Chapter 2 Therapeutics and Routine Procedures
VENIPUNCTURE
The jugular vein is the major vein used to administer large volumes of intravenous (IV) fluids in dairy cattle. The middle caudal vein (“tail vein”) is used for collection of blood samples and for administration of small volumes (less than 5.0 ml) of medications. If the tail vein is used for drug administration, only aqueous agents that will be nonirritating (should they leak perivascularly) should be used because it is harder to avoid some degree of leakage at this location than when a well-seated needle is used in the jugular vein. The mammary vein should not be used for either blood sampling or drug administration because complications of mammary venipuncture may have disastrous results, such as mammary vein thrombosis or phlebitis (see Figures 3-20 and 3-21), persistent unilateral mammary edema, and endocarditis. In general, it is contraindicated to use the mammary vein therapeutically unless the cow has a life-threatening illness and is in a compromised position, such that the jugular vein is inaccessible. Cattle with bilateral jugular vein thrombosis also may necessitate the risk of mammary vein venipuncture. In severely dehydrated calves, it is necessary occasionally to use a cephalic or dorsal metatarsal vein should the jugular veins become thrombosed during repeated fluid administration. Before any venipuncture, the overlying skin and hair should be moistened and smoothed down with alcohol. The vein should be “held off” by applying digital pressure proximal to the heart from the site of venipuncture (Figure 2-1). Neophytes seldom apply pressure of sufficient magnitude or duration before venipuncture and consequently have difficulty palpating or viewing the distended vein. Experienced clinicians are very patient and allow the vein adequate time to fill with blood, making venipuncture easier. Choke ropes or chains seldom are necessary in routine jugular venipuncture but may be helpful in extremely dehydrated patients. Utilizing gravity by allowing the head to hang over the side of a raised platform or table or even by hanging the calf over a stall divider or gate can distend the jugular vein significantly to facilitate venous access in very dehydrated calves. Commercial instruments such as Witte’s neck chain and Schecker’s vein clamp are available aids used in Europe.
Jugular venipuncture may be performed with a variety of needles, but the needle must be suited to the drug’s viscosity, volume, and the duration of time anticipated for delivery. Stainless steel 14-gauge needles that are 5.0 to 7.5 cm in length are favored for most fluid infusions that do not exceed 2 to 4 L and that are to be administered promptly. Although many practitioners use disposable 14-gauge needles that are 3.75 cm in length, these needles are too short and so sharp that, with minimal patient struggling, such complications as laceration of the intima of the vein or perivascular administration of medications may occur. These shorter, disposable needles are acceptable for recumbent or extremely well-restrained cattle only. In general, venous complications such as thrombosis and perivascular injections are more common with the shorter needles. The longer 5.0- to 7.5-cm stainless steel needles are long enough to remain well positioned within the vein, are less sharp and therefore less likely to lacerate the intima of the vein and thus tend to cause less frustration to the practitioner faced with an unruly patient. The disadvantage of stainless steel 14-gauge needles is that they require cleaning, sterilization between uses, and periodic sharpening with an Arkansas stone. Cleaning and sterilization between uses are extremely important in preventing spread of bovine leukemia virus (BLV) and bacterial infections. Although most practitioners prefer 14-gauge needles, some practitioners successfully use 12-gauge, 5.0- to 7.5-cm stainless steel needles to allow an even more rapid administration of solutions such as dextrose and balanced electrolytes through the jugular vein. Careful pressure over the venipuncture site following removal of the needle is important in preventing hematoma formation, which may contribute to venous thrombosis.
Selection of appropriate needles for intramuscular (IM) injections in cattle requires consideration of density or viscosity of the drug to be administered, size of the patient, and desired depth of injection. Needles of too narrow bore prolong the time necessary for injection, often causing increased patient apprehension, struggling, or kicking. Needles too large of bore allow leakage of the administered drug from the site and cause more bleeding. Most aqueous-based drugs can be administered IM via an 18-gauge, 3.75-cm needle in adult cattle, whereas injection of oil-based or more viscous drugs (e.g., penicillin, oxytetracycline HCL) is facilitated by a 16-gauge, 3.75-cm needle. Most practitioners use disposable needles for IM injections to avoid the bothersome task of cleaning and sterilizing used needles. Increasing concerns regarding carcass spoilage as a result of the IM administration of therapeutic and biologic agents in grade dairy cattle have prompted a move toward subcutaneous administration of many products (antibiotics, hormones) that were previously given IM. Carcass trimming with subsequent lost revenue from meat is a relevant issue because the slaughter value of a culled dairy cow represents a significant revenue stream for many modern producers.
The primary site for IM injections in cattle is the caudal thigh muscles, especially the semimembranosus and semitendinosus. Occasionally the caudal biceps femoris is used as well (Figure 2-3). The gluteal region should not be used for IM injections in calves or adult dairy cattle because of the relative lack of musculature in a “dairy-type” animal. Injections in this area risk temporary or permanent injury to the sciatic nerve branches traversing the gluteal region when repeated IM injections or an IM injection of irritating drugs is necessary. Gluteal injections are especially contraindicated in dairy calves (Figure 2-4). Although many textbooks and publications advocate IM injections in the gluteal regions, this procedure should be avoided in dairy cattle.

Figure 2-4 Sciatic nerve injury secondary to intramuscular injection in the gluteal region of a Holstein calf.
Selecting a clean site (free of manure and moisture) and swabbing it with 70% alcohol should precede IM injections. The needle is held by the hub between the thumb and forefinger, and the cow is slapped repeatedly with the back of the clinician’s hand near the site of the injection. Quickly rotating the hand, the clinician then slaps the needle into the selected IM site. The needle must be submerged all the way to its hub. A visual inspection for blood coming from the needle is made, and if none is seen, the syringe of medication is quickly attached to the needle. Aspiration on the syringe plunger will detect needles placed within vessels. If blood is aspirated, the injection is aborted, and the needle should be placed at a different site. If no blood is observed, the injection is made as quickly as possible. Up to 20 ml of drug may be deposited at an IM site in an adult cow, but probably no more than 5 ml should be placed at any one site in a young calf. Consideration of the drug’s irritability to tissue may also influence specific volumes deposited at IM sites.
In adult dairy cattle, a needle at least 5.0 cm in length would be necessary for intraperitoneal injection, and risks of damage to viscera are minimized by rolling a recumbent cow to her left side before puncturing the right paralumbar fossa.
Complications of jugular IV injections include hematoma formation, thrombosis, thrombophlebitis, perivascular injections of irritating drugs, endocarditis, and Horner’s syndrome (see Chapter 3, Figures 3-19 and 3-5). The most irritating and dangerous drugs commonly administered IV in cattle are 40 to 50% dextrose, 20% sodium iodide, and calcium. Avoiding perivascular deposition of these three drugs is extremely important. Good technique and adequate restraint are the keys to avoiding complications from IV injections.

Figure 2-8 Complete sloughing of the tail in a Holstein cow following perivascular injection of phenylbutazone.
Complications of IM injections include tissue necrosis with subsequent lameness; peripheral nerve injury, especially sciatic nerve branches in the gluteal region or tibial branches in the caudal thigh muscles of calves; clostridial myositis; and procaine reactions. Peripheral nerve injury can be prevented best by avoiding the gluteal region when performing IM injections. In calves, palpation of the groove separating the biceps femoris and semitendinosus proximal to the stifle and injecting medial or lateral to this groove will help avoid sciatic nerve injury. Clostridial myositis is always a risk when injecting irritating drugs that may create a focal area of tissue necrosis and subsequent anaerobic environment in the IM site. Although Clostridium chauvoei (blackleg) spores may be in tissue locations already, most clostridial myositis secondary to IM injections is caused by Clostridium perfringens or Clostridium septicum. Currently prostaglandin solutions are the most commonly incriminated solutions to result in clostridial myositis (see Chapter 15, Figures 15-1 and 15-2). Using sterile syringes, sterile needles, and avoiding contamination of multidose drug vials are important preventive measures. In addition, IM injections should not be made through skin covered by dirt or manure without first cleaning the site.
Various cannulas and commercial mastitis tubes are available for intramammary infusions. Individual sterile plastic cannulas (2-cm) with syringe adapters are used most commonly for infusion of noncommercial mastitis products, whereas stainless steel 14-gauge, 5.0-10-cm blunt-tip teat cannulas are sometimes used to facilitate milk-out from injured teats or for diagnostic probing of obstructed teats.
STOMACH TUBES
A variety of stomach tubes are available. For cattle, a tube should have some flexibility, and the flexibility should be adjustable by temperature so that either warm or cold water can be used to add flexibility or add rigidity, respectively. Tubes that are too soft and flexible will double back during passage, whereas tubes that are completely inflexible risk iatrogenic injury to the pharynx, soft palate, or esophagus. Stomach tubes for adult cattle should have at least ¾-inch outside diameter (1.88 cm) to speed delivery of medications or evacuation of gas (Figure 2-12). Tubes of smaller diameter plug with rumen digesta too easily. Larger tubes, up to the “ultimate tube”—the Kingman—require excellent patient restraint, an appropriate gag or speculum, lubrication of the tube, and appropriate head position of the patient (Figure 2-13).
The increasingly common practice of routine or therapeutic drenching of periparturient and postparturient cattle has led to the widespread use of the McGrath pump (Figure 2-14) on modern dairies. This apparatus has the advantage of only requiring one person to position and then administer the fluids because it is maintained in place by a built-in set of nose tongs. Veterinarians should not hesitate to train laypeople in the proper restraint, positioning, and administration techniques when using this or any other stomach tube/oral drenching device because inadvertent aspiration and drowning are tragic but occasional consequences of their use by unqualified or poorly trained personnel.
ESOPHAGEAL FEEDERS
Popular for delivery of colostrum or electrolyte solutions to newborn or young calves, esophageal feeder devices are potentially dangerous when used by impatient or poorly trained laypeople. Pharyngeal and esophageal lacerations are all too common iatrogenic complications, and inhalation pneumonia is a less common complication. Laypeople should only be allowed to use these devices following training by a veterinarian. Proper disinfection of esophageal feeders that have been used to administer colostrum, milk replacer, or electrolyte solution is an important preventative measure in the control of infectious enteric disease in calves.
GENERAL PRINCIPLES FOR ADMINISTRATION OF ORAL MEDICATIONS
Once securely positioned, the operator exerts pressure on the patient’s hard palate using the hand that is holding the cow. This gentle pressure causes the patient’s mouth to open and allows medications or devices to be positioned. Common errors to be avoided during oral medication procedures include:
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