Fort Collins Veterinary Clinic: Paws of the Rockies Animal Hospital

Summer 2007 - In this Issue: > Re-emergence of Leptospirosis > Update on Plague > West Nile Virus
Re-emergence of Leptospirosis

There are many types of bacteria that can infect dogs. Leptospirosis is a bacterial disease of dogs that can affect the blood, liver or kidneys. It is caused by bacteria that are spiral shaped. There are multiple strains of this bacteria which are responsible for causing disease. Bacteria are carried mainly by rats and other rodents, but infected dogs can also act as a source of the infection. Ingestion of infected urine is the most important means of transmission, but some forms of the bacteria can penetrate damaged or very thin skin. The incubation period (from infection to onset of clinical signs) is usually 4-12 days. Many infections do undetected, but many other cases can be life threatening. There are three main forms of the disease: hemorrhagic (bleeding), icteric (liver) and renal (kidney). In the hemorrhagic disease there is early high fever with lethargy and loss of appetite. Multiple small hemorrhages occur in the mouth and on the whites of the eyes. Bloody diarrhea and vomiting may occur. This form is often fatal.	The jaundice form begins much like the hemorrhagic form, and many of the signs are the same. It differs in the presence of a yellow color (jaundice or icterus) in the mouth and whites of the eyes. The renal form causes kidney failure. These dogs are very lethargic, anorexic, and experience vomiting. Their mouth may have a very offensive odor, and the ulcers often develop on the tongue. This form may be fatal, but recovered dogs often have chronic kidney disease. Most patients have a combination of both liver and kidney failure when presented to the hospital with illness. Treatment involves hospitalization and intensive nursing care, including intravenous fluids and antibiotics.	There is a vaccination available against Leptospirosis. Previous vaccinations provided protection against 2 of the 6 subtypes of Leptospirosis. Because of the decreased incidence of cases in this part of the country, vaccination against Leptospirosis had dropped off. More recently there have been documented cases of Leptospirosis in Denver, Boulder and Ft. Collins. The doctors at Paws of the Rockies Animal Hospital are recommending vaccination against Leptospirosis for all of their canine patients. The current Leptospirosis vaccination provides protection against 4 of the 6 subtypes. If your pet has not yet received the Leptospirosis vaccines, they will need a series of 2 boosters. After that time, the vaccine is given annual. Please call for an appointment today and get your dog protected against this potentially fatal disease.

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Update on Plague

Recently, the media has been reporting on cases of plague in the Denver Metro area. Our hospital has been receiving calls from concerned owners regarding the specifics of plague and the risk to their pets. This article will shed some light on the specifics of plague and ways to protect yourself as well as your pets.

Plague is caused by Yersinia pestis, a bacteria that can be found in most areas of the western United States. The hot spots for plague activity generally occur in semi-arid, cooler climates usually adjacent to deserts. The western United States from California to the Rocky Mountains have the most distribution of reported cases. Ninety percent of human cases of plague have been reported in California, Arizona, and New Mexico. Since 1949, New Mexico annually has reported more than 50% of plague cases. Epidemics of plague occur in wild rodents (rock squirrels, prairie dogs, ground squirrels, chipmunks, packrats and others). Mortality rates approach 100% in these wild species.

Most people acquire plague by the bite of an infected rodent flea. Humans can also become infected by inhaling respiratory secretions from infected cats. Inn some reports

Cats and dogs may also become infected through the bite of an infected flea.

They also can become infected if they ingest or inhale the tissue from the carcass of an infected rodent or rabbit. Cats are particularly susceptible to plague are a common source of direct exposure to humans. There are three forms of plague seen in cats and humans: pneumonic (respiratory), bubonic (swollen lymph nodes) and septicemic (systemic or whole body illness).

Signs of infection in cats may include swelling and sores around the mouth, head, and neck regions and coughing if the cats develops pneumonia due to plague. Symptoms may occur within 4-10 days after exposure to an infected flea. In the natural environment, the mortality in cats approaches 50%. Dogs appear to be less affected by plague than other carnivores. Dogs develop mild fever and lymph node swellings. Dogs can still, however, carry the infected fleas into homes where they may come in contact with humans. For this reason, flea control is important for dogs who roam in high risk areas such as prairie dog colonies or mountain and foothill areas with high rodent populations.

Signs of infection in humans include sudden onset of fever and chills, severe headache, muscular aches, nausea, vomiting, and a general feeling of systemic illness. With bubonic plague, there is extreme pain and swelling of the lymph nodes nearest the site of the flea bite, generally the groin and armpit regions. In pneumonic plague, severe coughing with frothy, bloody phlegm and labored breathing occur. Untreated cases of pneumonic plague in humans is 100% fatal.

There is specific testing available for suspected cases of plague. Because it may take several weeks to obtain a diagnosis, it is very important to treat suspected plague cases with antibiotics as soon as possible.

Flea control in both dogs and cats is very important in preventing plague transmission. Dogs and cats should not be allowed to come in contact with burrows or have access to carcasses of dead rodents or rabbits. Cats should be kept indoors as much as possible.

Owners of cats with suspected plague symptoms should seek veterinary care as soon as possible. Humans with signs of plague, after potential exposure, should seek medical care as soon as possible.

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West Nile Virus

West Nile virus is a virus that is transmitted by mosquitoes that causes encephalitis. Most infections have been identified in wild birds, but the virus can also infect horses, dogs, cats, bat chipmunks, skunks, squirrels, domestic rabbits, domestic birds and humans.

West Nile virus was first identified in the West Nile district of Uganda in 1037 and has since been found in Africa, Eastern Europe, West Asia, the Middle East and the United States.

Mosquitos draw the virus from infected birds and transmit it to animals and humans through bites. West Nile viral encephalitis develops in animals and humans when the virus multiplies and crosses the blood-brain barrier. West Nile virus is not transmitted directly from person to person, animal to person, person to animal, or animal to animal. Ticks infected with the virus have been found in Asia and Africa;however there are no verified reports of ticks spreading the virus and their role in transmission has not been determined.

The risk of becoming ill from a single mosquito bite is extremely low. In areas where mosquitoes carry the virus, less than 1% are actually infected. Even if mosquitoes are infected, less than 1% of people bitten and infected by these mosquitoes become severely ill.

Humans infected with the virus are m mild flu-like symptoms including fever, headache, body aches and in some cases, skin rash and swollen lymph glands.

Signs of more severe infections include high fever, neck stiffness, muscle weakness, convulsions and paralysis. Death rates associated with severe infection range from 3% to 15% are are highest among the elderly. Horses with infection display weakness, especially in the hind quarters. Weakness may be indicated by a widened stance, stumbling, leaning to one side and toe dragging. In extreme cases, paralysis may follow. Fever is sometimes evident, as are depression and fearfulness. Approximately 40% of cases of West Nile viral encephalitis in horses proved to be fatal during the 1999 outbreak in the U.S.

Wild birds infected with the West Nile virus in the U.S. are most often found dead; therefore, descriptions of clinical signs in the wild birds are not readily available. Nor have clinical signs associated with West Nile virus infection in dogs, cats, bats, chipmunks, skunks, squirrels, domestic rabbits, domestic birds been well described. It appears that although they may be infected, many of these other species of animals may not develop clinical signs of the disease.

Diagnosis of West Nile viral encephalitis is based in history of exposure, clinical signs and results of diagnostic blood tests. As for all viral diseases, treatment consists of providing support (i.e. hospitalization, intravenous fluids, respiratory support and prevention of secondary infections) while the affected individual’s immune system responds to the infection. A vaccine is now available for horses. For humans and other animals, limiting exposure to mosquitos is considered effective prevention.

The following actions may reduce the risk of mosquito bites and possible exposure to West Nile virus:

•	Check the integrity of screens around your home, porch, and patio
•	During the warm months, avoid outdoor activities at dusk and dawn
•	If you must be outdoors during hours when mosquitoes are most active, cover up with shoes, socks, long pants and long-sleeved shirts.
•	Use mosquito repellant on exposed skin and spray clothing with repellants containing permethrin or 35% DEET (N,N-diethyl-metatoluamide) since mosquitoes may bite through thin clothing. When using insecticides or insect repellants, be sure to only use products that are approved for use in domestic animals.
•	Eliminate stagnant water from any receptacles in which mosquitoes might breed.

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