| Bacterial diseases are common in all reptilian orders. Most infections are caused by opportunistic agents that infect immunosuppressed hosts. A comprehensive approach is required to ensure the success of a therapeutic plan. It is important not only to determine the causative agent but also to correct environmental and nutritional deficiencies. Treatment with antibiotics (see
Table:
Antimicrobial Drugs for Use in Reptiles ) for a specific microbial agent in the absence of proper heat, light, hydration, nutrition, etc, will not be successful. |
| Culture and sensitivity are essential in determining appropriate therapy. Most bacterial infections involve gram-negative bacteria, many of which are considered to be commensal organisms. These agents can remain dormant until the reptile becomes immunosuppressed. Anaerobic infections are more common than once thought and may be involved in up to 40% of all bacterial infections. If a therapeutic agent was selected based on an aerobic culture and sensitivity and response is poor,
then the presence of an additional anaerobic agent should be considered. |
| Although it has been advocated that all antimicrobial drugs be administered parenterally, orally administered drugs, can be used effectively. The factors involved in oral administration that can alter absorption and use of a drug include GI transit time, temperature, and the presence of food. However, drugs administered orally at a given temperature and in the absence of food appear to have a fairly predictable rate of absorption and use. Oral medications are especially useful in
extremely small specimens (eg, the true chameleons and smaller geckos) that lack adequate muscle mass for, and will be adversely affected by, a painful injection. Parenteral injections are preferred in larger specimens or when working around the head and mouth would be dangerous. The normal route of administration (IM or SC) should be used. |
| Environmental temperatures should be maintained near the upper limit preferred by the species to enhance immune function. Higher metabolic rates of anorectic reptiles may necessitate force-feeding or increased rate of feeding. However, heat and feeding also raise uric acid levels. If a particular drug is potentially nephrotoxic, uric acid levels should be determined before the drug is administered; if the uric acid level is increased, feeding should be delayed (so as not to further
increase uric acid levels). Fluid administration should be considered as well. |
| Because most infected reptiles have some level of immunosuppression, bactericidal drugs are preferable to bacteriostatic ones. |
| The aminoglycosides are some of the most frequently used antibiotics against the gram-negative organisms of reptiles. However, neomycin, streptomycin, kanamycin, and gentamicin should not be used systemically in reptiles because they have been associated with numerous reports of renal toxicity. Amikacin is the aminoglycoside of choice. |
| Mixed or resistant infections may require combinations of antibiotics. Amikacin is commonly used in conjunction with penicillin drugs (eg, ampicillin, carbenicillin, or piperacillin) in the treatment of severe gram-negative sepsis such as that caused by
Pseudomonas
. Ceftazidime can be given with amikacin or enrofloxacin to broaden the spectrum as well as to take advantage of the ability of ceftazidime to control anaerobic bacteria. Metronidazole can be given with either amikacin or enrofloxacin for the same reason. |
| A number of infectious conditions are similar in appearance regardless of species.
Septicemia is a common cause of death. The systemic disease may be preceded by trauma, local abscessation, parasitism, or environmental stress.
Aeromonas
and
Pseudomonas
spp are frequently isolated; the former may be transmitted by the snake mite
Ophionyssus
natricis
. Death may be peracute or chronic. Common signs are respiratory distress, lethargy, convulsions, and incoordination. Petechiae may be found on the ventral abdomen, and chelonians develop erythema of the plastron. Sanitation and husbandry can be significant factors in reducing outbreaks. Affected reptiles should be isolated, and antibiotic therapy initiated. |
|
Septicemic cutaneous ulcerative disease (SCUD) in turtles is often caused by
Citrobacter
freundii
.
Serratia
spp
may act synergistically by facilitating entry of
C
freundii
into the turtle. The scutes are pitted and may slough with an underlying purulent discharge. Anorexia, lethargy, and petechial hemorrhages on the shell and skin are seen; liver necrosis is common. Systemic antibiotics are recommended. Good sanitation is paramount in prevention. |
| Another shell disease of turtles is caused by
Beneckea
chitinovora
, a common infectious agent of crustaceans. Erythema and pitting of the shell with ulceration is seen. Septicemia is uncommon. Treatment with topical iodine is recommended. The practice of feeding crayfish is often implicated in this condition and should be discouraged. |
|
Ulcerative or necrotic dermatitis (scale rot) is seen in snakes and lizard. Humidity and environmental contamination have been considered the main predisposing factors. Moist, contaminated bedding allows bacterial and fungal growth which, when coupled with exposure to fecal degradation products, can predispose to small cutaneous erosions. Secondary infection with
Aeromonas
spp
,
Pseudomonas
spp
, and a number of other bacteria may result in septicemia and death if untreated. Erythema, necrosis, and ulceration of the dermis, and an exudative discharge are common. While lesions are often a sequelae of skin injuries, they more often develop from within, as is the case with classic necrotic dermatitis in the ball python. The disease can develop even when these animals are maintained under pristine conditions, so it is not simply a matter of excessive moisture and poor
hygiene. The condition starts with hemorrhage into scales, followed by pustules that eventually lead to open and ulcerated lesions. Treatment with systemic antibiotics, topical antibiotic ointment, and excellent hygiene and husbandry are essential. |
|
Blister disease has traditionally been considered a separate entity but is simply an early stage of ulcerative (necrotic) dermatitis. The cutaneous involvement is characterized by pustules or blisters that may resolve without development of ulcerative lesions if treatment is started early. A low-grade thermal injury may mimic blister disease due to the potential development of fluid filled vesicles. |
|
Abscesses caused by traumatic injury, bite wounds, or poor environmental quality are seen in all orders of reptiles. Subcutaneous abscesses are seen as nodules or swellings. Differential diagnoses include parasitic nodules, tumors, and hematomas. Isolates of the anaerobic organism
Peptostreptococcus
and of the aerobes
Pseudomonas
,
Aeromonas
,
Serratia
,
Salmonella
,
Micrococcus
,
Erysipelothrix
,
Citrobacter
freundii
,
Morganella
morganii
,
Proteus
,
Staphylococcus
,
Streptococcus
,
Escherichia
coli
,
Klebsiella
,
Arizona
, and
Dermatophilus
have been recovered from reptilian abscesses, often in combinations. Small localized abscesses should be completely excised to avoid recurrence, which is frequent. Larger abscesses should be incised, followed by aggressive local wound treatment. The lining of the abscess must be aggressively scraped to remove as much material as possible. Appropriate systemic antibiotics may also be indicated. Anaerobic bacteria are common in these lesions, and an appropriate antimicrobial
agent (eg, metronidazole, ceftazidime, or a potentiated penicillin product) may need to be used or added to a current regimen. |
| Visceral abscessation may occur as a result of hematogenous infection. Abscesses of the female reproductive system are common and may result in coelomitis. Surgical intervention is indicated; systemic antibiotics alone are rarely successful. |
| Subspectacle abscessation is seen in snakes, and conjunctivitis in the other orders. The severity ranges from mild inflammation to panophthalmitis and may occur as a result of ascending infectious stomatitis (see below). Topical antibiotic ointments are used in turtles, lizards without spectacles, and crocodilians. In snakes and lizards with spectacles, drainage is achieved by surgically removing a small wedge from the spectacle and flushing the subspectacular
space and lacrimal duct with an antibiotic solution (eg, gentamicin). Some affected reptiles, especially turtles, may need supplemental vitamin A.
|
|
Star-gazing refers to any neurologic disorder characterized by mental dullness, abnormal posturing, and an inability to move forward in a normal fashion. This is more commonly seen in, but not restricted to, snakes, and is characterized by a severely twisted cervical positioning, creating a “starward gaze.” A retrovirus causing a viral meningitis/encephalitis in boids (boas and pythons) is the most commonly diagnosed “star-gazing” syndrome. The virus is not a new;
rather, there is increased awareness of an epidemic in the making for over 2 decades. This syndrome is referred to as inclusion body disease due to the presence of characteristic inclusion bodies in affected cells (see
viral diseases,
Nervous System). Among other possible causes of star-gazing protozoa, heat damage, trauma, and bacterial agents are the most common. Bacterial meningitis or encephalitis usually results from hematogenous infection or bacterial emboli from an abscess elsewhere in the body. The prognosis varies with the cause but is generally guarded. Systemic antibiotics that can cross the blood-brain barrier (eg, ceftazidime, metronidazole, penicillins, etc) are indicated in
bacterial cases. Prednisolone acetate at a dosage of 1 mg/kg, IM, once has been recommended for inflammation associated with these infections. Because lesions may resolve slowly, an early response to therapy is rarely seen, and good supportive care (eg, fluids and nutrient supplementation) is essential. |
|
Infectious stomatitis is seen in snakes, lizards, and turtles. It is characterized early by petechiae in the oral cavity; caseous material develops along the dental arcade as the condition worsens. In severe cases, infection extends into the bony structures of the mouth.
Aeromonas
and
Pseudomonas
spp
, common oral inhabitants, are most frequently isolated, along with a variety of other gram-negative and gram-positive bacteria. Respiratory or GI infection may develop in poorly managed cases. Debridement, irrigation with antiseptics or antibiotics, systemic antibiotics, and supportive therapy are indicated. In severe cases with ulceration or granuloma formation, more aggressive surgery may be indicated. Vitamin supplementation, especially with vitamins A and C, has been
advocated but does not always affect the disease course. |
|
Respiratory infections are common; the incidence can be influenced by respiratory or systemic parasitism, unfavorable environmental temperatures, unsanitary conditions, concurrent disease, malnutrition, and hypovitaminosis A. Open-mouth breathing, nasal discharge, and dyspnea are frequent signs.
Aeromonas
and
Pseudomonas
spp
are frequently isolated, but many respiratory infections are mixed. Septicemia may develop in severe or prolonged cases. Treatment consists of improving husbandry and initiating systemic antibiotics. Nebulization therapy with antibiotics diluted in saline, in combination with acetylcysteine, has been used together with parenteral antibiotics to treat bacterial pneumonia. Reptiles with respiratory infections should be maintained at the mid to upper end of their preferred
optimal temperatures. Increased temperatures are important not only to stimulate the immune system but also to help mobilize respiratory secretions. Turtles often have an underlying vitamin A deficiency, and supplementation at 200 IU/kg, IM, should be given once a week for 2 wk if needed. Many turtles treated for pneumonia fail to improve until after treatment for vitamin A deficiency. |
|
Ear infections occur in turtles, most frequently in box turtles and aquatic turtles. Marked swelling is seen at the tympanic membrane, and caseous material is present.
Proteus
spp
,
Pseudomonas
spp
,
Citrobacter
spp
,
Morganella
morganii
,
Enterobacter
spp
, and other bacteria have been isolated. Drainage and systemic antibiotics are appropriate. The tympanic membrane must be incised, and aggressive curettage of the area performed. The open area should be flushed with diluted povidone-iodine or a similar product for a few days to prevent premature closure and to keep the area clean. Ear infections may be secondary to hypovitaminosis A; parenteral and dietary supplementation of vitamin A may be beneficial. |
|
Infectious cloacitis is characterized by edema and hemorrhagic discharge. The cause may be traumatic. Cloacal calculi may form in vitamin or mineral imbalances and should be manually removed and followed by dietary correction. In pericloacal abscesses, the infection often migrates cranially by subcutaneous or coelomic tissue pathways. Ascending urinary or genital tract infections are common sequelae. Aggressive therapy, including surgical debridement, local wound
treatment, and appropriate systemic antibiotics, is indicated. Fecal examinations should be performed to identify potential parasitic causes. |
|
Mycobacterial infections are often associated with chronic wasting and are seen as granulomatous lesions at necropsy. Chelonians generally exhibit pulmonary involvement, while lizards, snakes, and crocodilians show visceral granulomas. Rifampin and isoniazid are hepatotoxic in reptiles, and the longterm administration required is unlikely to be safe. The species isolated are
Mycobacterium
ulcerans
,
M
chelonae
,
M
hemophilus
, and
M
marinum
. All are cultured at reduced temperatures and may require long periods for growth. |
|
Salmonella
,
Arizona
, and
Edwardsiella
spp
have been isolated from clinically normal turtles. The zoonotic nature of these organisms must be considered when handling or treating turtles. Attempts to eliminate these microorganisms from infected turtles and their eggs have been unsuccessful. |
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