, depending on the tick species.⁴³

Clinical Signs

In dogs and cats:⁴³

● Change or loss of voice
● Lack of coordination in hind legs
● Changes in breathing rate and effort
● Gagging
● Coughing
● Vomiting
● Dilated pupils

Diagnosis and testing

Diagnosis is primarily based on the presence of a tick and the observation of clinical signs. Specific laboratory tests are not typically available for tick paralysis.⁴³

Treatment

Treating tick paralysis involves several crucial steps. First and foremost is the removal of the attached tick. Supportive care, such as IV fluids and respiratory support, is also important, as is reducing anxiety and stress in your pet.⁴³

References:

43. Tick Paralysis in Animals. Merck Vet Manual. https://www.merckvetmanual.com/nervous-system/tick-paralysis/tick-paralysis-in-animals

Tularemia

Tularemia, sometimes called rabbit fever, is a disease caused by the bacteria Francisella tularensis. It’s aserious condition that affects both dogs and cats. Even with early diagnosis and treatment, the death rate among cats with tularemia is high. In dogs, early treatment is crucial to prevent death, and in some cases, prolonged treatment may be necessary.^{44, 45}

Clinical Signs

In cats and dogs:^{44, 45}

● Sudden high fever
● Swollen glands
● Decreased energy
● Loss of appetite

Some cats may show no signs of the disease, while others may become very ill.⁴⁵

Diagnosis and testing

Diagnosis involves blood tests to detect antibodies that indicate the presence of the bacteria.⁴⁶

Treatment

Treatment typically involves the antibiotics streptomycin, gentamicin, and tetracycline.⁴⁶ In dogs, early treatment is essential to prevent death, and some dogs may require prolonged treatment, depending on the severity of the infection.⁴⁴