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reptile pathology
September 2011 Shannon Martinson, Diagnostic Services, AVC Reptile pathology: Introduction • Need good resources! Reptile pathology: Introduction Poor husbandry is a major contributing factor in many diseases of captive reptiles! • Species specific requirements are often unknown • Problems often related to: – Housing conditions • Temperature • Lighting • Humidity – Nutrition • Dietary excesses • Dietary deficiencies Herbivores, Omnivores, and Carnivores…oh my! Abandoned snakes: Albino Cornsnake (?) & Boa constrictor (?) Suspect hypothermia / Starvation Abandoned snakes: Albino Cornsnake (?) & Boa constrictor (?) Cornsnakes are much smaller and don’t have heat pits…. Albino Burmese python Abandoned snakes: Albino Cornsnake (?) & Boa constrictor (?) Boa constrictors don’t have heat pits…. Ball python Abandoned snakes: Albino Burmese python and Ball python Ball python • Prominent swelling of the body • Marked distension of the entire intestinal tract Urolith Abandoned snakes: Albino Burmese python and Ball python Ball python - Urolithiasis • Water deprivation • Inappropriate/excess protein in diet • Associated with foreign body acting as a nidus Burmese python – no significant findings • Starvation? • No – abundant body fat in both snakes • Hypothermia could not be ruled out • I wasn’t provided with any information regarding the housing of these animals! Don’tUrolith assume the species of snake on the submission form is correct... ‘Leopard Gecko’ • ~ 16 year old, female, Gecko • History of inappetance and weight loss • Euthanized Dysecdysis : • Incomplete/retained shed • Low humidity • Vitamin A deficiency? • Underlying disease ‘Leopard Gecko’ Articular / periarticular gout ‘Leopard Gecko’ Gout • The build-up of uric acid to toxic levels → crystalline deposits in tissues • Uric acid is a product of protein metabolism → excreted by kidneys • Levels become excessive : • • • If too much animal based protein is fed (especially to herbivores) If the animal is dehydrated If the animal has existing renal disease* ‘Leopard Gecko’ Gout • Clinical signs: • Reluctance to move → Pain and decreased range of motion of affected joints • Anorexia and decreased water consumption • Visceral Gout: Deposits in pericardium, liver, kidney, spleen On Histology – glomerular lesions: • What are the causes in geckos? • Are glomerulopathies typically associated with gout? • Interstitial nephritis ‘Igor’ – Ball python • 3 – 4 year old, female, Ball python • Eating less than normal over the past 1 ½ year • Found dead Healthy mojave ball python (juvenile) ‘Igor’ – Ball python ‘Igor’ – Ball python ‘Igor’ – Ball python • Clotted blood in the pericardial sac • Fibrinous plaques on the epicardium • Fill thickness necrosis of the myocardium • Crater-like lesions ‘Igor’ – Ball python Igor’s heart Normal heart (boa) ‘Igor’ – Ball python Histology: Plaques noted grossly ‘Igor’ – Ball python • Bacterial culture results: • Streptococcus agalactiae • Rare reports of Strep. agalactiae in reptiles 1. 2. Hetzel et al. Septicaemia in emerald monitors (Varanus prasinus Schlegel 1839) caused by Streptococcus agalactiae acquired from mice. Veterinary Microbiology 95 (2003) 283–293. Bishop EJ, Shilton C, Benedict S et al. Necrotizing fasciitis in captive juvenile Crocodylus porosus caused by Streptococcus agalactiae: an outbreak and review of the animal and human literature. Epidemiol. Infect 2007;135:1248–1255. Wild-caught Northern red-belly snakes • Four wild-caught snakes placed in captivity • One snake had small white skin lesions, which worsened • The rest developed skin lesions, lethargy, laboured breathing • One snake died, the rest were submitted for euthanasia Wild-caught Northern red-belly snakes • All 4 snakes were gravid females!! • Skin lesions: • White, cloudy discolouration of the scales • Rare foci of hemorrhage and ulceration Wild-caught Northern red-belly snakes Histology: Normal scale • Heterophilic infiltration • Crusting • Embedded bacteria Wild-caught Northern red-belly snakes • Ulcerative dermatitis – “scale rot” or “blister disease” • Predisposing factors: excessive humidity and environmental contamination • Moist bedding allows bacterial and fungal growth • Lesions are typically located on the ventral aspect of the body (unlike this case) Mixed bacterial growth: Large Gram-positive cocci in the lesion Wild-caught Northern red-belly snakes • Laboured breathing evident, but no gross lung lesions • Histology: • Large numbers of nematodes/larvae in the airways • Proliferative pneumonia Lungworm in reptiles: • Rhabdias spp. • Free-living or parasitic • Direct transmission • Larvae penetrate skin or oral mucosa • Enter circulation → Lung Wild-caught Northern red-belly snakes Summary: • Concurrent opportunistic infections • Lung worm • Necrotic dermatitis • Likely related to: • Stress of captivity • Stress of pregnancy • Poor cage hygiene?? You should leave wild animals in the wild… ‘Bright-eyes’: Gecko • • • • 8 yr old female gecko Intermittent anorexia for 2 months Force feeding for 3 weeks U/S: Fecal impaction in the lower GI with possible stricture ‘Bright-eyes’: Gecko • Marked distension of the intestine • Band of narrowing distally ‘Bright-eyes’: Gecko Focal thickening of the intestinal wall and narrowing of the lumen – scarring (stricture)? ‘Bright-eyes’: Gecko Histology: Region of thickening Mucosal / luminal surface ‘Bright-eyes’: Gecko Histology: Mass-like lesion expanding the muscularis of the intestine ‘Bright-eyes’: Gecko Histology: ‘Bright-eyes’: Gecko Histology: Composed of bundles of spindle cells – possible leiomyosarcoma or Gastrointestinal stromal tumour ‘Bright-eyes’: Gecko • Impaction in reptiles is common and is most often a result of: • Substrate ingestion • “Digestible” calcium carbonate sand • Also other sands, gravel, corn cob • Non-discriminate eating habits • Pica / Geophagy • Better options for substrate: Newspaper, carpet, alfalfa pellets, large size bark mulch, sphagnum moss • Other reports of Intestinal tumours in geckos?? • Intestinal leiomyosarcoma has been reported / mentioned in a single gecko • MM Garner, SM Hernandez-Divers, JT Raymond. Reptile neoplasia: a retrospective study of case submissions to a specialty diagnostic service. Vet Clin Exot Anim 7 (2004) 653 – 671 Boa constrictor: ‘Virgin Mary’ ~ 15 yr old female Boa • Housed singly, no brumation, and not bred Images: Courtesy of Greg Heckbert Boa constrictor breeding Warning: The following content is graphic in nature! • Often ↓ T prior to breeding = brumation • Ovulate 5 -11 wks after bred Ovoviviparous • Give birth to live young • 120 – 140 d after ovulation • Avg ~ 25 in a clutch ‘Play-boa’ images: Courtesy of Greg Heckbert Boa constrictor: ‘Virgin Mary’ Surprise! ~ 15 yr old female Boa • Housed singly, no brumation, and not bred Images: Courtesy of Greg Heckbert 9 ‘slugs’, 5 live snakes, 3 stillborn Boa constrictor: ‘Virgin Mary’ A gift from God?? ~ 15 yr old female Boa • Housed singly, no brumation, and not bred Images: Courtesy of Greg Heckbert • No. • 2 Possible explanations • Sperm storage • Common • Usually few months • Reported for up to a few years • Parthenogenesis • Very rare in snakes • Recently proven in a boa constrictor W Booth, DH Johnson, S Moore, C Schal, EL Vargo: Evidence for viable, non-clonal but fatherless Boa constrictors. Biol. Lett. published online 3 November 2010 Boa constrictor: ‘Virgin Mary’ • 4/5 live-born snakes died • 3 submitted for necropsy • All with similar findings • Distension of the body caudal to umbilicus • Yolk material within coelom • Normal??? • No inflammation… Retention of the yolk is likely normal for 10 – 14 days – for this reason, breeders don’t feed the young until after the first shed Boa constrictor: ‘Virgin Mary’ • • • • • • ~ 1 year later Decreased appetite Increased urate production Found dead Externally: Good body condition Proliferative skin lesion present caudal to the vent, involving the hemipenile homologue and anal glands Boa constrictor: ‘Virgin Mary’ • Several follicles on the ovary/within the oviduct • Often dark red and friable (necrosis) • Covered by clumps of friable yellow material Boa constrictor: ‘Virgin Mary’ Fibrinous coelomitis (peritonitis), locally extensive acute, severe Boa constrictor: ‘Virgin Mary’ Pericardial effusion • Light growth of Providencia rettaeri isolated from pericardial swab • Heavy growth of mixed coliforms isolated from the oviduct Boa constrictor: ‘Virgin Mary’ Fibrin and bacteria covering ulcers in oviduct Yolk material free in the coelom • Yolk coelomitis: • Much more common in lizards than snakes • In snakes: • May be associated with rough handling of gravid females • Secondary to salpingitis* • Possible ascending infection from skin Boa constrictor: ‘Virgin Mary’ Fibrin and bacteria covering ulcers in oviduct Yolk material free in the coelom • Yolk coelomitis: • Much more common in lizards than snakes • In snakes: • May be associated with rough handling of gravid females • Secondary to salpingitis* • Possible ascending infection from skin Boa constrictor: ‘Virgin Mary’ Additional interesting finding: • Eosinophilic granules in the renal tubular epithelial cells • Similar to sexual segment in boid males….. • Significance?? Piebald ball python - Unabsorbed yolk sac Oviparous – lay eggs • Ovulation: 6 – 30 d after copulation • Postovulatory shed: 20 d • Oviposition: 24 – 34 d after postovulatory shed • 1 – 11 eggs (avg ~ 6) • Near hatching, the yolk sac should be drawn into the body • Occasionally this does not occur • Snake born with external yolk sac • Ascending infections Images: Courtesy of Greg Heckbert ‘Ayna’– Waterdragon • Adult waterdragon • Severe stomatitis • No improvement with antibiotics Courtesy of Drs Buote & Legge, AVC ‘Ayna’– Waterdragon Gross: • Yellow to black discolouration of the oral mucosa membranes • Ulceration/necrosis Courtesy of Drs Buote & Legge, AVC ‘Ayna’– Waterdragon Histology: • Epidermal hyperplasia • Crusting • Embedded bacteria ‘Ayna’– Waterdragon “Mouth Rot” • Ulcerative stomatitis • Common in reptiles • Bacterial: • Aeromonas • Pseudomona • Variety of others • Often secondary: • Vitamin A deficiency has been implicated Courtesy of Drs Buote & Legge, AVC ‘Chaos’ – Boa constrictor • A 1.78 kg, male, San Andreas Boa constrictor • Wild caught in 2000, acquired by owner in 2007 • Within 2 months , became sick • Open mouthed breathing and wouldn’t eat • Writhing, then went limp • Physical exam: firm contraction of the musculature proximally and caudally the body was limp • Radiographs: Focal lucency of vertebra – suspect fracture ‘Chaos’ – Boa constrictor Gross: • Mild edema and congestion within the musculature in the affected area • No other significant gross findings Histology: • Marked infiltration of the vertebral bone by heterophils and macrophages • Evidence of spinal cord compression ‘Chaos’ – Boa constrictor Vertebral osteomyelitis with secondary pathologic fracture • Frequently reported in snakes in association with: • Salmonella arizonae* • Streptococcus spp • Osteitis deformans in snakes may represent chronic osteomyelitis 1. 2. EC Ramsay, GB Daniel, BW Tryon, JI Merryman, PJ Morris, DA Bemis. Osteomyelitis associated with Salmonella enterica SS arizonae in a colony of ridgenose rattlesnakes (Crotalus willardi). J. Zoo and Wildl. Med. 33(4): 301–310, 2002 Isaza, R., M. Gardiner, and E. Jacobson. Proliferative osteoarthritis and osteoarthrosis in 15 snakes. J. Zoo Wildl. Med. 31: 20–27, 2000 The ‘wild’ PEI Boa constrictor • Adult male Boa found dead at the side of the road in Oyster Bed Bridge • Escaped? • Discarded? • Gross exam: • Enteritis • Renal urate deposits (suggest dehydration) The ‘wild’ PEI Boa constrictor • The mucosal surface is ulcerated and covered by fibrin, degenerate inflammatory cells and bacterial colonies Fibrinonecrotizing enteritis The ‘wild’ PEI Boa constrictor Bacterial colonies Protozoa Fibrinonecrotizing enteritis The ‘wild’ PEI Boa constrictor Amoebic gastrointestinal disease in snakes • Entamoeba • 1 of the most clinically significant parasites in captive reptiles • Infective spores are shed in the feces and persist in the environment • Many are commensal • Entamoeba invadens • Important pathogen • Necrotizing enteritis and hepatitis • Clinical signs: listlessness, anorexia, mucoid/bloody feces • May cause neurological signs if trophozoites invade the blood → brain Protozoa The ‘wild’ PEI Boa constrictor Inclusion Body Disease! The ‘wild’ PEI Boa constrictor Inclusion Body Disease • C-type Retrovirus • Originally described in the Boidae family • Pythons* • Boa constrictors • More recently • Palm vipers, Corn snakes, King snake • Multisystemic disease – inclusions are present in the epithelial cells of most organs and neurons with the brain • Probable world-wide distribution The ‘wild’ PEI Boa constrictor Inclusion Body Disease • Clinical signs • Anorexia, regurgitation • Neurologic signs: stargazing, incoordination, paresis • Increased susceptibility to infectious disease • Pneumonia • Mouth rot • Eventual death / euthanasia • Increased incidence of neoplasia? • Cutaneous sarcoma • Leukemia Opisthotonus - boa Image from: D Vancraeynest, F Pasmans, A Martel, K Chiers, G Meulemans, J. Mast, P Zwart, R Ducatelle. Inclusion body disease in snakes: a review and description of three cases in boa constrictors in Belgium. Veterinary Record (2006) 158, 757-761 The ‘wild’ PEI Boa constrictor Inclusion Body Disease • Points of confusion: • Etiology – Retrovirus? • Can not be identified in all snakes with IBD inclusions • Is identified in healthy snakes without IBD inclusions • Not all snakes with IBD inclusions in tissues exhibit signs of disease • Asymptomatic carriers? • Differential diagnoses? • Regurgitation: • Stomatitis, Inappropriate environmental temp, Sepsis, Neoplasia, GI infection • Neurological signs: • Paramyxovirus* • Amoebiasis / meningitis • Organophosphate toxicity The ‘wild’ PEI Boa constrictor Inclusion Body Disease • No treatment – poor prognosis in snakes with clinical signs • Prevention? • Isolate newly acquired snakes for 6 months – 1 year! • Antemortem diagnosis? • Flank incision and wedge biopsy of the liver • Cytology on buffy coat? • Inclusions in WBCs ‘Iggy’ – Green iguana • 3year old, male, Green iguana • Housed in large enclosure, adequate UV light • Diet: juvenile iguana pellets with occasional strawberries • 1 week history of anorexia, seizures, tremors • Radiographs: NSF Iggy Normal range Potassium ↑↑ 7.4 2.1 – 4.1 Calcium ↓↓ 1.65 2.15 – 3.44 Phos ↑↑ 11.9 1.07 – 4.29 Creat ↑ 112 17.7 – 70.7 CK ↑↑↑ 366880 124 - 4194 AST ↑↑ 5912 0 - 180 ALT ↑↑ 701 0 - 85 ‘Iggy’ – Green iguana Underlying problems: • ↓ dietary Calcium • ↓ dietary Vitamin D • Lack of UV exposure • Kidney disease Leads to metastatic mineralization Potassium ↑↑ Calcium ↓↓ Phos ↑↑ Creat ↑ CK ↑↑↑ AST ↑↑ ALT ↑↑ ‘Iggy’ – Green iguana Potassium ↑↑ Calcium ↓↓ Phos ↑↑ Creat ↑ CK ↑↑↑ AST ↑↑ ALT ↑↑ Caused by muscle necrosis ‘Iggy’ – Green iguana • Massive rhabdolysis in other species has been reported to cause hyperkalemia and hyperphosphatemia Caused by muscle necrosis? Potassium ↑↑ Calcium ↓↓ Phos ↑↑ Creat ↑ CK ↑↑↑ AST ↑↑ ALT ↑↑ ‘Iggy’ – Green iguana • Massive rhabdolysis!!! • Secondary to mineralization? • Selenium deficiency • Suggested in iguanas • Reported in geckos • Measured liver Selenium – but no reference available L Gabor. Nutritional degenerative myopathy in a population of captive bred Uroplatus phantasticus (satanic leaf-tailed geckoes). J Vet Diagn Invest 2005 Jan;17(1):71-3 ‘Anole’ • An adult, male, Anole • Large slow-growing mass on head Abscess, Granuloma or Neoplasia? ‘Anole’ • An adult, male, Anole • Large slow-growing mass on head Abscess, Granuloma or Neoplasia? ‘Anole’ • 1.5 x 1 cm, bilobed cervical mass • Firm to fluctuant • On cut section: • White viscous material • Yellow-tinged fluid Abscess or Granuloma ‘Anole’ • Histologically: • • • Epithelial-lined cyst Proteinaceous fluid and mineral Granulomatous inflammation Cystic dilation and inspissation of the endolymphatic sac ‘Moe’ – Green iguana • • • • 8 – 10 year old, male, Green iguana Suddenly become depressed Radiographs normal and CBC/biochemistry unremarkable Despite fluids, antibiotics, and glucose became very depressed and weak → euthanized ‘Moe’ – Green iguana • Spleen enlarged, firm, and dark with gritty yellow material on the capsule and on cut surface • Adhesions to surrounding tissue • Granulomatous splenitis ‘Moe’ – Green iguana Histology Marked splenitis with intralesional bacteria Also lesions in the liver, intestine, brain, pancreas Pure culture of Moraxella sp. was isolated from the spleen → Sepsis ‘Moe’ – Green iguana Histology Another interesting finding: In the liver there was marked biliary proliferation GH Wilson, DK Fontenot, CA Brown, MA Kling, N Stedman, CB Greenacre. Pseudocarcinomatous biliary hyperplasia in two Green iguanas, Iguana iguana. Journal of Herpetological Medicine and Surgery: 14 (4), 12- 2004 • Affected animals survived for 6+ years following a diagnosis of cholangiocellular carcinoma! • No metastasis • Well-differentiated biliary epithelium
