ClinQuiz: Fast tick facts

Figure 1

1) A 3-year-old mixed-breed spayed female dog presents with fever, depression, and ocular discharge. On physical examination, the dog is in pain and has moderate muscle atrophy of the right hindlimb. A complete blood count reveals severe neutrophilic leukocytosis with gamonts seen in leukocytes in a Giemsa-stained blood smear (see Figure 1). How did the dog most likely become infected with this parasite?

A. Dog bite

B. Mosquito bite

C. Ingestion of an infected tick

2) You are practicing in a rural area in western Arkansas, one of the top five states for reported cases of Rocky Mountain spotted fever. A client with two dogs and two children who is concerned about Rocky Mountain spotted fever mentions that she checks the children and dogs once a day, removing all attached ticks, as she is aware that tick-borne diseases cannot be transmitted in less than 48 hours. How do you respond?

A. Actually, all tick-borne diseases in North America require ticks to feed for at least 72 hours before they can move from the tick to a person or dog, so you can probably cut back on checking for ticks to every three days or so.

B. Good for you! You are absolutely right that all tick-borne diseases require at least 24 to 48 hours of tick feeding before transmission. By checking and removing ticks once a day, you are protecting your pets and family from all tick-borne diseases, including Rocky Mountain spotted fever.

C. Actually, some data suggest that the Rocky Mountain spotted fever agent may be transmitted in as little as six to 12 hours of tick feeding. Limiting exposure to tick-infested areas, checking for attached ticks frequently, and carefully removing ticks as soon as you find them are the best approach.

Figure 2

3) You move from a practice in New York to one in Georgia and find that the protocols at the new practice do not recommend routinely vaccinating dogs against Borrelia burgdorferi, the agent of Lyme borreliosis. Routine vaccination of all dogs followed by annual boosters was stressed at your former practice. What do you think most likely accounts for the difference in vaccination protocol recommendations?

A. Ixodes scapularis (see Figure 2), the tick that transmits Borrelia burgdorferi in the eastern United States, is not present in the South.

B. Locally acquired, laboratory-confirmed cases of Lyme disease have not been reported in people or dogs south of Maryland or Virginia, suggesting autochthonous transmission of B. burgdorferi to dogs is rare, if it occurs at all, in this area of the country.

C. Dogs vaccinated against Lyme borreliosis will have positive test results on common in-clinic tests for antibodies, such as the SNAP 3Dx and 4Dx tests (IDEXX), so many practices choose not to administer them.

4) A client with three adult German shepherds calls for advice because his home is heavily infested with ticks. He has seen ticks crawling on the walls and in and out of the acoustic tiles in the dropped ceiling in his basement. This morning, he stepped on an engorged female tick on the kitchen floor while on his way to make coffee. He occasionally finds ticks on the dogs but never on himself or his cats. Which of the following ticks is most likely infesting this home?

Figure A

Figure B

Figure C

A. The lone star tick, Amblyomma americanum (see Figure A)

B. Ixodes scapularis, the deer tick or blacklegged tick (see Figure B)

C. The brown dog tick, or kennel tick, Rhipicephalus sanguineus (see Figure C)

5) A client comes in on a Monday morning in late April with her two Weimaraners. She took them backpacking in North Carolina over the weekend. They both have a few lone star ticks attached. She is upset because she has been applying a monthly acaricide, which she obtains from your practice. The last application was two weeks ago, and she has not bathed the dogs. She would like an explanation for why the treatment failed to keep her dogs tick-free. Which of the following explanations most likely accounts for the fact that ticks are attached to these dogs?

A. The dogs likely entered an area with massive seasonal tick pressure with lone star ticks (A. americanum), which allowed a few ticks to attach despite the overall efficacy of the product being used.

B. Amblyomma americanum has recently been shown to be resistant to commonly used acaricides.

C. The commonly used monthly acaricides are not effective against Amblyomma species ticks, the genus of tick these dogs encountered.

Susan E. Little, DVM, PhD, DEVPC

This quiz was provided by Susan E. Little, DVM, PhD, DEVPC, Department of Veterinary Pathobiology, Center for Veterinary Health Sciences, Oklahoma State University, Stillwater, OK 74078.

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