Critical Review of the LSD SOP Recommended for Field Veterinarians in Maharashtra
Dr Abdul Samad, M.V.Sc., Ph. D. (Canada) Former Dean, Faculty of Veterinary Sciences, MAFSU
Many veterinarians have been calling me to know the line of treatment in LSD, especially, in the serious cases suffering from generalized and brisket oedema, respiratory complications and recumbency. Based on their queries, I have written this blog to remove common myths and doubts.
Choice of antibiotics:
The vets have been enquiring if antibiotics can be used, and if yes, preferred one. If secondary infection is suspected, antibiotic can be used, preferably the one which has better diffusion in pulmonary, soft tissues and skin. My vote goes to levofloxacin injection. As a follow up trimethoprim sulpha can be used, since these are absorbed in ruminants when given by oral route.
Ivermectin as an antiviral drug-
The veterinary friends have been asking me if ivermectin could be useful as antiviral therapy. There is no report in the literature to support using of this drug in LSD, except one paper, wherein its efficacy was studied in the vitro model. Such a claim was also made during the early phase of COVID outbreak. But later, even WHO retracted the recommendations due to lack of convincing scientific evidence. Most of the papers published have described efficacy of ivermectin in RNA viral diseases, whereas, LSD is caused by a DNA virus. In my opinion, specific DNA antiviral drug could be of immense help, which I will be describing in my next blog.
Antihistamine and anti-inflammatory:
A common question asked is whether chlorphenamine malleate and NSAID should be prescribed. It must be understood that in case of LSD (and other pox diseases) the inflammation mediators do not belong to COX2-pathway and not associated with histamine release. To be specific, the published research shows that the mediators belong to kinin, coagulation factors, complement cascade, fibrinolytic systems and catabolic pathways of arachidonic acid. Hence, antihistamines and NSAID would not be of any specific help. On the contrary, in LSD, such drugs should be avoided because the inflammatory response in combination with host defence responses are essential for recovery from systemic infection recovery.
1 A recent study also suggested that inflammatory process, in combination with immune T cells, is required to slow the progression of disease to clear the virus infection. Administration of anti-inflammatory COX2 inhibitors, therefore, may interfere in virus clearance and delay recovery. I am of opinion that the clinician should administer antipyretic only when fever is very high and causing serious discomfort to the animal. For this, my choice will be restricted to administration of paracetamol injection
(iv) followed by oral, for 2-3 days, twice a day.
Herbal Hepato-protectant:
The available evidence does not support hepatic function compromise. The post-mortem lesions described in the literature are: extensive greyish-pink skin nodules with caseous necrotic centres, similar nodules in the nasopharynx, trachea, bronchi, lungs, rumen, abomasum, renal cortex, testicles and uterus; swollen and congested lymph nodes with petechial haemorrhages
- There are no specific references pointing out liver lesions3. show that I am always amused when the term liver tonic is used in allopathy stream. Stability of active principles of herbs in rumen environment is also a grey area. On the contrary, it is basic rumen physiology that, except the fat, most of the plant biochemicals are broken down into elemental forms to become part of the rumen microbial mass. Injection Dexamethasone:
Another question asked is if dexamethasone in tapering doses would be useful, especially in complicated cases of LSD. First, ensuring tapering dose regimen is not a feasible option as the tapering requires one week protocol, and logistically a vet cannot visit an animal daily, in the face of wide-spread outbreak. Moreover, dexamethasone is also an immuno-suppressive drug which may accentuate suppression further.
Magnesium sulphate-glycerine paste:
Last night a field vet called me to know if he can apply magnesium-glycerine paste to alleviate brisket oedema. Application of magnesium sulphate-glycerine paste is useful only in inflammatory swelling, such as, phlebitis due to extravasation of irritant drugs / fluids and muscle rigidity. In LSD, brisket oedema is non-inflammatory, caused due to pulmonary arterial hypertension (PAH). The primary cause is extensive pulmonary oedema, leading to right heart failure and accumulation of fluid in the brisket and other body regions. Hence such a paste might give local soothing effect but not relive oedema. In such cases, medication to improve cardiac output would be a scientific option.
Fluid therapy:
The SOP has recommended administration of fluids, in complicated cases, with a rider that it should not be used in animals having oedema and respiratory distress. In fact, involvement of lungs and heart, and resulting oedema are present in almost all such cases. Injecting 25% dextrose as source of energy is also misleading, as once the glucose is metabolized, the net water load would further increase. It is necessary to pursue other strategies to support glucose supply to stimulate metabolic functions. Except as a diluent to drugs, fluid administration in complicated cases of LSD should be avoided, except when there is dehydration die to lack of water intake.
Diuretic:
A question was also raised whether instead of Lasix, mannitol (20%) injection can be used as a diuretic to relieve oedema. The scientific literature on mannitol is very clear; being an osmotic diuretic, it is indicated only in acute renal failure, cerebral oedema and glaucoma. It is not a diuretic of choice when oedema is due to right heart function compromise.
Bromelain and serratiopeptidase:
These enzymes have fibrinolytic, antioedematous, antithrombotic, and anti-inflammatory activities. In human, when bromelain is given orally, only 40% is absorbed through the intestine. I could not find any reference to prove their stability in rumen or rumen-bypass effect. I would therefore refrain from using anything non-specific for avoiding increase in the cost of treatment. However, bromelain, has been used as a premix in dairy feed to pre-digest proteins by breaking the peptide bonds making it easier for intestine to absorb nutrients
- Methylene blue (MB) as adjunct therapy: There was also a reference to the GoI advisory on using methylene blue orally as antiviral in LSD. There are reports on use of MB in Zica and COVID viral infections, both RNA viruses. Intravenous MB in is commonly used in nitrate poisoning, but I could not find if it is absorbed when given orally to ruminants. The United States Pharmacopeial Convention (2008) has documented methylene blue (veterinary- systemic- 5), which is silent on oral bioavailability of methylene blue and describes intravenous case studies. Please do share your feedback on my email- drasamad11@gmail.com. In next blog I will share my LSD protocol.
Reference:
1.Mark and Palumbo, 1991, Microbiol. Rev., 55: 80-122)
2 Tuppurainen, E., Alexandrov, T. & Beltrán-Alcrudo, D. 2017. Lumpy skin disease field manual –FAO Animal Production and Health Manual No. 20
3 Lumpy Skin Disease, New South Wales, Australia,
4 www ultrezenzymes.com
5.https://cdn.ymaws.com/www.aavpt.org/resource/resmgr/imported/methyleneBlue.pdf
