Page 284 - Small Animal Clinical Nutrition 5th Edition

Feeding Reproducing Dogs 289

VetBooks.ir Box 15-2. Eclampsia in the Bitch.

Eclampsia is an acute, life-threatening condition due to a sudden resulting in restlessness and whining, stiffness of gait, ataxia and
decrease in extracellular calcium concentration. Bitches are at tonic-clonic seizures. Decrease in extracellular calcium ion levels
highest risk for developing eclampsia (puerperal tetany) during leads to increased permeability of nerve cells (primarily of periph-
Weeks 2 and 3 of lactation when calcium losses via secretion in eral nerves) to sodium ions. Neuromuscular irritability is directly
milk are highest. Eclampsia is less common during Weeks 1 and 4 proportional to:
of lactation, and is seen rarely in the last two weeks of gestation. [Na ] x [K ] ÷ [Ca ] x [Mg ] x [H ]
+
+
++
+
++
Occasionally, bitches may be affected at or just before whelping. Suggested causes of hypocalcemia during the periparturient
The number of nursing puppies is the most important stimulus period include calcium supplementation during pregnancy, poor
for milk production; therefore, it is not surprising that eclampsia is dietary calcium and loss of calcium through fetal skeletal ossifica-
seen commonly in bitches nursing large litters. Typically, affected tion and lactation. High calcium intake may down-regulate
bitches are primipara, are less than four years of age, are toy- parathyroid gland secretion and impair normal mobilization of cal-
breed dogs and have low body weight-to-litter size ratio. cium from skeletal stores. As demand for calcium increases dur-
Investigators have suggested that toy breeds may be more predis- ing late gestation and lactation, calcium homeostasis is unable to
posed to developing eclampsia than large breeds because toy maintain critical serum levels.
breeds tend to receive more meat-based homemade foods, which Slow intravenous infusion (over five to 10 minutes) of 10% cal-
are low in calcium. Serum total calcium and ionized calcium con- cium gluconate, administered to effect (1 to 2 mg calcium/kg body
centrations usually are decreased. Serum total calcium concentra- weight), results in rapid clinical improvement. Heart monitoring
tion is an insensitive measure of ionized calcium concentration. (e.g., auscultation, electrocardiography) should be performed dur-
Ionized calcium is the biologically active form. In-hospital serum ing intravenous calcium gluconate infusion. If bradycardia or dys-
chemistry analyzers and point-of-care analyzers allow veterinari- rhythmias develop, the infusion must be slowed or discontinued. In
ans to obtain serum total calcium and ionized calcium concentra- addition, body temperature should be monitored because
tions rapidly. Diagnosis of hypocalcemia is based on low serum hypothermia may occur following calcium gluconate administra-
ionized calcium concentrations. Serum ionized calcium concentra- tion. To lessen the risk of relapse, calcium may be injected subcu-
tions were <0.8 mmol/l (reference range, 1.13 to 1.33 mmol/l) in taneously or intramuscularly, in addition to the immediate intra-
a retrospective study of eclampsia in the bitch. Other causes of venous infusion. However, subcutaneous injections may cause skin
clinical signs typical of hypocalcemia should be considered if the necrosis and should be administered only when other routes are
serum ionized calcium concentration is >0.8 mmol/l. inaccessible. Following correction of acute signs, the bitch should
Although most bitches with eclampsia are hypocalcemic, some be provided with oral vitamin D and calcium supplementation (e.g.,
may be normocalcemic. Some bitches with hypocalcemia, on the calcium carbonate, 100 mg/kg/day, divided with meals) through-
other hand, may not exhibit clinical signs. Typical clinical signs are out lactation.
anxiety, panting, whining, hypersalivation, vomiting, ataxia, stiff If possible, puppies should be separated from the bitch for the
gait, muscle tremors, tetany and seizures. Other signs include first 24 hours of treatment and fed canine milk replacer by bottle
hyperthermia, tachycardia and death, if the condition is untreated. or orogastric tube feeding. If tetany recurs during the same lacta-
However, clinical signs vary, based on the degree of hypocalcemia tion, the puppies should be weaned. Administration of corticos-
and the time over which it develops. teroids is contraindicated because they may further decrease plas-
Lack of clinical signs may indicate that factors other than ma calcium levels.
hypocalcemia determine whether tetany manifests clinically or not. Prevention of eclampsia starts during pregnancy by feeding a
The bitch may have additional serum biochemical abnormalities. balanced food, without excess calcium and with a balanced calci-
Blood glucose should be measured, because hypoglycemia may um-phosphorus ratio. Foods with a calcium-phosphorus ratio close
be present concurrently. Magnesium levels in bitches with eclamp- to 1:1 have been recommended during pregnancy. Vitamin D ther-
sia may be low or normal. The ratio of serum total magnesium to apy (10,000 to 25,000 IU daily) during the last week of gestation
total calcium may be significantly lower in affected bitches than in has been proposed, just as cows are treated to prevent postpar-
normal bitches. Hyperkalemia has been reported and some bitch- turient paresis.This approach may not be valid for bitches because
es may have abnormal serum phosphorus concentrations (either eclampsia and the highest calcium losses generally do not occur
hypophosphatemia or hyperphosphatemia). Further study is need- immediately after whelping.
ed about the role of other serum biochemical abnormalities in the
clinical signs of eclampsia. The incorporation of magnesium into The Bibliography for Box 15-2 can be found at
the treatment and prevention of the disorder should be evaluated. www.markmorris.org.
Hypocalcemia leads to increased neuromuscular irritability

density of 4 kcal ME/g (16.7 kJ/g) or higher have more fat and Other Nutritional Factors
less fiber. Fat is typically highly digestible; fiber is poorly In addition to the key nutritional factors for commercial foods
digestible. Thus, high-fat, low-fiber foods are usually more discussed above, the following nutritional factors are highlight-
digestible. ed because they are of particular concern for homemade foods