Canine Tick-Borne Diseases

Canine tick-borne diseases are a growing concern for veterinary professionals across North America. According to the Companion Animal Parasite Council (CAPC), in 2023:

3.93% (1 in 30 dogs) tested positive for Lyme disease
5.62% (1 in 20) tested positive for Anaplasmosis
2.75% (1 in 30) tested positive for Ehrlichiosis

With the expanding range of tick vectors, the disease that these ticks carry as a result of temperature fluctuations, the movement of animals and people, and the ever-present threat of zoonotic transmission, staying vigilant and informed about these illnesses is of paramount importance. These diseases can cause a variety of concerning symptoms, from lethargy and fever to joint pain and neurological complications. With early detection and diagnosis, treatment can be started immediately, which can improve the prognosis.

Tick-borne disease develops when ticks carrying a pathogen bite a dog and transmit the pathogen to the dog’s body. Many of these pathogens are zoonotic, indicating their ability to infect humans too. Transmission of disease between dogs and humans does not occur directly. The pathogens responsible for the diseases need to undergo a certain lifecycle phase within ticks to cause infection.

Common ticks in North America

Ixodid ticks of the most importance to dogs in North America include:

Amblyomma americanum (Lone Star tick)
Amblyomma maculatum (Gulf Coast tick)
Dermacentor variabilis (American dog tick)
Haemaphysalis longicornis (longhorned or bush tick)
Ixodes pacificus (western black-legged tick)
Ixodes scapularis (eastern black-legged or deer tick)
Rhipicephalus spp. (brown dog ticks)

Common canine tick-borne diseases: Lyme Disease

Vector	Signs	Diagnosis	Treatment	Prevention
Ixodes scapularis (Black-Legged Tick, Deer Tick)	Fever, lameness, joint pain/swelling, enlargement of lymph nodes, and lethargy Kidney disease can be a major complication	Antibody Tests Lyme Multiplex assay ELISA (enzyme-linked immunosorbent assay) -based diagnostic tests	Doxycycline for 28-30 days Amoxicillin can be administered to dogs that can’t tolerate doxycycline. Ceftriaxone can sometimes be used for severe cases and administered IV	Vaccination

Common canine tick-borne diseases: Anaplasmosis

Vector	Signs	Diagnosis	Treatment	Prevention
Ixodes scapularis Ixodes pacificus Ixodes ricinus Rhipicephalus sanguineus	Fever, lameness, joint pain/swelling, loss of appetite, vomiting, diarrhea, enlargement of lymph nodes, lethargy, low blood platelets (cyclic thrombocytopenia) Extreme cases can lead to seizures.	Enzyme-linked immunosorbent assay (ELISA) Indirect fluorescent antibody (IFA) assay for immunoglobulin G (IgG) using A. phagocytophilum antigen Polymerase chain reaction (PCR) test Immuno-histochemical (IHC) assays	Doxycycline for 2-4 weeks	Aggressive year-round tick preventive measures No vaccine

Common canine tick-borne diseases: Ehrlichiosis

Ehrlichiosis is also called tracker dog disease and tropical canine pancytopenia.

Vector	Signs	Diagnosis	Treatment	Prevention
Rhipicephalus sanguineus Amblyomma americanum (Lone Star Tick) Ixodes scapularis Dermacentor variabilis (American dog tick)	Fever, lethargy, poor appetite, and low blood platelets (noted by nose bleeds, bruising, anemia), and neurological disturbances (rare)	ELISA or DNA/PCR	Doxycycline for 4 weeks Supportive medications such as steroids may be needed	Aggressive year-round tick preventive measures No vaccine

Common canine tick-borne diseases: Babesiosis

Vector	Signs	Diagnosis	Treatment	Prevention
Ixodid ticks Rhipicephalus sanguineus	Hemolysis (dark-colored urine, jaundice), lethargy, fever, weakness, pale mucous membranes, depression, enlargement of lymph nodes, and an enlarged spleen Sudden collapse with systemic shock	FA (fluorescent antibody) test ELISA PCR	Azithromycin and Atovaquone combination Imidocarb Clindamycin Other supportive treatments, such as blood transfusions and intravenous fluids, may be recommended.	Aggressive year-round tick preventive measures A vaccine based on some types of Babesia is available, but it doesn’t protect against all types.

Common canine tick-borne diseases: Rocky Mountain Spotted Fever (RMSF)

Vector	Signs	Diagnosis	Treatment	Prevention
Dermacentor variabilis Dermacentor andersoni (Rocky Mountain Wood Tick) Amblyomma americanum Ixodes scapulari Rhipicephalus sanguineus	Fever, poor appetite, swollen lymph nodes, joint pain, swelling of the face or legs, low platelet count, neurological signs, such as ataxia, weak limbs, and painful hypersensitivity In severe cases, necrosis of the extremities	Indirect Immuno-fluorescent Assay (IFA) test	Doxycycline for 7-21 days Tetracycline for 14-21 days (requires more frequent administration) Enrofloxacin Chloramphenicol	Aggressive year-round tick preventive measures No vaccine

Common canine tick-borne diseases: Hepatozoonosis

Vector	Signs	Diagnosis	Treatment	Prevention
Amblyomma maculatum (Gulf Coast Tick) Brown dog tick	Myalgia, reluctance to stand or move, lethargy, decreased appetite, fever, unexplained weight loss, muscle wasting, and mild-to-moderate anemia, ocular and nasal discharge Severely debilitating and often fatal Infected dogs rarely show signs of illness. With high parasite numbers, the condition can be potentially severe and life-threatening. Fever, weight loss, lethargy, anemia, and enlarged spleen.	Microscopic examination of the dog’s blood PCR to identify and distinguish between H. americanum and H. canis ELISA Muscle biopsy	H.americanum can be managed but not cured. Parasiticidal treatment (either of the two can be administered) H.canis generally is not cured; typically managed with 1-4 injections of imidocarb. Oral doxycycline (antibiotic) may be combined with imidocarb injections.	Aggressive year-round tick preventive measures No vaccine

Differential diagnosis for canine tick-borne illnesses

Diagnosing tick-borne disease in canines is a complicated process. Many of these tick-borne conditions manifest similar clinical signs, thus highlighting the need for an accurate differential diagnosis.

Clinical symptoms can be non-specific during the early stages of tick-borne illnesses in dogs. Therefore, it’s necessary to consider other potential causes before reaching a definitive diagnosis. Fever, lethargy, and loss of appetite can be associated with various other health issues. This makes it necessary to explore other potential causes before making a final diagnosis.

Also, tick-borne diseases in dogs may have similar symptoms to other medical conditions like immune-mediated polyarthritis, leptospirosis, etc. Eliminating possible conditions can help guarantee appropriate treatment for the underlying cause, leading to optimal outcomes.

To effectively navigate the differential diagnosis, veterinarians should take into consideration several important factors:

Detailed medical history
A comprehensive physical examination
Specific diagnostic tests such as serological tests, bloodwork, urinalysis, and imaging techniques

Pet owner education

Keeping dogs tick-free is a multi-pronged approach. Educating pet owners about tick control empowers them to take an active role in safeguarding their dogs. Here are some tips on how veterinarians can educate pet owners about tick prevention.

Explaining the threat: Discuss the prevalence of tick-borne diseases in the region and the potential health risks they pose to dogs.
Acaricides: What types of acaricides are available (topical medications, collars, chewable tablets, spot-on, etc.)? Explain the advantages and disadvantages of each product (in terms of ease of use, cost, duration of protection, etc.). Highlight the importance of choosing a product that’s effective against tick species that are prevalent in the area. It’s also important to advise pet owners why they should strictly follow the recommended dosing schedule.
Environmental control measures: Discuss the importance of regular lawn maintenance and professional yard treatment for tick control.
Regular tick checks: Emphasize the importance of routine tick checks, particularly after outdoor activities. Teach pet owners how to perform tick checks. Show them what areas to focus on, such as ears, armpits, paws, and the base of the tail. Demonstrate how to properly remove ticks using fine-tipped tweezers. Emphasize the importance of prompt removal to minimize the risk of disease transmission.

Conclusion

Canine tick-borne diseases pose a significant threat to our furry friends.Vigilance and a comprehensive understanding of these illnesses are of optimum importance.

Veterinarians play a vital role in protecting dogs from canine tick-borne illnesses. With vigilance, diagnostic tools, and appropriate treatment protocols, veterinarians can contribute to optimal patient outcomes. By educating pet owners on tick prevention strategies, veterinarians can help reduce the risk of tick-borne diseases in both animals and humans.