Gross Pathology of Herons and Egrets at a Wildlife Rehabilitation Center in Northern California
Molly Horgan DVM Candidate, Class of 2020 UC Davis School of Veterinary Medicine Study • Necropsy of all herons/ egrets that died in a 6 week period in the summer of 2018 (June – August) • Gross, occasionally diff-quick cytology • Budget ~ $0
• Objectives: • Metabolic bone disease • Why birds die/ don’t do well
• Limitations • Only gross findings • Short period of time, vast majority young animals, one region TOTAL NECROPSIES n=145
EUTHANIZED DIED n=108 n=37
METABOLIC BONE DISEASE CLINICAL DECLINE TRAUMA SEPTIC ARTHRITIS OTHER n= 39 n= 32 n= 24 n= 9 n= 4 Species and age Number SPECIES Black-Crowned Night Heron (Nycticorax nycticorax) 33 Cattle Egret (Bulbulcus ibis) 9 GreatYoung Blue Heron (Ardea Herodias) snowy egrets,2 black Great Egret (Ardea alba) 7 Green Heron (Butoroides virescens) 21 Snowy Egretcrowned (Egretta thula) night herons,73 LIFE STAGE Hatchling 5 Nestling green herons 35 Fledgling 95 Older juvenile 9 Adult 1 Anatomy
TRACHEA
THYROID GLAND PARATHYROID GLAND
HEART
LIVER Anatomy
ESOPHAGUS TRACHEA KIDNEYS LUNGS LUNGS
HEART SPLEEN
LIVER
VENTRICULUS Anatomy
OVARY TESTES
Female Male 43/145 Birds 43/145 Birds Definitive bird host
Bird sheds parasite eggs into the environ- ment in feces
Birds feed on infected transport hosts. Infective larvae reach sexual maturity within bird host Bird feeds on infected fish then larvae develop to sexual maturity
Eustrongylides sp. Transport (paratenic hosts)
First stage larvae develop in eggs eaten by oligochaetes (freshwater aquatic worms)
Infected minnows are fed upon by species other than birds First intermediate host
Minnows and other small fish feed upon oligochaetes Third stage larvae become encapsulated Eggs hatch within oligochaetes; within body of fish second-and third-stage larvae are Second intermediate host produced within oligochaetes
Figure 29.1 Life cycle of Eustrongylides sp.
224 Field Manual of Wildlife Diseases: Birds Secondary infections • Abscesses • Liver (7) • Lung (5) • Airsacculitis (3) • Renal (1) Eustrongylides • 43/145 birds • Death – 10 • Anorexia, weight loss, hypothermia à euthanasia – 12 • Incidental/ resolving – 21
Metabolic Bone Disease
• Most common reason for euthanasia during study time period Metabolic Bone Disease
NORMAL METABOLIC BONE DISEASE • Main components of bone:
• Organic matrix – mostly collagen
• Mineral – hydroxyapatite = calcium and phosphorous
MBD = family of bone disorders resulting from a disturbance in Ca homeostasis
Many potential causes: diet, toxins, hormonal imbalances, renal failure, neoplasia… Parathyroid hormone
MAIN FUNCTION PTH = PREVENT Activation of BLOOD CALCIUM Blood Ca vitamin D FROM GETTING Ca reabsorption TOO LOW
Ca pulled from bone blood Ca Metabolic Bone Disease NO MBD MBD
Parathyroid gland diameter 4
3
2
diameter (mm) 1
0
MBD No MBD
Yellow arrows = thyroid gland; red arrows = parathyroid gland Vitamin D Inactive vitamin D in blood
Ca and P absorption from GI tract liver Ca reabsorption in kidney Bone formation kidneys
Active vitamin D Metabolic Bone Disease
• Increase from previous year in both numbers at intake and developing in care • Considered separately MBD in care - Diet • Dietary causes of MBD: ↓ Ca, ↓ P, ↓ Ca:P ratio, ↓ Vitamin D
• 2017 – night smelt • No MBD $$$$$
• 2018 – capelin • Supplemented CaCO3 for Ca:P ratio of 2:1 • Lots of MBD Capelin Vitamin D Content • Capelin – 99IU/100g • Herring – 1257IU/100g
• MBD in African penguins fed capelin
• No measurable Vitamin D in capelin Proportion of birds necropsied with MBD
Supplementation = 3240 IU/kg BW Oral Vitamin D3
* Only including animals that developed MBD in care Vitamin D
Parathyroid hyperplasia PTH
Ca and P absorption from GI tract Blood Ca
Ca reabsorption in Calcium pulled from kidney bone Bone formation
MBD at intake from April 1st –August 9th Location 2017 2018 Total 28/637 (4%) 51/446 (11%)
At intake = noted at intake exam or within 3 days of admission MBD at intake from April 1st –August 9th Location 2017 2018 Total 28/637 (4%) 51/446 (11%) Concord 2/15 (13%) 0/20 (0%) Fairfield 4/86 (5%) 3/39 (8%) Oakland 2/105 (2%) 4/25 (16%) Sacramento 5/36 (14%) 2/61 (3%) Santa Rosa 11/258 (4%) 35/176 (20%)
At intake = noted at intake exam or within 3 days of admission MBD at intake from April 1st –August 9th Location 2017 2018 Total 28/637 (4%) 51/446 (11%) Concord 2/15 (13%) 0/20 (0%) Fairfield 4/86 (5%) 3/39 (8%) Oakland 2/105 (2%) 4/25 (16%) Sacramento 5/36 (14%) 2/61 (3%) Santa Rosa 11/258 (4%) 35/176 (20%)
At intake = noted at intake exam or within 3 days of admission https://sanfrancisco.cbslocal.com/video/3743071-santa-rosa-hilton-hotel-engulfed-in-flames-from-tubbs-fire/ TOXINS?
Laguna de Santa Rosa Watershed
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Legend
Laguna Watershed 0 1 2 3 4 5 Miles Streams
Incorporated Cities 012345Km https://www.nytimes.com/interactive/2017/10/14/us/california-fire-building-damage.html
Visceral Gout – 10/37 birds that died Visceral Gout J Protein Uric acid breakdown Excreted by kidneys Visceral Gout J Protein Uric acid breakdown Excreted by kidneys
Reduced excretion by kidneys L ? Toxin? Visceral Gout DOSE = 0.5MG/KG SID
• 8 on current course, mean tx 12 days, median 4 days, range 2-36. • 2 died weeks after receiving 1 or 2 doses
• Significantly associated with administration of meloxicam (p=0.001)
• Not majority of animals treated with meloxicam • 57 birds necropsied that received meloxicam • 15 released during study time period Intestinal perforation
• n = 4 (3 BCNH, 1 GRHE)
• 1 died, 3 euthanized
• Significantly associated with meloxicam (p = 0.02) • Mean tx 17 days, range 9- 31 days Pinterest.com 1.6mg/kg PO BID x 15d “No apparent negative changes in several renal, gastrointestinal, or hemostatic variables in healthy Hispaniolan Amazon parrots”. Beautyofbirds.com 0.5mg/kg IM BID x 14d “does not cause clinically relevant changes in CBC or plasma biochemical values, renal-associated lesions, or adverse muscle effects” Allaboutbirds.org
1, 10, 20mg/kg PO BID x 7d “No clinical signs or mortality were observed in any group. No significant differences of clinical relevance were found in results of the packed cell volume, total solids, and biochemical panel, and no evidence of renal toxicity was found in the treatment or control groups.” https://www.hbw.com/ibc/species/indian-vulture-gyps-indicus Survey-based study of vets and zoos on outcome of NSAID treatment of over 870 birds from 79 species
Diclofenac, carprofen, flunixin à mortality reported
“In contrast, there were no reported mortalities for the NSAID meloxicam, which was administered to over 700 birds from 60 species.” Meloxicam • Need more studies to say definitively that meloxicam is a cause of renal failure/ intestinal perforation in herons/egrets
• Possible reasons for adverse effects in herons/egrets vs other birds • Extended half life • Young age/ illness • Increased sensitivity to COX inhibition EUSTRONGYLIDES – 10 GOUT - 10
EUSTRONGYLIDES – 12 INTESTINAL PERFORATION - 2 Other findings Finding Number of animals affected Metabolic bone disease 47 Eustrongylidiasis 43 Liver abscess(es) 14 Visceral gout 10 Septic arthritis 9 Lung abscess(es) 8 Intestinal perforation 4 Conclusions
• Gross necropsy can be useful! • (but there are limitations)
• Suspect Eustrongylides in young herons/egrets that die or have persistent weight loss, anorexia, hypothermia, regurgitation
• Consider Vitamin D deficiency when faced with MBD, supplement birds on a diet of capelin
• Caution may be warranted using meloxicam in herons and egrets THANK YOU!
•Dr. Rebecca Duerr •Staff/ volunteers at IBR •Dr. Brian Murphy •NWRA •Shak Makhijani – photo credit (live birds) References • California Water Boards – Laguna de Santa Rosa TMDLs [monograph on the Internet]. [cited 2019 January 5]. Available from:
• Hoppes, L. and T. Clauss. 2016. Investigation of a potential Vitamin D3 deficiency in an African Penguin (Spheniscus demersus) collection [abstract]. In IAAAM; 2016 May 21-26. Virginia Beach, VA. • Madrone Audubon Society – West 9th Street Heronry [monograph on the internet]. [cited 2019 January 5]. Available from:
• Slifka, K., S. D. Crissey, S. Khan, A. Moser, T. C. Chen, J. Mathieu and M. F. Holick. 2001. Nutritional status in captive Bottlenose Dolphins (Tursiops truncates). Pp. 151-157 in Proceedings of the Fourth Conference on Zoo and Wildlife Nutrition (Edwards M, Lisi KJ, Schlegel ML, Bray RE, Eds.). AZA Nutrition Advisory Group, Lake Buena Vista, FL. • Spalding, M. G., G. T. Bancroft and D. J. Forrester. 1993. The epizootiology of eustrongylidosis in wading birds (Ciconiiformes) in Florida. Journal of Wildlife Diseases. 29(2):237-249. • Spalding, M. G. and D. J. Forrester. 1993. Pathogenesis of Eustrongylides ignotus (Nematoda: Dioctophymatoidea) in ciconiiformes. Journal of Wildlife Diseases. 29(2):250-260. • Summa, N. M., D. S. Guzman, S. Larrat, E. Troncy, D. M. Bird, S. Lair, and G. Fitzgerald. 2017. Evaluation of high dosages of oral meloxicam in American Kestrels (Falco sparverius). Journal of Avian Medicine and Surgery. 31(2):108-116. • Thompson, H. M., A. Fernandes, M. Rose, S. White and A. Blackburn. 2006. Possible chemical causes of skeletal deformities in grey heron nestlings (Ardea cinerea) in North Nottinghamshire, UK. Chemosphere. 65: 400–409. • Van Franeker, J. A. 2004. Save the North Sea fulmar–litter–EcoQO manual part 1: collection and dissection procedures. Alterra: Wageningen, Netherlands. [cited 2018 December 27]. Available from: