History
An approximately 5-year-old 0.203-kg (0.45-lb) sexually intact male hognose snake (Heterodon nasicus) was presented for evaluation of multifocal dermal nodules. The snake was housed in a plastic crate with newspaper bedding and was fed every 2 weeks. The referring veterinarian had submitted a fine-needle aspirate sample of one of the nodules for cytologic examination; however, results did not indicate a definitive diagnosis, and the snake was referred for further evaluation.
On referral examination, the snake was lethargic, had increased respiratory effort, and had multiple nodules (approx 1 cm in diameter) disseminated over its entire body. Palpation revealed 2 suspected intracoelomic masses located in the midregion of the coelomic cavity. A fecal float was performed, and no ova were detected. The owner declined further diagnostic tests but did approve radiographic examination. For the procedure, the snake was coerced into a polyvinyl chloride tube that was large enough for the snake to enter easily but not turn around. Once the snake was fully in the tube, fabric was placed over the ends of the tube and held in place with rubber bands. Whole-body radiographic images were obtained (Figure 1).
Right lateral (A) and dorsoventral (B) radiographic images of the caudal half of an approximately 5-year-old 0.203-kg (0.45-lb) sexually intact male hognose snake (Heterodon nasicus) referred for evaluation of multifocal dermal nodules. The snake is imaged in a polyvinyl chloride tube large enough for the snake to enter easily but not turn around. Fabric is held in place over the tube ends with rubber bands. A—The snake's head is toward the left of the image. B—The snake's head and right side are toward the top and left of the image, respectively.
Citation: Journal of the American Veterinary Medical Association 259, 2; 10.2460/javma.259.2.137
Right lateral (A) and dorsoventral (B) radiographic images of the caudal half of an approximately 5-year-old 0.203-kg (0.45-lb) sexually intact male hognose snake (Heterodon nasicus) referred for evaluation of multifocal dermal nodules. The snake is imaged in a polyvinyl chloride tube large enough for the snake to enter easily but not turn around. Fabric is held in place over the tube ends with rubber bands. A—The snake's head is toward the left of the image. B—The snake's head and right side are toward the top and left of the image, respectively.
Citation: Journal of the American Veterinary Medical Association 259, 2; 10.2460/javma.259.2.137
Right lateral (A) and dorsoventral (B) radiographic images of the caudal half of an approximately 5-year-old 0.203-kg (0.45-lb) sexually intact male hognose snake (Heterodon nasicus) referred for evaluation of multifocal dermal nodules. The snake is imaged in a polyvinyl chloride tube large enough for the snake to enter easily but not turn around. Fabric is held in place over the tube ends with rubber bands. A—The snake's head is toward the left of the image. B—The snake's head and right side are toward the top and left of the image, respectively.
Citation: Journal of the American Veterinary Medical Association 259, 2; 10.2460/javma.259.2.137
Right lateral (A) and dorsoventral (B) radiographic images of the caudal half of an approximately 5-year-old 0.203-kg (0.45-lb) sexually intact male hognose snake (Heterodon nasicus) referred for evaluation of multifocal dermal nodules. The snake is imaged in a polyvinyl chloride tube large enough for the snake to enter easily but not turn around. Fabric is held in place over the tube ends with rubber bands. A—The snake's head is toward the left of the image. B—The snake's head and right side are toward the top and left of the image, respectively.
Citation: Journal of the American Veterinary Medical Association 259, 2; 10.2460/javma.259.2.137
Right lateral (A) and dorsoventral (B) radiographic images of the caudal half of an approximately 5-year-old 0.203-kg (0.45-lb) sexually intact male hognose snake (Heterodon nasicus) referred for evaluation of multifocal dermal nodules. The snake is imaged in a polyvinyl chloride tube large enough for the snake to enter easily but not turn around. Fabric is held in place over the tube ends with rubber bands. A—The snake's head is toward the left of the image. B—The snake's head and right side are toward the top and left of the image, respectively.
Citation: Journal of the American Veterinary Medical Association 259, 2; 10.2460/javma.259.2.137
Radiographic Findings and Interpretation
There was diffuse increased soft tissue opacity throughout the coelomic cavity, with a loss of normal coelomic detail (Figure 2), potentially caused by emaciation, species variation, neoplastic effusion, modified transudate, exudate, hemorrhage, or, less likely, pure transudate. In the coelomic cavity approximately midway between the nose and the vent, there was a small amount of faint, stippled mineral opaque material, which was likely ingesta, but a mineralized mass associated with neoplasia, granuloma, or hematoma formation was not ruled out. The snake also had 2 ill-defined, ovoid, expansile, soft tissue–opaque masses with focal lysis of vertebrae at the level just cranial to the vent. Possible origins for these 2 lesions included bone or nerve tissues (spinal cord, meninges, or nerve roots), with differential diagnoses of neoplasia and osteomyelitis. The snake's lungs had low volume but were otherwise radiographically normal.
Same radiographic images as in Figure 1. The snake has 2 regions of expansion and lysis (white arrows) in caudal vertebrae and stippled mineral opaque material (white arrowhead) approximately midway between the nose and the vent.
Citation: Journal of the American Veterinary Medical Association 259, 2; 10.2460/javma.259.2.137
Same radiographic images as in Figure 1. The snake has 2 regions of expansion and lysis (white arrows) in caudal vertebrae and stippled mineral opaque material (white arrowhead) approximately midway between the nose and the vent.
Citation: Journal of the American Veterinary Medical Association 259, 2; 10.2460/javma.259.2.137
Same radiographic images as in Figure 1. The snake has 2 regions of expansion and lysis (white arrows) in caudal vertebrae and stippled mineral opaque material (white arrowhead) approximately midway between the nose and the vent.
Citation: Journal of the American Veterinary Medical Association 259, 2; 10.2460/javma.259.2.137
Same radiographic images as in Figure 1. The snake has 2 regions of expansion and lysis (white arrows) in caudal vertebrae and stippled mineral opaque material (white arrowhead) approximately midway between the nose and the vent.
Citation: Journal of the American Veterinary Medical Association 259, 2; 10.2460/javma.259.2.137
Same radiographic images as in Figure 1. The snake has 2 regions of expansion and lysis (white arrows) in caudal vertebrae and stippled mineral opaque material (white arrowhead) approximately midway between the nose and the vent.
Citation: Journal of the American Veterinary Medical Association 259, 2; 10.2460/javma.259.2.137
Treatment and Outcome
The owner was instructed to house the snake in a larger vivarium with appropriate UV lighting and heat source, and the snake was treated with ceftazidime (20 mg/kg [9.1 mg/lb], SC, q 72 h) and tube-fed a slurry of a dieta with a high energy concentration (1% of the snake's body weight, q 48 h) for 10 weeks. The snake's condition declined over the next several months, with progressive lethargy and anorexia, loss of fat and muscle mass, enlargement of dermal nodules (diameter, ≤ 3 cm), increased respiratory effort, and potential development of neurologic deficits despite treatment, increases in tube feeding, and habitat adjustments.
During coelomic ultrasonography 16 weeks after the referral examination, the snake was initially restrained in dorsal recumbency but became limp and did not attempt to right itself. Ultrasonography revealed multiple hyper- and hypoechoic nodules throughout the snake's liver and spleen, consistent with neoplasia or infection; a small amount of anechoic free fluid in the coelomic cavity, consistent with earlier radiographic findings; multiple anechoic structures in the liver with thin, hyperechoic rims that caused distal acoustic enhancement, consistent with degenerative hepatic cysts, cystic neoplasia, or parasitic cysts; and a large, hyperechoic coelomic mass (3.1 × 2.0 × 1.8 cm) with irregular margins caudal to the gallbladder and liver (Supplementary Figure S1, available at: avmajournals.avma.org/doi/suppl/10.2460/javma.259.2.137). Cytologic examination of fine-needle aspirate samples of the coelomic mass revealed macrophagic inflammation, necrotic debris, and many small cocci and small, slender, rod-shaped bacteria; cellular atypia was not identified.
Radiography was repeated 22 weeks after the initial referral examination, and changes in findings, compared with the earlier radiographic examination, included substantial loss of body mass, enlargement of several dermal nodules, and expansion of the vertebral lytic lesions (Figure 3). The snake had more labored respirations and greater loss of fat and muscle mass than on previous examinations, and its heart sounds could not be auscultated. Also at this point, the snake dragged its tail and had no sign of deep pain response in the most caudal aspect of its tail.
Right lateral (A) and dorsoventral (B) radiographic images of the caudal portion of the same snake 22 weeks after the radiographic images in Figure 1 were obtained. Compared with earlier findings, there is evidence of substantial loss of body mass, enlargement of dermal nodules (open white arrows), and expansion of the vertebral lytic lesions (solid white arrows). Stippled mineral opaque material (white arrowhead) is again present in the coelomic cavity. Several gas lucencies (black arrows) are visible, a normal finding consistent with gas within the gastrointestinal tract.
Citation: Journal of the American Veterinary Medical Association 259, 2; 10.2460/javma.259.2.137
Right lateral (A) and dorsoventral (B) radiographic images of the caudal portion of the same snake 22 weeks after the radiographic images in Figure 1 were obtained. Compared with earlier findings, there is evidence of substantial loss of body mass, enlargement of dermal nodules (open white arrows), and expansion of the vertebral lytic lesions (solid white arrows). Stippled mineral opaque material (white arrowhead) is again present in the coelomic cavity. Several gas lucencies (black arrows) are visible, a normal finding consistent with gas within the gastrointestinal tract.
Citation: Journal of the American Veterinary Medical Association 259, 2; 10.2460/javma.259.2.137
Right lateral (A) and dorsoventral (B) radiographic images of the caudal portion of the same snake 22 weeks after the radiographic images in Figure 1 were obtained. Compared with earlier findings, there is evidence of substantial loss of body mass, enlargement of dermal nodules (open white arrows), and expansion of the vertebral lytic lesions (solid white arrows). Stippled mineral opaque material (white arrowhead) is again present in the coelomic cavity. Several gas lucencies (black arrows) are visible, a normal finding consistent with gas within the gastrointestinal tract.
Citation: Journal of the American Veterinary Medical Association 259, 2; 10.2460/javma.259.2.137
Right lateral (A) and dorsoventral (B) radiographic images of the caudal portion of the same snake 22 weeks after the radiographic images in Figure 1 were obtained. Compared with earlier findings, there is evidence of substantial loss of body mass, enlargement of dermal nodules (open white arrows), and expansion of the vertebral lytic lesions (solid white arrows). Stippled mineral opaque material (white arrowhead) is again present in the coelomic cavity. Several gas lucencies (black arrows) are visible, a normal finding consistent with gas within the gastrointestinal tract.
Citation: Journal of the American Veterinary Medical Association 259, 2; 10.2460/javma.259.2.137
Right lateral (A) and dorsoventral (B) radiographic images of the caudal portion of the same snake 22 weeks after the radiographic images in Figure 1 were obtained. Compared with earlier findings, there is evidence of substantial loss of body mass, enlargement of dermal nodules (open white arrows), and expansion of the vertebral lytic lesions (solid white arrows). Stippled mineral opaque material (white arrowhead) is again present in the coelomic cavity. Several gas lucencies (black arrows) are visible, a normal finding consistent with gas within the gastrointestinal tract.
Citation: Journal of the American Veterinary Medical Association 259, 2; 10.2460/javma.259.2.137
Ten days later, the snake died. Necropsy was performed, and histologic diagnoses were hepatocellular adenoma (approx 2 × 3-cm intrahepatic mass) and disseminated bacterial granulomatous disease in the subcutis, musculature, vertebrae (particularly the tail), kidneys, lungs, heart, peritoneum, and pancreas. In the tail, granulomas were associated with marked osteolysis and fractures of vertebrae and compression of the spinal cord. Bacterial culture of a coelomic mass yielded an Enterococcus sp, Pseudomonas aeruginosa, and Morganella morganii.
Comments
The snake of the present report had disseminated bacterial granulomatous disease, and noticing the snake's dermal nodules prompted the owner to seek veterinary care. Other clinical signs observed by owners of affected snakes may be lethargy and decreased appetite, which also developed in this snake. Typical routes of infection include entry through dermal wounds, the respiratory system, or the gastrointestinal tract. Local bacterial infections can lead to sepsis and disseminated granulomatous lesions. In the snake of the present report, all organisms cultured were commensal bacteria that can be opportunistic. We suspected that the infection spread from the cloaca because the surrounding region was the most severely affected on necropsy and that septicemia likely allowed for the diffuse granulomatous lesions and osteomyelitis.
Radiographic examination of the snake of the present report revealed regions of expansile lysis in vertebrae of the caudal aspect of the vertebral column and ill-defined soft tissue–opaque nodules disseminated throughout the snake's body. Further, coelomic ultrasonography revealed multiple cyst-like structures in the liver and additional coelomic nodules. If the owner would have allowed additional diagnostic tests, such as blood work, we may have been able to have narrowed our primary differential diagnosis list (neoplasia, granulomas, abscesses, and cysts) with evidence (eg, heterophilia, lymphocytosis, or eosinophilia) of the underlying disease process.1 For instance, monocytosis is common in snakes with granulomatous disease; however, findings vary among snake species, are generally seasonal, and must be interpreted along with the clinical signs and physical examination findings.1
The lack of self-righting observed during ultrasonography of the snake of the present report may or may not have indicated a neurologic component to the disease involving the vestibular system or the CNS. Snakes positioned on their backs instinctively attempt to become sternal; however, hognose snakes are known to feign death, which can mimic the lack of self-righting.2 Further, the snake dragged its tail and had no sign of deep pain response in its tail during its last examination. Pathological considerations for a lack of self-righting and dragging of the tail include encephalitis secondary to microabscess or toxic, viral, bacterial, mycotic, or parasitic causes.2
The snake of the present report had focal lysis of vertebrae at the level just cranial to the vent. Although vertebral lesions in snakes may have numerous causes (eg, trauma, neoplasia, infection, hypovitaminosis D, hypervitaminosis A, and prolonged inactivity),3 we prioritized neoplasia or osteomyelitis for this snake, and findings on necropsy confirmed that granulomas in the tail were associated with marked osteolysis and fractures of vertebrae and compression of the spinal cord. Despite aggressive treatment with antimicrobials, analgesics, and potentially surgical debridement, snakes with vertebral osteomyelitis typically have a poor to grave prognosis owing to the advanced stage of the disease at the time of diagnosis.2,3
The radiographic lesions identified in the vertebral column of the snake of the present report were also similar to those that could occur during the early stage of Paget disease, also known as osteitis deformans, which is characterized by a high rate of bone turnover and abnormal remodeling.5,6 However, histologic examination of affected vertebrae in this snake confirmed bacterial granulomatous disease.
Additionally, the snake of the present report had hepatocellular adenoma, a benign neoplasm. A study7 on neoplasia in snakes shows that 36 of the 291 snakes had neoplastic lesions identified postmortem, with malignant neoplasms more common than benign, and with benign neoplasms of the liver and biliary tract (n = 7) third most common after benign neoplasms of lymphoid and hematopoietic tissues (12).
The outcome for snakes with diffuse granulomatous infections with osteomyelitis is usually poor, as was the case for the snake of the present report. We recommend prompt and aggressive treatment, including targeted antimicrobial use, to improve the chances of positive outcomes for affected snakes.
Acknowledgments
The authors declare that there were no conflicts of interest.
Footnotes
Pro Plan Veterinary Diets CN Critical Nutrition diet, Purina, St Louis, Mo.
References
- 1. ↑
Campbell T. Clinical pathology of reptiles. In: Divers SJ, Mader DM, eds. Reptile medicine and surgery. 2nd ed. Philadelphia: Saunders Co, 2006;453–470.
- 2. ↑
Done L. Neurologic disorders. In: Divers SJ, Mader DM, eds. Reptile medicine and surgery. 2nd ed. Philadelphia: Saunders Co, 2006;856–857.
- 3. ↑
Fitzgerald K, Vera R. Spinal osteopathy. In: Divers SJ, Mader DM, eds. Reptile medicine and surgery. 2nd ed. Philadelphia: Saunders Co, 2006;906–912.
- 4.
Jacobson ER. Bacterial diseases in reptiles. In: Jacobson ER, ed. Infectious diseases and pathology of reptiles. Boca Raton, Fla: CRC Press, 2007;461–526.
- 5. ↑
Klein RM, Norman A. Diagnostic procedures for Paget's disease. Radiologic, pathologic, and laboratory testing. Endocrinol Metab Clin North Am 1995;24:437–450.
- 6. ↑
Preziosi R, Diana A, Florio D, et al.. Osteitis deformans (Paget's disease) in a Burmese python (Python molurus bivittatus)—a case report. Vet J 2007;174:669–672.
- 7. ↑
Catão-Dias JL, Nichols DK. Neoplasia in snakes at the National Zoological Park, Washington, DC (1978–1997). J Comp Pathol 1999;120:89–95.
