1. the case i had was a female grey seal
the samples the clinpath unit received were..
there weren’t any more details for e.g about her age or clinical history
but the samples were sent in april 2009
2. thought would start off with some basic facts about seals and grey seals
Seals belong to a group of animals called pinnipeds. This means ‘winged-feet’
and refers to their flippers, which are specially adapted for life in the sea.
the pinnipeds include three families - the seals, sealions & fur seals and walruses.
Most noticeable difference between them is that while fur seals and sealions can
walk about on all fours, seals can only wriggle on their stomachs. Fur seals and
sealions also have ears, whereas seals’ ears are so small that they can only be
seen when they are wet. walruses have tusks.
Male seals are known as ‘bulls’ and female seals as‘cows’.
the two resident species found in british coastal waters are: the grey seal and
common/harbour seal (phoca vitulina vitulina). no sealions or fur seals in
european waters! v occasionally, arctic ice-breeding species (e.g.bearded seals)
may visit but otherwise, these would be the 2 vets might possibly get brought in
3. how to tell grey seals and harbour seals apart
it can be difficult, especially when they are wet but grey seals have a very
distinctive face, with a longer muzzle. and males can have quite a pronounced
Grey seals are also larger than common seals
males grow to about 2.3m while females are smaller and average 1.8m in length
(harbour seals average 1.5m and 1.4m)
4. The name ‘grey’ seal is rather misleading, since there is a lot of variation in colour
from almost black or dark brown to light grey with blotches and some have
lighter or darker patches.and grey seal pups are born with a long coat of silky
white hair (lanugo) which they shed after about 16-21days, round about
Seals spend most of their time at sea, and come ashore for just three reasons: to
breed, to moult, and to rest between fishing expeditions.
they’ll start to congregate at traditional pupping sites called rookeries in the
autumn and pups are born from end Sept to mid Dec.
moulting is between mid Jan to late Feb for the females and mid Feb to early
April for the males.
Reason I’ve put this down: was just important for looking up the reference
so i was thinking since the sample was sent in april, she would have more likely
been a subadult/adult rather than a weanling pup.
5. one of the questions I had was how would you get a blood sample from a seal?
from the extradural intravertebral vein!
this is accessed via the L3-L4 intervertebral space with the seal in sternal
recumbency. and you have to use quite a long needle.
6. first will look at her biochemistry data
main problem was not having any reference ranges – felt really lost when faced
with just a single column of values
thankfully found in the trusty bsava manual of wildlife casualties some reference
ranges for grey seals
the bsava manual didn’t have reference ranges for all the analytes though so for
those I didn’t have anything for yet, the next best i could find were reference
ranges for harbour seals.
(They were not in the SI units though e.g. mg/dl and not mmol/l but found out
from Elspeth that there are conversion formulas!)
I double checked the ranges for some of the other analytes (e.g. sodium,
potassium) and they seemed to be quite similar/corroborate so figured it would
be okay to use the chloride and calcium values as well.
12. Problem list - these were the major worries the clinpath people/the vet would
have had for the seal
13. blood smear had reported that the anaemia was poorly regenerative, probably
because no or minimal polychromasia was seen
because non-regenerative anaemia in marine mammals is reported to be quite
uncommon in general (due mainly to things like bone marrow neoplasia or sulfa-
drug induced pancytopaenia – but seal’s wbc values were fine), was thinking
maybe it could have been acute blood loss or haemolysis before sufficient time
had elapsed for a reticulocyte response
but one thing against acute blood loss was that her TP was normal and not low.
Overall, the list of possible reasons for a normocytic, normochromic anaemia
14. compared with terrestrial mammals, marine mammals have the lowest overall
their RBC indices such as RBC size and Hb concentrations
heart weights &
are all generally higher as adaptations for diving
gives them increased oxygen carrying capacity.
they also have high concs of muscle myoglobin.
so during long dives, deoxygenated blood is pooled in large venous sinuses and
there is pronounced bradycardia. remaining oxygenated blood is diverted
solely to nervous tissue and heart while muscles respire anaerobically.
grey seals can dive to depths of around 70 metres when searching for food and
are able to remain underwater for up to 16 minutes.
15. discussion about the smear report of toxic neutrophils being seen.
Has been found that seals and dolphins
–often have Dohle bodies in their neutrophils and
–their neutrophils can vary greatly in terms of degree of nuclei lobulation &
amount /staining intensity of granules they contain
While these morphological changes are indicators of infection and possible sepsis
in most species, in seals and dolphins, it seems that they can be present with no
evident sinister reason
16. here are the possible reasons for each of her biochemistry changes.
know they are a really long list but after thinking it through, the things that
seemed to come up again and again and fit the most were dehydration or renal
Hypercholesterolaemia + hypertriglyceridaemia (what I found the most
postprandial pinnipeds tends to have lipemic sera high in TGs
and pregnant harbour seals may have higher TGs than nonpregnant seals
since cholesterol and TGs are typically processed and eliminated by bile acids,
one situation where they are increased could be with cholestatic disease but
found this much less likely because her liver enzymes seemed fine
wondered if seals can get something like equine hyperlipidemia?
where there is mobilisation of fatty acids from the adipose tissues usually
because of a physiologic or pathologic state that creates a negative energy
17. in conclusion
-think the anaemia would have been the most problematic, especially to a seal as
it would mean her diving would be compromised
-think she most probably would have had a component of dehydration - and this
would be something the vet could make a difference about, with fluid therapy
-possibility of renal disease?
even though my reference intervals were sort of a hotch potch, think they were
still a useful guide.
it is difficult and not very straightforward because we don’t see these species so
often and their parameters are not as well-studied as our everyday veterinary
but learnt to just be resourceful and make the best of what we’ve got
important to remember to take values with a pinch of salt, using them as a guide
but ultimately considering the animal and the whole picture
*additional info about first aid
seal pups, partic if malnourished, are usually dehydrated.
give fluid therapy as routine:
-restrain in sternal recumbency, proprietary oral rehydration solution by
lubricated stomach tube (approx 1cm external diameter) at volume of 150-250ml
18. for grey seal pups
-additional glucose can be given where hypoglycaemia is suspected.
-tubing ever 3-4h.
If severely debilitated - can give IVFT using blood sampling sites.
Tight application of the skin to the blubber layer makes it diff to give adq volumes
subcut but it can still be a useful technique.
correct hyperthermia (cold-hosing) OR hypothermia (esp if small and emaciated.
short floats in water only. supplementary heat and towels.)
oral rehydration of adults seals possible only in weaker/moribund animals or if
more lively adults can be encouraged to drink from a freshwater pool or hose or
fed fish injected with fluids.
advisable to move all seals to appropriate rehab facilities as soon as intial
assessment and tx have been completed.