Is Raw Milk Safe?
Many Raw Milk Dangers Depend on Animal Health
Reading Time: 5 minutes
–by Dr. Katie Estill DVM Goat milk and goat dairy products are gaining popularity at a rapid rate. A 2020 Washington Post article cites the USDA census indicating a 61% increase in dairy goats from 2007 to 2017. While goat dairies exist on a large scale, locally sourced products with local artisans continue to be popular. There is no denying that people want to know where their food comes from and how it was made. If “organic” is the buzzword of farming, “raw” is that of dairy. Some may tout raw or unpasteurized milk for its health benefits, while others emphasize its improved qualities for products such as cheese and yogurt. But is raw milk safe?
Understanding milk consumption risks to determine if raw milk is safe.
If you are milking goats for your consumption or sale to others, it is important to understand milk consumption risks, whether raw or pasteurized. If you are selling or planning to see dairy products, it is also important to know your state’s regulations. Is raw milk illegal? Raw milk sale regulations vary by state. You can check out where your state stands by visiting the Farm-to-Consumer Legal Defense Fund’s interactive map at https://www.farmtoconsumer.org/raw-milk-nation-interactive-map/.
What pathogens can be found in milk?
Pasteurized milk is milk that has been heated to a specific temperature to remove certain pathogens. During this process, proteins and fats within the milk can also be changed, making it less desirable for drinking or cheese making. If your goal is to provide raw milk or its products, it is essential to know if raw milk is safe and what pathogens can be found in milk, what they can do, and how to prevent their presence in your product.
Brucella bacteria
Brucella bacteria are perhaps one of the most well-known pathogens in milk. There are three varieties of Brucella that can occur in ruminants. Brucella ovis causes infertility in sheep. Brucella abortus causes reproductive losses in cattle. Brucella meletensis infects sheep and goats primarily but can infect most domestic species. Thankfully, this disease is not currently found in the United States. However, it is endemic in Central America and parts of Europe. Goats infected with the bacteria can experience abortion, weak kids, or mastitis. Goats can also be persistent carriers of the disease, showing no clinical signs at all. Humans can become infected with B. meletensis by contact with infected animals or consuming raw meat or milk products. Infection in humans can cause a variety of signs, from fever and sweats to weight loss and muscle aches. It is often difficult to diagnose and treat infection in humans. Any human consuming infected products or having contact with infected animals is at risk of contracting an infection.
If your goal is to provide raw milk or its products, it is essential to know what pathogens can be found in milk, what they can do, and how to prevent their presence in your product.
Coxiella burnetti
Coxiella burnetti is the bacteria responsible for “Q fever” in humans. Goats infected with this bacterium tend to show no outward signs; however, they can shed large quantities of bacteria, particularly in birthing fluid and milk. This bacterium is very hardy in the environment, and the most common human infection is due to exposure to contaminated environments. The pasteurization process of heating milk to 72 degrees Celsius (161 degrees F) for 15 seconds was designed to prevent milk consumption infection. Humans infected with Q fever can show signs of acute fever and malaise and develop severe chronic illness. Immunocompromised individuals are most likely to develop Q fever after exposure.
E. coli
A frequent food contaminant, Escherichia coli is also a common milk contaminant. Goats can shed E. coli in milk in low numbers, but E. coli can also enter milk via environmental contamination. It is frequently shed in cattle feces. The bacteria are hardy enough to survive the cheese-making process when using raw milk. E. coli, depending upon the strain, can affect any individual, causing diarrhea and other GI signs.
Listeria monocytogenes
Another bacterium that can be shed in milk and also contaminate milk from the environment is Listeria monocytogenes. Goats with subclinical mastitis can shed listeria. It can also frequently be found in silage, soil, and healthy animal feces. This bacterium can even survive the cheese-making process and grows readily in soft cheeses. Humans infected with this bacterium generally show signs of GI illness. Immunocompromised individuals can develop more severe clinical symptoms.
Salmonella
Salmonella bacteria are also frequently found to be the cause of food-borne illness. This bacterium is shed in infected animal feces and can contaminate milk products, and some animals can be infected without showing clinical signs. Very few organisms are needed to cause disease in people. Similar to E. coli, Salmonella species cause gastrointestinal illness in people. Immunocompromised individuals will experience more severe disease.
Parasites in milk
In addition to bacteria that can shed in milk, goats can also shed parasites in their milk. Toxoplasma gondii is among the most notable of these. Goats become infected with this parasite by consuming infected cat feces. The primary sign of infection in goats is abortion. People contract this infection by consuming undercooked meat products, but the parasite can also be shed in milk. The parasite can survive the cheese-making process if using raw milk. Infection in humans is often asymptomatic. However, immunocompromised or pregnant individuals have a greater risk of contracting a severe illness. In these individuals, the parasite can cause severe neurologic disease, birth defects, or abortion.
There is a multitude of other pathogens that can be found in milk and milk products. It is important to identify the areas of greatest risk in your dairy herd.
At-home tests, such as the California Mastitis Test, are not recommended for goats; due to cow milk’s different composition to goat, the tests are not accurate in identifying mastitis, especially potentially subclinical mastitis.
How to keep raw milk safe
If dairy products, particularly raw, are your goal, you need to establish animal health and milk care protocols. Working closely with your herd veterinarian can ensure that you have covered all of your bases.
When beginning or adding goats to your dairy herd, it is important to test for important pathogens. Blood tests are readily available for Coxiella burnetti, as well as production-reducing infections such as caseous lymphadenitis. Animals within your herd can also be routinely tested for signs of bacteria within their milk. At-home tests, such as the California Mastitis Test, are not recommended for goats; due to cow milk’s different composition to goat, the tests are not accurate in identifying mastitis, especially potentially subclinical mastitis. Rather, it is recommended to send milk out to a lab for culture. Animals with subclinical mastitis can be a reservoir for disease in your herd.
Developing a milk handling protocol will reduce the risk of environmental contamination of your milk. Dipping teats in disinfectant before and after milking will reduce bacteria coming from the teat itself. Cleaning or sterilizing milking equipment will also reduce contamination. Rapid cooling to refrigerated temperature can also slow bacterial and yeast growth. Having a written protocol for your milking process will ensure consistent handling.
Is raw milk safe? Whether you are milking your goats for yourself or selling commercially, it is crucial to managing your herd to prevent the risk of disease transmission. Even if raw milk isn’t your goal, meticulous protocols will ensure both human and animal health.
Sources:
- https://pubmed.ncbi.nlm.nih.gov/3727324/
- https://www.cdfa.ca.gov/ahfss/animal_health/pdfs/B_MelitensisFactSheet.pdf
- https://www.foodstandards.govt.nz/code/proposals/documents/P1007%20PPPS%20for%20raw%20milk%201AR%20SD2%20Goat%20milk%20Risk%20Assessment.pdf
- https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7227596/
- https://pubmed.ncbi.nlm.nih.gov/3727324/
- https://www.washingtonpost.com/business/2019/04/23/americas-new-pastime-milking-goats/
Originally published in the May/June 2021 issue of Goat Journal and regularly vetted for accuracy.
Dr. Katie Estill DVM is a veterinarian working with larger livestock at Desert Trails Veterinary Services in Winnemucca, Nevada. She serves as veterinarian consultant for Goat Journal and Countryside & Small Stock Journal. You can read more of Dr. Estill’s valuable goat health stories, written exclusively for Goat Journal.
