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 r k e e e r C v i R ek Cre n reek h C ilo a Sh i Po s ol s r o s u d n C R i reek W st We k ar M L a g u n a Santa Ros a Cr eek M a n t a d n e z a s C re ek k S ee a Cr n n lga ta Co R Hinebaugh Creek os a Copeland Cr eek 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: <https://www.waterboards.ca.gov/northcoast/water_issues/programs/tmdls/laguna_de_santa_rosa/#mer>. • Coker, S. M. , S. M. Hernandez, W. M. Kistler, S. E. Curry, C. N. Welch, H. W. Barron, S.Harsch, M. H. Murray and M. J. Yabsley. 2017. Diversity and prevalence of hemoparasites of wading birds in Southern Florida, USA. International Journal for Parasitology: Parasites and Wildlife. 6(3):220-225. • Cuthbert, R., J. Parry-Jones, R. E. Green and D. J. Pain. 2007. NSAIDs and scavenging birds: potential impacts beyond Asia’s critically endangered vultures. Biology Letters. 3:90-93. • Deardorff, T. L., N. J. Karch and S. E. Holm. 2008. Dioxin levels in ash and soil generated in southern California fires. Organohalogen Compounds. 70:2284-2288. • De Matos, R. 2008. Calcium metabolism in birds. Veterinary Clinics of North America: Exotic Animal Practice. 11:59-82. • Dijkstra, B., D. S. Guzman, K. Gustavsen, S. D. Owens, C. Hass, P. H. Kass and J. R. Paul-Murphy. 2015. Renal, gastrointestinal, and hemostatic effects of oral administration of meloxicam to Hispaniolan Amazon parrots (Amazona ventralis). American Journal of Veterinary Research. 76(4):308-317. • Dyer, F., G. Diesel, S. Cooles and A. Tait. 2010. Suspected adverse reactions, 2009. Veterinary Record. 167:118-121. • Enberg, T. B., L. D. Braun and A. B. Kuzma. 2006. Gastrointestinal perforation in five dogs associated with the administration of meloxicam. Journal of Veterinary Emergency and Critical Care. 16(1):34-43. • Engelhardt, G. 1996. Pharmacology of meloxicam, a new non-steroidal anti-inflammatory drug with an improved safety profile through preferential inhibition of COX-2. British Journal of Rheumatology.