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BDMLR - Marine Mammal Medic Handbook
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APPENDIX V: VETERINARY SECTION - CETACEANS

PLEASE MAKE THE ATTENDING VET AWARE THAT YOU ARE CARRYING THIS INFORMATION, SO HE / SHE CAN REFER TO IT, AS WELL AS TO THE INFORMATION IN THE MAIN TEXT OF THE HANDBOOK.

Please note that this section is intended for the use of vets. The exceptions to this are the section on fluid therapy, for the use of those with experience in stomach tubing, and the information on euthanasia by shooting, for the use of licensed firearms users, which is included in the triage.

Clinical Triage for Stranded Cetaceans

The following triage is designed as a guide for vets called upon to assess and treat stranded cetaceans. We would also suggest that those inexperienced in the management of stranded cetaceans should contact one of the following vets for further advice.

Veterinary Advice

James Barnett, British Divers Marine Life Rescue 01403 730176
07703 855399 (mobile)
Paul Jepson, Institute of Zoology, London
(Strandings Programme, England and Wales)
020 7449 6691
Ian Robinson, R.S.P.C.A. Norfolk Wildlife Hospital 01553 842336
Tony Patterson, SAC Veterinary Services, Inverness
(Strandings Programme, Scotland)
01463 243030

 

NOTES

To determine if alive, look for opening and closing of blowhole. N.B. big whales may hold breath for 20 mins. In these animals, checking for a corneal reflex and assessing other reflexes (see below) will help.

triage1.gif (16529 bytes)
Abnormal behaviour includes twitching, muscle tremors, pronounced and sustained lateral or ventral flexion, listing, lack of responsiveness movement. Such behaviour may take several hours to correct.
Umbilicus may be present in neonates. Dependent calves of harbour porpoises strand more frequently than calves of other species: born mainly June/July, suckle for seven to ten months, and are 90 – 95 cm in length when weaned. Very occasionally, mother may still be offshore.
Body condition assessed by examination of shape of lumbar muscles below dorsal fin. Reasonable if flat to convex in profile. If concave visible neck, not suitable for refloat. Interpretation complicated by number of factors: blubber thickness often seasonally and age dependent and may be maintained despite atrophy of underlying muscles, shape of animal may be distorted when beached and animals in good body condition may suffer from acute illness.
Superficial trauma (often occurs on stranding) generally not clinically significant, despite often heavy bleeding. Deeper wounds, penetrating muscle layer, extensive abscesses or haematomas affect prognosis, as do fractures and dislocations, although may be difficult to detect. N.B. stress and trauma of stranding can cause significant muscle damage, which may not be clinically apparent.

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Skin condition deteriorates out of water; exacerbated by wind and high temps.; skin wrinkles, peels, cracks and blisters. Excessive skin loss leads to fluid loss and increased risk of secondary infection. This is associated with a poor prognosis. triage2.gif (18471 bytes)
Can assess jaw and tongue tone, blowhole, flipper and palpebral reflexes. Poor reflexes and muscle tone may be associated with shock and a decreased level of consciousness, and are a poor prognostic sign.
Supportive treatment (oral fluids, i/v steroids, etc.) and moving the animal into the water may well be required to improve reflexes and muscle tone, i.e. reverse the onset of shock. If no reflexes or evidence of jaw and tongue tone are seen over the course of an hour, the prognosis is likely to be poor.
Deep bleeding from anus, blowhole and mouth is a poor prognostic sign.
Signs of respiratory disease include shallow respirations, strong smelling exhalations, mucopurulent blowhole discharge, occasionally coughing and sneezing, and adventitious lung sounds (N.B. latter only detectable in animals < 3 metres).
Breathing rates for small cetaceans, e.g. common dolphin:
2-5 breaths/min. - normal
over 6 breaths/min. - mild stress or respiratory compromise
over 10 breaths/min. - severe stress or over 10 breaths/min. - severe stress or respiratory compromise.
Normal rate for pilot whale : 1 breath/min.
Normal rate for sperm whale : as low as 1 breath/20 mins.
If increased respiratory rate is due to stress, then removal of stressors should bring the rate down in a few minutes. If due to hyperthermia, rate should come down quickly after extensive cooling.
Prolonged expiration-inspiration gap (> 4 secs.) may be seen with respiratory disease, or with onset of shock. Capillary refill time normally <= 2 secs.

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Supportive treatment (oral fluids, i/v steroids, etc.) and moving the animal into the water may well be required to reduce the gap between expiration and inspiration, i.e. reverse the onset of shock. If a response is not seen over the course of an hour, the prognosis is likely to be poor. triage3.gif (19865 bytes)
Temperatures taken with standard digital thermometer in animals < 50kg. In larger animals, thermistor probe should be inserted min. 20cm into rectum, although sealed digital thermometer securely attached to length of stomach tubing may suffice. Positive response to cooling in hyperthermic animals is good prognostic sign.
Sample small cetaceans from central tail veins, running near midline of ventral and dorsal surfaces of each tail fluke. In larger animals, alternative site is central arteriovenous complex in midline of dorsal fin. Apart from harbour porpoise, no reference ranges available. Results (particularly from ‘in practice’ analysers) should be interpreted with caution; only muscle enzyme (CK, AST) levels much higher than expected should influence prognosis. Serial bleeding during prolonged refloat may give useful information about stability of condition. As speed of response important, delaying refloat for results is not advisable.
A decrease in the muscle enzyme levels is unlikely to occur until the cetacean is moved into the water and refloating is initiated (see below). This decrease may take several hours to occur.
Carry into waist deep water or, if too heavy, refloat on tide, in a pontoon (N.B. refloatation of very large cetaceans is not usually feasible). Support with blowhole above water, until control of breathing is regained; rock gently to alleviate muscle stiffness or circulatory impairment, and to help restore.
See notes above re. behaviour in water. Also : inability to lift head to breathe, no closure of blowhole on immersion, no co-ordinated, forceful efforts to swim. Some signs not necessarily associated with poor prognosis, as may take several hours to correct.

 

When appears able to support itself, and making an effort to swim, move into deeper water to see if muscle stiffness abated sufficiently to allow swimming unaided. If so, guide seawards, or take further out for release with boats pontoons. N.B. successful refloat may take several hours to complete. triage4.gif (11188 bytes)
As animal may restrand, it is essential that some post release monitoring is carried out. At very least, dorsal fin should be photographed, and watch maintained on coastline for min. 48 hours. Biodegradable ribbon tied loosely around tail stock will also help identification. Repeated restranding after optimal care on beach is indicative of poor prognosis.
Euthanasia generally is performed by intramuscular injection of Large Animal Immobilon. Intravenous barbiturates are preferred for animals under 2 metres and, depending on size of animal and length of needles available, intraperitoneal barbiturates can be used in larger animals if LA Immobilon is not available. Animals under 3 metres can be shot from close range through blowhole with rifle (greater than .22 calibre), aiming towards line midway between pectoral flippers. Very large cetaceans are best left to die naturally.
Until improved, long term monitoring of refloated animals is implemented, success can only be assumed. Satellite tracking may well be implemented in the future, but present concerns include logistics, cost and the welfare of the tagged animal.

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Fluid therapy

Where practically possible, rehydration through stomach tubing is advisable, as most stranded cetaceans are dehydrated. Cetacean stomachs are relatively small and, therefore, volumes of rehydration fluid need to be kept low (1% v/w, e.g. 1 litre for an adult common dolphin). The procedure is also stressful and should not be carried out more than 4 times in a 24 hour period. Oral fluids that have been administered to stranded cetaceans include Lectade Plus, and Ringer’s, Hartmanns and glucose-saline solutions.

Stomach tubing can be carried out in the water, with adequate support, or out of the water, on an air mattress or moistened foam. Most small cetaceans will open their mouths relatively easily when introducing a stomach tube. Larger or intractable animals may require additional measures, such as working towels into the mouth, which then can be used to pull the jaws apart gently. After negotiating the centrally located, dorsally pointing larynx, an appropriately sized lubricated equine stomach tube is passed to a point between the pectoral and dorsal fins, to enter the stomach. Before fluids are passed, the animal is allowed to take a breath to ensure the larynx has not been dislodged.

Cross section of dolphin head showing larynx.
Click Illustration for full-page view

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Therapeutics

Antibiotics may be administered to animals to be refloated, to reduce the risk of secondary infection of any wounds sustained by the animal on stranding. Antibiotics administered to live strandings in the U.K. to date include depot amoxycillin (15 mg/kg, Clamoxyl LA), potentiated amoxycillin (8.75 mg/kg, Synulox), depot oxytetracycline (20 mg/kg, Engemycin 10%) and enrofloxacin (5 mg/kg, Baytril), all by intramuscular injection. Depot preparations may be useful prior to an early refloat, while short acting preparations can be administered daily to animals requiring two or more days’ treatment before refloatation.

Intramuscular flunixin (1.0 mg/kg) has been used in cetaceans for its analgesic and anti-inflammatory properties. If used, decisions regarding prognosis should not be made within eight hours of administration, due to the potential masking of clinical signs. Steroids may be beneficial in the treatment of shock but, again, any decisions regarding prognosis should be delayed until after their effects have worn off; their value in animals considered fit enough for an early refloat is questionable.Multivitamin injections may be beneficial, but anthelminthics are contraindicated, as the ‘die off’ of any lungworm present may precipitate a severe inflammatory response in species, such as harbour porpoises, known to carry a heavy burden. Diazepam (0.15 mg/kg) has been used to sedate cetaceans prior to transport, but cannot be recommended for animals that are to be refloated immediately afterwards. Generally, tranquillisers are contraindicated, due to their adverse effects on respiration and thermoregulation.

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Injection sites and needle sizes

In small cetaceans, intravenous injections can be given into the paired central tail veins, running along the midline of the ventral and dorsal surfaces of each tail fluke (see diagram under blood sampling).

In larger animals, where tail restraint is difficult, a more suitable site is the large central arteriovenous complex in the midline of the dorsal fin, which has small vessels running parallel to it. Sites in the pectoral fins and caudal peduncle have been used, but there is a greater risk of extensive necrosis following thrombovasculitis if these sites are used. 1 - 3.5 inch, 18 - 21 gauge needles will be required, depending on the size of the animal.

Intramuscular injections are given into the lumbar muscles lateral and caudal to the dorsal fin.

Needles should bridge the blubber layer and sizes needed to achieve this will be 1.5 - 10 inch, 14 - 21 gauge, depending on the size of the animal. Certainly, a minimum 3.5 inch (9 cm) spinal needle should be used in an adult common or striped dolphin or larger animals.

James Barnett administering drugs to a stranded orca
Click Photo for full-page view

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Eye and wound care

The eyes of stranded cetaceans are vulnerable to desiccation, irritation and trauma. Flushing with saline and application of ocular lubricant and antibiotic preparations may be beneficial. Superficial wounds can be cleaned and flushed, but topical preparations usually wash off on immersion, except possibly Orabase (ConvaTec). Suturing of wounds is not advisable, as dehiscence is likely.

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Blood sampling

See triage for information. Needle sizes are as for intravenous injections (see above). The diagram below illustrates the commonly used sampling sites. In addition to the central tail veins and central arteriovenous complex in the dorsal fin, sites in the pectoral fins and caudal peduncle have been used, but there is likely to be a greater risk of thrombovasculitis if these sites are repeatedly sampled.

Blood sampling sites in cetaceans
Click Illustration for full-page view

 

Dave Coombs bleeding a juvenile striped dolphin
Click Photo for full-page view

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Euthanasia

See triage for information. More details on drug-induced euthanasia are given below.

Large Animal Immobilon:

Dose rates:

Dolphins and porpoises: 0.5 mls per 1.5 metres

Whales: 4.0 mls per 1.5 metres

Route of administration: injections ideally should be made through the blubber layer into the lumbar muscles, lateral and caudal to the dorsal fin. Needle sizes are given above - large cetaceans may require needles up to 10 inches (25 cm) in length. However, if no suitable sized needles are available, then injections with shorter needles will still produce results, as the blubber layer contains an effective capillary network. Care must be taken when injecting into the blubber layer, as its fibrous nature makes injection of large volumes difficult and there is a risk of needle separation from the syringe due to the resultant pressure. It may prove necessary to inject small volumes at several different sites.

After LA Immobilon administration, it may take several minutes for an animal to die, particularly if the injection was given into the blubber layer. There also may be an excitatory phase prior to death, which can be distressing for onlookers.

Barbiturates:

Dose rates: Give to effect. Rates required may significantly exceed those for terrestrial mammals.

Route of administration: in small cetaceans, the intravenous route is recommended, via the central tail veins (see blood sampling). The intraperitoneal route can also be used in larger animals if LA Immobilon is not available and adequately sized needles are to hand.

N.B. Carcasses of cetaceans euthanased with drugs should be disposed of safely, to avoid poisoning scavengers.

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