2 Pathogenesis and Clinical Findings

Transcript

Hello vets,

Now we are on a second lesson, so in the previous class we saw about the Introduction of Hypercalcemia and How does it occur and the Various Risk factors involved, and the Economic Importance of Hypoglycemia.

Today in this class we are going to see about the Pathogenesis and Clinical signs of Hypercalcemia.

In the Clinical signs, we are going to see about different stages of Hypercalcemia; stage-1, stage-2, and stage-3.

Actually, Calcium is required mainly for membrane stability, that is the nerve cell membrane stability and contractility of the skeletal and smooth muscle and the release of acetylcholine at a neuromuscular junction, thus it aids in the contractility of all muscles.

So what happens if there is Hypocalcemia that is <8mg/per deciliter and this nerve cell membrane becomes stabilities get altered and there will be severe irritability, so always if you used to see excitatory signs due to loss of dysfunction, so the animal becomes there is an increased twitching of a group of muscles called Fasciculation on the shoulder and the head muscles, and there will be mild titanium, that is the animal will have a disinclination to move, and there is the twitching of muscle and there there is bruxism.

So all these signs are mainly due to decreased membrane stability, and this Hypocalcemia causes loss of muscular contractility in both the skeletal and smooth muscle, then what happens to contractility muscle that is flaccid paresis that is why the animal becomes recumbent. and Smooth muscle loss of smooth muscle contractility, so all the smooth muscles get involved in cardiac muscle, so there is a loss of cardiac contractility, so cardiac output decreases.

And vascular smooth muscle loss of tonicity or contractility leads to vasodilation, so ultimately there is hypotension, which is the major pathognomic sign in Hypocalcemia.

Apart from that, there is reduced rumen motility and intestinal contraction, that’s why you are getting scanty feces and the bloat.

And there is a decreased release of acetylcholine, so there is a reduced neurotransmitter secretion at various levels, mainly you can see pupillary dilatation as a cause of reduced acetylcholine release.

There is a certain correlation between serum calcium level and the occurrence of clinical signs, So normal animals you can say it will be 8 to 10.5 milligram/deciliter and in mild Hypocalcemia, sub-clinical Hypocalcemia is very common and there will be a mild reduction in a calcium level like 7.5 milligram/deciliter and there will be reduced mild reduction in milk yield and rumen activity and reduced appetite. Only certain changes are absorbed.

And in Clinical Hypocalcemia to occur the value will be <6 or as low as 2 milligrams also can be recorded. So accordingly the animals may you may get a stage-1, stage-2, and stage-3 from standing to the sternum to lateral recumbency.

But strictly speaking, there is no exact positive correlation between the level of Calcium and Clinical sign occurrence, but however, the ionized calcium level is playing a major role in may influence the occurrence of Clinical signs.

Hypercalcemia is classified as stage-1, stage-2, and stage-3.

Stage-1; is a standing posture, so the animal still is able to stand but it is unable to walk mind the titanium signs, so the calcium values are it can range from 4.9 to 7.5 and

Stage-2;  it’s a severe form, there is severe muscle flaccidity, now the animal becomes recumbent, so it is sternal recumbency and

still severe form is

Stage-3; it  is complete there is flaccidity of all muscles, animals become lateral recumbency, and there is a reduced cardiac output, and the animal is mostly comatose

So this is the classical form of Hypercalcemia of Stage-1, it’s a Stage of Excitement as I already explained due to that is a nerve cell membrane instability.  So, in this stage, if the animals are treated at Stage-1, you can avoid there is they may not go for sternal or lateral recumbency.

So the classical signs of Stage-1(Stage of Excitement ) are :

• still the animal standing,
• but it has mild titanium signs,
• so it is a disinclination to move,
• disinflation to food, and there will be otherwise the temperature pulse and other normal or
• due to this muscle’s increased contractility, there will be that is a stiffening of muscle, an increase in temperature, and
• there will be grinding of teeth and
• protrusion of tongue
• reduced rumen activity
• the volume of dung voided also less and this is the classical form of stage-1 milk fever.
• another important sign at this stage is Fasciculation, which is the twitching of a group of muscles, especially on the shoulder and neck muscles and the head.

Stage-2(Sternal Recumbency): is a severe form of Hypocalcemia the animals are on Sternal Recumbency. In these animals there will be;

• pupillary dilatation,
• reduced rumen activity, and
• reaction reflux, so it will have bloat
• scanty feces
• the temperature may be normal as abnormal temperature due to reduced cardiac output
• peripheral circulatory failure pupillary dilatation and
• here the heart rate is more than is tachycardia but even then you are unable to auscultate that is a weak cardiac contraction, so it’s very difficult to hear the cardiac sounds
• likewise, the pulse is also rapid, but it is very weak
• another important sign at a field level you can see there it’s very difficult to raise the jugular vein, which is the classical sign due to loss of vascular tonicity.

In this the class we are seeing about :

• the Pathogenesis of Hypercalcemia is how the nerve cell membrane gets affected and
• the loss of acetylcholine release, and
• the reduced contractility of musculature both skeletal and smooth muscle and
• the various stages of milk fever-like –

stage-1 standing posture and

stage 2 sternal recumbency.

So, see you in the next class.

Thank you!