Newsletter: Volume 4, Issue 3 November 2000
Streptococcal Toxic Shock Syndrome (STSS)
While the vast majority of the episodes of Familial Shar-Pei Fever (FSF) seen in Shar-Pei run a fairly benign course there are occasional exceptions which can have live-threatening consequences. Over the last few years Streptococcal Toxic Shock Syndrome (STSS) has been seen more frequently as a complication of FSF in the Chinese Shar-Pei. STSS involves infection with a group G streptococcus called Streptococcus canis. In the Shar-Pei cases I’ve seen this streptococcal infection is a rapidly progressing, highly invasive process which results in a necrotizing faciitis and/or STSS leading to a shock-like syndrome and multi-organ failure. If not recognized early STSS can lead to death in 24 hours or less. A similar syndrome has been seen in human medicine, the so-called “flesh-eating bacteria”.
I consider this a localized form of streptococcal infection. Dogs with NF tend to develop extensive soft tissue sloughing along fascial planes. Fascia is dense connective tissue which covers the muscles. Usually this syndrome presents as large areas of skin and the underlying fatty tissue dying and peeling away, hence it has been called “flesh eating bacteria”. Many of these dogs will survive with debridement or clearing away of the dead tissue, but healing is prolonged and skin grafts are often necessary. Long-term management is intense with frequent bandage changes, cleaning of the wounds, antibiotic therapy and the need for multiple anesthetic procedures to repair and reconstruct the damaged areas. The areas I’ve seen involved are often the hock joints, the flanks and the abdominal skin.
Streptococcal Toxic Shock Syndrome
STSS seems to be a generalized or systemic form of streptococcal infection. Streptococcus canis in a potent exotoxin producer and it is thought that in cases of STSS the toxin may be responsible for the rapid progression of sepsis, shock and multi-organ failure (MODS). On necropsy these dogs show severe edema of the gastrointestinal tract, congestion of multiple organs, severe pulmonary (lung) congestion and evidence of thromboembolism (blood clots) all pointing to shock due to sepsis or toxemia. These dogs typically die within 24-48 hours in spite of aggressive fluid therapy, antibiotic treatment and intensive supportive care.
Clinical signs in the localized form of STSS, necrotizing fasciitis, consist of areas of skin bruising, dead skin and/or areas of sloughing where the skin is falling away. Usually there is a pus discharge from these areas. The dogs are very painful, running a high temperature, depressed and, in general, sick dogs. Often there is a history of an FSF episode, dog fight wounds, or other traumatic event. In the generalized or systemic form of STSS symptoms have a much more rapid onset and are more shock-like such as severe weakness, rapid heart rate, pale mucous membranes, extreme pain, collapse, coma and acute death. Many of these dogs develop DIC (disseminated intravascular coagulation) which rapidly leads to multiple organ dysfunction syndrome (MODS) and death despite heroic efforts at treatment.
The cause of this condition is unknown. It is known that Streptococcus canis can be part of the normal bacterial flora of the dog and that NF and STSS have occurred in other breed. Predisposing factors in the Shar-Pei may be related to:
- The increased amounts of mucin in the subcutaneous tissues.
- The prevalence of FSF in the breed.
- The prevalence of dog fights and bite wounds in the breed.
- An increase in skin laxity resulting in more trauma.
- Immune system insufficiencies.
- Perhaps an increased virulence of some strain of Streptococcus canis.
Diagnosis is based on the history of previous trauma or FSF episode, bacterial culture and sensitivity of discharges or tissue samples, and clinical signs. One important point is that the organism is often resistant to enrofloxicin (Baytril®) and the aminoglycosides such as Amikacin® and Gentocin®. Consider the use of multiple antibiotic therapy with agents such as Clavamox®, cephalexin, clindamycin, lincomycin, erythromycin, penicillin and the potentiated sulfas. Of course, the best approach is based on sensitivity information from a culture, but that takes some time to generate.
Treatment of the necrotizing fasciitis involves appropriate antibiotic selection and administration, and basic wound care of the affected areas. I have seen dogs have recurrence of necrotizing fasciitis with repeat FSF episodes. Usually they seem to slough out the same area every time. Treatment of the STSS involves intensive care with intravenous fluid therapy, shock treatment with IV antibiotics, pain management, steroids (?), and intensive monitoring for the development of DIC, etc. At this time the prognosis for systemic STSS must be considered very poor.
Increased owner awareness of NF and STSS, rapid initiation of appropriate antibiotic therapy and intensive supportive care are the keys to survival in this condition. An excellent article on STSS appeared in the October 15, 1996 issue of the Journal of the American Veterinary Medical Association, Volume 209, Number 8, pages 1421-1426 by C. Miller, J. Prescott, K. Mathews et al. entitled “Streptococcal Toxic Shock Syndrome in Dogs”.
Pneumonia In Shar-Pei
As you come in the door that afternoon you know something is wrong. Your 3 month-old Shar-Pei pup is not a the door to greet you. You search the house and find him in the family room huddled in the corner, ears down, tail limp, droopy eyes, breathing heavily and coughing softly. He feels warm to the touch. His temperature is 103 degrees and you know you’ve got trouble.
The scenario above is pretty typical for pneumonia in the Chinese Shar-Pei. It often occurs in pups 8 – 16 weeks old and seems to come out of nowhere. The only specific signs which may suggest pneumonia are heavy breathing usually with an abdominal component and sometimes a productive cough. By the time these signs are present, you have a very sick puppy and generally have a very little time to do much about it. Diagnosis must be quick, accurate and specific. A minimal database must includea CBC and a chest radiograph. We are primarily interested in the white blood cell count (WBC).What we want to see in the sick pup is a high WBC with some young white blood cells called “bands”. This would signal an appropriate response and that the pup is fighting the infectioin. A bad sign would be a normal or low WBC with gigh numbers of bands. This indicates the infection is winning and this pup may die. Radiographic signs of pneumonia are pretty classic and usually apparent on chest X-rays. Positioninig may be less than ideal as the pups will resist being put on their side and we don’t want to fight them too much – depending on the degree of lung involvement stress may overwhelm them. It is also helpful to try to stretch out the wrinkles over the chest when the radiograph is taken. Those folds can often obscure the lung changes seen in pneumonia. Pneumonia appears as fluid in the lungs seen in the vertral (lowest) lung fields and located in the cranial (forward) lung lobes. Fluid may accumulate in one lung lobe, cover multiple lobes and also occur in both sides of the chest. The fluid will often obscure the heart shadow on a chest radiograph. The definitive iagnosis is based on a tracheal wash. In this procedure, a catheter is introduced into the trachea and sterile water is flushed into the trachea and then aspirated back out hopefully with the offending bacteria in it. This sample can then be cultured and an anitbiotic sensitivity done. This procedure is usually done under sedation or light anesthesia and has some risk involved in it, especially in a sick pup, but the information gathered is critical to instituting the appropriate antibiotic therapy.
What causes pneumonia in Shar-Pei pups? By the time we have a sick pup the lungs have been infected by bacteria. These are usually Gram (-) bacteria such as E. Coli, Klebsiella and Bordetella. Gram (+) cocci such as Streptococcus may also be isolated. It is also known that viruses such as canine distemper, adenovirus and parainfluensa can also cause pneumonia. Shar-Pei also have an IgA deficiency which occurs in the vast majority of dogs. IgA is a protective immunoglobulin found in body secretions such as tears, mucous, saliva, etc. It is responsible for local immunity in the respiratory, gastrointestinal, and urogenital systems as well as the skin. IgA deficiency may predispose an animal to bacterial pneumonia. Ciliary dyskinesis is a condition that has been reported in the Shar-Pei in which teh cilia of the respiratory tract are abnormal or not present. Cilia are hair-like projections on the lining of the trachea and larger bronchi which are involved in clearance of debris-laden mucous out of the bronchi. This mechanism is vital in preventing accumulation of bacteria in the bronchi and subsequent development of bacterial pneumonia. It appears that this is a heritable condition. Lastly, Shar-Pei are prone to megaesophagus. This is an abnormality involving the esophagus or “food tube” which can result in accumulation of food and secretions in the esophagus. Regurgitation is a common finding in pupuies with this condition and this can lead to aspiration pneumonia. Megaesophagus can often be picked up on chest radiographs underlining the importance of doing chest X-rays in any pneumonia workup. Due to the wide range or underlying causes of bacterial pneumonia it is very important to autopsy any Shar-Pei who dies of pneumonia.
Treatment of pneumonia involves the use of antibiotic therapy based on the culture and sensitivity results obtained via the tracheal wash. Pending getting these results back from the laboratory which may take 2-3 days it is necessary to use “Four Quadrant Therapy”. This is antibacterial therapy effective against all becterial groups – Gram (+) aerobes and anaerobes and Gram (-) aerobes and anaerobes. My initial choice is an aminoglycoside and a penicillin. Use of injectable medications is indicated initially. Another choice is the use of a quinolone and a penicillin. This has the advantage of being given orally. Once the culture and sensitivity results are back specific antibiotic therapy is based on those results. I like to use a different antibiotic every 2 weeks for at least 4-6 weeks. The therapy should be continued for 2 weeks after the chest radiographs appear normal. There is a very real danger of not reating pneumonia long enough and having it recur with the possibility that the antibiotic therapy used either selected for a resistant strain of bacteria or a new bacteria is causing the problem. A “smoldering-type” pneumonia develops and can cause respiratory problems for a long time. This is more apt to occur when a tracheal wash – culture/sensitivity is not done. Injectable antibiotics may be used in a nebulizer which allows the abtibiotic to be breathed into the deeper airways and reach the lungs. Additional therapy is supportive. Fluid ( IV or subcutaneous ) are very important to maintain hydration in the sick pup and to keep secretions thin. This allows the normal respiratory defense mechanisms such as coughing and ciliary functions to clear the bacteria from the lungs. Use of a humidifier is useful in this regard. Adequate nutrition is vital to maintain evergy levels in the pup and prevent secondary disease. Coupage (thumping the chest) is useful to stimulate coughing, mobilizing fluid in the chest and stimulate deep breaths to prevent collapsed lungs (atelectasis). Mild, frequent periods of exercise help to mobilize secretions and maintain the pup’s interest and mental well-being.
Prevention centers around decreasing the pup’s exposure to infectious agents. Check your vaccines and be sure they are in-date and stored properly. Be aware of the adverse effects of stress on puppies. Puppy matches, traveling, etc. may need be in the best interest of the young Shar-Pei pup. Isolate puppies frm visiting adult dogs. Clean puppy areas with disinfectant frequently. Isolate any sick puppyies and care for them last always going from healthy puppies to the sick ones. The use of Bordetella vaccine may be useful although this bacterial agent probably represents a small number of the pneumonia cases.
Maintaining a high index of suspicion for pneumonia in the 8 – 16 week-old puppy is the best way to discover the problem early and get treatment fast. Also remember that pneumonia isn’t the only condition which can result in a fever in pups – every fever is not pneumonia especially if not confirmed by the complete blood count and chest radiographs.