Miscellaneous Treatments/Medicine

L-lysine Treatment for Cats Infected with FHV-1

Efficacy of oral supplementation with L-lysine in cats latently infected with feline herpesvirus
Maggs et al. of the College of Veterinary Medicine, University of Missouri examined the effects of orally administered L-lysine on clinical signs of feline herpesvirus type 1 (FHV-1) infection and ocular shedding of FHV-1 in latently infected cats. Fewer cats and eyes were affected by conjunctivitis, and onset of clinical signs of infection was delayed on average by 7 days in cats receiving L-lysine 400 mg once daily for 30 days, compared with cats in the control group. Significantly fewer viral shedding episodes were identified in the treatment group cats, compared with the control group cats. This dose caused a significant but short-term increase in plasma L-lysine concentration without altering plasma arginine concentration or inducing adverse clinical effects.

Am J Vet Res 2003 Jan;64(1):37-42

Dextromethorphan

 Of the seven major human cough suppressants, only dextromethorphan is indicated for treating cough in small animals. If after reviewing the indications and contraindications, cough suppression is desired, the available human products must be screened carefully as a very limited number contain dextromethorphan without other potentially harmful ingredients. Typically, the dose in dogs and cats is 1 to 2 mg/kg three to four times daily. Human products are not flavored to an animal’s taste, and may require administering a significant volume (typical strength is 15 mg/5 ml) to adequately dose an average size dog.

Stool Softeners

Docusate (DSS) can be used to assist in the passage of hard or dry feces that may occur secondary to dehydration or use of opioid analgesics or metoclopramide. While capsules hide the bitter taste, they can not be divided for appropriate dosing in smaller animals. The recommended dose in dogs and cats is 2 mg/kg once daily. For more severe cases, appropriately dosed DSS enemas may offer an alternative to phosphate-solution enemas.

Merck Veterinary Manual, 8th Edition, pp. 1691

Ursodiol for Gallstones

The purpose of this study, reported in Am J Health-Syst Pharm (Vol. 52) was to prepare an oral dosage form of the bile acid ursodiol (also known as ursodeoxycholic acid) from commercially available capsules and to determine the short-term stability of this formulation.  The formula used for this extemporaneous compound was found to be stable for up to 35 days.

Ursodiol in a Dog with Chronic Hepatitis

 A dog with severe cholestasis secondary to chronic hepatitis was treated with ursodeoxycholic acid (ursodiol) orally. After 2 weeks of daily treatment, the dog was more active and had an improved appetite. Monthly serum biochemical determinations and analysis of individual bile acid profiles documented improvement in hepatobiliary tests and a marked reduction in the concentrations of potentially hepatotoxic endogenous bile acids. These effects were maintained for approximately 6 months.

J Vet Intern Med 1997 May-Jun;11(3):195-7

Studies have found an extemporaneously compounded ursodiol suspension to be stable for up to 35 days refrigerated. This drug is well absorbed orally and enters the liver directly from the portal system, and is then secreted into bile. Ursodiol should be administered orally as the first-pass effect is vital for effectiveness.

Aminocaproic Acid for Degenerative Myelopathy (DM) in Dogs

DM appears with relative frequency only in the German Shepherd breed (GSD); confirmation of the diagnosis is important in other breeds before assuming that they have DM of GSD. During the past two decades, R.M. Clemmons, DVM, Ph.D., and other researchers at the University of Florida have provided important new insights into the pathoetiology of DM. Recently, they have found that when combined with the history, neurologic signs, CSF protein concentration and EMG, an elevated CSF acetylcholinesterase level helps confirm the diagnosis. It is increasingly clear that DM is caused by an autoimmune disease attacking the nervous systems of patients, leading to progressive neural tissue damage. In many respects, DM is similar to Multiple Sclerosis in human beings.

The Integrative Medical Approach to Treatment of Degenerative Myelopathy involves four basic approaches:

1. exercise
2. dietary supplementation
3. medication
4. other supportive measures

Conventional medicine has little to offer patients with DM. On the other hand, use of exercise, certain vitamins and selected drugs have delayed or prevented progression of DM in many afflicted dogs.

Clemmons et al have found 2 medications which appear to prevent progression or result in clinical remission of DM in up to 80% of patients – aminocaproic acid (EACA) and n-acetylcysteine (NAC). They propose that circulating immune-complexes lead to endothelial cell damage in the vessels of the CNS. Subsequently, fibrin is deposited in the perivascular spaces. When this degrades (point of action of aminocaproic acid), inflammatory cells are stimulated to migrate into the lesions. The inflammatory cells release prostaglandins and cytokines (point of action of vitamin E and C) which lead to the activation of tissue enzymes and the formation of oxygen free-radicals (point of action of acetylcysteine) which, in turn, leads to tissue damage.They recommend giving EACA as a flavored solution, 500 mg orally every 8 hours. A “source for EACA is to have a compounding pharmacy make the solution from chemical grade EACA.”  The only side effects that have been attributed to EACA have been occasional gastrointestinal irritation. This has presented a problem only in a few patients, typically those with pre-existing GI problems. The only known drug interaction is with high dose estrogen compounds.

N-Acetylcysteine is a potent anti-oxidant which has powerful neuroprotective effects. Clemmons et al give 75 mg/kg divided in 3 doses a day for 2 weeks; then, 3 doses every other day. The N-acetylcysteine must be diluted to a 5% solution; otherwise, it will cause stomach upset. “This new treatment is expensive unless purchased through compounding pharmacies.” NAC can produce vomiting (due to the sodium content of the pharmaceutical product, which requires high concentration of base to buffer) and may increase the bleeding time. Giving fresh ginger 30 minutes before NAC or administering NAC with food (or on a full stomach) often reduces this effect.

The chances of successful treatment are improved if the therapy is begun early in the course of DM rather than later. A response to the drugs should be evident within the first 7-10 days.

Chlorpromazine for Anti-Emesis

Chlorpromazine (Thorazine®) is a phenothiazine and works at the emetic center, the chemoreceptor trigger zone, and peripheral receptors; it is this veterinarian’s “all purpose anti-emetic of choice” for cats.1 Chlorpromazine may cause extrapyramidal symptoms in cats when administered at high doses. The drug may discolor urine pink or red-brown, cause mild sedation, and may potentiate hypotension in dehydrated patients. Phenothiazines should not be given within one month of worming with an organophosphate agent. The recommended oral doses in dogs and cats is 3.3 mg/kg PO one to four times daily. Due to extensive first pass metabolism2, it may be necessary to reduce the dose in animals with liver disease. A liquid concentrate can be appropriately flavored for dogs or cats.

Todd R. Tams, DVM, Dip ACVIM in CA VMA C/E Conf Procd, 2000
Veterinary Drug Handbook 3rd edition, Donald C. Plumb, ed.;  pp. 129-30

Managing Anorexia in Uremic Dogs and Cats

H2-receptor antagonists (cimetidine, ranitidine, and famotidine) can be useful to reduce gastric acid secretion. Increased gastrin concentrations in serum during chronic renal failure may stimulate excessive secretion of gastric acid and cause ulcer formation. Some uremic dogs and cats dramatically increase their interest in food and food intake after therapy with an H2 blocker. According to a presentation at the Atlantic Coast Veterinary Conference by Dennis J. Chew, DVM, Dip and C.A. Buffington, DVM, some uremic animals may need this medication for an extended period of time (months to rest of their lives). Much of the experience of these veterinarians has been either with cimetidine at an initial dose of 10 mg/kg, followed by 5 mg/kg PO BID or famotidine at 1 mg/kg daily.

The Capsule Report, Vol. 19, No. 10, Jan. 2001

Doxycycline for Prophylaxis and Treatment of Osteoarthritis in Dogs

Prophylactic administration of doxycycline (a tetracycline) has markedly reduced the severity of canine osteoarthritis (OA) in weight-bearing regions of the medial femoral condyle, and therapeutic administration of oral doxycycline has been shown to reduce the severity of articular cartilage breakdown in various animal models of OA. This disease modifying effect is associated with reductions in the levels of active and total collagenase and gelatinase in articular cartilage of the involved joint.

A prospective, clinical study of eighty-one dogs with OA secondary to spontaneous cranial cruciate ligament (CCL) rupture concluded that doxycycline inhibits nitric oxide production in cartilage in dogs with CCL rupture, and that doxycycline may have a role in the treatment of canine OA. Dogs with OA secondary to CCL rupture were divided into 2 groups before surgery. The Doxy-CCL group (n = 35) received 3 to 4 mg/kg doxycycline orally every 24 hours for 7 to 10 days. The CCL group (n = 46) received no treatment. Synovial fluid, articular cartilage, synovial membrane, and CCL samples were collected during surgery or immediately after euthanasia from healthy dogs (control group). Total nitric oxide concentrations measured in cartilage were significantly lower in the Doxy-CCL group than in the CCL group, but were not different from those measured in the control group.

In another study, ten healthy adult mongrel dogs underwent transection of the left anterior cruciate ligament, which resulted in a marked decrease in bone mass, with increased osteoclastic activity and increased bone formation. Doxycycline treatment did not significantly affect either bone formation or bone resorption. The authors concluded that doxycycline protects against joint breakdown in this OA model via inhibition of matrix metalloproteinases in articular cartilage, rather than through an effect on subchondral bone.

Vet Surg 2001 Mar-Apr;30(2):132-9
J Rheumatol 1996 Jan;23(1):137-42
J Rheumatol Suppl 1995 Feb;43:149-51
Vet Clin North Am Small Anim Pract 1997 Jul;27(4):863-81
Arthritis Rheum 1992 Oct;35(10):1150-9

Cisapride: A Prokinetic Drug

Cisapride (Propulsid® – Janssen Pharmaceutica), was removed from the U.S. and Canadian markets by its manufacturer because of serious cardiac effects in humans. However, cisapride is now available as a bulk chemical for veterinary use only and can be compounded as per your prescription order.

Cisapride is chemically related to metoclopramide, but unlike metoclopramide, it does not cross the blood-brain barrier or have antidopaminergic effects or cause extrapyramidal reactions. Cisapride “is more potent and has broader prokinetic activity than metoclopramide, increasing the motility of the colon, esophagus (in cats and guinea pigs), stomach, and small intestine… [Cisapride] has been used in managing gastric stasis, idiopathic constipation, gastroesophageal reflux, and postoperative ileus in dogs and cats. Practitioners found cisapride especially useful in managing chronic constipation in cats with megacolon; in many cases, it alleviated or delayed the need for subtotal colectomy. Cisapride was also used in managing cats with hairball problems.”
“Cisapride appeared to be well tolerated by dogs and cats. Adverse reactions to cisapride have not been reported to the United States Pharmacopeia’s Veterinary Practitioners’ Reporting Program… Disorders of GI motility are common and frustrating clinical problems in dogs and cats. Cisapride, with its extensive prokinetic action, was a welcome addition to veterinary medicine.”

Veterinary Medicine, September 2000, pp. 678-685

Doses for Dogs: as a promotility agent: initially 0.5mg/kg three times daily To reduce regurgitation associated with megaesophagus: 0.55mg/kg; orally one to three times daily, no less than 30 minutes before feeding; As an antiemetic: 0.1-0.5mg/kg orally every 8 hours.

Doses for Cats: for chronic constipation: initially, 2.5mg for cats up to 10#; 5mg for cats 11-15#; up to 7.5mg for cats over 16# three times daily, 30 minutes before food, in combination with stool softener and bulk agent.

Cisapride is contraindicated in patients in whom increased GI motility could be harmful (e.g., perforation, obstruction, GI hemorrhage). Absorption of other orally-administered drugs may be affected. Cisapride may enhance anticoagulants’ effects; additional monitoring and anticoagulant dosage adjustments may be required. Cisapride may enhance the sedative effects of benzodiazepines. Clients should be advised to monitor the animal and report any adverse effects.

Veterinary Drug Handbook, 3rd edition, Donald C. Plumb, editor. pp. 139-140

Hairball Remedy

Cat and ferret owners continually search for specialized foods and treats that their pets will readily consume and will also be effective for hairball prevention or elimination. Call us for a customized, flavored hairball remedy for your patients!

Stanozolol

In a study conducted at the Animal Health Unit and Gastrointestinal Sciences, University of Calgary, Alberta, ten healthy, intact, adult male sled dogs received either stanozolol tablets, 2 mg/dog PO, q12h, for 25 days or an intramuscular injection of stanozolol 25 mg on Days 7, 14, 21, and 28. A 15N amino acid (5.27 mmol) was infused intravenously into each dog on Day 0 (before stanozolol treatment) and on Day 31 (after stanozolol treatment). Both oral and injectable stanozolol resulted in significant increases in amino acid nitrogen retention compared to pretreatment values. Oral stanozolol increased nitrogen retention from 29.2 +/-8.2% to 50.3 +/- 9.2%, while stanozolol injection increased nitrogen retention from 26.6 +/- 9.9% to 67.0 +/- 7.5%. The nitrogen retention action of stanozolol may be beneficial in dogs under stress of surgical trauma and chronic disease.

In a separate blinded crossover trial at the College of Veterinary Medicine, Kansas State University, 22 castrated Beagles with experimentally induced chronic renal failure were treated with stanozolol. Cowan et al. concluded that for dogs with mild-to-moderate, nonuremic, experimentally induced, chronic renal failure, stanozolol had positive effects on nitrogen balance and lean body mass. Stanozolol did not have a significant effect on body fat, bone mineral content, or food consumption per kilogram of body weight.

Anabolic steroids such as stanozolol have been used to treat geriatric dogs. These drugs can increase nitrogen and mineral retention so that the body can better utilize dietary protein. As a result, the dog’s appetite may improve, resulting in more strength, energy, and weight gain. There is one reported case of the use of stanozolol (0.5 mg/kg, SQ, BID, PRN) to stimulate appetite in a rabbit. However, this class of drugs is not without potentially serious side-effects which must be considered before using them. Anabolic steroids should be used with caution in animals with heart, liver, or kidney problems, or in animals with breast or prostate cancer. Stanozolol should not be used in pregnant animals, during lactation, in young animals, or in male breeding animals. Anabolic steroids may increase the effects of warfarin and other anticoagulants.

In dogs, reported side effects are mainly androgenic, including increased aggression, increased activity, weight gain and mood alterations. However, in cats with and without chronic renal failure, there are reported cases of hepatotoxicity that appear to be related to the use of stanozolol.

J Am Vet Med Assoc. 1997 Sep 15;211(6):719-22
Can J Vet Res. 2000 Oct;64(4):246-8
Veterinary Forum. April 1999