Heat Stress, Heartworms & Lyme Disease Are Outdoor Dangers To Labrador Retrievers

image of black Labrador running


An outgoing, friendly breed, the Labrador Retriever is often described as an ideal companion. Owners and trainers should take preventive steps to avoid the potential dangers of heat stress, heartworms and Lyme disease.

Heat Stress Watchouts    
Veterinary emergency and critical care specialist Justine Lee, DVM, DACVECC, DABT, says, “If you add the outdoor temperature to the humidity level and it equals 160 or more, then it’s too hot to exercise a dog. Senior dogs, obese dogs, and dogs with underlying health problems may not be able to tolerate even the 160 combination.”

According to a retrospective study of 54 cases of heatstroke in dogs between 1999 and 2004 published in 2006 in the Journal of Veterinary Internal Medicine, several large breeds, including Labrador Retrievers and Golden Retrievers, were significantly overrepresented. Among the predisposing risk factors for heatstroke in the retrievers in the study, the article cited obesity and an active, playful character.

“Labrador Retrievers love to fetch and retrieve,” Dr. Lee says. “When they carry things like bumpers and tennis balls in their mouths in hot weather, it impedes their ability to open their mouths wide enough to pant, making them less able to thermoregulate and cool down by panting.”

Whereas a dog’s normal body temperature is between 100 to 102.5 degrees, heatstroke is a highly fatal condition in which the core body temperature reaches more than 106 degrees. Most dogs are good at controlling their core body temperature — until their temperature goes past a critical level.

Testing for Heartworms 
Known by the scientific name Dirofilaria immmitis, heartworms can be fatal in dogs. The bite of a mosquito carrying a larval form of the heartworm sets in motion the process that causes lung disease, heart failure and sometimes death. Heartworms can live five to seven years in dogs, and infected dogs can have 30 or more heartworms. Monthly preventives, such as Heartgard®, are the best way to prevent a dog from getting the disease.

Although the steps of heartworm treatment for an individual dog may vary based on the severity of disease, treatment in general involves:

  • Restricting exercise right away to help stabilize the dog. If the dog is not already on a heartworm preventive, treatment should begin.
  • Dogs that test positive for microfilariae are prescribed an antihistamine and prednisone to help reduce the risk of anaphylaxis, a potentially life-threatening allergic reaction from dying microfilariae.
  • Four weeks of twice-daily doses of the antibiotic doxycycline help to combat a potential infection from Wolbachia bacteria released by dying heartworms.
  • Once a dog is stable, injections of melarsomine, or Immiticide®, are given to kill heartworms in the heart and blood vessels. The first vaccine is followed one month later by two injections given within 24 hours.
  • During the month between vaccinations and one month afterward, dogs are not allowed to exercise due to the risk of lung embolism. Adult heartworms die a few days after vaccination. As they decompose, they break up and travel to the lungs where they become lodged in small blood vessels until they are reabsorbed by the body.

Lyme Disease & Labrador Retrievers
The most common vector-borne disease in the U.S., Lyme disease is challenging to detect because dogs rarely show signs and the poppy-seed size of the nymph form of the blacklegged tick or deer tick (Ixodes scapularis) and the Western blacklegged tick (Ixodes pacificus) is virtually impossible to recognize. A tick infected with the bacteria Borrelia burgdorferi can transmit Lyme disease in 24 to 48 hours.

Joint pain, fever, swollen lymph nodes, lethargy, loss of appetite, and lameness are signs of Lyme disease. The best prevention for Lyme disease in dogs is year-round protection. Along with taking time to check your dog for ticks after being outdoors and avoiding heavy woods and grassy areas, you are doing your part to keep your dog safe from ticks and Lyme disease.