Actinomycosis in Dogs
Actinomycosis is an infectious disease caused by gram positive, branching, pleomorphic (can change shape somewhat between a rod and coccus), rod-shaped bacteria of the genus Actinomyces, most commonly the A. viscosus species. Able to survive with little (microaerophilic) or no oxygen (anaerobic), Actinomyces is rarely found as the single bacterial agent in a lesion. It is more often a component of a polymicrobial infection with several bacteria present. In fact, there may even be synergism between Actinomyces and other organisms.
Symptoms and Types
- Pain and fever
- Infections on the face or neck area; usually localized but may be spread out
- Skin swellings or abscesses with draining tracts; sometimes yellow granules
- Inflammation of the cellular tissue behind the peritoneum, the smooth membrane which lines the abdomen (retroperitonitis)
- Inflammation of the bone or vertebrae (osteomyelitis), especially long bones such as those found in the limbs; this is secondary to the skin infection
- When associated with spinal cord compression, motor and sensory deficits (i.e., trouble walking, touching, etc.)
Causes
Actinomycosis is thought to occur as an opportunistic infection; i.e., Actinomyces spp. is a normal inhabitant of dog's mouth, but cuts, scrapes, or bite wounds in the mucosa or skin can cause an imbalance in the bacterial microenvironment. Other risk factors include periodontal disease and immunosuppressive disorders.
Diagnosis
You will need to give a thorough history of your dog’s health, including the onset and nature of the symptoms, to the veterinarian. He or she will then perform a complete physical examination as well as a biochemistry profile, urinalysis, complete blood count, and electrolyte panel. X-rays of dogs with actinomycosis will typically demonstrate periosteal (outer layer of bone) new bone production, reactive osteosclerosis (hardening of bone), and osteolysis (dissolution of bone).
For a more definitive diagnosis your veterinarian will submit a specimen of pus or osteolytic bone fragments for culturing. Gram staining, cytology, and acid-fast staining may also be employed.
osteomyelitis
A medical condition in which bone and bone marrow becomes inflamed
peritoneum
The membrane that covers the wall of the abdomen and pelvic area
urinalysis
An in-depth examination of the properties of urine; used to determine the presence or absence of illness
opportunistic
The ability to create a disease where a disease might not normally be found, usually due to an ill timed or unlikely weakness
pus
A product made of fluid, cell waste, and cells
microbes
The term for plant life or animal life that is microscopic
anaerobic
a) living in an environment lacking free oxygen b) pertaining to an organism with the ability to live in an environment lacking free oxygen.
genus
The species that a living thing has descended from
lesion
A change in the way that tissue is constructed; a sore
acid-fast
Resists the effects of acids; has less of a chance of losing color due to acidic properties
