Equine Health Update EHU Vol 20 Issue 02 | Page 34

EQUINE | International News

EQUINE | International News

One case of equine neorickettsiosis was recorded in Washington State , USA . Rotaviral enteritis was confirmed in Argentina ( two outbreaks in 2-month-old Thoroughbred foals on separate premises ) and France ( a single case ).
The USA reported cases of proliferative enteropathy caused by Lawsonia intracellularis in Kentucky ( 10 cases ) and Pennsylvania ( one case ).
Clostridial enteritis / enterocolitis due to Clostridium perfringens Type C toxin was linked to six cases of disease in Kentucky . The USA confirmed 30 cases of Eastern equine encephalomyelitis in the fourth quarter of 2017 , 12 of which were diagnosed in Wisconsin .
103 cases of West Nile encephalitis were reported across numerous states in the USA , with New York and Utah each responsible for 26 cases . Rhodococcalrelated disease is endemic in the USA , with eight cases confirmed during the review period . Infection with Corynebacterium pseudotuberculosis , the cause of Pigeon Fever is endemic in the USA ; a single case was diagnosed in Washington State .
Cutaneous Lymphangitis
The lymphatic system is an important component of the cardiovascular system and consists of lymphatic vessels , lymph nodes , tonsils , spleen , and thymus . Lymph , which is a clear colorless fluid , is formed from fluid loss that occurs during normal nutrient exchange in capillary beds . Lymph is transported by lymphatic vessels to regional lymph nodes for filtration to aid in immunologic detection of microorganisms , toxins , and foreign material . Once filtered , the lymph is again transported by lymphatic vessels to large veins , which ultimately return it back into the circulatory system to replenish the fluid lost from the capillaries .
Lymphatic disease can occur when lymph vessels become inflamed , leaky , and / or blocked . Cutaneous lymphangitis — inflammation of lymphatic vessels of the skin — is fairly uncommon in horses , does not exhibit age , sex , or breed predilections , and can develop from both infectious and non-infectious causes . Clinically , cutaneous lymphangitis can manifest as a swollen limb , skin abnormalities characterized as multiple skin nodules that can abscess or develop draining tracts , and / or lameness . Cutaneous lymphangitis typically affects the distal portion of a single hind limb , between the hock and hoof . Due to the characteristic appearance of affected limbs , the disease is commonly referred to as “ big leg ” or “ fat leg .”
Infectious cutaneous lymphangitis has traditionally been associated with poor hygiene and insect transmission of microorganisms . It is sporadically diagnosed in horses , but sometimes occurs simultaneously in multiple horses on the same farm . Infection of the lymphatic system develops following contamination of skin wounds by various bacteria , most commonly Corynebacterium pseudotuberculosis ( the causative agent of ulcerative lymphangitis / pigeon fever ). However , pure or mixed infections with other bacteria , such as Staphylococcus sp ., Streptococcus sp ., Trueperella pyogenes , Rhodococcus equi , Pasteurella haemolytica , Pseudomonas aeruginosa , Fusobacterium necrophorum , Actinobacillus equuli , and Burkholderia mallei ( the cause of glanders ) can also result in cutaneous lymphangitis . Additionally , pathogenic fungi such as Sporothrix sp . ( the cause of sporothricosis ) or Histoplasma farciminosum ( the cause of epizootic lymphangitis ) also have been associated with lymphatic system infection . The USA is currently free from glanders and epizootic lymphangitis . Treatment of infectious cutaneous lymphangitis includes appropriate antimicrobials , nonsteroidal anti-inflammatory drugs , hydrotherapy , and surgical fluid drainage .
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