Increased Numbers of Animals with Leptospirosis in Arizona

Yesterday, I received a Veterinary Alert from the Arizona Veterinary Medical Association regarding an outbreak of Leptospirosis in dogs  in Maricopa County, Arizona.  In addition to the outbreak that occurred last February, there has been a second one associated with a boarding facility. The infected dogs showed a diverse array of clinical sings from conjunctivitis to kidney failure. Some dogs showed no signs at all which is especially troubling.

Leptospirosis is a serious disease that affects dogs, cats, horses, swine, sheep, goats, deer, marine mammals and humans. Signs of leptospirosis vary greatly from mild malaise to death. The incubation period is usually 7 days. The most common signs in dogs in the early phase are fever, shivering, lethargy, decreased appetite and muscle tenderness. As the disease progresses, increased thirst and urination, abdominal pain, vomiting, eye disease, diarrhea, joint stiffness, bruising of the skin, coughing and a runny nose are just a few of the symptoms that can occur.  The exact symptoms depend upon which organ is affected. Animals with liver involvement become jaundiced (yellow color of the skin). If the nervous system is involved, animals may seizure, have problems walking or suffer neurologic deficits.

Diagnosis of leptospirosis requires special testing to identify the organism. Routine blood work, urinalysis and clotting tests will make it a rule-out but not make the diagnosis. 87-100% of dogs present with elevated creatinine and BUN.

Leptospira bacteria like to live in warm moist environments with alkaline soil. Under these conditions, the bacteria can survive for months. Infections occur through direct exposure to the urine, saliva (bite wounds) or tissues of animals infected with the disease.  It can also be contracted indirectly by contact with water, soil, food or bedding that is contaminated with the organism. The leptospires can penetrate mucous membranes and damaged skin.  In the February 2016, nine dogs tested positive for this disease in Scottsdale, Arizona. It is thought that heavy storms left standing water that was contaminated by pack rats. Unfortunately, one dog did not respond to treatment and died.

Prevention is the key to dealing with leptospirosis. Thankfully, there are two vaccines available for dogs in the United Sates. One is a bivalent which means it only contains two serovars, icterohaemorrhagiae and canicola. I recommend the other vaccine which contains 4 serovars – canicola, icterohaemorrhagiae, grippotyphosa and pomona. This vaccine is licensed for pups 6 weeks and older. The manufacturer recommends 2 doses of the vaccine given 2-3 weeks apart and then boosted annually.

More information is available at www.ncbi.nlm.nih.gov/pmc/articles/PMC3040842/. 

Sources:

-Adams, Laura. Canine Leptospirosis in Arizona, Arizona Veterinary News, Arizona Veterinary Medical Association, March 2016.

-Arizona Veterinary Medical Association, Veterinary Alert: Leptospirosis Outbreak in Dogs in Maricopa County. November 10, 2016.

-Morgan, Rhea. Leptospirosis (Zoonotic), Associate Database, Veterinary Information Network, 1/29/2014, Last updated by Kari Rothrock 1/20/2012.

 

 

Brown Dog Tick (Rhipicephalus sangineus)

The brown dog tick (Rhipicephalus sangineus) came to the United States from Europe. Both the nymphs and adults are brown in color with 8 legs. They prefer to feed on dogs but will use other animals or people when dogs aren’t available. The larvae only have 6 legs but their small size makes it hard to count. They look like seeds or speaks of dirt lodged on the skin which is how they got their nick name ‘seed tick’. These little vampires attach to the skin of their host, bite and then feed on the blood from their victim. Their saliva contains an anticoagulant to keep the blood from clotting. Unfortunately, the saliva may also contain infectious diseases including Ehrlichiosis (Tick Fever) and Babesiosis,

tick-pic

The life cycle of the brown dog tick starts with a female laying eggs in a protected crevice. The eggs hatch two weeks later producing the 6 legged nymph stage. Brown dog ticks are ‘negative geotrophic’ which means they crawl to the highest point they can find. When they are ready to feed, they crawl down and wait for a dog or other host. After feeding on a host, they drop off, climb to a high point and molt into the next stage called a nymph. The nymph finds a host for a meal and repeats the process emerging as an adult. The adult females need another blood meal in order to lay eggs. Brown dog ticks are the only tick that can complete their entire life cycle indoors. In fact, they may feed off the same animal for every stage of development. They entire life cycle can be completed in just over two months.

ticks-with-penny

Once the ticks are established in a home, kennel or shelter, they can be difficult to eradicate because the females produce large numbers of eggs, up to 5,000 eggs per well-fed female. The tick can also survive for three to five months between feedings. The best success is achieved when the animals and the environment are treated simultaneously. Since the life cycle is long, it will take several months of consistent treatment to eradicate the tick infestation.

For the dog, there are many options to choose from. Here is a list of the different chemicals.

  1. Fipronil (sprays and spot ons)
  2. Amitraz (collars)
  3. permethrin (sprays and shampoos)
  4. deltamethrin (shampoo)
  5. fluralaner (oral tablet)

Please consult with a veterinarian who is familiar with your pet’s medical history to determine the best method of treatment for your specific animal. Many of the medications take anywhere from 2-6 hours to kill the tick after it has ingested a blood meal, I recommend twice a day tick checks at the very minimum. Ticks can lodge anywhere in the body, but I find them most between the toes, on the insides of the ears, under the collar and in the underarms. When a tick is found, grasp it with a tweezers and then apply slow steady pressure until the tick is removed. Ticks do not leave their heads buried in the skin unless they are cut off from their body. This urban myth came from the fact that the saliva from the tick creates a red mark from inflammation, not from the tick leaving its head in the skin. Be sure to kill the tick after removal to keep it from infecting another animal.

For the environment, I recommend hiring a professional exterminator who is familiar with this pest. Treat the indoors as well as the outdoors. Since this tick likes to climb, the walls and ceilings must be addressed in addition to the floors. Don’t forget to check the areas under all furniture as well as between cushions. A strong vacuum is a great way to get them off the ceiling and walls. After vacuuming, remove the bag and secure it in a plastic bag to keep the ticks from escaping. In addition to treating the backyard with insecticide, it is important to keep wildlife out to prevent re-infestation. Although chain-link fence may keep bigger animals out, it does not prevent mice, rats, and other rodents from entering. At my home in Arizona, I added a 1/4 inch screen to the bottom half of my yard fence. It has done a good job of keeping rabbits, snakes and toads out of my backyard.

More detailed information on the biology of the brown dog tick is available at the University of Florida Entomology Department.

Source:

University of Florida, Entomology Department