Milk Flow Disorder – Surgical Intervention or not?

Milk flow disorders can be related to a herd issue, e.g., milking equipment function or can be caused in individual cows by an anatomical obstruction causing a slow milking quarter. Culling and replacement of the cow or ending milk production in the affected quarter could be immediate decisions made. However, surgical intervention may be an option if the cow is one that you want to keep in the herd. This article is intended to help with that decision.

Bruckmaier and colleagues in Germany explored the question of whether surgical intervention to improve milk flow in a blocked quarter is worthwhile. When evaluating whether surgery will be beneficial on a dairy farm it is important to evaluate study conditions and how they may be different from those on an individual farm.

Some questions to ask when considering surgical intervention of a teat with an anatomical obstruction will be proposed at the end of this article. This study found that milk flow disorders do reduce milk yield and milk flow of affected teats. In addition, they found that surgical intervention of anatomical obstructions appeared to result in substantial improvements in both milk yield and peak milk flow within 6-months post-surgery. However, neither milk yield nor peak milk flow reached levels post-surgery when compared with similar quarters without milk flow disorders. 


Querengasser and co-workers selected study cows and quarters from cows submitted to their Veterinary Hospital in Germany, and that had individual quarters with some type of milk flow disorder. For example, teats did not milk out like other quarters in same cow or in other cows and indicated an anatomical obstruction. One-hundred quarters from 97 cows were identified as hard to milk and were included in the study. Teat canals and teat cisterns were evaluated using endoscopy in order to classify the physical reason for the milk flow disorder. Peak and average milk flow plus milk yield measurements were used to evaluate the impact of milk flow disorders between affected and non-affected teats and within quarters before- and after surgery and recovery. A Lactocorder attached to a quarter-milker was used to evaluate impacts of milk flow disorders and then the impact of surgical intervention on the same key performance measures.


Milk flow disorders decrease a cow’s value because of increased labor, treatment costs, increased risk of mastitis, and premature culling. Technologies are available to diagnose presence of anatomical obstructions and may be used effectively to reduce costs of milk flow disorders. It is important to note that many cow and equipment factors can independently alter milk flow. Research has shown that increased milk yield, lactation number, teat canal width, pre-milking stimulation, and vacuum level may all increase milk flow. Increasing DIM, hyperkeratosis, teat canal length, and increased air turbulence in the claw may decrease milk flow. Studies are contradictory but in general suggest that rear teats may normally have higher milk flow compared with front quarters.

Diagnosis & Surgical Intervention:

This study used teat endoscopy1 to classify anatomical obstructions and study veterinarians did surgery based on these findings to remove obstructions. Obstructions were classified into one of the following: a). rupture of teat canal skin, muscle, or connective tissue in the teat canal without dislocation of the tissue, b). Rupture in the teat canal with dislocation of the tissue, c). Other. Surgical intervention included one or more of the following: a). Removal of dislocated tissue; b). Dilated narrowed teat canal; c). Extracted free tissue from the teat cistern.

Impacts of Milk Flow Disorders & Surgical Intervention:

To evaluate cow milk flow disorders and surgical intervention, researchers statistically controlled for cow-related factors that may otherwise affect milk flow such as days in milk, lactation number, age, breed, etc. Table 1 shows a comparison of milk performance in a teat with a milk flow disorder compared with a similar teat (control) without a milk flow disorder. Teats with a milk flow disorder produced 53% or about one-half of what they would have produced without a milk flow disorder. Peak milk flow rate was only 20%, and average milk flow rate was only 14% of teats without a milk flow obstruction.

Being able to milk the cow normally is a justifiable concern after surgery. Table 2 provides research information on the effect of surgery at 1-month and then 6-months later compared with a similar teat without a milk flow disorder. One-month after surgery, 95% of teats could be milked by machine. This percentage rose to 99% 6-months after surgery. Milk yield increased substantially after surgery. At 1-month, milk production was 67% of a teat without a milk flow disorder and 72% of normal after 6-months. Speed of milk flow also improved after surgery. Peak milk flow rate rose to 78% of a normal teat at 6-months after surgery. Results show a substantial increase in amount of milk and speed of milking. However, the average teat never returned to its ‘genetic potential’ for volume or speed of harvest.


Value of Milk:

The following calculations provide a rough estimate of the cost of a milk flow disorder and potential impact of surgery. The cost of a milk flow disorder based on just the decrease in milk production is about $1.08 per day. If surgery is done, 1-month after surgery, the milk value will be $0.56 per day higher and 6-months later is estimated at $0.76 per day more than if no surgery is done.

Example: Given $0.16/lb. milk price and 25 lbs. milk per day from ‘normal teat’ 

  • Milk Value from ‘normal teat’ = $3.20
  • Milk Value from teat with milk flow disorder = $2.12
  • Milk Value from teat with surgery of milk flow disorder = 
    • 1-month post-surgery = $2.68; increased value from no surgery = +$0.56 per day
    • 6-month post-surgery = $2.88; increased value over no surgery = +$0.76 per day

* note: these values do not include risk of mastitis, or time impact from milk flow, and which may or may not occur based on compensations made by herd management. Both factors will be farm specific.


When deciding whether to have your herd veterinarian or University vet clinic perform surgery on a cow with a milk flow disorder what questions should be asked to evaluate cost-benefit?


  1. Current cow value– pregnancy status, milk yield, mastitis risk, lifetime and current lactation yield projection, quarters affected by milk flow disorder. Is the value of the cow, independent of the milk flow disorder, high enough to consider surgical intervention? 
    • Does the computer estimate of cow value include health events? If not, they should be included
    • Does computer assessment agree with your intuitive assessment of cow value? If not, why not – what additional factors are you considering and are these valid?
  2. If her value is positive, what is the potential impact of best case and worst-case scenario with and without surgical intervention given endoscopy (or other test) results?

Teat Milk Flow Disorder:

  1. Cost of pre-surgery exploration of milk flow disorder by your veterinarian – endoscopy or other beneficial procedure to identify anatomical cause of obstruction
    • Experience of veterinarian with procedure
    • Accuracy of diagnosis and likelihood of restoring milk flow and milk yield with surgery
    • Hygiene during and after surgery by veterinarian and on-farm technicians – risk of mastitis and likelihood of recovery
  2. Cost of down time and impact of potential surgery on cow milk production
    • Will cow need time to recover following surgery? If so, what is that time and what is the impact on milk production and risk of mastitis – time in sick pen, risk of mastitis, any withhold time, reduced milking frequency in affected quarter and non-affected quarters, increased labor needs, cost of post-surgery treatments (e.g., bandages, antibiotics, disinfectant, bedding, space in pen, etc.)
    • What is actual cost of the surgical procedure and supportive care by the attending veterinarian?
    • The teat will naturally decrease milk yield if not milked or if frequency of milking is decreased; however, recovery time may be needed post-surgery for animal welfare reasons
  3. Benefit of surgery
    • If expected benefit of surgery is like those observed in this study, what is the potential economic benefit or risk?
    • If surgery is not done: 
      1. average cost: 53% reduced milk ($), peak milk flow (time) is 20% of non-affected teat
      2. Risk of mastitis was not evaluated but would be increased due to potential incomplete milking in affected quarter.
    • If surgery is done:
      1. Milk yield is expected to be 72% of non-affected teat
      2. Peak milk flow is expected to be 78% of non-affected teat
    • Compare estimate of cow/quarter change in production and milk flow after surgery compared with research estimation. Was apparent impact better or worse than this estimate?
      1. Note: There will be individual cow differences in result.
      2. Consider cause of obstruction and changes in milk yield and milk flow 1 and 6-months after surgery
      3. What are possible causes for differences in results?

1Teat endoscopy: also known as theloscopy, is a veterinary procedure to diagnose milk flow disorders and to visualize the cistern during surgery. Equipment includes a small wireless battery-operated theloscope and surgical instruments. The animal should be sedated and restrained. Following disinfection of the teat, an anesthetic should be injected into the teat vein. The affected teat should be drained, a rubber ring placed at the base of the teat and the cistern flushed with saline. Theloscopy can be done through the teat canal or the lateral teat wall.

If the procedure is done through the teat wall, a small opening is made for endoscopic exam. It is sutured after the procedure is finished. When endoscopy is done through the teat canal, the teat canal and teat cistern can be inspected through the theloscope in an upwards direction When endoscopy is done through the lateral teat wall, the teat cistern and inner opening of the teat canal can be easily seen. With this method, the view is directed downwards

Theloscopy is considered a useful tool to diagnose and treat milk flow disorders. Be sure to check with your veterinarian to see if there are additional procedures or newer procedures available.


Querengasser, J., Geishauser, T.  Querengasser, K., Bruckmaier, R., Fehlings, K. 2002. Investigations on milk flow and milk yield from teats with milk flow disorders. J. Dairy Sci. 85:810-817.

Querengasser, K., Geishauser, T. 2001. Teat endoscopy (theloscopy) – equipment and procedure. Der Praktische Tierarzt. 82(7): 527-534. https://www.researchgate.net/publication/290191186_Teat_endoscopy_theloscopy_-_Equipment_and_procedure [Reviewed 2020, 02-13]

Google Search for Teat Endoscopy: https://www.google.com/search?q=what+is+teat+endoscopy&rlz=1C1CHBF_enUS863US863&oq=what+is+teat+endoscopy&aqs=chrome..69i57.4086j0j7&sourceid=chrome&ie=UTF-8 [Reviewed 2020, 02-13]

Dr. Sandy Costello

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