PINNIPED PHARMACEUTICALS

Tavishi

A crucial part of medicine is treatment. A great deal of my Kradigan posts deal with illness, but rarely delve further into the exciting world of pharmaceuticals. And as an alliteration afficionado, naturally, I had to combine pharmaceuticals with my favorite animals: pinnipeds. (Not technically alliteration but I am not in AP Lit right now. I am free to commit crimes of alliteration.) Methods of drug administration in pinnipeds is very similar to humans and domestic animals. Most commonly, drugs are administered orally in the form of pills or tablets. Subcutaneous injection of drugs is less common in pinnipeds because of the thick blubber layer. (Blubber layer is part of the skin, and so, for subcutaneous injection to occur, the needle has to be insanely thick.) While human skin is about 4 mm at its thickest (soles of our feet), seal blubber itself can be up to 150 mm thick. However, neonatal (just born) pinnipeds have a much thinner blubber layer, as it hasn't quite developed yet, and so, they can experience subcutaneous drug injection.

bro is smol and will get poked under skin :(

Intramuscular injection is also an option for drug administration, but often requires multiple sites of injection because of the sheer size of some pinnipeds. Because of these multiple sites, it can be awfully difficult to administer medication to a sassy seal. Additionally, you have to be pretty precise with injection, as it isn't fun if the needle doesn't go all the way in. More than likely, the drug will end up in the blubber layer. If the drug is water-soluble, it'll just be boppin' around with the fat, but if it's fat-soluble, the medication won't properly distribute. Either way, the desired effect won't be produced.

intramuscular vaccination for phocine distemper virus in Hawaiian monk seal

Anesthetics administered to pinnipeds are typically inhalant or intratracheal. Inhalant and intratracheal anesthetics are much less invasive than intravenous (IV) anesthetics, and thus, much preferred in large, wild animals like pinnipeds.

Inhalant anesthesia (isoflurane) on a Guadalupe fur seal

Intratracheal anesthetic on harbor seal

The drugs used for pinniped treatment generally have much overlap with that used for domestic animals and humans. For example, antibiotics. Three classes of antibiotics are typically used with pinnipeds: fluoroquinolones, cephalosporins, and aminoglycosides. What really differs is how marine mammals tend to react differently to drugs and different drug combinations. Fluoroquinolones are generally more trusted than cephalosporins and aminoglycosides, but tend to have a higher elimination rate and lower absorption rate than is liked. (Seal poop/pee out drug, not absorb enough.) Fluoroquinolones also have a higher bacterial resistance rate than other antibiotic classes. In pinnipeds, commonly used fluoroquinolones include ciprofloxacin and enrofloxacin.

Additionally, cephalosporin has been found to produce a deficiency of vitamin K in odontocetes (toothed whales). This isn't necessarily an issue in pinnipeds, but it is something that should be observed with care. Earlier generations of cephalosporin have been found to produce a reaction in those allergic to penicillin. In pinnipeds, commonly used cephalosporins include cephalexin, cefuroxime, and cephaloridine (mostly first generation).

general structure of fluoroquinolones!

Antiparasitic medication used in pinnipeds varies by the parasitic species. Naturally, ivermectin is a go-to, but ivermectin has caused adverse effects in certain species. Additionally, intramuscular injection of levamisole is used for treatment of various parasites, in combination with ivermectin and fenbendazole. However, levamisole phosphate has been found to have neurological effects in pinnipeds and cetaceans, and so it's not always used nearly as commonly as ivermectin. When treating protozoan parasites like Sarcocystis and Toxoplasma, a cocktail of prednisolone, clindamycin, and ponazuril are used, but these drugs aren't always super effective. Sarcocystis starts causing muscle wasting, and Toxoplasma starts causing severe encephalitis producing a point of no return.

Lovebug (pictured above) survived both Toxoplasmosis and Sarcocystis

And finally, anesthetics! As mentioned above, inhalant and intratracheal anesthetics are preferred in pinnipeds. Anesthetics typically used for inhalant anesthesia include sevoflurane and isoflurane. Intravenous administration of propofol, atropine, and midazolam is often an accompaniment to inhalant anesthetics. Oral consumption of gabapentin is also used, but typically as more of a sedative.