Mycobacterium Avium Infection

What is ATB?

ATB (aka AVTB) ~ mycobacterium avium is a mycrobacterial infection in the tuberculosis family.  It is an environmental pathogen that is believed to be contracted through contact with infected bird droppings, contaminated water,etc.  While it is a disease primarily found in birds, it has also been diagnosed in dogs, cats, goats, rabbits and humans with compromised immune systems.  While the symptoms may be temporarily suppressed by antibiotics and certain drugs used for HIV patients, it is almost always fatal to the host.  Most miniature schnauzer cases are not diagnosed until the dog is 11/2 years or older.

ATB is Frequently Misdiagnosed

The disease is frequently misdiagnosed as it resembles lymphatic cancer (lymphosarcoma), and other cancers/illnesses.


The main symptoms include lethargy/weakness, anorexia (loss of appetite), extremely swollen lymph nodes.  Other symptoms may include diarrhea, vomitting, and fever and lameness.  Specific cultures must be taken to diagnose the disease.  A dog diagnosed with AVTB should have blood samples drawn and stored (for DNA purposes), and be humanely euthanised as quickly as possible to avoid unnecessary suffering.  The disease is described as a wasting disease, not unlike AIDS.

Some History

The first known case in minis was diagnosed approx ten years ago, and at the time, believed to be a 'fluke'.  Since then dozens more confirmed cases and an even larger number of suspected cases have been diagnosed.  It is believed that a genetic mutation occurred, leading to a compromised immune system.  All these dogs have in common a genetic heritage, specifically traced to an American bitch who was the dam of several popular bloodlines.  These bloodlines travelled throughout the US, Canada, and eventually Europe.

The Defect

It should be noted that the genetic 'flaw' (the inability of the dog's immune system to defend against certain infections a mini schnauzer could normally fight off ) which allows dogs to contract AVTB was not seen in the first two generations (it was carried, however), and the breeders/owners of the dogs at that time would not have known there was a potential problem.  The defect appears to work as a recessive, and so it was not until the 2nd and 3rd generations were bred to one another that the problem surfaced.  Even then, it is a later onset disease, so the disease was at least five years away from the original mutation.  Several dogs, (later discovered to carry the defect) stood at stud or were exported to Europe.


Without question, dogs in European breeding programs will have inherited this defect.  Currently, dogs known to have produced cases of AVTB in North America are being offered at stud in Europe.  While crossing these dogs with bloodlines from the earlier carriers may not show problems immediately, I would predict that in two to four years, European breeders will have dogs begin to die.

Further, and very important, these dogs have the potential to be reservoirs for infection to humans who may be immune system compromised (chemotherapy, AIDS and Hepatitis patients).  I do not, by any means suggest that these bloodlines should be abandoned.  I, myself, am working to preserve this line that I love so much, however, breedings should be done prudently, and should cases appear, disclosed in the interest of helping researchers develop a test procedure that will identify carriers, before they produce affected offspring.

Research Underway

Research is currently underway at Auburn University in the US.  Two test litters have been bred, but additional DNA samples from dogs known to be affected, or carriers would be greatly appreciated.   The AMSC has suggested that dogs known to have produced affecteds be removed from public stud/offerings.    Unfortunately, for some, this appears merely to have meant shipping the dogs to kennels overseas.  I have had one affected, and one of my males has produced two.  One of the test litters for Auburn was by my bitch (with the cooperation of Errolyn Martin - Chattelane Kennels USA).  While intact for test breeding purposes, the dogs are not currently used in any general breeding program.

Determining Risk Factors In Your Line

A formula for assessing risk factors is available, assuming you are aware of potential carriers in your line.  Breeders are welcome to contact me if they are uncertain about existing risk factors.

The following links can provide more information, or readers may contact me directly with specific questions or concerns.

Tracy Hiuser
Meinkismah Reg'd

Permission to reprint this article in whole or in part should be made directly to the author.

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