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Mastitis in dogs

Mastitis describes inflammation of the mammary tissue (breast tissue) that enables mothers to produce milk for new offspring. Mastitis is painful inflammation or infection of one or more of the mammary glands, often caused by bacteria. This potentially life-threatening condition mainly affects bitches after they give birth, although it occasionally occurs with phantom pregnancies too. Here we discuss the possible causes of mastitis and what to look out for.

This article was written by a FirstVet vet

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Signs of mastitis

  • Depression or lethargy
  • Inappetence
  • Fever (temperature >39.2oC)
  • Dehydration
  • Not wanting to nurse the puppies or seeming uncomfortable when nursing
  • Failure of the puppies to thrive
  • Hot, firm, swollen and painful mammary gland(s)
  • Thin cream coloured watery or blood-tinged fluid can be expressed from the affected gland(s)
  • Septic shock
  • Abscess or gangrene of the affected gland(s) if left untreated


Causes of mastitis

Mastitis is caused by several well known bacteria: Escherichia coli (E. coli), Staphylococci, and β-hemolytic Streptococci are most commonly cultured.

Bacteria gain access to the mammary gland by several possible routes. Firstly, an ascending infection, up the teat canal from the skin. Secondly, an infection can be caused by trauma to the nipple, teat canal or mammary glands from the puppies teeth or toe nails. Thirdly, due to poor environmental hygiene. Fourthly, due to the spread of a systemic infection going on elsewhere in the body. Lastly, due to prolonged periods of milk accumulation in the gland without milk removal, hence why many cases follow sudden weaning of the puppies.


What can you do to help your dog?

In most cases, mastitis can be prevented.

  • Keep the environment and whelping box scrupulously clean
  • Ensure that all the mammary glands are used for nursing
  • Although only small, clip the very tip of the puppies nails to stop them scratching the mother’s skin and causing trauma
  • Keep the mother’s skin clean: excessive hair can be carefully clipped and the skin rinsed with warm saline twice a day (1 teaspoon of salt in 1 pint/500ml cooled boiled water). The skin should be patted dry afterwards
  • A warm or cold gel compress wrapped in a cloth can be used to reduce inflammation. They are gently held against the affected area for up to 20 minutes; there is no benefit of doing so for longer


Treatment of mastitis

The prognosis for mastitis in one or more glands is good, as long as it is spotted and treated promptly. Blood and milk samples will be analysed to find the likely cause and to identify what supportive treatment is required. The mother is likely to require antibiotic medication, specific to the bacteria involved.

If the infection is mild, then the puppies will be allowed to continue nursing, which is good for both the mother and her puppies. Your vet may advise you to strip the milk from the infected gland several times daily to help to clear the infection. This improves the mother’s comfort levels, encourages blood flow and promotes healing. It is important to monitor the puppies closely for any side effects of the medication, which will be present in the milk at low levels.

If the mother is systemically unwell or in septic shock, then she will need to be hospitalised. Intravenous fluids, pain relief and specific antibiotics for the infection will be essential. The prognosis for these cases is guarded, even with aggressive treatment. Unfortunately, abscessed or gangrenous glands will require surgical removal under general anaesthesia.

When is it time to visit a vet?

  • If you notice that your dog has mastitis
  • She is not comfortable nursing her puppies
  • She has a fever


Still worried?

Book a video appointment to have a chat with one of our vets.

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