What Is Your Diagnosis? Author(s): Source: Journal of Avian Medicine and Surgery, 28(1):69-72. 2014. Published By: Association of Avian Veterinarians DOI: http://dx.doi.org/10.1647/2012-071 URL: http://www.bioone.org/doi/full/10.1647/2012-071

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Journal of Avian Medicine and Surgery 28(1):69–72, 2014 Ó 2014 by the Association of Avian Veterinarians

What Is Your Diagnosis? USA). The bird was sedated with 2% isoflurane administered by face mask to obtain well-positioned radiographs and to complete a thorough physical examination. No visible or palpable abnormalities were detected on examination; however the bird was in poor body condition. Radiographic views in right lateral recumbency and in dorsal recumbency were obtained (Figs 1 and 2).

History A first-year northern gannet (Morus bassanus) was presented to the Cape Wildlife Center by staff at the Falmouth Animal Control, Falmouth, MA, USA. The bird had been captured an hour before admittance because of abnormal behavior and inappropriate location. The bird was found trapped in a tennis court after a recent windstorm and was reported to be easy to catch. On presentation, the bird was aggressive, alert, responsive, and well hydrated and weighed 1.9 kg (adult gannet, reference interval, 2.47–3.61 kg).1 A moderate hypothermia of 36.88C (reference range, 37.38C–38.98C) was observed.2 Severe pediculosis was treated with a topical insecticide (Scalex mite and lice spray for birds, Gps Group, Atlanta, GA,

Figure 1. Lateral survey radiograph of an immature northern gannet that presented for abnormal behavior after being found in a tennis court.

Figure 2. Ventrodorsal survey radiograph of the gannet described in Figure 1.

At this time, please evaluate the radiographs in Figures 1 and 2 before continuing. List any additional diagnostic tests needed, a diagnostic differential list, and possible treatment plans. 69

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Figure 3. Lateral view of gannet in described in Figure 1.

Figure 4. Markedly eroded nail that was removed from ventriculus of the gannet described in Figure 1.

Diagnosis

Discussion

Survey radiographs revealed a 7.6-cm metaldense foreign object in the region of the ventriculus (Fig 3, lateral view of ventriculus with leg repositioned). A diagnosis of a ventricular metallic foreign body was made. The metal was of an unknown composition, but given its shape and size, was presumed to be a nail. The gannet was treated with meloxicam (1 mg/kg SC; Metacam, Boehringer Ingleheim Vetmedica Inc, St Joseph, MO, USA) and recovered uneventfully. The bird was then referred to Tufts University Wildlife Clinic for endoscopic removal of the nail. A blood sample was drawn to measure the blood lead level, packed cell volume (PCV), and total protein level. Results showed a lead level of 1.5 lg/dL measured by a desktop analytic system (LeadCare, Magellan Diagnostics, North Billerica, MA, USA), a PCV of 15%, and total protein of 0.8 g/dL measured by refractometer. After being induced with isoflurane by mask induction, the bird was intubated, placed in dorsal recumbency, and prepared for endoscopy. Cardiac and respiratory monitoring were performed, and intraoperative fluids were given during the procedure. On endoscopic examination, the tip of the nail was found to be embedded in the wall of the ventriculus, but it was easily freed and removed, with no visible bleeding. The bird recovered uneventfully from anesthesia but died overnight. The nail was markedly eroded (Fig 4) but was suspected to be zinc-galvanized because of the size and appearance. Zinc toxicosis was also consistent with the bird’s presenting behavior and clinical course.

Gannets are opportunistic foragers and prey on a wide variety of pelagic fish and squid.3 Gannets commonly scavenge behind fishing boats and trawlers for whole fish and offal. They are even said to dominate gulls (Laridae), skuas (Stercorarius species), and fulmars (Fulmarus species) that may be competing with them.4 A 60-cm brass welding rod and a long loop of iron wire, among other objects, have been removed from the gastrointestinal tract of gannets that mysteriously sickened and died.4 Gannets are true pelagic birds; therefore, how a large nail could have found its way into this bird’s stomach is a primary question. A likely hypothesis is that the gannet ingested the nail, but how it was exposed is an important question and concern. Because gannets feed at sea, the nail was most likely in a food source. Plastic is the most extensively documented type of debris ingestion in marine wildlife.5 Currently, 44% of all seabird species have been confirmed to ingest plastic, underscoring the vast scale of the phenomenon.6 The impact that ghost net and longline fisheries have on gannets and other seabirds has also been well documented. Larger, surface-foraging, scavenging seabirds that can swallow baited hooks are most frequently caught on longline hooks,7 and approximately 3500 albatross (Diomedia species) are caught per year in the North Pacific pelagic longline fisheries.8 Commercial fisheries discard nylon and other synthetic materials that are generally buoyant and far less degradable than older natural fibers. These lines and nets entangle many marine animals (sea turtles, mammals, seabirds, fish, and crustaceans).9 Entanglement in fishing gear causing death

WHAT IS YOUR DIAGNOSIS?

has been documented in northern gannets,10 but this case highlights additional man-made perils, other than entanglement and plastic ingestion, that seabirds face. Less well documented, but equally important, is the ingestion of metal foreign bodies. This case raises clear questions about dangerous materials present in this bird’s ecosystem, but it also presents an interesting clinical challenge. There are several concerns with a seabird presenting with metal foreign body ingestion. Action to remove the nail was taken in this particular case, but this decision should be based on the health status of the patient and depends primarily on what the foreign object is and where it is located in the digestive tract. This bird was alert and aggressive, but it had a heavy external parasite load and was anemic and hypoproteinemic. Metal toxicosis was also a concern in this case because of the presence of the nail; however, the blood lead level was below levels shown to produce clinical signs of toxicosis.11 Zinc toxicosis was also a possibility as the nail may have been galvanized. Unlike as with lead, no rapid desktop test is available for zinc. Lead and zinc are common causes of toxicity in birds and should be high on the differential list when heavy metal toxicosis is suspected.12 The proventriculus of fish-eating birds secretes acidic gastric juices, creating an environment with a pH of 0.2 to 1.2.11 This acidic environment can break down metallic objects ingested by the bird and would have dissolved the galvanized layer of this nail, exposing the gannet to zinc. Clinical signs of zinc poisoning pertinent to this case were weight loss, weakness, and anemia.12 Systemic effects are related to hypoproteinemia-induced damage in the kidneys, gastrointestinal system, and pancreas.12 Serum zinc levels above 200 lg/dL are diagnostic for zinc toxicosis.11 However, tissue sampling from pancreas, kidneys, and liver is a more reliable source of measuring zinc levels.11 Zinc levels were not measured in this case. The treatment protocol for birds presenting with heavy metal toxicosis varies depending on the severity of the case and the location of the foreign object. The primary treatment involves removal of the foreign body. If a bird has ingested galvanized wire, this zinc-coated ferrous metal can sometimes be removed by using a powerful neodymium-ferrobarium alloy magnet attached to a small-diameter catheter with a removable, flexible-steel guide wire. Fluoroscopic-guided removal is ideal; however, particles can also be removed by repeatedly passing the apparatus into the ventriculus until no further metal particles are removed. The success of the

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removal process can be determined with radiographs. Often zinc foreign bodies can be removed with bulk cathartics (sodium sulfate), activated charcoal, or mineral oil. Surgical removal may be necessary if the object cannot be removed with other methods.12 Chelation treatment with calcium-ethylenediaminetetraacetic acid (CaEDTA, Sigma Chemical Co, St Louis, MO, USA) (50– 100 mg/kg diluted in 50 mL saline SC q12h) is initiated based on clinical signs and blood lead and zinc levels, and treatment is continued for 5 days. After a 2–3 day hiatus, the regimen is repeated again and continued in this fashion until blood lead levels are below 0.2 ppm.13 The chelation process may be augmented by the simultaneous administration of dimercaptosuccinic acid at (30 mg/kg PO q12h). A combination of these treatments used in the appropriate manner should be used while still keeping in mind the overall stability and health of the patient. Fisheries have numerous effects on nontarget animals. Stomach content analysis suggested that 1300–2048 items of gear are currently consumed per year by the wandering albatross (Diomedea exulans) population.14 Despite control measures, fisheries affect more than 40 seabird species, causing a decline in many populations, most notably longer-lived Procellariiformes.15 Of the myriad of anthropogenic and natural threats to seabirds, one of the most critical global problems is incidental mortality in longline fisheries.8 A device known as a ‘‘yo-yo’’ rig has been used for both commercial and small-scale fishing of large saltwater fish such as striped bass. The use of these rigs was banned in Massachusetts state waters by a Marine Fisheries regulation passed in 2011. The regulation prohibits the use of natural bait embedded with materials that are not attached to the terminal tackle.16 In the original ‘‘yo-yo’’ rig, baitfish were embedded with weights and metal skewer-type objects to maintain weight and form. These embedded objects were not attached to the terminal tackle so would be ingested by the animal eating the bait instead of staying attached to the line (see Fig 5).16 In this gannet, we suspected that the nail was used as one of these metal skewers and was ingested by this bird, along with the piece of bait to which it was attached. The method of foraging by gannets lends them to picking up bait fish on longlines, as they are considered to obtain prey usually by rapid, vertical, shallow plunge dives17 and are notorious for picking up floating debris, including netting, from the sea surface.18 The use of yo-yo rigs for fishing is still practiced legally in other states, including Rhode Island.

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Figure 5. An assortment of lead weights and hardware found in the stomach of a large striped bass, resulting from the use of yo-yo rigs with unattached tackle. Courtesy Commonwealth of Massachusetts Department of Marine Fisheries. Photo by Bob Zunwalt.

Seabirds are considered to be useful bio-monitors of various characteristics of marine environments, including plastic pollution. Few studies have addressed their potential for monitoring discard rates of hooks and other fishing gear.14 More research is needed to fully understand the impact that fisheries and other origins of metal debris have on the marine ecosystem. This case was submitted by Cynthia Hopf, BS and Mark Pokras, DVM, from Tufts University Cummings School of Veterinary Medicine, 200 Westboro Rd, North Grafton, MA 01536, USA and Roberto F. Aguilar, DVM, from Cape Wildlife Center, Humane Society of the United States, 4011 Main St, Barnstable, MA 02630, USA.

References 1. Dunning JB. CRC Handbook of Avian Body Masses. 2nd ed. Boca Raton, FL: Taylor and Francis Group; 2008. 2. Kerley GIH, Erasmus T. Oil pollution of cape gannets: to clean or not to clean? Mar Pollut Bull. 1986;17(11):498–500. 3. Montevecchi WA, Myers RA. Centurial and decadal oceanographic influences on changes in northern gannet populations and diets in the north-west Atlantic: implications for climate change. ICES J Mar Sci. 1997;54:608–614. 4. Nelson B. The Gannet. Vermillion, SD: Buteo Books; 1978.

5. Robards MD, Piatt JF, Wohl DD. Increasing frequency of plastic particles ingested by seabirds in the subarctic North Pacific. Mar Pollut Bull. 1995;30(2):151–157. 6. Titmus AJ, Hyrenbach KD. Habitat associations of floating debris and marine birds in the north east Pacific Ocean at coarse and meso spatial scales. Mar Pollut Bull. 2011;62:2496–2506. 7. Brothers NP. Catching Fish Not Birds: A Guide to Improving Your Longline Fishing Efficiency. Hobart, Australia: Tasmania Parks & Wildlife Service; 1995. 8. Gilman E. Integrated management to address the incidental mortality of seabirds in longline fisheries. Aquat Conserv. 2001:11:391–414. 9. Gregory MR. Environmental implications of plastic debris in marine settings— entanglement, ingestion, smothering, hangers-on, hitch-hiking and alien invasions. Philos Trans R Soc Lond B Biol Sci. 2009;364(1526):2013–2025. 10. Votier SC, Archibald K, Morgan G, Morgan L. The use of plastic debris as nesting material by a colonial seabird and associated entanglement mortality. Mar Pollut Bull. 2011;62:68–172. 11. Bauck L, LaBonde J. Toxic diseases. In: Altman RB, Clubb SL, Dorrestein GM, Quesenberry K, eds. Avian Medicine and Surgery. Philadelphia, PA: WB Saunders Company; 1997:604–613. 12. Dumonceaux G, Harrison GJ. Toxins. In: Ritchie BW, Harrison GJ, Harrison LR, eds. Avian Medicine: Principles and Application. Lake Worth, FL: Wingers Publishing Inc; 1994:1030–1052. 13. Robinson I. Seabirds. In: Tully TN, Dorrestein GM, Jones AK, eds. Handbook of Avian Medicine. 2nd ed. Philadelphia, PA: Saunders Elsevier; 2009:377–403. 14. Phillips RA, Ridley C, Reid K, et al. Ingestion of fishing gear and entanglements of seabirds; monitoring and implications for management. Biol Conserv. 2010;143:501–512. 15. Ridley C, Harrison NM, Phillips RA, Pugh FJA. Identifying the origins of fishing gear ingested by seabirds: a novel multivariate approach. Aquat Conserv. 2010;20:621–631. 16. Commonwealth of Massachusetts Division of Marine Fisheries. Commercial striped bass fishery to open July 12, 2012 and Massachusetts prohibits the use of yo-yo rig gear. Marine Fisheries Advisory. 2012;322:CMR 6.42. 17. Garthe S, Benvenuti S, Montevecchi WA. Pursuit plunging by northern gannets (Sula bassana) feeding on capelin (Mallotus villosus). Proc Biol Soc. 2000;267(1454):1717–1722. 18. Tasker ML, Camphuysen CJ, Cooper J, et al. The impacts of fishing on marine birds. ICES J Mar Sci. 2000;57:531–547.

What is your diagnosis? Ventricular metallic foreign body.

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