What causes SCC?
Squamous cell carcinoma (SCC) is caused by DNA damage that leads to abnormal changes (mutations) in the squamous cells in the outermost layer of skin.
What are the risk factors?
UV exposure: Unprotected exposure to ultraviolet (UV) radiation from the sun, especially at higher elevations (Colorado e.g.) where the atmosphere is thin. In animals, unpigmented and hairless areas are the most likely areas to be affected. In Nigerians, squamous almost always occurs under the tail. But it can also be ocular (growing around the eye) and can also grow directly on top of the head, usually in the hairless area in an animal that has been disbudded.
Immunosuppression: Weakened immune system can be a contributing factor.
Age: SCCs tend to appear in older people and animals, most commonly from middle age onward.
Fair skin: Unpigmented or partly pigmented skin presents an increased risk for SCC.
Genetics: it is unknown whether genetics play a role in Nigerian Dwarf SCC but in other animals (like the Haflinger horse) genetics have been shown to be a strong factor.
What can I do to prevent SCC?
The best form of protection is to breed for a pigmented (dark) tail. For a fair-skinned animal, sunscreen of SPF30 or higher is a good idea – a spray-on works well, and when the area is damp from spray, you can also use a puffer to puff powdered zinc oxide over the area to completely block UV rays. If you are concerned about milk withdrawal, there are straight zinc oxide creams or so-called “mineral” sunscreens – usually variations on a zinc oxide cream with none of the high-powered chemicals in some high spf sunblocks. The drawback to a cream sunscreen (as opposed to spray) is that it has to be applied directly, which may be uncomfortable for a goat that already has SCC. Look for a sunscreen that is advertised as “reef friendly” or “oxybenzone free” to avoid the harshest chemicals.
Link to Puffer
Link to Zinc oxide powder
Link to Natural or “mineral” sunscreen.
Link to reef-friendly sunscreen
In people who have had skin cancer, a study shows that a daily dose of 500 mg nicotinamide, also known in a slightly different form as niacinamide (vitamin B3), resulted in a 23% reduction of subsequent skin cancers. Nicotinamide is available otc at many pharmacies and online.
Obviously don’t clip your animals unnecessarily, and where possible avoid the high sun of the day – between 10 a.m. and 4 pm. Do your best to provide shade on sunny days. It is probably a good idea to look at your pastures as well: some very common plants, including St. John’s Wort, make the skin more sensitive to UV rays, which in turn could accelerate SCC.
Per the NIH: “St. John’s wort may cause increased sensitivity to sunlight, especially when taken in large doses.”
One thing to be mindful of is the powerful effect of immune suppression on cancer growth. Try to avoid it, and be aware that some common goat issues (lice infestation for example) exert a powerful negative force on the immune system.
SCC is confirmed in goats by punch biopsy. Some people express concern about getting biopsies because they have heard that getting a biopsy will spread the disease. There isn’t any definitive evidence to support this. And while there are no studies in goats, the Mayo Clinic performed a large study in human cancer patients. “A study of more than 2,000 patients by researchers at Mayo Clinic’s campus in Jacksonville, Florida, has dispelled the myth that cancer biopsies cause cancer to spread.” But of course this decision is up to each individual owner.
Once SCC has been confirmed, there are some treatments available.
Herbal Treatments – McDowell’s. This Australian company has various herbal SCC treatments for animals. I have no personal knowledge of the results of using these remedies in goats. If you have personal experience please send a message. https://www.mcdowellsherbal.com/cancer/horse-cancer/905-squamous-cell-carcinoma
Imiquimod – Imiquimod is a topical cream applied to the affected area. While it is by prescription only, it is not expensive and can be applied by the owner. It comes in a small box with enough packets for several weeks of treatment. Cost is about $30, although it may be available more cheaply at online pharmacies. It was developed to treat sarcoid tumors in horses but has been around for a while and most large or mixed animal vets are comfortable prescribing it for a goat. It works by stimulating the immune system to respond to the tumor. Because of this, when you start treatment there is usually a period where the affected area looks much worse than when you started. As you get several weeks into the treatment (applying the cream 2 or 3 times a week), the area usually starts to look better.
I have used this on one of my does and the results have been good but not miraculous. If you have used it, please share your results. In her case, she starts the treatment and after one or two applications the area becomes very angry and red and usually some sores will erupt – this is the immune system coming online, and is a sign the medication is working. After a couple of weeks the area starts to heal and look much better. In her case it looked almost normal after the end of the first round of treatment. After a few months the SCC began to creep back, and we started treatment again with the same results. We are now on the third round of treatment (total cost $90 after cost of biopsy) and two years since the SCC first appeared, and she is functioning well, otherwise healthy and happy, and looks no worse than she did two years ago. Just my personal experience. Once the treatment starts it will be uncomfortable to apply the cream, so keep a good supply of animal crackers handy.
Imiquimod/Aldara (brand name) – From the University of Minnesota study in horses: “Treatment leads to a local inflammatory response. The drug has been shown to have potent antitumor and antiviral effects. It works by stimulating macrophages, Langerhans cells, natural killers and B lymphocytes through the induction of inflammatory mediators. Expect redness, swelling, oozing, crusts and pain on palpation. The tumor will usually look worse before it looks better.”
Cryogenic (Freezing Treatment) – If the SCC is relatively self-contained and in early stages, it can sometimes be frozen off. The vet may suggest a follow-up treatment of some kind.
Combination therapies – Some vets may ‘debulk’ the tumor, where possible (SCC doesn’t always lend itself to this), which means they reduce the size by excision or other means then proceed to a cream or cryogenic treatment. A lot will depend on the stage of the cancer.