The number of teats in the dog varies from 8 to 12, with 4 to 6 gland complexes on each side of the midline. Ten is the most common number in larger breeds, four pairs are more common in the smaller breeds. In bitches with ten normal teats, the pattern is two pairs thoracic teats, two pairs abdominal teats, and one pair of inguinal teats. 

Cats usually have four pairs of glands, two thoracic and two abdominal, which are about equidistantly spaced. Supernumerary teats do occur in both dogs and cats, and are generally removed. 

The number of ducts opening on a teat varies from 8 to 20 external openings per teat for the dog and 1 to 7 for the cat. The openings are located on the blunt end of the teat in an irregular pattern. Dog owners should remember that each milk exit can be an entry point for bacteria. Keeping the bitch's environment especially clean during the nursing period is important to minimize incidence of mastitis. The streak canal, or teat canal, is 1/4 to 1/3 the length of the dog's teat. The teat sinus extends upward from the teat canal into the parenchyma of the gland. The teat sinuses are small uniformly wide passages and not wide dilations as in cattle. The parenchyma, or secretory tissue, is present only during pregnancy, pseudopregnancy, during lactation, and for 40 to 50 days after weaning. 

The blood supply of the mammary glands of dogs and cats are similar except for the thoracic glands. In the dog the first pair of thoracic mammary glands receives blood from two sternal branches of the internal thoracic artery, passing between the first and second ribs. The second pair of thoracic mammary glands is supplied by small branches of the mediastinal, or internal mammary, arteries before they anastamose with the sternal branches serving the first pair of glands. 

The abdominal and inguinal pairs of glands are served by the femoral arteries. Branches pass anteriorly to become the external pudic, then the posterior mammary arteries. They supply the abdominal glands and anastamose with the anterior abdominal arteries which are extensions of the previously mentioned mediastinal, or internal mammary arteries. 

Tumors are frequently seen in the mammary gland of the dog. They may belong to the connective tissue or the epithelial series of mammary tumors, or both. Tumors of the epithelial series are of great importance. Those observed are adenomas, carcinomas, and above all, mixed mammary tumors. 

The mixed tumor of the mammary gland is the most frequent form of tumor found in the dog. It is of great comparative pathological importance due to its similarity to the mixed tumor of the parotid gland seen in man. The preferential site of these tumors is the posterior, or inguinal, mammary glands, although others may be involved. While in most cases only one tumor is seen, multiple tumors are also seen. These tumors vary in size; fist-size is not uncommon. The skin is generally freely movable over the tumor and the tumor itself is surrounded by a fibrous capsule, from which it can be readily removed surgically. These are mostly benign. It is different in the case of the cat. Tumors of the mammary gland are generally rare in cats, but if a tumor is present, it is generally an infiltrating carcinoma with early metastasis in the regional lymph nodes.

Milk Composition

Composition of milks at mid-lactation: 


% DM

% fat

% protein

% sugar

% ash































Composition of milks as a percent of dry matter: 


% fat

% protein

% sugar

% ash

gross energy































Whey protein and casein (as percent of total composition) in milks: 



whey protein
















The milk of the dog changes composition during the course of lactation. Milk composition through the first 45 days of lactation has several changes: 

  • protein concentration increases from 4.3% to 6.3% 

  • fat concentration increases from 2.4% to 4.5% early in the period and then dropped to 2.7% 

  • carbohydrate concentration does not change significantly 

  • iron decreased from 13 micrograms/ml to 6 micrograms/ml 

  • zinc decreased from 9.7 micrograms/ml to 8.7 micrograms/ml 

  • calcium increased from 1366 micrograms/ml to 1757 micrograms/ml 

  • magnesium, copper, and manganese do not change significantly 

The iron concentration in cat milk is 5 to 6 micrograms/ml decreasing to 3 micrograms/ml. The iron concentration of dog milk, about 10 ug/ml was much higher than human, 0.2 to 0.5 micrograms/ml or dairy animals (0.2 to 0.3 micrograms/ml), but about equal to rat milk. The iron concentration is strongly influenced by the stage of lactation, and decreases with time. 

Nutrition During Lactation

This lactating bitch provides an example of the nutritional stresses associated with lactation. The characteristics of the litter which determine the level of nutritional stress on the mother are: the size of the puppies, the number of puppies in the litter, and their age. The peak energy needs of the bitch occur when puppies are 3 to 4 weeks old. If a bitch is nursing more than 4 to 5 puppies she should receive a diet containing 28 to 30% protein and 20 to 25% fat during heavy lactation. 

Proper vitamins and trace minerals also must be provided. Supplementation may be necessary, but a proper calcium:phosphorus ratio should be carefully maintained. 

These are some observations on feeding the lactating bitch. She should be fed 1.5 times maintenance for the first week, 2 times maintenance for the second, and 2 to 3 times maintenance amounts for the third week of lactation. Ontko and Phillips noted little or no loss of weight when lactating bitches were fed a basal diet of 427 calories per 100 gm. of ration, but a weight loss occurred when bitches nursing four or more puppies were fed a diet containing 310 calories per 100 gm. Therefore, increasing the caloric density of the diet assures improved lactation. Care must be exercised in adding fat or a diet of higher caloric density. Problems in low birth weights and high death rates occur in litters which have only an increased fat percentage. Fat must be balanced by protein increases, so that 17% protein should balance with 7.5% fat, 25% protein should balance with 20% fat, and 29% protein should balance with 30% fat to assure that increased caloric density will not induce protein deficiency. A protein intake of 25 to 50% of the diet on a dry weight basis appears optimal. A commercial maintenance diet should have 2 to 4% animal protein added, such as liver. Increases of fat also make the diet more palatable. 

The digestive capacity of the pet must be considered when increasing the ration of a companion animal during lactation. If the quantity of food required exceeds the amount she can eat in one feeding, then divide that into three or four feedings per day. 

Most puppies are weaned at 6 to 7 weeks of age. This appears to be the optimum time from both the nutritional and behavioral standpoints. At this age they are sufficiently adapted to their species yet young enough so that they adapt well to people and, therefore, become good pets. 

It is helpful to restrict the food intake of the bitch before and during weaning to prevent excessive distension of the mammary glands and discomfort after weaning, particularly for good milk-producing bitches with large litters. This may be accomplished by separating the bitch from the litter during the day and withholding all food the day before weaning, but reuniting the bitch and pups that night and removing the food from the pups. Then gradually increase the amount fed the bitch after the pups are completely removed so that by several days after weaning she is receiving the amount needed for maintenance.

The behavior of both lactating cats and their kittens is affected by a protein restricted diet. Vocalization and movement in the home box are both higher in kittens whose mothers are not receiving enough protein in the diet. Nursing behavior was abnormal in those queens, also. 


Turner and Gomez, in their 1934 work on the mammary gland of the dog described a condition called "complete pseudopregnancy." In the dog this condition extends for a period comparable to normal pregnancy and the development of the mammary gland includes the growth phase during the first half and the gradual initiation of lactation during the second half of the false pregnancy. Therefore, normal secretory activity is not dependent either upon the fetus or fetal membranes. The uterus is apparently not necessary either, as a hysterectomized female was given hormones and began the glandular growth phase. 

Pseudopregnancy can be very helpful to the breeder who needs a foster mother to nurse orphaned, abandoned, or extra puppies. On the other hand, the home owner with a single, female dog who is not allowed to mate during estrus will frequently have to contend with unwanted milk dripping. Veterinarians can administer bromocriptine to "dry up" the milk. Behaviorists note nesting behavior and even straining movements which simulate parturition about nine weeks after estrus. The dog owner is counseled to discourage nesting behavior, not to let the dog "nurse" any rolled-up socks she has stolen, and provide interesting outside activities. 


Eclampsia (convulsions not associated with other cerebral conditions such as epilepsy or cerebral hemorrhage) can occur in the dog as a result of lactation. The greater the quantity of milk produced, the more likely it is that eclampsia will occur. When calcium is lost in the milk faster than it is absorbed, or than it can be mobilized from the skeletal system, hypocalcemia results. Signs are muscle fasciculations, tetany, and death. The treatment is to slowly (10-15 min) administer a calcium solution intravenously. As you treat, the amplitude of heart sounds will increase, and the heart rate will decrease. If the heart rate increases, or becomes arrhythmic immediately stop calcium administration. 

A bitch with a large litter two to four weeks into lactation is especially susceptible to eclampsia. Some would suggest giving extra Ca prior to the time it is needed. However, this does not help, because excess Ca intake decreases the efficiency of Ca absorption from the intestine, inhibits parathyroid hormone secretion, and stimulates thyrocalcitonin secretion. These changes decrease the ability of the dog to mobilize Ca from the bone, when additional Ca is needed; it takes 1 to 3 weeks to reverse the effects. Of course, this is not fast enough, and hypocalcemia and eclampsia occur. Giving Ca when it is needed, during the first week through the fourth or fifth week of lactation, may be helpful; 500 mg of calcium carbonate (about one Tums, the antacid you take for upset stomach) per 5 kg of body weight per day, but only for the bitch in which eclampsia has previously occurred. The best treatment is to get the puppies off the dam as quickly as possible, either onto solid food or a bitch's milk replacer. 

Lactation in Dogs and Cats
W L Hurley
Department of Animal Sciences
University of Illinois
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- Signs Of Nutritional Deficiency -
Pregnancy is stressful to the biology of a dog. Whilst a healthy male dog can father hundreds of puppies without any significant stress (except perhaps the problem of STD's), female dogs use a lot of energy and nutrient during pregnancy and lactation.

If a dog is not fed enough good quality food to supply these nutrients, she will have to use the ones stored in her own body's tissues. This will lead to malnourishment. And if she depletes her own body's sources of vitamins and minerals, a whole host of other problems will develop.

When a dog is pregnant, poor diet can express in the following ways:
  1. An "out of condition" appearance of the dog. This may not be apparent until after the puppies are born. An actual loss in body weight throughout pregnancy can happen, but it's unusual in most instances.

  2. Uncontrollable diarrhea after whelping (when the puppies are born), and throughout most of lactation. This is most often seen when she must increase her food intake too much to meet the increased demands of lactational because the food she has been eating is poorly digested or low in calories.

  3. The "fading puppy" syndrome. The puppy may appear normal at birth, but several hours to days later it is found crying or whimpering, and chilled. It is off by itself, obviously disowned by the mother. Attempts to reunite the two are usually met with failure. The puppy's stomach will be empty and its body will be dehydrated. When weighed, it will weigh the same or less than the day before. 

  4. Anemias. When anemia occurs as the result of a dietary deficiency during pregnancy, it will be present in both the dam and pup. When both mother and pup are anemic, the first place to look for is the diet of the mother.

When the puppies are born, an inadequate diet during lactation is most likely to appear as:

  1. Lactation failure (agalactia). This is a complete failure of the mammary glands. The dog produces no milk at all from which the pups can be nourished. These pups cry continuously, fail to gain weight, and unless immediate remedial feeding is started, the pups will die.

  2. Lactation depression (dysgalactia). While the mammary glands are functional, they are unable to produce enough of milk to fully support the pups' complete nutritional needs. The pups' growth rate is restricted, and they may become stunted. 

  3. Deficient milk. The milk, although it may be produced in adequate amounts, is deficient in one or more nutrients. 

The Fortified Milk Mix Formula
Great booster for the newly-whelped bitch
  • one cup or 250 ml of milk [preferably raw]
  • one teaspoon of honey
  • one or two teaspoons of flax seed oil
  • one raw egg [or two egg yolks] - about 60 gm
  • one or two junket [rennet] tablets
  • multi-B and C vitamins 

This is blended, brought to body temperature, and kept at body temperature for ten minutes to allow the junket tablet to work. Preferably, you will have tried this mix on her prior to whelping so you will know that she will drink it and that it does not cause digestive upset.

Appetite Stimulate for the Feeding Mother
  • cup of plain yoghurt
  • a teaspoon of raw honey
  • some salmon oil
  • two egg yolks
  • water

Whisk all together and feed at room temperature. You can continue to give this daily during the nursing period. Add oatmeal (soaked overnight) every now and then.

Pudding Recipe for Nursing Mothers
  • 1 x package Vanilla Pudding (cooked kind)

  • 1/2 cup sugar

  • 4 cups milk

  • 4 egg yolks

Cook on low heat to a pudding consistency.
Feed at least 20cc twice per day, by syringe if necessary.

If you don't have a package of vanilla pudding on hand you can mix the following in a saucepan and cook to pudding consistency.

  • 2/3 cup sugar

  • 6 tablespoons cornstarch

  • 1/2 teaspoon salt

  • 4 cups milk (or one can evaporated milk plus equal parts water to make quart)

  • 4 egg yolks

  • 3 teaspoon vanilla


** Hint
Give your girl a drink of beer, warmed if necessary and with honey added. This can help to stimulate milk production.

  • 1 cup of milk
  • 1 teaspoon honey
  • 1 teaspoon Flax seed oil

  • 2 raw egg yolks
  • 1-2 junket tablets

Put it in a bottle, shake it vigorously, then stand it in hot water, it goes into a custard type consistency. You can also add liquid vitamins (B & C), but if that puts her off drinking it, then don't give it in the food.

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