What are Opportunistic Mycobacteriosis?
Opportunistic mycobacteriosis can be zoonotic, meaning it can pass from dog to human or dog to cat. This may become a health concern and caution will need to be taken to when treating your dog. If you have a compromised immune system, it will be best to hospitalize your dog during their treatments to keep exposure to a minimum.
Mycobacteria are categorized into three groups that are based on the cultural growth patterns.
- Slow growing or opportunistic which are mycobacterium tuberculosis complex, M. bovis and M. tuberculosis, and non-tuberculous mycobacteria, M. avium intracellulare-complex species
- Rapidly growing which are non-tuberculous mycobacteria
- Difficult to grow which are mycobacteria that cause leprosy syndrome in cats and dogs
Opportunistic mycobacteriosis in dogs is rare but there has been a slight rise in cases over the past few years. Dogs that have undergone immunosuppressive therapy are at a higher risk than those who do not have a weakened immune system. Basset Hounds and Miniature Schnauzers seem to be predisposed to the infection but other breeds can also be affected. Generally. opportunistic mycobacteriosis will occur in dogs between the ages of 2 and 4.
Symptoms of Opportunistic Mycobacteriosis in Dogs
Opportunistic mycobacteriosis can be somewhat difficult to detect until it has become a severe infection. That is why it is important that if you notice any symptoms that could be signs of an infection, you have your veterinarian examine your dog. Early detection and aggressive treatments are needed for opportunistic mycobacteriosis.
- Stilted gait
- Hypermetria or inability to judge distance or force of their movements
- Muscle spasms
- Lateral recumbency
- Lymph node adenopathy
- Slight fever
Causes of Opportunistic Mycobacteriosis in Dogs
There is still not enough research available to fully understand the pathogenesis of M. bovis, M. tuberculosis and M. avium, the bacteria that causes opportunistic mycobacteriosis in dogs. There have been immunologic studies conducted but the results have been inconclusive.
It is believed that the bacteria is passed from infected dog to non-infected dog through direct contact or through ingesting contaminated food such as infected poultry or swine. Feeding a raw diet increases your dog’s risk of contracting opportunistic mycobacteriosis.
Diagnosis of Opportunistic Mycobacteriosis in Dogs
When your veterinarian first examines your dog, they will want to take down a full medical history and any symptoms that you have noticed. A full physical examination will be conducted, paying close attention to your dog’s lymph nodes and checking for abnormal shape or size.
A complete blood count will be done searching for signs of an infection. A biochemistry panel and urinalysis will also be completed. A fecal exam may be done to rule out any internal parasites.
Skin scrapings of any present lesions may be taken and cultured. It usually will take about 2 weeks for the results to be returned but it is worth the wait because you then know which antimicrobials will work best for the infection.
If the lymph nodes are swollen or misshapen, your veterinarian may opt to do a biopsy of the affected lymph node. This procedure is done under general anesthetic. A wedge shaped section of the lymph node is removed and submitted for histopathologic examination. The findings from the biopsy will determine whether or not your dog is infected with opportunistic mycobacteriosis.
Treatment of Opportunistic Mycobacteriosis in Dogs
Once your veterinarian has diagnosed opportunistic mycobacteriosis in your dog, they will then discuss what treatment options are available. Since there is the potential for zoonotic transmission from dog to human, extreme caution should be taken when treating your dog. If you have a suppressed immune system, you should not be the one to give treatments to your dog and should, in fact, stay away from your dog until they have been cleared of the infection.
Your veterinarian will discuss with you the prognosis for successful treatment, in many cases the prognosis is very poor and euthanasia is recommended. Successful treatments will depend strongly on the strength of your dog’s immune system, the level of infection, and the susceptibility to isolate the antimicrobials.
In order for treatment of opportunistic mycobacteriosis to be successful it is usually necessary for a combination of antimicrobials to be administered over a period of time, from 3 months to 12 months.
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Recovery of Opportunistic Mycobacteriosis in Dogs
Opportunistic mycobacteriosis in dogs is difficult to treat and has a low survival rate. Your dog’s prognosis will be guarded. Once treatments have begun and your veterinarian can see how your dog is responding to treatments, they will be able to give you a more specific prognosis and timeline for recovery.