Saturday, September 8, 2012

Salmonella – A Significant Problem, Or Not?

by Jennifer Coates, DVM

If you spend much time on websites dedicated to canine nutrition, you’re bound to run into a debate over Salmonella.

In general, veterinarians have considered salmonellosis (disease caused by infection with Salmonella bacteria) to primarily be a problem in dogs that are fed raw or undercooked meats. However, this summer’s Diamond pet food recall shows that to protect both dogs and people, all owners need to be informed about the disease, regardless of what they feed their pets.


Canine salmonellosis is an interesting condition. 

Many healthy, adult dogs that become infected never show any clinical signs – dogs are actually quite resistant to the disease. These individuals are still problematic, however, because they are capable of infecting people and other animals when they shed the bacteria in their feces.

It’s the very young, very old, or dogs that are stressed or have compromised immune systems that are at the greatest risk for developing salmonellosis.

Let’s take a look at what happens in a dog’s body when its natural defenses cannot keep Salmonella under wraps.

Salmonella bacteria that survive their trip through the acid environment of the stomach attach to the tips of intestinal villi, the tiny finger-like projections, covering the inner surface of the small intestine that greatly increase the organ’s surface area and absorptive capacity.

From there, they invade deeper into the lining of the intestine and multiply. 

This process, along with the inflammatory response that results, leads to tissue injury, death, and sloughing, thereby reducing the intestine’s absorptive surface area, causing liquid to leak through the intestinal wall, and disrupting the motility of the intestinal tract.

The bacteria can survive in and be shed from a dog’s intestinal lining for at least three to six weeks after infection has occurred.

Salmonella can also hide out in cells within intestinal lymph nodes, the spleen, or liver. 

When these “carrier” dogs become stressed or immunocompromised, the bacteria can take advantage of the situation and become active again, producing illness and/or fecal contamination.

The most common clinical signs associated with a Salmonella infection that is limited to a dog’s digestive system are diarrhea (often containing mucus or blood), fever, lethargy, loss of appetite, dehydration, weight loss, and abdominal pain.

If damage to the intestinal lining is significant enough, Salmonella bacteria have direct access to a dog’s blood stream.

This can lead to septicemia (the presence of bacteria within the blood) and endotoxemia (the release of bacterial toxins into the blood stream when some types of bacteria die or are damaged).

These potentially life threatening conditions produce symptoms such as pale mucous membranes, rapid breathing, a rapid heart rate, collapse, seizures, shock and death, often as a result of disseminated intravascular coagulation (a condition during which blood fails to clot or clots inappropriately throughout the body) and multiple organ failure.

So, even though Salmonella infections rarely cause disease in healthy dogs in the prime of their lives, its potential effect on puppies, older dogs, sick animals, and people is so catastrophic that all dog owners should pay the bacteria the respect it deserves.

***

Jennifer Coates, DVM graduated with honors from the Virginia-Maryland Regional College of Veterinary Medicine in 1999.  In the years since, she has practiced veterinary medicine in Virginia, Wyoming, and Colorado.  She is the author of several books about veterinary medicine and animal care, including the Dictionary of Veterinary Terms: Vet-speak Deciphered for the Non-veterinarian

Dr. Coates has recently joined the PetMD team and she is now writing for the Fully Vetted column; great blog, do check it out.

Jennifer also writes short stories that focus on the strength and importance of the human-animal bond and freelance articles relating to a variety of animal care and veterinary topics.  Dr. Coates lives in Fort Collins, Colorado with her husband, daughter, and pets.


Articles by Dr. Coates:
Kidney Disease – Say What? 
What Happens In The Dog's Body When The Kidneys Fail To Function Properly? 
Heat Stroke: What Happens In The Dog's Body?  
The Perplexities of Pancreatitis
The Other Side Of The Coin: The Cost Of Defensive Medicine
To Neuter Or Not To Neuter… That Is The Question
Don’t Forget the Physical Therapy
Common Misdiagnoses (Part 1)
Common Misdiagnoses (Part 2)
Picking the Right Dog to Breed
When Is It An Emergency?
Dog Allergies: Common, Commonly Misdiagnosed, or Both? 
Why Does The Spleen Get No Respect?
Protect Your Dog From Snake Bites 
More Creepy Crawlies
Why I Dislike Inflammatory Bowel Disease 

3 comments

  1. That's super scary - love all the information you share on your site with us :)

    Wags to all,

    Your pal Snoopy :)

    ReplyDelete
  2. This is excellent info. I agree that for most healthy dogs, salmonella is really not a risk. For those humans with compromised immune systems immediate poop pick up and an attention to cleanliness (and common sense) can really decrease that risk too. After all, I wouldn't let me toddler or ailing relative handle the raw chicken at dinner, why on Earth would I let them play in an environment with feces lying around? GROSS.

    ReplyDelete
    Replies
    1. Yes, common sense is all that should be needed. (Is common sense still common sense when it's not so common any more?)

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