This article needs additional citations for verification .(March 2012) |
Strangles (equine distemper) is a contagious upper respiratory tract infection of horses and other equines caused by a Gram-positive bacterium, Streptococcus equi. [1] As a result, the lymph nodes swell, compressing the pharynx, larynx, and trachea, and can cause airway obstruction leading to death, hence the name strangles. [2] Strangles is enzootic in domesticated horses worldwide. The contagious nature of the infection has at times led to limitations on sporting events. [3]
A horse with strangles typically develops abscesses in the lymph nodes of the head and neck, causing coughing fits and difficulty swallowing. Clinical signs include fever up to 106 °F (41 °C) and yellow-coloured nasal discharge from both the nose and eyes. [2]
Abscesses may form in other areas of the body, such as the abdomen, lungs, and brain. [1] This is considered a chronic form of strangles called "bastard strangles", which can have serious implications if the abscesses rupture. Horses develop this form of strangles when their immune systems are compromised or if the bacteria rapidly invade the body. [2]
Possible complications include the horse becoming a chronic carrier of the disease, asphyxia due to enlarged lymph nodes compressing the larynx or windpipe, bastard strangles (spreading to other areas of the body), pneumonia, guttural pouch filled with pus, abscesses, purpura haemorrhagica, and heart disease. The average course of this disease is 23 days.
The disease is spread by an infected horse when nasal discharge or pus from the draining lymph nodes contaminate pastures, feed troughs, brushes, bedding, tack, etc. [2]
Both intramuscular [4] and intranasal [5] vaccines are available, although their efficacy is rated at no more than 50%. [6] Isolation of new horses for four to six weeks, immediate isolation of infected horses, and disinfection of stalls, water buckets, feed troughs, and other equipment can help prevent the spread of strangles. [6] As with any contagious disease, hand washing is a simple and effective tool. [7]
As with many streptococcal infections, beta-lactam antibiotics (e.g penicillins) are the most effective treatments, but some authorities are of the opinion that use of antibiotics is contraindicated once abscesses have begun to form, as they predispose to lymphatic spread of the infection (bastard strangles), which has a much higher mortality rate.
After an abscess has burst, keeping the wound clean is important. A diluted povidone-iodine solution has been used with good results to disinfect the open hole, flushing the inside with a syringe-tipped catheter or with a teat cannula, followed by gentle scrubbing to keep the surrounding area clean.
Symptomatic therapy is an alternative treatment, and is where warm packs are used to mature the abscesses so making them less painful and more comfortable for the horse, but once the abscesses have been matured, they must be kept clean to prevent further infections. This treatment for S. equi only helps reduce pain for the horse rather than curing the infection.
Strangles has an 8.1% mortality rate. [2] Mortality is lower in cases without complications than it is in cases of bastard strangles. The disease is very contagious and morbidity is high. Precautions to limit the spread of the illness are necessary and those affected are normally isolated. An isolation period of 4–6 weeks is usually necessary to ensure that the disease is not still incubating before ending the quarantine.
Equines of any age may contract the disease, although younger and elderly equines are more susceptible. Young equines may lack immunity to the disease because they have not had prior exposure. Geriatric equines may have a weaker immune system.
Scarlet fever, also known as scarlatina, is an infectious disease caused by Streptococcus pyogenes, a Group A streptococcus (GAS). It most commonly affects children between five and 15 years of age. The signs and symptoms include a sore throat, fever, headache, swollen lymph nodes, and a characteristic rash. The face is flushed and the rash is red and blanching. It typically feels like sandpaper and the tongue may be red and bumpy. The rash occurs as a result of capillary damage by exotoxins produced by S.pyogenes. On darker-pigmented skin the rash may be hard to discern.
Streptococcal pharyngitis, also known as streptococcal sore throat, is pharyngitis caused by Streptococcus pyogenes, a gram-positive, group A streptococcus. Common symptoms include fever, sore throat, red tonsils, and enlarged lymph nodes in the front of the neck. A headache and nausea or vomiting may also occur. Some develop a sandpaper-like rash which is known as scarlet fever. Symptoms typically begin one to three days after exposure and last seven to ten days.
Cellulitis is usually a bacterial infection involving the inner layers of the skin. It specifically affects the dermis and subcutaneous fat. Signs and symptoms include an area of redness which increases in size over a few days. The borders of the area of redness are generally not sharp and the skin may be swollen. While the redness often turns white when pressure is applied, this is not always the case. The area of infection is usually painful. Lymphatic vessels may occasionally be involved, and the person may have a fever and feel tired.
Kennel cough is an upper respiratory infection affecting dogs. There are multiple causative agents, the most common being the bacterium Bordetella bronchiseptica, followed by canine parainfluenza virus, and to a lesser extent canine coronavirus. It is highly contagious; however, adult dogs may display immunity to reinfection even under constant exposure. Kennel cough is so named because the infection can spread quickly among dogs in the close quarters of a kennel or animal shelter.
African horse sickness (AHS) is a highly infectious and often fatal disease caused by African horse sickness virus. It commonly affects horses, mules, and donkeys. It is caused by a virus of the genus Orbivirus belonging to the family Reoviridae. This disease can be caused by any of the nine serotypes of this virus. AHS is not directly contagious, but is known to be spread by insect vectors.
Equid alphaherpesvirus 4, formerly Equine herpesvirus 4 (EHV-4) is a virus of the family Herpesviridae that cause rhinopneumonitis in horses. It is the most important viral cause of respiratory infection in foals. Like other herpes viruses, EHV-4 causes a lifelong latent infection in affected animals. These horses are usually the source for new infection for foals over two months old, weanlings, and yearlings. Symptoms include fever, loss of appetite, and discharge from the nose. Most infected animals recover in one to three weeks, but death can occur in environments with overcrowding and other stress factors. There are several vaccines available.
Equid alphaherpesvirus 1, formerly Equine herpesvirus 1 (EHV-1), is a virus of the family Herpesviridae that causes abortion, respiratory disease and occasionally neonatal mortality in horses. Initial spread of EHV-1 by a newly introduced horse through direct and indirect contact can lead to abortion and perinatal infection in up to 70 percent of a previously unexposed herd. Abortion usually occurs in the last four months of gestation, two to four weeks after infection of the mare. Perinatal infection can lead to pneumonia and death. Encephalitis can occur in affected animals, leading to ataxia, paralysis, and death. There is a vaccine available, however its efficacy is questionable. The virus varies in severity from sub-clinical to very severe. Most horses have been infected with EHV-1, but the virus can become latent and persist without ever causing signs of infection. In 2006, an outbreak of EHV-1 among stables in Florida resulted in the institution of quarantine measures. The outbreak was determined to have originated in horses imported from Europe via New York, before being shipped to Florida.
Sheeppox is a highly contagious disease of sheep caused by a poxvirus different from the benign orf. This virus is in the family Poxviridae and genus Capripoxvirus. Sheeppox virus (SPV) is the most severe of all the animal pox diseases and can result in some of the most significant economic consequences due to poor wool and leather quality.
Epizootic lymphangitis is a contagious lymphangitis disease of horses and mules caused by the fungus Histoplasma farciminosum. Cattle are also susceptible, but more resistant to the disease than equids.
A staphylococcal infection or staph infection is an infection caused by members of the Staphylococcus genus of bacteria.
Gastroenterocolitis is a condition characterized by inflammation of the stomach, small intestines, and colon.
Streptococcus zooepidemicus is a Lancefield group C streptococcus that was first isolated in 1934 by P. R. Edwards, and named Animal pyogens A. It is a mucosal commensal and opportunistic pathogen that infects several animals and humans, but most commonly isolated from the uterus of mares. It is a subspecies of Streptococcus equi, a contagious upper respiratory tract infection of horses, and shares greater than 98% DNA homology, as well as many of the same virulence factors.
S. equi may refer to:
Caseous lymphadenitis (CLA) is an infectious disease caused by the bacterium Corynebacterium pseudotuberculosis, that affects the lymphatic system, resulting in abscesses in the lymph nodes and internal organs. It is found mostly in goats and sheep and at the moment it has no cure.
Guttural pouches are large, auditory-tube diverticula that contain between 300 and 600 ml of air. They are present in odd-toed mammals, some bats, hyraxes, and the American forest mouse. They are paired bilaterally just below the ears, behind the skull and connect to the nasopharynx.
Porcine epidemic diarrhea is a condition caused by the porcine epidemic diarrhea virus that leads to severe gastrointestinal disease in pigs.
Purpura haemorrhagica is a rare complication of equine strangles and is caused by bleeding from capillaries which results in red spots on the skin and mucous membranes together with oedema (swelling) of the limbs and the head. Purpura hemorrhagica is more common in younger animals.
Pigeon fever is a disease of horses, also known as dryland distemper or equine distemper, caused by the Gram-positive bacteria Corynebacterium pseudotuberculosis biovar equi. Infected horses commonly have swelling in the chest area, making it look similar to a "pigeon chest". This disease is common in dry areas. Pigeon fever is sometimes confused with strangles, another infection that causes abscesses.
Theiler's disease is a viral hepatitis that affects horses. It is one of the most common cause of acute hepatitis and liver failure in the horse.
Corynebacterium pseudotuberculosis is a Gram-positive bacterium known to infect ruminants, horses, and rarely people. It is a facultative anaerobic organism that is catalase-positive and capable of beta-hemolysis. In small ruminants, C. pseudotuberculosis causes a disease called caseous lymphadenitis, which is characterized by pyogranulomatous abscess formation. In general, the bacterium causes lesions of the skin, lymph nodes, and internal organs. A disease known as ulcerative lymphagenitis can also result from infection with C. pseudotuberculosis in the distal limbs of horses. This bacterium uses the virulence factors phospholipase D and mycolic acid to damage eukaryotic cell walls and resist phagocytic lysosomal degradation, respectively. Infection with this bacterium is often confirmed by bacterial culture of the purulent exudate. Once the diagnosis has been made, treatment of the infection can begin, but this is difficult due to the nature of the organism and the lesions it forms. Specifically, C. pseudotuberculosis is intrinsically resistant to streptomycin, with varying resistance to penicillin and neomycin depending on the strain. It has been shown to be susceptible to ampicillin, gentamicin, tetracycline, lincomycin, and chloramphenicol. Vaccines have also been produced to develop acquired immunity to this infection.