Feeding of Casualty Seals (Wildlife Casualty Management)
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Summary Information
Type of technique Health & Management / UK Wildlife Casualty Management / Techniques:
Synonyms and Keywords N.B.  This information should be read in association with Wildlife Casualty & Convalescent Feeding which contains background information together with links to the Electronic Library and Organisations (UK Contacts). The related Species pages contain similar linkages.
Description This page has been prepared for the "UK Wildlife: First Aid and Care" Wildpro module, and is designed for the needs of the following species: Halichoerus grypus - Grey seal, Phoca vitulina - Common seal.
  • These species are within the family Phocidae.
  • These species commonly present as pups. Further information including detailed considerations of feeding pups is included in: Hand-rearing Seals

Fluids (water):

  • Offer a rehydration (electrolyte) solution such as Lectade (Pfizer Limited) to drink on admission.
  • Water should be freely available at all times unless the casualty is unconscious or severely debilitated and unable to hold its head up.
  • Both water and a rehydration (electrolyte) solution, in separate containers, should be made available initially.
  • (V.w5, V.w26)
  • Initial stomach tubing with a rehydration (electrolyte) solution is likely to be required. (V.w26)

Convalescent Diet:

Suggested convalescent diets include:

  • Stomach tubing with a liquidised fish mixture may be required for individuals which will not take whole fish or pieces of fish initially. (P24.335.w9, V.w26)

Short term Maintenance Diet:

Suggested short term maintenance diets include:

  • Whole fish such as herring and smelt. (B224, P24.335.w9)
    • The nutritional value of fish which have been eviscerated is lower than that of whole fish.
  • The amount of fish required will vary depending on the size of the seal, any injury or disease, activity level and environmental temperature, and should be worked out by calculating the caloric requirements of the individual animal. 
  • As a general guideline an adult seal is likely to require 45-80kcal per kg bodyweight per day and a juvenile is likely to require 70-100 kcal per kg bodyweight per day . (P24.335.w9)
  • Supplements required include:
  • Thiamine 25-35mg/kg fish fed due to the presence of thiaminase in fish.
  • Sodium chloride 2-3 3g/kg fish fed if keeping seals in fresh rather than salt water. (P24.335.w9, P26.2000.w1)
  • Vitamin E at 100 iu per kg fish fed as this may be deficient in frozen fatty fish.
  • Iron as ferrous sulphate at 200mg per animal per day may be given to avoid the development of anaemia. 
  • Fisheater tablets, e.g. Aquavits (Special Diet Services), 1/2 tablet for up to 500g of fish, 1 tablet for over 500g fish, given at each feed. (P26.2000.w1)
  • (P24.335.w9, P26.2000.w1)
  • Force-feeding of sick seals may be required (P24.335.w9); a detailed description is given in: Hand-rearing Seals
Appropriate Use (?)
  • Fresh drinking water should always be available in a container of an appropriate size and type for the species concerned.
  • Fluid replacement therapy other than oral fluids may be required for casualties which are extremely dehydrated on admission or are unable to take in and absorb oral fluids.
    • Fluid therapy should continue until the animal is no longer dehydrated, even if it is self feeding
  • Feeding of convalescents should take into account their requirement for additional nutrients for healing as well as maintenance requirements.
  • The required fluid intake for maintenance should be considered when designing convalescent diets.
  • Energy requirements for maintenance and healing should be calculated and used to determine the quantity of food required for both convalescence and short-term maintenance diets.
  • Convalescent diets should be easily absorbed/digested.
  • Care should be taken not to under or over supplement with vitamins/minerals.
  • Diets intended for feeding from a syringe or by stomach tube (gavage) must be of a sufficiently fluid consistency to pass through the syringe nozzle or down the tube without it becoming blocked.
  • The natural diet should be considered when deciding on suitable ingredients, including consideration of taste/smell.
  • Fresh food must be provided daily.
  • Regular cleaning of food and drinking water containers (e.g. daily) is important to reduce the risk of disease.
  • Food and water containers should be sited to minimise the risk of contamination with droppings/faeces/urine. 
  • Frozen fish should be kept at or below -25 to -30C (P24.335.w9)
  • Thaw frozen fish slowly in a refrigerator before use and discard unused fish after 24 hours.
Complications/ Limitations / Risk
  • Water bowls should not be left in the accommodation of a casualty which is unconscious or is severely debilitated and unable to hold its head up.
  • Dehydrated and malnourished individuals sometimes drink rehydration fluids but refuse plain water initially; other will drink water but not rehydration fluids. Both should be made available.
  • No diet, however well balanced nutritionally, is useful if the animal does not eat it, for example because it is not recognised as food.
  • Ingestion of food should be monitored, not assumed. This may include weighing food before presentation and weighing waste food after removal, and periodic weighing of the animal.
  • Monitoring of weight/body condition is particularly important for group housed/group fed animals, within which some individuals may take more food and others not get the food they require.
  • Diets suggested on this page are intended for short term use for wildlife casualties; they are not necessarily suitable for long-term use or in individuals which are breeding.
  • Diets suggested on this page are not necessarily suitable for feeding infants; information on appropriate diets for very young individuals are described in the page on hand-rearing.
  • The feeding of only a single type of fish should be avoided.
  • Fish of poor quality should not be used.
  • Slow freezing and improper thawing methods induce reductions in fish quality such as dehydration, denaturing of protein, deterioration of lipids, losses of vitamins and sometimes production of exogenous toxins (P24.335.w9).
Equipment / Chemicals required and Suppliers
  • Oral rehydration (electrolyte) solutions are widely available from veterinary suppliers and chemists. 
  • A basic oral rehydration (electrolyte) solution may be made by dissolving one tablespoon of sugar and one teaspoon of salt in one litre of water. (B203)
  • Lectade, Pfizer Limited: from veterinary suppliers and agricultural feed suppliers.
  • Dietary vitamin supplements: from veterinary suppliers and specialist feed feed suppliers.
  • Fish may be bought from fishmongers or specialist animal food suppliers.
Expertise level / Ease of Use
  • Expertise is required if force-feeding of adult seals is necessary.
Cost/ Availability
  • The cost of fish for feeding adult seals for more than a short period may be considerable.
Legal and Ethical Considerations
  • Under the Protection of Animals Acts 1911-2000 it is an offence not to provide animals (including captive wild animals) with necessary food and water. (J35.147.w1, B156.21.w21, B223, P19.2.w1)
  • Care should be taken not to let an individual become accustomed to a single food item as this may result in difficulties in feeding the animal if the food item becomes unavailable, and in preparing it for release.
  • Every effort should be made to provide appropriate natural, locally available foods to animals which have been maintained in captivity for prolonged periods before they are released, in order to re-accustom them to a natural diet and reduce the chance of digestive problems following release. (P24.233.w11)
  • The release of animals which, by virtue of an inadequate or inappropriate diet whilst in captivity, are not fit to survive when released may be considered an offence under the Abandonment of Animals Act, 1960. (J35.147.w1, B156.21.w21, B223, W5.Jan01)
Author Debra Bourne
Referee Becki Lawson and Suzanne Boardman

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